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Rec.Bicycles Frequently Asked Questions Posting Part 4/5

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Archive-name: bicycles-faq/part4

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Subject: 8f.5 Cassette or Freewheel Hubs take 2 From: David Keppel <pardo@cs.washington.edu> People often ask ``should I use a freewheel or a freehub?'' The answer is usually ``yes.'' The hub is the center of a wheel and is composed of an axle, bolted to the bike frame, a hub shell or hub body, where the spokes attatch, and bearings to let the shell rotate around the axle. Freewheels screw onto threads on the rear hub's shell, and cogs attatch to the freewheel. The freewheel's job is to provide a ratchet between the cogs and the hub shell, so that you can coast. Freehubs are similar but combine parts of the freewheel with parts of the hub shell. Freehubs are also sometimes called ``cassettes''. The usual problem with rear hubs is that axles bend and break. This is because the axle diameter was chosen when single cogs were used and the hub bearing was positioned close to the frame. Since then, wider cog clusters have become the norm, the bearings and frame have moved further apart and leverage on the axle has increased. But since the axle has not gotten any stronger, it now has a tendency to fail. Cassettes fix the problem by incorporating one hub bearing in to the freewheel mechanism, so that the bearing is once again outboard and the axle is carrying its load under less leverage. Some freewheel hubs solve the problem by using fatter axles. Since increasing the axle diameter dramatically improves axle strength, this is an effective solution and it is possible to use a fat axle that is aluminum and thus lighter than a standard skinny (weaker) steel axle. Neither solution is perfect -- cassette hubs let you use standard replacement axles, cones, washers, etc., but force you to use cogs and spacers and whatnot by a particular manufacturer (and possibly derailleurs and shifters -- e.g. XTR uses 4.9mm cog-to-cog spacing instead of the normal 5.0mm). On the other hand, fat axles are nonstandard as are some other replacement parts. As an aside, the cassette solution leaves a fairly long unsupported axle stub on the left side, and this is sometimes a source of more bending problems. Fatter axles solve the problem on both sides. Note also that many cassette systems allow you to remove the cogs using a lightweight tool and thus give you ready access to the spokes in case of breakage. Freewheels attatch with a fine thread (another historical artifact, I believe) and are thus more difficult to remove on the road, making spoke replacement harder. In principle, freehubs have all cogs attatch using the same size and shape of spline, so, e.g., a 20T cog can be used as both a large cog for a corncob cluster and as a middle cog for wide-range cluster. However, Shimano's marketing is just the opposite and is directed at selling whole clusters, without letting you replace individual cogs. (Shimano's policy is relevant here since they sell 90+% of such hubs.) Freewheels have several spline diameters in order to clear the bearings and ratchet. Further, small cogs typically screw on to the freewheel body or special cogs with extra threads. This introduces stocking problems and may make it hard to build some cog combinations. I'm not a fan of freehubs for the simple reason that they lock me in to one maker's choices about cogs and cog spacing. For example, I had a 1988 Shimano 6-speed freehub and by 1991 Shimano had, according to my local bike store, discontinued 6-speed replacement cogs. Thus, simply replacing one worn cog meant upgrading to a 7-speed system, which in turn requires all new cogs, a new freehub body (lucky me -- for some it requires a new hub and thus new wheel), and, if I wanted to keep index shifting, new thumbshifters. Had this been a freewheel-equipped bicycle, I could have easily switched to another maker's 6-speed freewheels. Fortunately, the market is stablizing, with a growing number of makers producing hubs and cogs using a spline pattern like the more recent Shimano 7-speed freehubs. However, it hasn't settled entirely, yet. ;-D oN ( A hubalaboo ) Pardo
Subject: 8f.6 "Sealed" Bearings From: Jobst Brandt <jobst.brandt@stanfordalumni.org> > Has anyone had any major problems with the Shimono XT "sealed" Bottom > bracket besides me? This subject comes up often and has been beat around a bit. There is a basic misconception about seals. The seals commonly sold in the bicycle business are not capable of sealing out water because they were never designed for that purpose. These seals are designed to prevent air from being drawn through the bearing when used in, typically, electric motors where the motor rotation pumps air that would centrifugally be drawn through the bearing. If this were permitted, the lubricant would act as fly paper and capture all the dust that passes, rendering the lubricant uselessly contaminated. Seal practice requires a seal to leak if it is to work. The seepage lubricates the interface between shaft and seal and without this small amount of weeping, the seal lip would burn and develop a gap. In the presence of water on the outside, the weeping oil emulsifies and circulates back under the lip to introduce moisture into the bearing. This is usually not fatal because it is only a small amount, but the displaced grease on the lip dries out and leaves the lip unlubricated. The next time water contacts the interface, it wicks into the gap by capillary action and begins to fill the bearing. This is an expected result for seal manufacturers who live by the rule that no two fluids can be effectively separated by a single seal lip. Two oils, for instance, must have separate seals with a ventilated air gap between them. If a seal is to work with only one lip the contained fluid must be at a higher pressure so that the flow is biased to prevent circulation. None of the effective methods are used in the so called 'sealed' bearings that Phil Wood introduced into bicycling years ago. His components failed at least as often as non sealed units and probably more often because they make field repair difficult. These are not liquid seals but merely air dams. jobst.brandt@stanfordalumni.org [More from Ben Escoto <bescoto@stanford.edu>] Date: Sat, 07 Nov 1998 21:31:31 -0800 Subject: Additional entry on bearings for FAQ Although the entry on "Sealed" Bearings (8.44 as of the 10/7/98 FAQ) provides useful technical information on seals, many readers may not be able to directly apply it to bicycling on a practical level. I asked about this on rec.bicycles.tech and received helpful responses from Jobst Brandt, Matt O'Toole, and Hans-Joachim Zierke, among others. I hope the following summary will be an interesting and useful supplement to the entry mentioned above. Firstly, it is important to distinguish between bearings that are protected by a seal and bearings that cannot be individually removed because they are locked in a larger structure. The first I will call "sealed bearings"; the second are more properly called "cartridge bearings." Bearings in hubs, bottom brackets, etc (whether cartridge or cup-and-cone) on modern quality bicycles are usually sealed. For a better description of the difference between cup-and-cone and cartridge bearings, see the entries under "Cartridge Bearings" and "Cup-and-Cone Bearing" in Sheldon Brown's excellent bicycle glossary (http://www.sheldonbrown.com/glossary.html). So, for the reasons Mr. Brandt explained in the other entry, bearings on bicycles are not truly sealed, in the sense that water and dirt cannot enter under any circumstances. The best designs include two seals: a contact seal closer to the bearing, and then either a labyrinth or a second contact seal further out. The outer seal in hubs with double contact sealing should be oiled when the hub is serviced, because this seal is not lubricated by the bearing grease like the inner seal. But even well-sealed bearings (of any type) can be contaminated if exposed to pressurized water, as can happen in heavy rain, if the bearings are submerged, or if you spray your hubs with water as you clean your bike. Given this, both cup-and-cone bearings and cartridge bearings will occasionally need to be serviced. Here are some pros and cons of cartridge and cup-and-cone bearings regarding their maintenance. Cup-and-Cone: Cup and cone bearings are usually easily disassembled and serviced by cleaning the races, replacing the bearings, relubing, and reassembling. Also, individual bearings are quite cheap to replace. Although the cup and cone races are usually resist pitting better than their cartridge bearing counterparts and rarely need to be replaced, a ruined cup in a cup-and-cone hub, for example, may require that the whole hub be scrapped. Campagnolo is one manufacturer who makes hubs with replaceable cups and keeps spare parts available enough that repairing hubs in this way is often feasible. Cartridge: Cartridge bearings are usually harder to service. The cartridge seal is easier to break during disassembly and often the cartridge is not removable so the bearings are much harder to clean. Additionally, the races inside the cartridge are often more poorly made than the races in cup-and-cone bearings and more prone to damage and rust. Components with irreplacable cartridge bearings are much less maintainable than those with cup-and-cone bearings. However, the cartridges in some components (for instance the hubs made by Phil Wood, Syncros, and others) can be replaced without a bearing press. These cartridges are much easier to repack and can be replaced easily if damaged. So, what practical significance does this have? Cup-and-cone bearings are superior (in terms of maintainance) to irreplacable cartridge bearings. There doesn't seem to be a consensus on cup-and-cone bearings vs the cartridge bearings found in, e.g., Phil Wood's hubs. As of this writing (Nov 98) both Campagnolo and Shimano have stuck with cup-and-cone bearings for their hubs, while most third parties are manufacturing cartridge bearings, probably because cartridges are much easier to manufacture than cup or cone races. Right now Shimano makes the best inexpensive hubs: they are sealed correctly (double contact or contact/labyrinth), are fairly durable, and are quite serviceable. Hubs such as Phil Wood's are much more expensive, but may be better in some respects (see above). -- Ben Escoto PGP/MIME mail welcome - finger bescoto@leland.stanford.edu for key
Subject: 8f.7 Ball Bearing Grades From: Bill Codding <peda@simplicity.Stanford.EDU>, Harry Phinney <harry@hpcvlx.cv.hp.com> Following is a description of the different grades of ball bearings. The grade specifies the sphericity of the balls in millionths of an inch. Thus, grade 25 are round to 25/10^6, while grade 1000 are good to 1/1000 (i.e. not all that round, but probably good enough for our uses). Grade 25: the highest quality normally available, aka "Campagnolo quality": hardened all the way through, best alloys, coatings, roundness, and durability. Evidently, a recent bottom-bracket overhaul article in "Bicycling Plus Mountain Bike" magazine recommended these. Campy's tech reps claim that the bearings in a set (usually in a little paper bag) are matched. One should not mix bearings from different sets. Grade 200: mid-range Grade 1000: seems to be the lowest, may only be surface hardened. Good sources for ball bearings: Your local bike shop (make sure you're getting the grade you want) Bike Parts Pacific Bike Nashbar 1-800-NASHBAR ($1-$3 per 100 Grade 25) The Third Hand 1-916-926-2600 ($4-$7 per 100 Grade 25)
Subject: 8f.8 Bottom Bracket Bearing adjustment From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Wed, 03 Jan 2001 16:50:20 PST This concerns conventional threaded adjustable and fixed cup bottom bracket (BB) bearings, not roller bearing or Ashtabula cranks. The conventional ball bearing Crank assembly, as has been common on three piece cranks, usually has 1/4" balls held in an 11 ball cage. Some less expensive bearings use only 9 or fewer. The balls are best left in the cage because removing it makes assembly difficult, does not make room for additional balls, and saves insignificant weight. The four kinds of BB threads in common use today are Italian, British, French, and Swiss, possibly in that order of occurrence. Diameter Pitch Right Left Cup -------- ----- ----- ----- Italian 36mm x 24F tpi right right tpi (threads per inch) British 1.370" x 24F tpi left right French 35mm x 1mm right right Swiss 35mm x 1mm left right Unless there is something wrong with the right hand cup it should not be removed because it can be wiped clean and greased from the left side. The type of thread is usually marked on the face of both left and right cups. Swiss threads are rare, but if you have one, it is good to know before attempting removal. A left hand thread is preferred on the right hand cup because it has a tendency to unscrew if not rigidly tight. The propensity to rotate is small, and will, depending on pedaling, sometimes unscrew a left hand thread that was not tight so that a left hand thread alone will not prevent loosening. The right hand cup should be made as tight as practical and not be removed during regular maintenance. Because cups seldom fail, right hand cups seldom require removal. No unusual greases are required for this bearing and a can of automotive wheel bearing grease will go a long way to lubricate this and other parts of the bicycle that require grease. After installing the spindle with greased bearings, the (adjustable) left cup should be advanced until an increase in rotational drag can be felt but where the spindle can still be turned using the tip of the thumb and forefinger. Without preload that causes this drag, the spindle will be riding on a single ball as each ball passes under the load. Known as "ball drop" this phenomenon can best be visualized on a loosely adjusted bearing where the spindle has appreciable clearance. Because the steel of the spindle, balls and cups is elastic, the load can be distributed over several balls, but only if these parts are already in contact before the load is applied. Ideally the preload should be large enough so that the balls on the top do not develop clearance, but this much preload is impractical for such a heavily loaded bearing. Because the feel of bearing adjustment is delicate, the spindle should be adjusted without the cranks. In a correctly adjusted bearing, the spindle should not spin freely were it not greased. Practically all industrial applications use axial springs (Belleville washers) to preload bearings typically on motor shafts. Although the BB bearing can operate without preload, its life is substantially extended with a light preload.
Subject: 8f.9 Crank noises From: Phil Etheridge <phil@massey.ac.nz> I've had the creaky crank problem on every bike I've owned which has had cotterless cranks. Until now, I've never known a good solution to the problem. One suggestion I had was to replace the crank, but that wasn't something I was prepared to do on 1 month old bike under warranty. The shop mechanic spent half an hour with me and my bike sorting it out. Tightening the crank bolts and pedal spindle (i.e. onto the crank) didn't help (as Jobst will tell you). Removing each crank, smearing the spindle with grease and replacing the crank eliminated most of the noise. Removing each pedal, smearing grease on the thread and replacing it got rid of the rest of the noise. Greasing the pedal threads is a new one on me, but it makes a lot of sense, since they are steel and the crank aluminum. I thought it was worth relating this story, as creaky cranks seems to be quite a common problem.
Subject: 8f.10 Cracking/Breaking Cranks From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Fri, 18 Jun 2004 12:47:58 -0700 Aluminum alloy cranks develop cracks principally at two places although other failures occur as can be seen in samples at: http://pardo.net/pardo/bike/pic/fail/FAIL-001.html The two most common failures are the pedal eye and the junction of the trailing spider leg and the right crank. The trailing spider leg adjacent to the crank generally has a thin web that connects it to the more rigid shaft of the crank, while the three preceding legs are more flexible, stress is concentrated at this web. These cracks are relatively benign because they are easily seen and rarely progress to failure. In contrast, the most common and most dangerous failure, one at the pedal eye has a different cause not directly related to a stress concentration, but one that might be apparent to a critical observer. That the left pedal has a left hand thread is taken for granted and seems not to be questioned because it has "always" been that way. What is less well remembered is that automobiles also used left hand threads to secure wheels on the left side of the vehicle before the advent of the conical lug nut commonly used today. The pedal attachment, as wheel nuts on cars of old, has a flat face that bears against the crank, a surface that cannot transmit any load except by friction because it is parallel to the applied force. Therefore, this joint always moves under load, a microscopic type of motion known as fretting. Fretting causes erosion of the interface and develops an undercut in the face of the crank that is visible when the pedal is removed. Besides, a left pedal without a left hand thread unscrews, regardless of how tightly the pedal is installed, proving that there is motion. Removing a pedal, ridden for a longer time, reveals erosion in the crank face having tiny cracks radiating from its circumference. In time, some of these cracks propagate into the crank and cause the end of the pedal eye to break off, releasing the pedal, usually at the worst possible moment, that of high stress of a rider pedaling in the standing position. Such failures generally cause the standing rider to fall to the side of failure because that foot is suddenly standing on the road at speed. A solution to this problem is to use a tapered face (~90 degree countersink) similar to the face of an automotive wheel nut in place of the flat face at the end of the pedal thread. This design has been tested in prototype with a rider who previously had more than two dozen such crank failures and has subsequently not had any for five years on the same cranks. Not only does it suppress fretting motion that causes failures, but it makes the left hand thread unnecessary, a bonus for manufacturing while secondarily giving one to tandem riders who generally have difficulty finding cranks with threads opposite to convention.
Subject: 8f.11 Installing Cranks From: Jobst Brandt <jobst.brandt@stanfordalumni.org> > My cranks get loose, quite quickly too; over about 10 miles or so > from being solid to flopping about in the breeze. Any suggestions? Your cranks are ruined! Once ridden in the "floppy" mode, the square taper in the crank can no longer be secured on the spindle. Get some new cranks and properly tighten them after lubricating the tapers. Proper tightness can be guaranteed only by torque wrench or a skilled mechanic. The second of these is less expensive and you might be able to get a demonstration of what is tight enough. The admonition to not lubricate the tapers of the crank spindle seems to find life only on bicycle cranks, of all the machines I have seen. I have pursued the "dry assembly" instruction by talking to crank manufacturers and discovered that they apparently had warranty claims from customers who split their cranks open. It is easy to prove that cranks cannot split by over-tightening simply by attempting to do so. It is not possible to split a major brand crank this way, the bolt will fail first. Crank failure from "over-tightening" is caused by the re-tightening of previously properly installed cranks. Once installed, a crank always squirms on its taper, and because the retaining bolt prevents it from coming off, it elbows itself away from the bolt and up the taper ever so slightly. This can be detected by the looseness of the retaining bolt after the bicycle has been ridden hard. Grease in this interface does not affect performance, because only the press fit, not friction, transmits load from crank to spindle. As any bicycle mechanic can tell you, crank bolts are often appreciably looser after use, the left one more so than the right. This occurs because the left crank transmits torque and bending simultaneously while the right crank transmits these forces one at a time. The right crank puts no significant torque into the spindle. Either way, the looseness occurs because loads make the crank squirm on the spindle and the only direction it can move is up the taper, the retaining bolt blocking motion in the other direction. Regardless, whether grease or no grease is used, in use the spindle and crank will make metal to metal contact and cause fretting corrosion for all but the lightest riders. The purpose of the lubricant is to give a predictable press fit for a known torque. If the spindle is completely dry this cannot be said, and even with marginal lubrication, some galling may occur on installation. Lubrication is only used to guarantee a proper press because the lubricant is displaced from the interface in use. Taper faces of spindles show erosion and rouge after substantial use, evidence that the lubricant was displaced. "Dust caps" aren't just dust caps but retention for loose bolts. It is not that the bolt unscrews but that the crank moves up the taper. However, once the screw is unloaded it can subsequently unscrew and fall out if there is no cap. Because cranks squirm farther up the taper when stressed highly, the unwitting mechanic believes the screw got loose, rather than that the crank got tighter. By pursuing the crank with its every move up the spindle, ultimately the crank will split. It is this splitting that has been incorrectly diagnosed as being caused by lubrication. I have never seen a warning against re-tightening cranks after having been installed with a proper press fit. It is here where the warning belongs, not with lubrication. For the press fit to work properly, the pressure must be great enough to prevent elastic separation between the crank and spindle under torque, bending, and shear loads. This means that no gap between crank and spindle should open when pedaling forcefully. Friction has no effect on the transmission of torque because the crank creeps into a position of equilibrium on the spindle in a few hard strokes. Failure of this interface occurs when the press fit is too loose allowing a gap open between spindle and crank. Torque is transmitted by the entire face of the press fit, both the leading edge whose contact pressure increases and the trailing edge whose contact pressure decreases. If lift-off occurs, the entire force bears only on the leading edge and plastic failure ensues (loose crank syndrome). Tightening the retaining screw afterward cannot re-establish a square hole in the crank because the retaining screw will break before the spindle can exert sufficient stress to reshape the bore. Beyond that, the crank would split before any plastic deformation could occur even if the screw were sufficiently strong. Because retaining screws could become entirely lose from squirming action, especially if the press is relatively light, "dust caps" should be used to prevent screws from subsequently unscrewing and causing crank bore failure. Besides, the loss of the screw won't be noticed until the crank comes off, long after the screw fell out. The argument that the greased spindle will enlarge the hole of the crank and ultimately reduce chainwheel clearance is also specious, because the crank does not operate in the plastic stress level. At the elastic limit it would break at the attachment knuckle in a short time from metal fatigue, that occurs rapidly at the yield stress. In fact, the depth of engagement (hole enlargement) can increase with an unlubricated fit faster than with a lubricated one, because installation friction is the only mechanism that reams the hole. Jobst Brandt <jobst.brandt@stanfordalumni.org>
Subject: 8f.12 Biopace chainrings Biopace chainrings have fallen into disfavor in recent years. They are hard to "pedal in circles". The early Biopace chainrings were designed for cadences of around 50-70 rpm, while most recommend a cadence of 80-100 rpm. Newer Biopace chainrings are less elliptical, but the general consensus is to (if you are buying a new bike) get the dealer to change the chainrings to round ones. Sheldon Brown has some information on Biopage chainrings at http://www.sheldonbrown.com/biopace.html.
Subject: 8f.13 Indexed Steering From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Thu, 10 Jun 2004 10:29:56 -0700 > In the several years I spent working in a pro shop, I have never > seen a case of "index steering" (yes, we called it that) that was > _not_ caused by a "brinelled" headset - one with divots in the > races. I am 99.999 percent certain that that is your problem. What > are you going to do if you don't fix it? I suggest that you fix the > headset even if you sell the bike, as a damaged headset could be > grounds for a lawsuit if the buyer crashes. I disagree on two points. First, because you use the term "Brinell" that conveys a notion as incorrect as the phrase "my chain stretched from climbing steep hills" and second, because there is no possibility of injury or damage from "indexed" steering head bearings. The effect is mostly perception of failure from the rattling noise and clunky feel while braking lightly. It has such a small effect that it is imperceptible when riding no-hands unless the bearing clearance has been adjusted in the straight ahead position. Then the bearing will bind off center. Damage to head bearings seems to be twofold in this case because properly adjusted steering can only become looser from dimples, dimples that cannot immobilize steering. Therefore, the head adjustment was too tight. However, dimpling is not caused by impact, but rather by lubrication failure that occurs while riding straight ahead, giving the steering a preferred home position. This occurs more easily with a correctly adjusted bearing than with a loose one that rattles and clunks. Rattling replenishes lubricant between balls and races, something that would otherwise not not occur. Off road bicycles suffer less from this malady than road bicycles because it occurs primarily during long straight descents that on which no steering motions, that might replenish lubricant, are made. If you believe it comes from hammering the balls into the races, you might try to cause some dimples by hammering on the underside of the fork crown of a clunker bike of your choice. Those who hammered cotters on steel cranks will recall no dimples on the spindle, even though it has a far smaller diameter than the head bearing and the blows were more severe and direct, supported by no more than one or two balls. Bearing balls make metal-to-metal contact only under fretting loads (microscopic oscillations) while the races are is not rotating. Any perceptible steering motion will replenish lubricant from the oily meniscus surrounding each ball contact patch. Peering over the bars at the front hub while coasting down a road at 20+ mph you will notice the fork ends vibrating fore and aft. This motion does not arise at the fork end, but at the fork crown, where it bends the steer tube. Both head bearings rotate in fretting motion crosswise to the normal plane of rotation as the steer tube bends. Dimples form in the forward and rearward quadrant of both upper and lower bearings from this fretting. That they also form in the upper bearing shows they are not directly load related. Lubrication failure from fretting causes metal to metal contact that forms microscopic welds between balls and races. These welds repeatedly tear material from the softer of the two causing elliptical milky dimples in both races. Were these Brinelling marks (embossed through force), they would be shiny and smooth and primarily on the inner race of the bearing. Various testimonials for the durability of one bearing over another are more likely an indication of lubrication than the design of the bearing. Ball bearings with separate cups and cones have been used as head bearings longer than they should considering their poor performance. The question has been raised whether steering to either side would reveal a second preferred position in which the balls fall into matching dimples. Since bearing balls move at roughly half the rate of steering motion, with 20 balls, this requires a steering angle of 36 degrees for dimples in both races to match again with the balls. However, the balls do not arrive exactly at the spot where dimples are again opposite because they move at a ratio of (od-bd)/(id+bd) od: outer race diameter, id: inner race diameter, bd: ball diameter. This ratio not being 1:1, the balls do not naturally arrive at the second coincidence of the race dimples although they usually drop in. Roller bearings of various designs have been tried, and it appears that they were possibly the ones that finally made obvious that fore and aft motion was the culprit all along; a motion that roller bearings were less capable of absorbing than balls. This recognition lead to using spherical alignment seats under the rollers. Although this stopped dimpling, these bearings worked poorly because the needle complement tended to shift off center, skewing the needles and causing large bearing friction as the rollers skate. Shimano, Chris King, Cane Creek and others, offer angular contact, full ball complement, spherically aligned cartridge bearings. The Shimano cartridge bearings have contact seals, not exposed to weather, to retain grease for life of the bearing. The races are sufficiently reentrant that they snap permanently together with sufficient preload to prevent rocking (fretting) motion perpendicular to the rotational axis. Spherical steel rings, that move as plain bearings against an aluminum housing, support the cartridge bearing to absorb, otherwise damaging, out-of-plane motion while the cartridge bearing does the steering.
Subject: 8f.14 Roller Head Bearings From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Fri, 13 Feb 2004 12:07:59 -0800 Although roller bearing headsets never worked well, they introduced a positive feature, not directly connected with rollers. The main advantage of some rollers was that they had two bearings, the rollers and a plain bearing back plate that was needed because rollers cannot run well with even the slightest misalignment of inner and outer race, something that conventional ball bearings do easily. The importance was that this feature separated rotary from swiveling motions. A head bearing serves mainly as the axis about which the fork steers, but it also carries fore and aft swiveling motion as the fork flexes. Swiveling motions are the ones that damage head bearings. As the bicycle is ridden, the fork absorbs shock by flexing, primarily at the fork crown, where it rotates fore and aft in the plane of the bicycle frame, a motion that can be seen by watching the front hub while sighting over the handle bars while rocking the bicycle fore and aft with the front brake locked. Although the wheel visibly moves, the angle through which the fork crown swivels is small and is not in itself damaging because it is readily absorbed by cup and cone ball bearings. However, occurring repeatedly in the absence of steering motions, bearing balls fret in place and displace lubrication that normally separates them from their races. Without lubricant, bearing balls weld to their races and tear out tiny particles, causing dimples having a matte finish. This phenomenon primarily affects road bicycles while coast down hills fast enough to make practically no steering motions that would move bearing balls from their straight ahead position to replenish lubrication. Because rollers cannot absorb swiveling motions, some were equipped with spherical backing plates that could. This design feature was then incorporated into ball head bearings that, in contrast to rollers, stay aligned to their races and cannot bind as rollers do by sliding off center, an effect that made them hardly useful for this application. The combination of ball and plain bearings has replaced rollers for this job.
Subject: 8f.15 Brakes from Skid Pads to V-brakes From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Fri, 11 Jun 1999 14:53:00 PDT Bicycle brakes have changed greatly since the original wagon wheel brake that pressed a skid pad against the tread, but they have also stayed the same, the skid pad brake still being used. The single pivot caliper brake, commonly called the side pull, came along about 100 years ago and is still the mainstay. This brake was displaced by the centerpull, a derivative of a cantilever brake, to take a large part of the sport market in the 1950s. Meanwhile the cantilever brake with its large tire clearance existed only in a limited way until the advent of the mountain bike that demanded this feature for its large tires and the dirt that sticks to them. Recently, other forms have emerged to meet changing demands of the sports bicycling market. Sidepull Until recently, most brakes had a hand lever ratio (mechanical advantage) of 4:1, with a caliper ratio of 1:1, making most brakes and levers interchangeable. The 4:1 ratio struck a convenient compromise between the reach of the hand, its strength, and brake pad clearance to the rim. At higher ratios too much hand movement is used to bring the pads into contact with the rim, a clearance that is necessary to prevent a dragging brake and to take up pad wear. An important feature of the single pivot is that it has practically no position error through its sweep, the pad remaining centered on the rim throughout its wear life. Its main weakness is poor centering (clearance), caused by sliding contact of its return springs. Exposed to road dirt, the sliding springs change their coefficient of friction unpredictably, causing the pads to retract unequally from the rim. To prevent dragging, liberal clearance is required, preventing the use of the higher mechanical advantage desired by today's avocational bicyclists. Centerpull The centerpull brake of the 1950's, was popular for nearly a decade, in spite of being entirely without merit, being worse in all respects than the side pull brake with which it competed. It had the same hand levers and its caliper the same 1:1 mechanical advantage, but had large position error, moving its pads upward into the tire with wear. Its symmetry may have been its main appeal, an aesthetic that people often admire without functional reason. Its acceptance might also have been from dissatisfaction with flimsy sidepull calipers of the time. It used a straddle cable on which the main cable pulled from a flimsy cable anchor attached to the tab washer under the head bearing locknut. Besides its two levers, it had a connecting bridge that flexed in bending and torsion, making it spongy. Although Mafac was one of the greatest proponents of this design it began to vanish on sport bicycles with the introduction of the Campagnolo sidepull brake. Cantilever The cantilever brake offers clearance that fat tires and mud demand. Its pads pivot from cantilever posts on the fork blades, giving it large tire clearance and a fairly rigid action, there being no significant bending elements in its mechanism. Nevertheless it has its drawbacks. Its reaction force spreads and twists the fork blades, something that became more apparent with suspension forks that require a substantial bridge plate to restrain these forces. Its pads sweep downward at about a 45 degree angle giving them such a large position error that, as they wear, they easily pop under the rim, causing unrecoverable brake failure. Its straddle cable is pulled by a main cable that requires a cable anchor that is difficult to accommodate with rear suspension, while the front straddle cable presents a hazard in the event of a main cable failure, because it can fall onto a knobby tire to cause wheel lockup. The cantilever received a large resurgence in popularity on the mountain bike, along with other innovative designs. One of these concepts was the servo brake that had cantilever posts with a steep helix that converted forward drag of its pads to contact force, a dangerous servo effect that re-emerges from time to time. Servo Brake Servo brakes, ones that use pad reaction force to reinforce braking force, have been designed often and without success, mainly because a small change in friction coefficient causes a large change in braking. The servo effect makes the relationship between application force and brake response unpredictable and difficult to control. The servo effect inherent in drum brakes is what caused automobiles and motorcycles to switch to disks. Brake application pressure being at right angles to the rotating disk, prevents any interaction between reaction and application force. For bicycles, that effectively already have disk brakes, introduction of servo effect is illogical. V-brake The V-brake is currently displacing the cantilever brake because it offers the same advantages while solving two critical problems, those of the brake hanger for suspension bicycles and brake pad dive. The cable hanger seems to have been the main goal because early V-brakes had rigidly mounted pads that traveled in the same arc as those of a cantilever. Newer versions use a parallelogram link that keeps pad motion perpendicular to the rim. As usual, these advantages are not gained without drawbacks, such as brake chatter arising from more complex linkage and clearance required for it to work in dirt, and incompatibility with other brakes by its higher mechanical advantage that requires different hand levers. The difference in mechanical advantage has been bridged by third party hardware, one of which is called the "travel agent", that uses a two diameter wheel to change the mechanical advantage to that of common road brake levers. The device can also be used in a 1:1 ratio to replace the elbow tube of the V-brake to reduce sliding friction. Dual Pivot Greater leverage for the same hand motion requires smaller pad-to-rim clearance, that the dual pivot brake achieves by using two pivot points to define a line of action about which its two arms are constrained to move equally and remain centered. Brake centering was essential in reducing the pad-to-rim clearance needed for a mechanical advantages of about 5.6:1. Higher leverage also required compromise. The offset arm (the short one) sweeps its pad upward into the tire so that this pad must be adjusted as it wears. The brake cannot track a crooked wheel with, for instance, a broken spoke, and because it has a high ratio, it does not work at all when the quick release is accidentally left open. And finally, it runs out of hand lever travel 40% faster with pad wear than the former single pivot brake. Its low pad clearance and narrow flange spacing of current wheels make the brake drag when climbing hills standing, so that racers often ride with the rear quick release open. Part of the light feel of the dual pivot brake arises from the lower (reverse) ratio of the caliper, whose springs now no longer exert as strong a return force on the cable and hand lever. Because this force is lower, a return spring has been added to the hand lever, lowering cable return force, that coincidentally reduces cable drag during free motion of the brake (before making contact with the rim). This makes the brake FEEL even more forceful than it is because it has such a light action in neutral. Delta (Campagnolo) For lack of power brakes that motor vehicles have, brakes with variable ratios have been designed for bicycles, one of which was a major blunder for Campagnolo. Campagnolo introduced the Delta brake (aka Modolo Kronos), whose mechanism is an equilateral parallelogram in which a cable draws two opposite corners of a "diamond" together, such that the other two corners expand. The motion can be visualized by placing the tips of the thumbs and forefingers together to form a diamond. Moving the tips of the diamond together at a constant rate demonstrates the progressive nature of the mechanism and the resulting braking action, the brake pads being connected by links to the knuckles as it were. The motion is a tangent function that goes from zero to infinity. An example of this is the motion of the top of a ladder, leaning steeply against a wall, as the foot of the ladder moves away from the wall at a constant rate. At first the the top of the ladder moves imperceptibly, gradually accelerating until, near the bottom, its speed approaches infinity. Although the Delta does not use the extremes of this range, it has this characteristic in contrast to a sidepull brake that has a constant 1:1 ratio throughout its range. Besides its adverse response curve, its pads moved in an upward arc toward the tire similar to a centerpull, which it essentially is. Hydraulic Hydraulic brakes have their own problems of complexity and reliability that keep them in an almost invisible presence in general bicycling. Their advocates insist that they are superior in all respects in spite of their lack of acceptance by the bicycling public at large.
Subject: 8f.16 Brake Squeal From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Fri, 11 May 2001 16:35:42 PDT Most car, motorcycle, and bicycle brakes squeal at one time or another because they involve stick-slip friction whose frequency is supposed to be out of audible range. Squeal is not only annoying, it decreases brake efficiency, especially in the lower frequencies where the length of slip motion exceeds that of stick. Brake noise requires elastic motion (vibration) at the sliding interface, with at least one element in rapid stop-start motion. Because bicycles use hand power and demand light weight, they use relatively flimsy mechanisms and demand pads with a high coefficient of friction. The brake material must be soft and pliable enough to achieve good contact on relatively rough rims. The brakes generally have a mechanical advantage between 4:1 and 6:1 from hand to rim, as described under "Brakes from Skid Pads to V-brakes." That's not much compared to motorcycles that have hydraulic disk brakes with practically no pad clearance. For a hand brake, free travel (pad clearance) and flexibility defines the limit of mechanical advantage. Soft brake pads and lightweight (flexible) calipers promote squeal and chatter, chatter being the mechanically more detrimental version of stick-slip behavior. Brake chatter is caused by gummy residue on the rim together with excessively flexible (skimpy dimensioned) brake mechanism. Rims can be cleaned but flexible brakes can only be fixed by using better brakes. If the rim becomes gummy again after cleaning, then either the rims are being contaminated by something like riding through tar weed or the pads are no good. My solution for pad quality is Kool-Stop salmon red pads. Squealing brakes, the more common problem, involves mainly brake pads that generate caterpillar like surface waves. The common advice is to bend the brake caliper to make the trailing edge of the pad (with respect to rim motion, the forward end of the front brake pad) contact first. This is not entirely without merit because toe-in is the natural state of a used, non squealing brake. Elasticity of the caliper, however small, allows the pad to follow the rim and rotate forward about the caliper arm, wearing the heel of the pad more than the toe, causing toe-in. Toe-in is preferred because a pad that makes full contact as it first touches the rim will rotate slightly from frictional drag, reducing contact... and drag, which allows it to snap back and repeat the action. This causes surface waves in the pad, especially when it is new and thick. For this reason, some pads are made with thin friction material to reduce elasticity. If the pad contacts the rim, trailing end first, it develops full contact stably as pressure and frictional drag increase. However, the brake may squeal anyway. This can occur with new rims or one with wax or oil, or from other contaminants like riding across a moist lawn. New pads often have a glossy sticky skin that should be removed either by sand paper or use. Many types of rim contaminants that increase stiction (stick-slip) can be removed easily by abrasive scrubbing. This can be done by braking at moderate speed with a dusting of household cleanser on a moist rim, followed by a water bottle squirt rinse (also while braking). This process is more conveniently achieved by slowly riding through a long mud puddle while braking or by descending a mountain road in the rain where there is usually plenty of fine grit and where rain supplies the rinse. Some rims have machined brake surfaces with fine grooves whose roughness reduces squeal tendencies so they don't have to be "broken in". Martano rims of old had somewhat larger grooves as part of the extrusion for this purpose. Avoid bending brake calipers. This is "cold setting" in its worst form. Aluminum in such cross sections doesn't bend far without structural damage. Besides, this remedy could lead to more bending with each occurrence of squeal that is better abated by other means.
Subject: 8f.17 Electronic Shifting From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Wed, 23 Aug 2000 17:08:29 PDT A reader asks whether the Mavic Mektronic is any better than the earlier Mavic Zap electronic shifting. New styling didn't fix the basic problems of this device, although it has an elegant speedometer and controls. The same basic problems remain in the derailleur mechanism that shifts by means of a ratchet pushrod that moves in and out with each idler wheel rotation. The faster the chain moves the faster it pumps. A shift occurs during 1/2 revolution but primarily in 1/4 revolution considering the profile of sinusoidal motion. The stroke takes place in about 35 milliseconds when pedaling a 52t chainwheel at 100rpm. This heavily loads the small electrically activated ratchet pawls, one for up and one for down, that engage one of the sides of the pushrod. The opposing ratchets of the pushrod have teeth space exactly one gear apart with little overshoot. Besides the ratchet problem, the upper idler must lie on axis with the derailleur pivot, a feature that reduces chain slack take-up. Today derailleurs have the pivot offset from and between the two idler wheels, and use a slant parallelogram (low friction) movement. The Mektronic uses a sliding post (like early Simplex derailleurs) that resists motion when chain tension loads it with torque. Moving it is similar to pulling a socket wrench off a nut while tightening it. A rubber boot covers the mechanism that must run in an oil bath. Drawing power to shift from the chain is both the novelty and the fault of this design. The novelty is that only control power is drawn from a battery while power for shifting comes from the chain and only while shifting. The fault is that to make this possible the function of the derailleur is compromised. Because it can support only a short tensioning arm due its sliding post, it cannot take up large chain differences typical of large to small chainwheel shifts. Most seriously, pushrod velocity is too great to be reliable at speed.
Subject: 8f.18 Bearing Seals From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Mon, 23 Dec 2002 15:04:39 PST Bearing Seals > What is a labyrinth seal? For that matter, even though I think I > can picture it, what is a contact seal? Moving seals are a more complicated than they first appear and are only slightly related to fixed seals such as beer caps, mason jars, and gas or radiator caps. This is best emphasized by the old saying that "the seal that doesn't leak, leaks" that being the essence of the problem. If the seal doesn't leak a little, its flexible sealing lip will burn for lack of lubrication from the fluid that it is intended to contain. Therefore, there must be fluid under the seal lip. If a seal is intended to contain oil and seal it from water, the principal problem is one of mixing disparate fluids under the seal lip. Because circulation occurs under the seal lip, an emulsion will develop and even if the volume of oil on the inside is too large to be contaminated significantly, the shaft will rust when standing, destroying the seal lip. Automotive bearings are sealed to retain grease and oil but are protected from water exposure by splash shields. Separating two fluids requires two seal lips separated by a drained dry space. This is done on automatic transmission and differential gears with incompatible oils, to prevent contamination by circulation under each seal lip. This is not possible with oil and water on bicycles because there is no water most of the time, leaving the water seal lip dry and unlubricated, which renders it useless when exposed to water. Most so called sealed bearings are not water tight, mainly because they have run dry, burning the seal lip which becomes a capillary to suck water when wet. Phil Wood used bearings designed for used in electric motors that use a rubber lip seal to prevent air (dust) flow that always occurs in rotating machinery that sucks at the axle and blows at the periphery. Such bearings were never meant to prevent water intrusion, something they can do only for a short time when new. This is the main reason why such "sealed" hubs were not available at the time he introduced them. To make this work, one would have to protect the seal lip from contacting anything but oil by a shield, otherwise known as a labyrinth seal. The most common labyrinth seals on bicycles are found on Campagnolo Pedals, threaded head bearings, and above all on Sturmey Archer 3-Speed hubs that are rust free and working more than 50 years after manufacture. Bendix and New Departure coaster brakes are also examples of excellent water rejection unless submerged. The nature of a labyrinth seal is that it uses gravity to purge water from its entrance. Typically this requires nothing more than two nested channel cross section washers of two diameters, one rotating in the other that is anchored in the housing. To visualize this make a "C" shape with both hands, interleaving the thumb and forefingers so they move freely in a rotary motion from the elbows. You can see that, vertically, water has no ability to enter, and tilting the pair either way only enhances the barrier. The last such device I am aware of was the New Winner Pro Sun Tour freewheel, whose labyrinth was visible as a tiny brass ring on both faces. It's problem was that such a seal must take into account the wetting angle of water and must have a large enough air gap to prevent capillary attraction. The Sun Tour execution lay at the lower limit with its small spacing but they worked under most conditions.
Subject: 8f.18 Sturmey-Archer 3-Speed Hubs From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Mon, 23 Dec 2002 15:04:39 PST Sturmey-Archer hubs have been in service for many years (1887): http://www.sturmey-archer.com/p11.htm Yet they have had a design flaw from the beginning that escaped scrutiny through most of the popular life of the common 3-speed AW hub. This flaw has consistently been "swept under the rug" or laid at the feet of the mechanic so completely that few have questioned why it jumps into free wheeling when ridden forcefully in top gear. I think the symptom and cause should be explained to prevent injuries. Drive is transmitted from the sprocket through a four slot driver, through which a small movable cross (clutch) protrudes to transmit drive in, low, direct,and high gear positions. In low gear, the clutch is moved to the right to lift the (high gear) pawls, driving the ring gear directly so that the ring gear drives the planets with output going through the planet cage and its (low gear) pawls at 3/4 the input speed. With one pair of pawls raised and the other pair driving, the typical clicking sound of AW hubs is absent. In second gear, (direct drive), the clutch drives the hub body directly through the right hand pawls, making the planet carrier (low gear) pawls click as they lag behind. Top gear engages when the clutch is fully extended to the left against the planet cage, between the four protruding planet (pinion) pins, to drive the planets that turn the ring gear 4/3 the input speed. In this position, the low gear pawls in the planet cage click as they lag behind. It is the inverse of low gear and hence the reciprocal relationship between low 1/3 down and high 1/4 up with respect to direct drive on AW hubs. Because the pinion pins are free fit in the housing, they are slightly skewed to the hub axis due to canting within the clearance when loaded by the clutch, a "tilt" that has a disengaging bias to the driving clutch. However, because the axle bends slightly from chain tension, depth of engagement between clutch and pinion pins varies during rotation. These two effects can disengage the clutch and pins under high torque, dropping the mechanism into free wheeling forward. The result is that the rider, if standing, dives over the bars, with the bicycle following. This condition is apparent upon examining the clutch and pins that both show wear, slanting to enhance disengagement. However, replacing these parts does not resolve the condition. SA has always maintained that the shift cable was misadjusted, something that is easily disproven by disengaging the shift chain entirely. With the cable disconnected, the clutch is free to make perfect contact with the face of the planet cage, the best adjustment possible for top gear, and still disengagement occurs. This problem could have been resolved by putting a slight flare to the ends of the planet pins and a similar matching slant on the clutch faces, giving their engagement a preferential retaining force instead of the opposite. Most motorcycle gear boxes use such features, especially in older non-synchronized sliding gear boxes... the classic clunk of BMW boxes for instance. Similarly, the spring-less ratchet of the SW (Silent) hub was sensitive to lubricant viscosity and with anything more than 10W oil could freewheel forward, the pawls clinging to the ramps by oil viscosity while not engaging. This hub was discontinued after a short run probably because one could not place blame on user error.
Subject: 8f.20 Loosening Splined Shimano Cranks From: "Jobst Brandt" <jobst.brandt@stanfordalumni.org> Date: Fri, 13 Feb 2004 12:07:59 -0800 > My 1 year old XTR crank on XTR splined BB loosens with use. > After each ride (an hour or so) the crank bolt looses up by about a > quarter turn. i.e. - when I tighten the bolt, my 8mm Allen key is > in the 12 o'clock position, after the ride, it is in the 9 o'clock > position. This crank attachment was apparently designed assuming that all riders lead with the left foot when standing on both pedals, typically over rough terrain. Properly tightened retaining bolts can loosen only with weight on both pedals, right foot forward, because this is the only condition under which the crank spindle torque reverses. Reverse torque takes up backlash in the splines and turns the retaining bolt slightly with each reversal. Backlash exists because the splines have no press fit and do not mesh snugly, so they have backlash at the outset. Elasticity of the spline teeth add backlash motion, and when repeated often, can unscrew the retaining bolt. Shimano, apparently in response to this problem, has a new design for all its cranks. These use a straight spline on a hollow spindle onto which left crank having a split knuckle is secured with two pinch bolts while the right crank is permanently attached to the spindle. This is not an entirely new idea but the execution appears promising. However, its BB bearings are external to the BB shell possibly presenting a new loosening problem as does the spindle, that has a free fit in these bearings. http://tinyurl.com/cdxe
Subject: 8g Tech Accessories
Subject: 8g.1 Milk Jug Mud Flaps From: Chuck Tryon <bilbo@bisco.kodak.com> Actually, I have used plastic like this (or in my case, some red plastic from a cheap note book cover -- it's heavier) to extend the bottom (rear) end of the front fender. The Zephals are good, but they don't stop the splash from where the tire hits the road from getting on my feet. What I did was cut a small triangle about 3in (~7cm) wide by 6in (~15cm) long, cut a hole in the top of it and the bottom end of the fender, and use a pop-rivet (with washers to prevent tear out) to attach it. On a road bike, it should be end up being within a few inches of the road. ATB's will need more clearance, so this won't work well off road. | | | | /| o |\ <----- rivet with washer on inside | \___/ | / \ <---- flap fits inside of the fender, and follows the | | curve, which gives it some stiffness. | | | | \_________/ | | | | <----- bottom of tire \_/
Subject: 8g.2 Storing NiCad Batteries From: Tom <tyounger@csc.UVic.CA> Date: Tue, 23 Feb 1999 13:23:29 -0800 > Michael GWell, the days are getting longer, and I won't be needing my > VistaLight 530 lights with a nicad battery for my nightly commute home until > October or November. My question is, what is the best way to prevent damage > to the battery from discharging over the next 6 months? Presumably, it will > lose charge slowly while in storage, so I will have to recharge it every now > and again. But how often is that? How can I be sure not to overcharge it > without going to the hassle of letting it discharge until the lights begin > to dim, then recharge it the 12-14 h stipulated in the manual? > You definately do NOT want to store NiCads charged. NiCads should be stored discharged. For more info, check out: http://www.cadex.com/html/battery.htm and especially check out: http://www.verinet.com/~dlc/battery.htm for NiCad storage info.
Subject: 8h Tech Ergonomics
Subject: 8h.1 Seat adjustments From: Roger Marquis <marquis@roble.com> [More up to date copies of Roger's articles can be found at http://www.roble.net/marquis/] The following method of setting saddle height is not the only method around for setting your saddle height but it is the most popular among experienced coaches and riders in the US and Europe. 1) First adjust the saddle angle. It should be level or very close to level, with no more than 2mm slope up or down at the nose. 2) Put on the shoes you normally ride in. Don't forget to lightly grease the seat post and binder bolt. Have a binder bolt wrench ready (usually a 5mm Allen). 3) Mount the bike and sit comfortably, leaning against a wall. Apply a brake with one hand (or mount the bike on a turbo trainer). 4) Placing your HEELS on the pedals pedal backwards at 30+ rpm without rocking your pelvis (very important). 5) Adjust seat height so the gap between pedal and heel at bottom dead center is: 5A) ZERO TO ONE HALF CM. for recreational riders (-50 mi/wk.), 5B) ONE HALF TO ONE CM. for experienced riders (50+ mi./wk.), 5C) ONE TO ONE AND ONE HALF CM. for endurance cyclists (250+ mi./wk.). NOTE: Modify these recommendations if your soles are considerably thicker at the cleat than at the heel. It can be difficult to make an accurate measurement without a mirror or friend to do a visual check of your heel and pedal at BDC. (This is especially true for Time and Look style cleats). 6) Ride. It may take a couple of rides to get used to the feel and possibly stretch the hamstrings and Achilles slightly. Roger Marquis (marquis@roble.com)
Subject: 8h.2 Cleat adjustments From: Roger Marquis <marquis@roble.com> [note: You may also want to consider going to a bike shop that does Fit Kit and have them do the Fit Kit RAD to adjust your cleats. Many people recommend it.] [More up to date copies of Roger's articles can be found at http://www.roble.com/marquis/] 1) Grease the cleat bolts and tighten moderately. NOTE: it can be *difficult* to tighten the bolts so they are loose enough to allow cleat movement but tight enough to stay in one place while clipping-out. Depending one the pedals it may be easier to have someone mark the cleat position with a pencil before dismounting. 2) Sitting on the bike, put your feet in the pedals and adjust until: 2B) The ball of your foot is directly above or, more commonly, slightly behind the pedal axle and, 2C) The inside edge of your ankle is approximately parallel with the inside edge of the ball of the foot. This position should feel natural and comfortable when first tried out. Cleats positioned too far forward (on the shoe) can cause excessive ankle movement and result in Achilles strain. When positioned too far back they will be ergonomically inefficient and can cause knee strain. 3) Tighten the cleat bolts fully and go out for a ride. If the position just doesn't feel right repeat steps 1 and 2 with small modifications. Consider also finding a bike shop that does Fit Kits. Many people recommend it for problematic shoes and pedals. Roger Marquis (marquis@roble.com)
Subject: 8h.3 Adjusting SPD Cleats Six adjustments can be made when setting up SPD cleats. With the foot parallel to the ground and pointing in the direction of travel, the adjustments are: 1) Left/right translation 2) Front/back translation 3) Up/down translation 4) Front to back tilt 5) Side to side tilt 6) Azimuth, often called "rotation" Front to back tilt is adjusted as the bicycle is pedaled since the pedals themselves rotate freely in this direction. Some people may need to adjust side to side tilt, but this requires the use of shims which are not provided and can cause the cleat to protrude beyond the tread of the shoe. Custom insoles that have one side slightly thicker than the other may have the same effect as shims between the cleat and the shoe. Separate up/down adjustments for each leg may be necessary for individuals with established leg length differences. To adjust up/down translation in one shoe use a combination of an insole and raise or lower the seat. To make small up/down changes equally in both legs, simply raise or lower the seat. The usual adjustments for SPD cleats are left/right, front/back, and Azimuth. Of these Azimuth is the most sensitive. For most people these three adjustments are sufficient to obtain a comfortable alignment. ----------------- Aligning SPD cleats: Position the cleat so that it lies on the imaginary line between the bony knob on the inside of your foot at the base of your big toe and a similar but smaller knob on the outside of the foot at the base of the smallest toe. Set azimuth so that the pointed end of the cleat points directly toward the front of the shoe. If you're switching from clips and straps, and you are satisfied with your current alignment, use the following alternate method. Position your SPD shoe fully in the clip of your old pedal and align the cleat to the spindle of your old pedal. Center the cleat in the X direction, leaving room to adjust either way should the need arise. Some people find pedaling more comfortable if their left and right feet are closer together. This is sometimes called the "Q-factor". If you prefer to start with a low Q-factor, then move the cleat so that it is as close as possible to the outside of the shoe. Tighten both cleat bolts before engaging the pedal. Adjust the release tension of the pedals so that it is somewhere in the low to middle part of the tension adjustment range. The higher the release tension, the harder it will be for you to disengage the pedals when dismounting. The lower the release tension, the easier it will be for you to inadvertently pull out of the pedals, especially when standing and pedaling. If you stand often to power up hills, consider setting the initial release tension higher as an unwanted release under these conditions can result in a painful spill. See the pedal instructions. Mount your bike on a trainer, if you have one, to make preliminary cleat and release tension adjustments. Practice engaging and disengaging the pedals a few times before you take a real ride. Soon you will find this easy. If you notice that a shoe rubs a crank or chainstay, adjust left/right translation and azimuth until the shoe no longer rubs. As you pedal, you will probably find the initial azimuth uncomfortable on one or both legs. Notice how your foot would like to rotate. Adjust the azimuth of the appropriate cleat in the same direction your foot wants to rotate. For example, if your foot wants to rotate clockwise, adjust the azimuth of the cleat (when looking at the bottom of the shoe) clockwise. Start by making moderate corrections. If you overshoot the adjustment, correct by half as much. As you approach optimum azimuth, you may need to ride longer before you notice discomfort. Take your bike off the trainer, and go for a real ride! And bring your 4mm allen key. You may find very small azimuth adjustments difficult to make. This happens because the cleat has made an indentation in the stiff sole material (usually plastic, sometimes with a tacky, glue-like material where a portion of the sole was removed). When you tighten the cleat after making a small correction, it will tend to slide back into the old indentation. Try moving the cleat one millimeter or so to the side or to the front or back, so the cleat can no longer slip into the old indentation pattern as it is being tightened. Pain in the ball of your foot can be relieved. One way is by moving the cleat rearward. Start by moving the cleat about two to three millimeters closer to the rear of the shoe. Be careful not to change the azimuth. When pedaling notice how far your heel is from the crank. After making a front/rear adjustment, check to make sure the crank-heel distance has not noticeably changed. Moving a cleat rearward on the shoe has the effect of raising your seat by a lesser amount for that leg. The exact expression is messy, but for an upright bike, the effect is similar to raising your seat by about y/3 for that leg, where y is the distance you moved the cleat to the rear. For example, if you move your cleat 6 millimeters to the rear, you might also want to lower your seat by about 2 millimeters. Remember, though, that unless both cleats are moved rearward the same amount, your other leg may feel that the seat is too low. Another way to relieve pain in the ball of the foot is to use a custom orthotic and/or a padded insole. Most cycling shoes provide poor arch support and even poorer padding. After riding for a while with your aligned cleats if you find yourself pulling out of the pedals while pedaling, you will need to tighten the release tension. After tightening the release tension the centering force of the pedals will be higher, and you may discover that the azimuth isn't optimum. Adjust the azimuth as described above. On the other hand, if you find you never pull out of the pedals while pedaling and if you find it difficult or uncomfortable to disengage the cleat, try loosening the release tension. People whose knees like some rotational slop in the cleat may be comfortable with very loose cleat retension. As with any modification that affects your fit on the bike, get used to your pedals gradually. Don't ride a century the day after you install SPDs. Give your body about two or three weeks of gradually longer rides to adapt to the new feel and alignment, especially if you've never ridden with clipless pedals before. Several months after installing SPDs, I occasionally tinker with the alignment. After performing the above adjustments if you are still uncomfortable, seek additional help. Some people can be helped by a FitKit. If you're lucky enough to have a good bike shop nearby, seek their advice. ----------------- Tightening cleat bolts: Tighten cleat bolts until they _begin_ to bind. This will happen when further tightening produces a vibration or squeal from the cleat. Tighten no further or you may damage the mounting plate on the inside of the shoe. After living for a while with a comfortable alignment, remove each mounting bolt separately, apply blue loctite on the threads, and reinstall. Should you later find you need to loosen a bolt to adjust the alignment, you will have to reapply the loctite. Keeping the Pedal/Cleat interface clean: Occasionally you may find the pedals suddenly more difficult to disengage. This usually happens because dirt or other contaminants get caught in the cleat or pedal mechanism. I have found that a good spray with a hose quickly and cleanly washes off dust, mud, or other gunk from the pedal and cleat. You may also wish to spray the pedal with a light silicone or teflon lubricant. Acknowledgements: John Unruh (jdu@ihlpb.att.com) Lawrence You (you@taligent.com) ----------------- Case History: I have sensitive legs--feet, ankles, knees, tendons, etc. If the cleats aren't aligned properly, I feel it. I took a long time to find a cleat alignment that was comfortable for long and/or intense rides. I ride a Bridgestone RB-T, 62cm frame, triple chainring. I wear size 48 Specialized Ground Control shoes--evil-looking black and red things. They were the only shoes I could find in my size that were comfortable. When I installed the M737 pedals, I had 175mm cranks. I set the release tension so that the indicator was at the loose end but so that I could see the entire nut in the slot. The azimuth I found most comfortable had both shoes pointing roughly straight ahead. The ball of my left foot began hurting, so I moved the left cleat back about 4-6mm. This placed the ball of my foot in front of the pedal spindle. I did not make any left/right adjustments. Unfortunately, on longer rides, the ball of my left foot still hurt, so I got a pair of custom CycleVac "Superfeet" insoles. I removed the stock insole from the shoe, and inserted the CycleVac insole. The CycleVac doesn't have any padding at the ball, and my foot didn't like the hard plastic sole of the shoe. I had a pair of thin green Spenco insoles lying around, so I put those under the CycleVacs to provide some padding. I didn't use the stock insoles because they are too thick. Finally, the pain was gone! If I remain pain-free for a while I may try moving the left cleat forward again. Then I replaced the 175mm cranks with 180mm cranks, and I lowered the seat 2.5mm. My left foot was still happy, but my right knee began to complain. Not only that, but my right foot felt as if it was being twisted to the right (supinating), toward the outside of the pedal. After fussing with the azimuth of the right cleat, I couldn't find a satisfactory position, though I could minimize the discomfort. I moved the right cleat as far as I could to the outside of the shoe, bringing my foot closer to the crank. I also reduced the release tension further. The red indicating dots are now just visible. This helped my knee, but my foot still felt as if it were being twisted, as if all the force were being transmitted through the outside of the foot. In addition, my left Achilles Tendon started to hurt at times. I lowered the seat another couple millimeters. This helped, but I felt that my right leg wasn't extending far enough. Then I tried _rotating_ the saddle just a little to the right, so the nose was pointing to the right of center. This helped. But my right foot still felt supinated, and my right knee started to hurt again. I removed the right CycleVac insole and Spenco insole and replaced them with the original stock insole that provides little arch support. Bingo. The discomfort was gone. It seems I need the arch support for the left foot but not for the right foot. How long will it be before I make another tweak? The saga continues... ----------------- Copyright 1993, Bill Bushnell. Feel free to distribute this article however you see fit, but please leave the article and this notice intact.
Subject: 8h.4 SPD cleat compatability From: Eric Salathe <cbcpres@cascade.org> Date: Wed, 10 Mar 1999 11:52:55 -0800 (PST) > 1) Could someone provide a definitive answer (I have been told > different things) about whether the newer Ultegra pedal will accept the > same cleat (I also have the PDA525 on another bike that I would like to > wear the same shoes with). According to the Shimano web page FAQ: =========== Frequently Asked Questions 19) What cleats work with which pedals? The SM-SH70 and SM-SH71 work best with both the PD-7410 and the PD-6500. The SM-SH51 and SM-SH55 work with the PD-M747, M636, M545, M535, M515, M434, M323, A525, M737 and M525. There are a couple usable combinations which can be substituted for the recommended cleat: PD-M747, M636 M545, M535, M515, M434 can use all cleats (70,71,51,55). The PD-A525 and PD-M323 work with all cleats except SM-SH70. The new SH-90, SH-81/91 and SH-82/92 are only compatible with the PD-7700, PD-6600 and PD-5500 SPD-R type pedals. ============== Based on this, I made the following table, which really ought to be on Sheldon's web page (the 70/71 cleats are the standard road-racing cleats and 50/51 are standard two-sided pedal cleats): M747 M636 M545 M535 M515 M434 M737 M525 A525 M323 7410 6500 SPD-R SH70 ok ok ok ok ok ok no no no no yes yes no SH71 ok ok ok ok ok ok no no ok ok yes yes no SH50 yes yes yes yes yes yes yes yes yes yes no no no SH51 yes yes yes yes yes yes yes yes yes yes no no no SPD-R no no no no no no no no no no no no yes So the direct answer is that only the multi-release SH71 cleat will work both with your A525s and with Ultegra 6500 SPDs. > 2) Does anyone have any leftover PDA525 single-sided road pedals > for sale? I don't see what purpose the one-sided A525s serve. Svelt one-sided road-racing pedals make sense for the extremes of weight shaving and corner clearance, but these are not met by the heavier and clunkier A525. You are just giving up the two-sided convienience of the M535 or M515 with no benefit in return except possibly the bogus claim that they are `road pedals' not `MTB pedals'
Subject: 8h.5 Shimmy or Speed Wobble From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Mon, 16 Aug 2004 00:29:14 -0700 Shimmy, a spontaneous steering oscillation of the front wheel, usually occurs at a predictable speed when riding no-hands. The likelihood of shimmy is greatest when the only rider-to-bicycle contact is at the saddle and pedals. This position gives the least damping by hands, arms, and legs. When shimmy occurs on descents, with hands on the bars, it is highly disconcerting because the most common rider response, of gripping the bars firmly, only increases it. Shimmy is not related to frame alignment or loose bearings, as is often claimed. Shimmy results from dynamics of front wheel rotation, mass of the handlebars, elasticity of the frame, and where the rider contacts the bicycle. Both perfectly aligned bicycles and ones with wheels out of plane to one another shimmy nearly equally well. It is as likely with properly adjusted bearings as loose ones. The idea that shimmy is related to bearing adjustment or alignment has been established by repetition. Bicycle shimmy is the lateral oscillation of the head tube about the road contact point of the front wheel and depends largely on frame geometry and the elasticity of the top and down tubes. It is driven by gyroscopic forces of the front wheel, making it largely speed dependent. It cannot be fixed by adjustments because it is inherent to the geometry and elasticity of the bicycle frame. The longer the frame and the higher the saddle, the greater the tendency to shimmy, other things being equal. Weight distribution also has no effect on shimmy although where that weight contacts the frame does. Bicycle shimmy is unchanged when riding no-hands, whether leaning forward or Shimmy requires a spring and a mass about which to oscillate and these are furnished by the frame and seated rider. Unloading the saddle (without standing up) will stop shimmy. Pedaling or rough road will also reduce the tendency to shimmy. In contrast, coasting no-hands downhill on a smooth road at more than 20mph with the cranks vertical seems to be the most shimmy prone condition. When coasting no-hands, laying one leg against the top tube is the most common way to inhibit shimmy and also one of the most common ways to coast no-hands. Compliant tread of knobby tires usually have sufficient squirming damping to suppress shimmy. Weight of the handlebar and its extension from of the steering axis also affects shimmy. Shimmy is caused by the gyroscopic force of the front wheel whose tilt is roughly at right angles to the steering axis, making the wheel steer to the left when it leans to the left. This steering action twists the toptube and downtube, storing energy that both limits travel and causes a return swing. Trail (caster) of the fork acts on the wheel to limit these excursions and return them toward center. Shimmy that concerns riders the most occurs with hands firmly on the bars and it is rider generated by muscular effect whose natural response is the same as the shimmy frequency, about that of Human shivering. Descending in cold weather can be difficult for this reason. The rider's "death grip" only enhances the incidence of shimmy in this situation. Loosely holding the bars between thumb and forefinger is a way of avoiding shimmy when cold.
Subject: 8h.6 Soft Bicycle Saddles From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Fri, 10 Dec 1999 10:26:21 PST > I was wondering if someone could direct me to a bike seat that is > soft. I have a Specialized-brand bike and the seat is hard. What > is the softest seat available? You may already have heard something like this but I think it bears repeating. Bicycle seats are much harder and narrower than you might expect because they are designed to bear on a small area, primarily the protuberances of the pelvic bone that you can feel as solid bumps if you feel under your buttocks as you sit in a chair. If you sit on a larger area, for instance on a soft cushion, you will be sitting on the muscles that propel the bicycle. Although this may be comfortable sitting still, pedaling, it causes a "charley horse" in these muscles for lack of adequate blood circulation. You will want to avoid such soft saddles if you plan to ride more than a few hundred yards because riding will become painful. A better course is to ride a conventional firm saddle, repeatedly, until your seating is no longer sensitive. All bicyclists who ride substantial distances achieve this condition, albeit with various saddles, none of which have the broad deep cushion often sought by newcomers. Even an experienced rider who is laid up or otherwise cannot ride for more than a month, experiences much the same discomfort you do when he returns to riding the saddle that he previously never gave a thought. The big cushioned saddles are made for people who don't ride bicycles. That is why there are so few of them available, and they are generally not found in bicycle shops where the regulars shop.
Subject: 8h.7 Black vs White Helmet - Thermal Test From: terry morse <tmorse@terrymorse.com> Date: Fri, 19 May 2000 10:20:57 -0700 At the encouragement of others, I ran a more elaborate test to see how black and white helmets react thermally in sunlight under forced air cooling. This new test aims to answer the question of whether or not a black helmet is hotter than a white one when worn in direct sunlight, both while at rest and while moving. First of all, many thanks to Mike of Chain Reaction Bicycles <http://www.chainreactionbicycles.com/> for the loan of two Trek Vapor helmets for the test. Mike: I'll be returning the helmets (none the worse for wear) very shortly. Test equiment: 1 regular household fan 1 150W halogen lamp 1 styrofoam head (from a wig store) 1 handheld anemometer 2 Trek Vapor helmets, size large (1 white, 1 black) 1 digital thermometer 1 stopwatch ( photo: <http://www.terrymorse.com/bike/imgs/thtest1.jpg> ) Procedure: Place the temperature probe at the crown of the styrofoam head, and put the helmet on the head. Hang the lamp 5" above the helmet, turn the fan on high speed (6.5 mph), record the temperature every minute until it stops changing. Set the fan on low speed (5.0 mph), record the temperature every minute until it stops changing. Turn off the fan, record the temperature until you can no longer stand it. Repeat test for the black helmet, white helmet, and bare head. Black helmet test photo: <http://www.terrymorse.com/bike/imgs/thtest3.jpg> Bare head test photo: <http://www.terrymorse.com/bike/imgs/thtest2.jpg> Results: Complete Results: <http://www.terrymorse.com/bike/imgs/temps1.jpg> Air-Cooled Detail: <http://www.terrymorse.com/bike/imgs/temps2.jpg> Air Speed | Delta T: Black Hemlet White Helmet Bare Head ----------|-------------------------------------------------- 6.5 mph | 1.4 F 1.1 0.6 5.0 | 2.5 1.5 1.0 0.0 (*) | 20.4 21.1 29.3 ----------|-------------------------------------------------- (*) 16 minutes after turning off fan As I had expected, there is a measurable difference between the black and the white helmets at these air speeds and radiant levels. The temperature rose quickly when the fan was turned off, and it continued to climb for several minutes. There was no significant difference between the white and black helmet in this "no air" sequence, as the temperature increased at basically the same rate for both. The small difference between the two might have been caused by a slight shift in the ambient temperature during the test run. One might conclude that the black surface got hotter and promoted free convection, which made the black helmet wearer slightly cooler. But I would hate to conclude that from these small temperature differences. The bare head test had the greatest and fastest temperature rise in the "no-air" test, even though I had surrounded the temperature probe with a radiation shield (aluminum foil). While styrofoam certainly is not thermally equivalent to the human head, this result add credence to the old adage of wearing a hat on a sunny day (at least when you're not moving).
Subject: 8h.8 Ankling, a pedaling style From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Thu, 09 Nov 2000 14:04:39 PST Ankling, a topic of much discussion, has been claimed to improved performance in bicycling, although not by racers and coaches. It has been touted as one of the techniques for excellence that appeals to bicyclists mainly because it requires no additional effort. That there are different ankle motions while pedaling is apparent, although most of these are not by choice nor do they effect efficiency. Because so much attention was given the subject in the 1960's, it prompted a study in Italy, in which some leading racers noted for their abilities as well as a distinct pedaling style were fit with instrumentation to numerically capture the stroke. Among them was Jacques Anquetil who had a noticeably different ankle motion. The study determined that there was no consistency among those tested and that ankling, much like people's walking gait, is caused by physical individuality rather than any advantage. Typically, some walking gaits are so pronounced that a person can be recognized by it at a distance. Some people raise their heel before stepping off on the next stride while others "peel" the foot from the floor in a continuous motion. To artificially emulate someone's ankle motion or lack thereof, while pedaling, is as useless as emulating a walking gait. The study laid ankling to rest for a while, but because urban legends have a life of their own, rising again at the slightest opportunity, ankling, with its lore, is assured a long life.
Subject: 8i Tech Misc
Subject: 8i.1 Weight = Speed? > I was wondering if anyone could help me figure out why heavier > people roll down hills faster than the little scrawnies like myself. Surface as well as cross sectional area of an object (a human body) increases more slowly than its weight (volume). Therefore, wind drag, that is largely dependent on surface, is proportionally smaller for a heavier and larger object than a smaller one of similar shape and composition. A good example is dust at a rock quarry that remains suspended in the air for a long time while the larger pieces such as sand, gravel, and rock fall increasingly faster to the ground. They are all the same material and have similar irregular shapes but have different weight to surface area ratios, and therefore, different wind resistance to weight ratios. This applies equally to bicyclists coasting down hills if other factors such as clothing and position on the bicycle are similar.
Subject: 8i.2 Traffic detector loops From: Bob Shanteau <shanteau@iname.com> A traffic loop detects metal objects such as cars and bicycles based on the change in inductance that they induce in the loop. The loop is an inductor in an LC circuit that is tuned to resonate at a certain frequency. A metal plate over the loop (like a car) causes the magnetic flux to be shorted, reducing the inductance of the loop. This causes a change in resonant frequency, which is detected and sent to the signal controller. One of the ways of testing a loop is to create a loop about 2 feet in diameter with several turns of wire (connecting the ends) and placing the test wire in the middle of the traffic loop. The test wire should cause a dectection, if all is working. The same effect is seen with a vertical piece of metal, such as a bicycle, but is weaker. Because aluminum conducts electricity quite well, aluminum rims help. Steel rims are OK. Non-metal rims cannot be picked up at all. A bicycle with aluminum rims will cause about 1/100 the change in inductance of a car. It is always possible to set a detector's sensitivity to pick up a bicycle. The trade-off is in longer detection times and the possibility of false detections from vehicles in adjacent lanes. Most people who set signal detectors use the lowest sensitivity setting that will pick up cars reliably. I advocate using the highest setting that will avoid picking up vehicles in adjacent lanes. Digital circuits used in modern detectors can use high sensitivity settings without unacceptable increases in detection times. Unfortunately, there are still a lot of old detectors out there, and most people who work on signals use principles based on the performance characteristics of old detectors. In any case, bicyclists should, as a general rule, place their wheels over one of the slots to maximize their chance of being detected. That is where the magnetic field perpindicular to the wheels is strongest. Bouncing the bike or moving it back and forth does no good. If you have a metal frame, another tactic that may work is to lay the bicycle down horizontally inside the loop until the light turns green. Advancements are under way that may make traffic loops obsolete some day. In particular, radar, infrared and sound detectors have been introduced. Systems based on video cameras are especially promising. Such systems can easily detect bicycles. Such a system may even be able to detect pedestrians some day. Bob Shanteau, PhD. PE Registered Traffic Engineer
Subject: 8i.3 The Continuously Variable Transmission From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Sat, 25 Jan 2003 13:49:06 -0800 (PST) The Continuously Variable Transmission (CVT) is the holy grail of many inventors who are not convinced that it is an impossibility. That is to say, the positive engagement, continuously variable transmission, that does not rely on friction, electrical, or hydraulic ratios but uses mechanical gearing, is not possible. By definition, continuously variable is analog while gears and chains are digital. The CVT does not exist, and I am convinced it will not. If it were possible, railway locomotives, trucks, buses, and cars would long ago have used them. Strangely, it is in bicycling that the strongest believers of the concept reside... as if there were more money to be made in bicycles. In fact, the bicycle, with its enormously adaptable human motor, doesn't need a CVT. In addition, its low input speed and extremely high torque, make the bicycle an especially difficult gearing challenge. For this reason high performance bicycles use derailleur chain drive that is found practically nowhere else. Non-gear CVT's, currently used elsewhere, have poorer efficiency than both planetary gears and derailleur chains. More importantly though, the low-speed high torque of bicycling would require transmissions that would weigh more than the bicycle, which makes them impractical.
Subject: 8i.4 Alenax Bicycle From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Sat, 24 Oct 1998 15:08:52 PDT > Has anyone heard of an Alenax bike? Instead of pedaling a circular > motion, the pedals pump up and down vertically. Strangest riding > bike I've tried. A friend bought one at a garage sale. The Alenax is a great example of an outsider inventing a solution to a perceived problem, creating something that is useless for the intended user. Much money was thrown into the design and manufacture of the Alenax and several years of bicycle show attendance with many models. As soon as you ride it, you'll realize why it doesn't work, even though it has a continuously variable gear ratio. It isn't a CVT (continuously variable transmission) because it relies on reciprocating levers to pull the chains, essentially a rowing machine on which the "oarlock" (fulcrum) is movable. The main problem is that the invention is based on constant velocity lever pedals, instead of circular cranks on which the rotating foot presents no inertial problems and on which the leg moves in sinusoidal motion. The Alenax requires the foot to reach full speed from a stop, before it catches up to the load it is trying to propel, after which it must stop suddenly from full speed at the bottom of the stroke. The action can be simulated by propelling a conventional bicycle with one foot locked into a pedal by rocking the pedal up and down through a small arc about the forward position. The early models had fully independent pedal levers that could be pedaled singly or in parallel or only only one if you wanted. This made the return stroke difficult because the leg and crank had to be pulled back to the top. What was worse is that in the event of a bump in the road, the rider could not stand up, because both pedals would go to the very bottom, fully extending the legs which prevented rising from the saddle. A later version employed a straddle cable over a pulley through which one pedal raised the other, also enabling one to stand on both pedals at half height as on a conventional bicycle. Wheel changes were complicated by two chains, one on each side of the rear wheel, each tensioned by a haulback spring. Each freewheel had one sprocket but I can imagine a large and small one to give more range with a smaller lever extension. The left side required a left handed freewheel. Summing it up, I think the inventor (and investors) did not realize that converting reciprocating motion into circular motion is best done by a rotary crank rather than a reciprocating lever, and above all, they weren't bicyclists. Jobst Brandt <jobst.brandt@stanfordalumni.org>
Subject: 8i.5 Stuck Pedal Removal From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Wed, 18 Feb 2004 12:47:21 -0800 > What's the trick to removing pedals? Of the three times that I have > tried to remove my pedals (I have two bikes and am in the process of > exchanging/switching pedals) I have only succeeded once. The main > problem is the pedals have been put on very tightly and I can't even > budge the damn thing. Left and right pedals have left and right threads respectively, and are best removed with a long handled 15mm pedal wrench. Rather than using any clever wrench orientation or other methods to determine which way to tighten or loosen pedals, use the rule that rotating "forward" (as the wheels of the bicycle do) tightens and rotating "backward" loosens. Pedals are often made with tight fitting threads in an effort to improve the hold of this poorly designed mechanical interface. The intent is to prevent relative motion under load although they move anyway. If that were not the case, the threads would not be left and right handed. That they move is also apparent from damage where the pedal axle frets against the crank face, the main causes of crank failures at the pedal eye. Besides damaging the crank face, fretting motion depletes thread lubrication and causes galling (aka welding) so that pedals often cannot be removed forcefully without damaging pedal shafts, wrenches, or cranks so that forceful removal strips threads. To remove "frozen" pedals from an aluminum crank, remove the crank and pedal from the BB spindle, heat the pedal end of the crank over gas flame cooking stove until it sizzles to the wet touch. Using a pedal wrench, the pedal usually unscrews relatively easily without damage. If a lubricated pedal with clean threads does not screw in easily, a thread tap should be run through the crank to prevent galling on insertion. This is best done on the bicycle, where the crank is held firmly by the BB and prevented from rotation by the chain. To keep chain tension to a minimum (so the rear wheel does not spin), keep the pedal wrench as parallel to the crank as possible rather than as an extension to the crank.
Subject: 8i.6 Removing Pedals From: Mike Iglesias <iglesias@draco.acs.uci.edu> Here's a simple rule to remember which direction to turn the pedals when removing them from the cranks: With the wrench at the 12 o'clock position, turn the wrench towards the rear tire. This works for both the left and right pedal. The left pedal has left-hand threads (tighten counter-clockwise), so it is the opposite of the normal right-hand treads found most everywhere else on the bike.
Subject: 8i.7 Bikecurrent FAQ From: William Burrow <aa126@fan.nb.ca> Date: Wed, 2 Feb 2000 22:57:29 -0400 The bikecurrent FAQ covers issues related to electricity on bicycles, primarily bicycle lighting and providing power to the lighting, whether by generator or battery. Terms and concepts are covered for starting the journey into understanding the topic in detail. http://www.purl.org/bicycling/FAQ/bikecurrent-FAQ/ William Burrow -- New Brunswick, Canada
Subject: 8i.8 Fretting damage in Bicycle Mechanics From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Fri, 11 May 2001 16:35:42 PDT Fretting or to fret: to eat or gnaw away, to erode. In machinery, fretting is the micro-motion of tightly fitting parts that superficially appear immobile with respect to each other. Classically, transmission shafts and gears or axles with a press fit show evidence of motion on disassembly by the presence of rouge, rouge being iron oxide particles that are generated in such interfaces by micro-motions far smaller than conventional measuring equipment can resolve. On bicycles such an interface occurs between the square taper on the pedal crank and its spindle, where rouge is evident on the face of the steel spindle regardless of whether it was assembled with grease or not. That fretting occurs is also evident by the need for a retaining bolt to prevent crank disengagement from its spindle and of pedals from their crank. Removing a crank requires substantial force with an extractor, yet continual fretting will disengage the crank in the absence of a retaining bolt. Likewise pedals are not easily removed, but without a left hand thread on left pedals, they will unscrew. In addition to disengaging the press fit of a crank, fretting moves cranks up the taper until the preload of the retaining and installation bolt matches the press times the slope of the taper. That is to say, fretting relaxes surface friction loads in the interface. Additionally, load distortion of a crank causes it to move away from the face of the retaining bolt, up the taper of the spindle. Pedals have similar relative motions in the attachment thread and pressure face on the shoulder of the spindle. This is also a dynamic joint that appears to be static. In the case of the pedal, fretting motion is directional and can cause precession by the "wandering" load whose center of pressure rotates in the crank thread opposite to the rotation of the crank. Even without clearance, elastic deformation of the crank and pedal spindle cause micro motions that, if not countered by an appropriate thread direction, will unscrew the pedal. The presence of a left hand thread on the left pedal and on many bottom bracket right side bearing cups is proof that fretting occurs. If these motions did not occur, then bolt locking devices, such as cotter pins, lock nuts and lock washers would not be necessary. Most nuts and bolts so secured do not come loose in service and therefore should not rotate. Presence of locking means gives evidence that fretting is more ubiquitous than most people (mechanics and engineers included) believe. Fretting in bearings is a different but similar effect, that is the bane of steering gears and other mechanical devices that are intended to rotate but are primarily used in a fixed position (straight ahead). Automotive patents for anti-fretting steering gears abound. Saginaw, Gemmer, and Ross steering gears come to mind. In bicycles this effect is seen in the bearings of the fork, or head bearings, that are meant to rotate but often experience straight ahead, non rotating use. Because fretting involves invisibly small motion, it remains difficult to understand and hard to convey to the user who suffers fretting symptoms on a piece of machinery. It was long believed that impact cause Brinelling of bicycle head bearings even though mechanics who installed cottered cranks should have noticed an inconsistency in that pounding in cotters with a large hammer with all the shock taken up by one 1/4" ball under the crank spindle never caused a dent, yet 20 balls loaded by a much smaller force through a rubber tire was believed to cause dimpled head bearings. Beyond that, the top bearing that carries practically no load and receives no impact, also became dimpled and, like the bottom load bearing one, did so in the fore and aft quadrant. These dimples were not shiny as Brinell indentations are, but are milky finish typical of tear-outs from asperity welding. Ball bearings operate in two modes that became apparent in the computer disk business because their data actuators often move step by step from track to track, with a radial arm about 1" long, there being more than 20,000 tracks per inch. Servo control engineers must analyze bearing drag to be overcome for this purpose. In such small motions, ball bearings are essentially locked solid with their lubricant film, the bearing appearing as welded balls acting as springs. This "pre-roll" stage of motion is the one that causes the dimples in the bicycle head bearings because they, unlike the disk bearings, have been lubricant depleted from fretting, not having made a larger motion for a longer time, motion that would replenish lubrication between ball and race. Ball bearings roll on a film of oil that is so thin that it does not present liquid properties, being several mono-molecular layers thick as it adheres to ball and race. If it weren't for this behavior, oil would not remain in the interface. However, with fretting, oil is displaced and pin point welding takes place. Bicycle head bearing fretting is caused by fore and aft rocking of the fork crown, a motion that lies below visible resolution, and is small enough to not replenish lubricant. Bearing damage appears as dimples from myriad asperity contacts that welded and broke loose as the ball fretted in place, leaving a milky finish. Road bicycles are more subject to this damage than off road bicycles because they spend more time traveling straight ahead, especially when coasting downhill. Fretting damage occurs during these times, because lubrication is not replenished by steering motions. The compound bearings offered by Shimano seem to have greatly reduced the problem by taking up fork crown rocking motion in a plain steel on aluminum spherical cup that is not prone to metal to metal contact, while steering rotations are borne in a pre-loaded full complement angular contact ball bearing supported by this plain bearing.
Subject: 8i.9 Left hand threads From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date: Wed, 28 Apr 2004 16:14:11 PST On bicycles, left hand threads are used mainly in three places, on left pedals, right bottom bracket (BB) bearing cups, and freewheel cones, to prevent unscrewing under operating loads. Unscrewing occurs from precession, in which a round object rolling in a circular ring in one direction will itself turn in the opposite direction. For a pedal, a rotating load arises form downward pedaling force on a spindle rotating with its crank making the predominantly downward force effectively rotate about the pedal spindle. What may be less evident is that even tightly fitting parts have relative clearance due to their elasticity, metals not being rigid materials as is evident from steel springs. Under load, micro deformations, enough to cause motion, occur in such joints. This can be seen from wear marks where pedal spindles seat on crank faces. Precession of right side BB cups is less obvious because the rotating load is only partial. The largest load being chain tension, that together with the moderately large downward force on the right crank and the smaller upward force from pushing down on the left crank, make 3/4 of a fully rotating load. For this reason some right BB cups have used right hand threads and some with left hand threads have loosened. The left BB cup with no significant rotating load has little tendency to turn. Freewheel cones are more obvious candidates for precession, their load being mainly radial, and rotating continuously in the direction that would unscrew a right hand thread. There are other such but less common threads on bicycles. Precession forces are large enough that no manner of thread locking glues, short of welding, will arrest them. Mechanical fretting, the micro-motion of tightly fitting parts moving against one another, is the mechanism of this motion. Motion in these joints causes visible fretting rouge, red iron oxide, on the shoulder of the BB cup and on the face of the pedal spindle. Left hand threads would not be required on left pedals if a design common on cars were used. Before the advent of conical lug nuts, many cars used left hand threads on left side wheels. Today, stories of wheels rolling away from cars no longer make news, the conical seat having solved this problem on car wheels as it could on bicycle pedals. However, unscrewing is not the main problem for pedals, but rather crank failure caused by fretting erosion of the pedal eye. Fretting initiates cracks that can cause sudden and unsuspected pedal separation when the eye of a crank breaks. Because this occurs equally with right and left cranks it is the more important reason for a conical spindle face and crank eye. This has been tested. ---------------------
Subject: 9 Misc
Subject: 9.1 Books and Magazines Magazines/Newsletters --------- Bicycling Magazine, and Bicycling Magazine+Mountain Bike insert 33 E Minor St Emmaus, PA 18098 (215) 967-5171 Bicycle Guide 711 Boylston Street Boston MA 02116 617-236-1885 Mountain Biking 7950 Deering Avenue Canoga Park CA 91304 818-887-0550 Mountain Bike Action Hi-Torque Publications, Inc. 10600 Sepulveda Boulevard Mission Hills, CA 91345 818-365-6831 Velo News P.O. Box 53397 Boulder, CO 80323-3397 velonews@aol.com Cycling Science P.O. Box 1510 Mount Shasta, California 96067 (916) 938-4411 Human Power (The Journal of the IHPVA*) (* IHPVA == International Human Powered Vehicle Association) HPVA PO Box 1307 San Luis Obispo, CA 93406-1307 USA 1 (360) 323-1384 fax <http://www.ihpva.org/> OnTour: The Newsletter for Bicycle Tourists OnTour Publications 2113 Arborview Ann Arbor, MI 48103. Sample issues are only $1, a six-issue subscription only $6 R.B.C.A./The Recumbent Cyclist 17650-B6-140th Ave. SE, Suite 341 Renton, WA 98058 USA Tandem Club of America Malcolm Boyd & Judy Allison 19 Lakeside Drive NW Medford Lakes, NJ 08550 Dues are currently $10/year Dirt Rag 5742 Third St. Verona, PA (412) 795 - 7495 FAX (412) 795 - 7439 Bike Culture Quarterly is an engaging magazine for "[people] who see cycling as a way of life rather than an occasional leisure activity". It has interviews with people building interesting bikes (Mike Burrows about the Obree bike), travel reports, discussions of bicycle advocacy, new equipment, and so on. Its summer issue is the "Encycleopedia" "a personal selection of unorthodox, thoughtful cycling products from around the world". Price is (British Pounds) 25/year. Order by phone UK: (0904) 654654 outside UK: +44904 654654 Post: Open Road 4 New Street York Y01 2RA, England They accept Visa, Access, Mastercard, and Eurocard. Eurocheques are also accepted. From the US, it's easiest to use a credit card. Books ----- Bicycling Magazine's Complete Guide to Bicycle Maintenance and Repair Rodale Press ISBN 0-87857-895-1 Effective Cycling by John Forester MIT Press ISBN 0-262-56026-7 The Bicycle Wheel by Jobst Brandt Avocet ISBN 0-9607236-6-8) English ISBN 0-9607236-4-1) German Bicycle Maintenance Manual by Eugene A. Sloan (a Fireside book, pub. Simon & Schuster, Inc.) ISBN 0-671-42806-3 Anybody's Bike Book by Tom Cuthbertson Bicycles and Tricycles An Elementary Treatise on Their Design and Construction by Archibald Sharp Reprint of the 1896 edition, with a foreword by David Gordon Wilson Anytime you hear of a "new" invention for bicycles, look it up in here, and you'll find it. MIT press - I have a paperback edition labelled $14.95 Bicyling Science by Frank Rowland Whitt and David Gordon Wilson A good book, and an excellent reference. Second Edition 1982, MIT press, paper $9.95 Bicycle Road Racing by Edward Borysewicz The Woman Cycist by Elaine Mariolle Contemporary Books Touring on Two Wheels by Dennis Coello Lyons and Berrfard, New York The Bicyclist's Sourcebook by Michael Leccese and Arlene Plevin Subtitled: "The Ultimate Directory of Cycling Information" Woodbine House, Inc. $16.95 ISBN 0-933149-41-7 Colorado Cycling Guide by Jean and Hartley Alley Pruett Publishing Company Boulder, Colorado The Canadian Rockies Bicycling Guide by Gail Helgason and John Dodd Lone Pine Publishing,Edmonton, Alberta A Women's Guide to Cycling by Susan Weaver Favorite Pedal Tours of Northern California by Naomi Bloom Fine Edge Productions, Route 2, Box 303, Bishop, CA 93514 Mountain Biking Near Boston: A Guide to the Best 25 Places to Ride by Stuart A. Johnstone, Active Publications (1991), ISBN 0-9627990-4-1 Mountain Bike: a manual of beginning to advanced technique by William Nealy, Menasha Ridge Press, 1992, ISBN 0-89732-114-6 Greater Washington (DC) Area Bicycle Atlas American Youth Travel Shops, 1108 K St, NW Wash, DC 20005 (202)783-4943 $12.95 Bicycle Parking by Ellen Fletcher Ellen Fletcher, 777-108 San Antonio Road, Palo Alto, CA 94303-4826 Cost: $5.95, plus 43 cents tax, plus $3 postage/handling Richards' Ultimate Bicycle Book Richard Ballantine, Richard Grant (Dorling Kindersley, London, 1992) Bicyclopedia: A Comprehensive Encyclopedia of Bicycles and Bicycling, Edited by Steven Olderr, ECI #290". (Wonder what "ECI #290" means. . . .) <http://homepage.interaccess.com/~opcc/bc/>. The Bicycle, by Pryor Dodge. Paris: Flammarion, 1996. ISBN 2-08013-551-1. Distributed in the US by Abbeville Press (same ISBN), $50. Lavishly produced hardback book about the history of the bicycle, intelligently written and superbly illustrated. Considering what you get, it is good value--especially as it is available discounted. (Amazon charge $35.) Bicycling Japan: A Touring Handbook, by Suzanne Lee. Carmichael, Calif.: Zievid Press, 1991. ISBN 0-9627458-0-4. $6.95. In print (I think). A slim paperback with a lot of information about cycling around Japan. Aimed toward people who are new to Japan, but still of use to those who know it other than as cyclists. Lacks information or tips about where are better places to go. Cycling Japan: A Personal Guide to Exploring Japan by Bicycle, ed. Bryan Harrell. Tokyo & New York: Kodansha International, 1993. ISBN 4-7700-1742-1. 2200 yen / US$18. In print. A paperback with some tips on cycling in Japan, but much more about particular itineraries. So specific--with phone numbers of minshuku (pensions), etc.--that it is likely to become dated and should therefore be used with care.
Subject: 9.2 Mail Order Addresses Here's the addresses/phone numbers of some popular cycling mail order outfits (you can get directory assistance for 800 numbers at 1-800-555-1212 if you don't see the mail order outfit you're looking for here): Bicycle Posters and Prints P.O. Box 7164 Hicksville, NY 11802-7164 Sells bicycle posters and other stuff. Branford Bike orders: 1-800-272-6367 info: 203-488-0482 fax: 203-483-0703 Colorado Cyclist orders: 1-800-688-8600 info: 719 591-4040 fax: 719 591-4041 WWW: http://www.coloradocyclist.com/ 3970 Bijou Street Colorado Springs, CO 80909-9946 Cyclo-Pedia (800) 678-1021 P.O. Box 884 Adrian MI 49221 Catalog $1 as of 4/91. Excel Sports International orders: 1-800-627-6664 info: 303-444-6737 fax: 303-444-7043 2045 32nd Street Boulder CO 80301 Loose Screws (541) 488-4800 (541) 488-0080 FAX 12225 HWY 66 Ashland OR 97520 Nashbar orders: 1-800-627-4227 (1-800-NASHBAR) 216-782-2244 Local and APO/FPO orders info: 216-788-6464 Tech. Support fax: 800-456-1223 WWW: http://www.nashbar.com/ 4111 Simon Road Youngstown, OH 44512-1343 Pedal Phernalia Phone: 1-313-995-1336 Box 2566-net Ann Arbor MI 48106-2566 Performance Bike Shop orders: 1-800-727-2453 (1-800-PBS-BIKE) 919-933-9113 Foreign orders info: 800-727-2433 Customer Support fax: WWW: http://www.performanceinc.com/PerfBicycle.html One Performance Way P.O. Box 2741 Chapel Hill, NC 27514 R&R Bicycles phone: 412-751-5341 WWW: http://www.rrbicycle.com/ 1026 E Smithfield Boston, PA 15135 Schwab Cycles orders: 1-800-343-5347 info: 303-238-0243 fax: 303-233-5273 1565 Pierce St. Lakewood, CO 80214 Triathlete Zombies (800-999-2215) The Womyn's Wheel, Inc. (Specializes in clothing and equipment for women) 800-795-7433 508-240-2437 P.O. Box 2820 Orleans MA 02653
Subject: 9.3 Road Gradient Units From: Jeff Berton <jeff344@voodoo.lerc.nasa.gov> The grade of an incline is its vertical rise, in feet, per every 100 horizontal feet traversed. (I say "feet" for clarity; one could use any consistent length measure.) Or, if you will accept my picture below, * d | a | o | y R Theta | *___)______________| x then Grade = y/x (Multiply by 100 to express as a percentage.) and Theta = arctan(y/x) So a grade of 100% is a 45 degree angle. A cliff has an infinite grade. [More from Jobst Brandt <jobst.brandt@stanfordalumni.org>] Date: Mon, 26 Apr 1999 16:11:44 PDT The steepness of a road is generally measured in % grade, which in mathematical terms is the slope, or TANGENT of the angle, measured from the horizontal. This is the ratio of elevation change per horizontal distance traveled, often called "rise over run". Typically a road that rises 1-in-10, is otherwise called 10% grade. Measuring the distance along the surface of the road instead of horizontally gives practically the same result for most road gradients. The distance along the road surface gives the SINE of the angle in contrast to the horizontal distance that gives the TANGENT. For practical purposes SINE equals TANGENT for small angles (up to ten degrees or so). For instance, a 20% grade (11.3 degrees), whereas measuring along the road surface gives a 19.6% grade. The slope of a road is more useful than its angle because it gives a direct way to assess the effort required to move forward against the grade, whereas the angle in degrees does not readily reveal this information. A 5% grade requires a forward force of approximately 5% of the vehicle weight (above and beyond the force it takes to travel similarly on flat ground). A 15% grade requires a propulsion force of approximately 15% of the vehicle weight. Although the angle may be more easily visualized, it does not convert easily to effort without a calculator. For instance a 20% grade is an 11.3 degree angle and is a steep and difficult gradient. The relationship between angle and slope is non linear becoming 100% (1:1) at a 45 degree angle. In contrast, the SINE of 45 degrees is 70.7% while the SINE of 90 degrees (straight up) is 100% for which the slope (TANGENT) is infinity (or undefined). The most accurate way to measure this without a precision inclinometer, is to use a level, a one meter long bar and a metric ruler. Resting one end of the rod (held level) on the road at a representative spot, measuring the distance down to the road at the other end in centimeters gives the percent grade directly. Using a carpenters level and a one meter long rectangular bar can give accurate readings to a couple of tenths of a percent.
Subject: 9.4 Helmet FAQ now on-line From: ab833@FreeNet.Carleton.CA (Avery Burdett) Date: 11 Nov 1998 20:39:30 GMT The net's first researched-based Helmet FAQ dealing with common misconceptions about helmets is now on-line at: http://www.magma.ca/~ocbc/hfaq.html It answers questions about testing procedures, helmet effectiveness, problems with modern helmets, the problem with Thompson and Rivara's claim of 85% reduction in risk, why some people wear helmets and some don't, whether cycling is dangerous, whether helmet wearing changes cyclist behaviour, helmet laws, helmet promotion, impact on health, and effective ways to reducing injuries. Among the materials linked are: - Failure Research Associates' Comparative Risk of Different Activities - Traumatic brain injury data and other stats - Fatality data from US National Highway Transportation Safety Administration - Fatality trend chart based NHTSA data - Two papers presented to Velo Australis, 1996 on results of Australian helmet laws - Abstract of the Scuffham/Langley paper on the effect of helmet use in New Zealand - Abstract of Dorothy Robinson's paper on the effect of helmet laws in Australi a - Summary of Mayer Hillman's publication "Cycle Helmets - the case for and against - industry test standards and procedures - Gerald Wilde's work on risk compensation - article on car helmets - the next "innovative" product from the safety industry - list of printed sources
Subject: 9.5 Terminology From: David Keppel <pardo@cs.washington.edu>, Charles Tryon <bilbo@bisco.kodak.com> Ashtabula Crank A one-piece crank -- the crank arm starts on one side of the bike, bends to go through the bottom bracket, and bends again on the other side to go down to the other pedal. Typically heavy, cheap, and robust. See ``cottered crank'' and ``cotterless crank''. Ashtabula is the name of the original manufacturer, I think. Biopace Chainring Chainrings that are more oval rather than round. The idea was to redistribute the forces of pedaling to different points as your feet go around, due to the fact that there are "dead spots" in the stroke. The concensus is pretty much that they work ok for novices, but get in the way for more experienced riders. Cassette Freewheel A cassette freewheel is used with a freehub. The part of a normal freewheel that contains the pawls that transfer chain motion to the wheel (or allows the wheel to spin while the chain doesn't move) is part of the wheel hub. The cassette is the cogs, usually held together with small screws. Cleat A cleat attaches to the bottom of a cycling shoe. Older style cleats have a slot that fits over the back of the pedal, and in conjunction with toe clips and straps, hold your foot on the pedal. New "clipless" pedals have a specially designed cleat that locks into the pedal, sometimes with some ability to move side-to-side so as not to stress knees. Cottered Crank A three-piece crank with two arms and an axle. The arms each have a hole that fits over the end of the axle and a second hole that runs tangential to the first. The crank axle has a tangential notch at each end. A *cotter* is a tapered and rounded bar of metal that is inserted in the tangential hole in the crank arm and presses against the tangential notch in the crank axle. The cotter is held in place by a nut screwed on at the thin end of the cotter. Ideally, the cotter is removed with a special tool. Often, however, it is removed by banging on it with a hammer. If you do the latter (gads!) be sure (a) to unscrew the nut until the end of the cotter is nearly flush, but leave it on so that it will straighten the threads when you unscrew it farther and (b) brace the other side of the crank with something very solid (the weight of the bike should be resting on that `something') so that the force of the banging is not transmitted through the bottom bracket bearings. Cotterless Crank A three-piece crank with two arms and an axle. Currently (1991) the most common kind of crank. The crank axle has tapered square ends, the crank arms have mating tapered square ends. The crank arm is pressed on and the taper ensures a snug fit. The crank arm is drawn on and held in place with either nuts (low cost, ``nutted'' cotterless cranks) or with bolts. A special tool is required to remove a cotterless crank. Crank Axle The axle about which the crank arms and pedals revolve. May be integrated with the cranks (Ashtabula) or a separate piece (cottered and cotterless). Fender Also called a ``mudguard''. Looked down upon by tweak cyclists, but used widely in the Pacific Northwest and many non-US parts of the world. Helps keep the rider cleaner and drier. Compare to ``rooster tail''. Frame Table A big strong table that Will Not Flex and which has anchors at critical places -- dropouts, bottom bracket, seat, head. It also has places to attach accurate measuring instruments like dial gauges, scratch needles, etc. The frame is clamped to the table and out-of-line parts are yielded into alignment. High-Wheeler A bicycle with one large wheel and one small wheel. The commonest are large front/small rear. A small number are small front/large rear. See ``ordinary'' or ``penny-farthing'' and contrast to ``safety''. Hyperglide Freewheel Freewheel cogs with small "ramps" cut into the sides of the cogs which tend to pull the chain more quickly to the next larger cog when shifting. Ordinary See ``penny-farthing''. Penny-Farthing An old-fashioned ``high wheeler'' bicycle with a large (60", 150cm) front wheel and a much smaller rear wheel, the rider sits astride the front wheel and the pedals are connected directly to the front wheel like on many children's tricycles. Also called ``ordinary'', and distinguished from either a small front/large rear high wheeler or a ``safety'' bicycle. Rooster Tail A spray of water flung off the back wheel as the bicycle rolls through water. Particularly pronounced on bikes without fenders. See also ``fender''. Safety Named after the ``Rover Safety'' bicycle, the contemporary layout of equal-sized wheels with rear chain drive. Compare to ``ordinary''. Spindle See ``crank axle''. Three-Piece Crank A cottered or cotterless crank; compare to Ashtabula.
Subject: 9.6 Avoiding Dogs From: Arnie Berger <arnie.berger@amd.com> There are varying degrees of defense against dogs. 1- Shout "NO!" as loud and authoritatively as you can. That works more than half the time against most dogs that consider chasing you just good sport. 2- Get away from their territory as fast as you can. 3- A water bottle squirt sometimes startles them. 4- If you're willing to sacifice your pump, whump'em on the head when they come in range. If they're waiting for you in the road and all you can see are teeth then you in a heap o' trouble. In those situations, I've turned around, slowly, not staring at the dog, and rode away. When I have been in a stand off situation, I keep the bike between me and the dog. "Halt" works pretty well, and I've used it at times. It's range is about 8 feet. I bought a "DAZER", from Heathkit. Its a small ultrasonic sound generator that you point at the dog. My wife and I were tandeming on a back road and used it on a mildly aggressive German Shephard. It seemed to cause the dog to back off. By far, without a doubt, hands down winner, is a squirt bottle full of reagent grade ammonia, fresh out of the jug. The kind that fumes when you remove the cap. When I lived in Illinois I had a big, mean dog that put its cross-hairs on my leg whenever I went by. After talking to the owner (redneck), I bought a handebar mount for a water bottle and loaded it with a lab squirt bottle of the above mentioned fluid. Just as the dog came alongside, I squirted him on his nose, eyes and mouth. The dog stopped dead in his tracks and started to roll around in the street. Although I continued to see that dog on my way to and from work, he never bothered me again. Finally, you can usually intimidate the most aggressive dog if there are more than one of you. Stopping, getting off your bikes and moving towards it will often cause it to back off. ( But not always ). My bottom line is to alway ride routes that I'm not familiar with, with someone else. As last resort, a nice compact, snubbed nose .25 caliber pistol will fit comfortably in your jersey pocket. :-)
Subject: 9.7 Shaving Your Legs How to do it (Garth Somerville somerville@bae.ncsu.edu) Many riders shave their legs and have no problems other than a nick or two once in a while. Maybe a duller blade would help. But some people (like me) need to be more careful to avoid rashes, infections (which can be serious), or just itchy legs that drive you to madness. For those people, here is my leg shaving procedure: Each time you shave your legs... 1) Wash your legs with soap and water, and a wash cloth. This removes dirt, oil, and dead skin cells. 2) Use a good blade and a good razor. I prefer a blade that has a lubricating strip (e.g. Atra blades). It is my personal experience that a used blade is better than a new one. I discard the blade when the lubricating strip is used up. 3) USE SHAVING CREAM. I prefer the gell type, and the kinds with aloe in them seem to be the best. Shaving cream gives you a better shave with fewer cuts, and goes a long way towards preventing infection. 4) Use *COLD* water. Do not use hot water, do not use warm water, use the coldest water you can stand. Run the cold water over your legs before you start, and rinse the blade often in cold water. 5) Be careful, and take your time. Behind the knees, and around the achilles tendon are places to be extra careful. 6) When finished, use a moisturizing lotion on your legs. Why shave legs (Jobst Brandt jobst.brandt@stanfordalumni.org) Why do bicyclists shave their legs? This question arises regularly, although sometimes it's a troll, sometimes it's a rider who didn't dare ask his shaven riding companions. Had he done so, among the real answer, he would probably have gotten: To prevent infection when crashing. To pull off bandages more painlessly after dressing a wound. To get a massage of the legs without hair pulling. To be more streamlined in the wind. etc Hair does not cause infections and if it is a gash that goes deeper than the typical raspberry, there will be more dirt in it han a few hairs. In any case, where a wound needs stiches the skin will be shaved around the opening anyway for the reson that hair inclusions are as bad as dirt inclusions. Don't put tape on a hairy leg or arm. Shave it first. Every medic kit should have a Bic razor or better anyway. Many folks with hair get massages and it has no effect on comfort. You'd think from this excuse, that those who shave get massages regularly and that massage parlors always shave their customers. Neither is true. If this is a streamlining increment, then the rider should first get a tight fitting Lycra jersey and shoe covers. The other excuses are just that. Bicycle athletes shave for the same reason body builders and women do it. Shaving exposes the sculptured lines of muscle definition (defo) or the absence of it for some women and some of the best legs are on bikies. Not only that, embrocation, (oiling up with exotic smelling greases or oils is the same as in body building and weight lifting), it emphasizes defo. If the soigner tells the rider that this will improve performance, he'll accept that gladly.
Subject: 9.8 Contact Lenses and Cycling From: Robert A. Novy <ra_novy@drl.mobil.com> I received on the order of 50 replies to my general query about contact lenses and bicycling. Thank you! To summarize, I have been wearing glasses for nearly all of my 28 years, and taking up bicycling has at last made me weary of them. I visited an optometrist last week, and he confirmed what I had lightly feared: I am farsighted with some astigmatism, so gas-permeable hard lenses are the ticket. He has had about a 25% success rate with soft lenses in cases such as mine. I am now acclimating my eyes to the lenses, adding one hour of wear per day. In case these don't work out, I'll try two options. First, bicycle without prescription lenses (my sight is nearly 20-20 without any). Second, get a pair of prescription sport glasses. I had a particular request for a summary, and this is likely a topic of great interest, so here goes. Please recognize the pruning that I must do to draw generalizations from many opinions. Some minority views might be overlooked. There is one nearly unanimous point: contact lenses are much more convenient than eyeglasses. I had to add the word "nearly" because I just saw one voice of dissent. Sandy A. (sandya@hpfcmdd.fc.hp.com) has found that prescription glasses are better suited to mountain biking on dusty trails. You can call me Doctor, but I have no medical degree. This is only friendly advice from a relatively ignorant user of the Internet. See the first point below! IN GENERAL + Get a reputable optometrist or ophthalmologist. Your eyes are precious. [Paul Taira (pault@hpspd.spd.hp.com) even has an iterative check-and-balance setup between his ophthalmologist and a contact lens professional.] + Wear sunglasses, preferably wrap-arounds, to keep debris out of eyes, to keep them from tearing or drying out, and to shield them from ultraviolet rays, which might or might NOT be on the rise. + Contacts are not more hazardous than glasses in accidents. + Contacts improve peripheral and low-light vision. + Extended-wear soft lenses are usually the best. Next come regular soft lenses and then gas-permeable hard lenses. Of course, there are dissenting opinions here. I'm glad to see that some people report success with gas perms. + One's prescription can limit the types of lenses available. And soft lenses for correcting astigmatisms seem pesky, for they tend to rotate and thus defocus the image. This is true even for the new type that are weighted to help prevent this. Seems that near-sighted people have the most choices. + If one type or brand of lens gives discomfort, try another. Don't suffer with it, and don't give up on contact lenses altogether. BEWARE + Some lenses will tend to blow off the eye. Soft lenses are apparently the least susceptible to this problem. PARTICULAR SUGGESTIONS + Consider disposable lenses. They may well be worth it. + Carry a tiny bottle of eye/lens reconditioner and a pair of eyeglasses just in case. A POSSIBLE AUTHORITY From David Elfstrom (david.elfstrom@canrem.com): Hamano and Ruben, _Contact Lenses_, Prentice-Hall Canada, 1985, ISBN 0-13-169970-9. I haven't laid hands on it, but it sounds relevant.
Subject: 9.9 How to deal with your clothes When you commute by bike to work, you'd probably like to have clean clothes that don't look like they've been at the bottom of your closet for a couple of years. Here are some suggestions for achieving this goal: Take a week's worth of clothes to work ahead of time and leave them there. You'll probably have to do this in a (gasp!) car. This means that you'll need room in your office for the clothes. Carefully pack your clothes in a backpack/pannier and take them to work each day. It has been suggested that rolling your clothes rather than folding them, with the least-likely to wrinkle on the inside. This method may not work too well for the suit-and-tie crowd, but then I wouldn't know about that. :-) I use the second method, and I leave a pair of tennis shoes at work so I don't have to carry them in. This leaves room in my backpack for a sweatshirt in case it's a cool day.
Subject: 9.10 Pete's Winter Cycling Tips From: Pete Hickey <pete@panda1.uottowa.ca> I am a commuter who cycles year round. I have been doing it for about twelve years. Winters here in Ottawa are relatively cold and snowy. Ottawa is the second coldest capital in the world. The following comments are the results my experiences. I am not recommending them, only telling you what works for me. You may find it useful, or you may find the stupid things that I do are humorous. PRELUDE Me: I am not a real cyclist. I just ride a bicycle. I have done a century, but that was still commuting. There was a networking conference 110 miles away, so I took my bicycle. There and back. (does that make two centuries?) I usually do not ride a bicycle just for a ride. Lots of things I say may make real cyclists pull out their hair. I have three kids, and cannot *afford* to be a bike weenie. People often ask me why I do it.... I don't know. I might say that it saves me money, but no. Gasoline produces more energy per dollar than food. (OK, I suppose if I would eat only beans, rice and pasta with nothing on them.... I like more variety) Do I do it for the environment? Nah! I never take issues with anything. I don't ride for health, although as I get older, I appreciate the benefits. I guess I must do it because I like it. Definitions Since words like "very", "not too", etc. are very subjective, I will use the following definitions: Cold : greater than 15 degrees F Very cold : 0 through 15 Degrees F Extreme cold : -15 through 0 degrees F Insane cold: below -15 degrees F Basic philosophy I have two: 1) If its good, don't ruin it, if its junk you needn't worry. 2) I use a brute force algorithm of cycling: Pedale long enough, and you'll get there. Bicycle riding in snow and ice is a problem of friction: Too much of the rolling type, and not enough of the sideways type. Road conditions: More will be covered below, but now let it suffice to say that a lot of salt is used on the roads here. Water splashed up tastes as salty as a cup of Lipton Chicken soup to which an additional spool of salt has been added. Salt eats metal. Bicycles dissolve. EQUIPMENT: Bicycle: Although I have a better bicycle which I ride in nice weather, I buy my commuting bikes at garage sales for about $25.00. They're disposable. Once they start dissolving, I remove any salvageable parts, then throw the rest away. Right now, I'm riding a '10-speed' bike. I used to ride mountain bikes, but I'm back to the '10-speed'. Here's why. Mountain bikes cost $50.00 at the garage sales. They're more in demand around here. Since I've ridden both, I'll comment on each one. The Mountain bikes do have better handling, but they're a tougher to ride through deep snow. The 10-speed cuts through the deep snow better. I can ride in deeper snow with it, and when the snow gets too deep to ride, its easier to carry. Fenders on the bike? Sounds like it might be a good idea, and someday I'll try it out. I think, however, that snow/ice will build up between the fender and the tire causing it to be real tough to pedal. I have a rack on the back with a piece of plywood to prevent too much junk being thrown on my back. I would *like* to be able to maintain the bike, but its tough to work outside in the winter. My wife (maybe I should write to Dear Abbey about this) will not let me bring my slop covered bicycle through the house to get it in the basement. About once a month We have a warm enough day that I am able to go out with a bucket of water, wash all of the gunk off of the bike, let it dry and then bring it in. I tear the thing down, clean it and put it together with lots of grease. I use some kind of grease made for farm equipment that is supposed to be more resistant to the elements. When I put it together, I grease the threads, then cover the nuts, screws, whatever with a layer of grease. This prevents them from rusting solidly in place making it impossible to remove. Protection against corrosion is the primary purpose of the grease. Lubrication is secondary. remember to put a drop of oil on the threads of each spoke, otherwise, the spokes rust solidly, and its impossible to do any truing Outside, I keep a plastic ketchup squirter, which I fill with automotive oil (lately its been 90 weight standard transmission oil). Every two or three days, I use it to re- oil my chain and derailleur, and brakes. It drips all over the snow beneath me when I do it, and gets onto my 'cuffs'(or whatever you call the bottom of those pants. See, I told you I don't cycle for the environment. I probably end up dumping an ounce of heavy oil into the snow run-off each year. Clothing Starting at the bottom, on my feet I wear Sorell Caribou boots. These are huge ugly things, but they keep my feet warm. I have found that in extreme to insane cold, my toes get cold otherwise. These boots do not make it easy to ride, but they do keep me warm (see rule 2, brute force). They do not fit into any toe-clips that I have seen. I used to wear lighter things for less cold weather, but I found judging the weather to be a pain. If its not too cold, I ride with them half unlaced. The colder it gets, the more I lace them, and finally, I'll tie them. Fortunately, wet days are not too cold, and cold days are not wet. When its dry, I wear a pair of cycling shorts, and one or two (depending on temp and wind) cotton sweat pants covering that. I know about lycra and polypro (and use them for skiing), but these things are destroyed by road-dirt, slush and mud.(see rule 1 above). I save my good clothes for x-country skiing. An important clothing item in extreme to insane cold, is a third sock. You put it in your pants. No, not to increase the bulge to impress the girls, but for insulation. Although several months after it happens it may be funny, when it does happens, frostbite on the penis is not funny. I speak from experience! Twice, no less! I have no idea of what to recommend to women in this section. Next in line, I wear a polypro shirt, covered by a wool sweater, covered by a 'ski-jacket' (a real ugly one with a stripe up the back. The ski jacket protects the rest of my clothes, and I can regulate my temperature with the zipper in front. I usually take a scarf with me. For years I have had a fear that the scarf would get caught in the spokes, and I'd be strangled in the middle of the street, but it has not yet happened. When the temp is extreme or colder, I like keeping my neck warm. I have one small problem. Sometimes the moisture in my breath will cause the scarf to freeze to my beard. On my hands, I wear wool mittens when its not too cold, and when it gets really cold, I wear my cross-country skiing gloves (swix) with wool mittens covering them. Hands sweat in certain areas (at least mine do), and I like watching the frost form on the outside of the mittens. By looking at the frost, I can tell which muscles are working. I am amused by things like this. On my head, I wear a toque (Ski-hat?) covered by a bicycle helmet. I don't wear one of those full face masks because I haven't yet been able to find one that fits well with eye glasses. In extreme to insane cold, my forehead will often get quite cold, and I have to keep pulling my hat down. The bottoms of my ears sometimes stick out from my hat, and they're always getting frostbitten. This year, I'm thinking of trying my son's Lifa/polypro balaclava. Its thin enough so that it won't bother me, and I only need a bit more protection from frostbite. I carry my clothes for the day in a knapsack. Everything that goes in the knapsack goes into a plastic bag. Check the plastic bag often for leaks. A small hole near the top may let in water which won't be able to get out. The net result is that things get more wet than would otherwise be expected. The zippers will eventually corrode. Even the plastic ones become useless after a few years. RIDING: In the winter, the road is narrower. There are snow banks on either side. Cars do not expect to see bicycles. There are less hours of daylight, and the its harder to maintain control of the bicycle. Be careful. I don't worry about what legal rights I have on the road, I simply worry about my life. I'd rather crash into a snow bank for sure rather than take a chance of crashing into a car. I haven't yet had a winter accident in 12 years. I've intentionally driven into many snow banks. Sometimes, during a storm, I get into places where I just can't ride. It is sometimes necessary to carry the bicycle across open fields. When this happens, I appreciate my boots. It takes a lot more energy to pedal. Grease gets thick, and parts (the bicycle's and mine) don't seem to move as easily. My traveling time increases about 30% in nice weather, and can even double during a raging storm. The wind seems to be always worse in winter. It's not uncommon to have to pedal to go down hills. Be careful on slushy days. Imagine an 8 inch snowfall followed by rain. This produces heavy slush. If a car rides quickly through deep slush, it may send a wave of the slush at you. This stuff is heavy. When it hits you, it really throws you off balance. Its roughly like getting a 10 lbs sack of rotten potatoes thrown at your back. This stuff could even knock over a pedestrian. Freezing rain is the worst. Oddly enough, I find it easier to ride across a parking lot covered with wet smooth ice than it is to walk across it. The only problem is that sometimes the bicycle simply slides sideways out from under you. I practice unicycle riding, and that may help my balance. (Maybe not, but its fun anyway) Beware of bridges that have metal grating. This stuff gets real slippery when snow covered. One time, I slid, hit an expansion joint, went over the handle bars, over the railing of the bridge. I don't know how, but one arm reached out and grabbed the railing. Kind of like being MacGyver. Stopping. There are several ways of stopping. The first one is to use the brakes. This does not always work. Breaks can ice up, a bit of water gets between the cable and its sheathing when the warm afternoon sun shines on the bike. It freezes solid after. Or the salt causes brake cables to break, etc. I have had brakes work on one corner, but stop working by the time I get to the next. I have several other means of stopping. The casual method. For a stop when you have plenty of time. Rest the ball of your foot on top of the front derailleur, and *gradually* work your heel between the tire and the frame. By varying the pressure, you can control your speed. Be sure that you don't let your foot get wedged in there! Faster method. Get your pedals in the 6-12 O'clock position. Stand up. The 6 O'clock foot remains on the pedal, while you place the other foot on the ground in front of the pedal. By varying your balance, you can apply more or less pressure to your foot. The pedal, wedged against the back of your calf, forces your foot down more, providing more friction. Really fast! Start with the fast method, but then dismount while sliding the bicycle in front of you. You will end up sliding on your two feet, holding onto the bike in front for balance. If it gets *really* critical, throw the bike ahead of you, and sit down and roll. Do not do this on dry pavement, your feet need to be able to slide. In some conditions, running into a snow bank on the side will stop you quickly, easily, and safely. If you're going too fast, you might want to dive off of the bicycle over the side. Only do this when the snow bank is soft. Make sure that there isn't a car hidden under that soft snow. Don't jump into fire hydrants either. ETC. Freezing locks. I recommend carrying a BIC lighter. Very often the lock will get wet, and freeze solid. Usually the heat from my hands applied for a minute or so (a real minute or so, not what seems like a minute) will melt it, but sometimes it just needs more than that. Eating Popsicles Something I like doing in the winter is to buy a Popsicle before I leave, and put it in my pocket. It won't melt! I take it out and start eating it just as I arrive at the University. Its fun to watch peoples' expressions when they see me, riding in the snow, eating a Popsicle. You have to be careful with Popsicles in the winter. I once had a horrible experience. You know how when you are a kid, your parents told you never to put your tongue onto a metal pole? In very cold weather, a Popsicle acts the same way. If you are not careful, your upper lip, lower lip, and tongue become cemented to the Popsicle. Although this sounds funny when I write about it, it was definitely not funny when it happened.
Subject: 9.11 Nancy's Cold/Wet Cycling Tips From: Name removed by request Here are some clothing suggestions, mix and match as you wish: Rain gear : I forked out the dollars for gore-tex when I did a week tour ... and I'm real glad I did. The stuff works reasonably as claimed, waterproof, and relatively breathable. (When the humidity is high, no fabric will work completely at letting sweat evaporate.) Unfortunately, typical prices are high. There are cheaper rainsuits, which I haven't tried. For short rides, or when the temperature is over about 50F, I don't usually wear the rain pants, as wet legs don't particularly bother me. Waterproof shoe covers. When the weather gets icky, I give up on the cleats (I'm not riding for performance then, anyway) and put the old-style pedals back on. This is basically because of the shoe covers I have that work better with touring shoes. The ones I have are made by Burley, and are available from Adventure Cycling Association, though I got them at a local shop. They are just the cover, no insulation. I continue to use them in winter since they are windproof, and get the insulation I need from warm socks. These aren't neoprene, but rather some high-tech waterproof fabric. Gaiters that hikers and cross-country skiers wear can help keep road spray off your legs and feet. Toe clip covers. I got them from Nashbar; they are insulated and fit over the toe clips ... another reason for going back to those pedals. They help quite a bit when the temperature goes into the 30's and below; they are too warm above that. [Joshua Putnam <Joshua_Putnam@happy-man.com> reports: Nashbar has apparently discontinued its toe clip covers. Traditional toe clip covers, also called toe warmers, are still made by Kucharik Bicycle Clothing. Kucharik's model is not insulated, just waterproof nylon cloth. It may be hard to find a shop that carries them, but if you have a good relationship with your local shop, they might be interested in dealing with Kucharik, which also makes great wool jerseys and tights, arm and leg warmers, etc. The company is: Kucharik Clothing 1745 W 182nd St Gardena, CA 90248 Please remember that this is a manufacturer/distributor, not a mail order catalog. ] For temperatures in the 40's I usually find that a polypropylene shirt, lightweight sweater (mine is polypro) and wind shell work well; I use the gore-tex jacket, since I have it, but any light weight jacket is OK. I have a lightweight pair of nylon-lycra tights, suitable in the 50's, and maybe the 40's; a heavier pair of polypro tights, for 40's, and a real warm pair of heavy, fleece-lined tights for colder weather. (I have been comfortable in them down to about 15-deg, which is about the minimum I will ride in.) My tights are several years old, and I think there are lots more variations on warm tights out now. I use thin polypro glove liners with my cycling gloves when it is a little cool; lightweight gloves for a little bit cooler; gore-tex and thinsulate gloves for cold weather (with the glove liners in the really cold weather.) It is really my fingers that limit my cold weather riding, as anything any thicker than that limits my ability to work brake levers. (Note: this may change this year as I've just bought a mountain bike; the brake levers are much more accessible than on my road bike. It may be possible to ride with warm over-mitts over a wool or similar glove.) When it gets down to the 20's, or if it's windy at warmer (!) temperatures, I'll add the gore-tex pants from my rain suit, mostly as wind protection, rather than rain protection. Cheaper wind pants are available (either at bike shops or at sporting goods stores) that will work just as well for that use. Warm socks. There are lots of choices; I use 1 pair of wool/polypropylene hiking socks (fairly thick). Then with the rain covers on my shoes to keep out wind, and (if necessary) the toe clip covers, I'm warm enough. There are also thin sock liners, like my glove liners, but I haven't needed them; there are also neoprene socks, which I've never tried, and neoprene shoe covers, which I've also never tried, and wool socks, and ski socks ... I have a polypropylene balaclava which fits comfortably under my helmet; good to most of the temperatures I'm willing to ride in; a little too warm for temperatures above freezing, unless it's also windy. I also have an ear-warmer band, good for 40's and useful with the balaclava for miserable weather. I also have a neoprene face mask; dorky looking, but it works. It is definitely too hot until the temperature (or wind) gets severe. I sometimes add ski goggles for the worst conditions, but they limit peripheral vision, so I only use them if I'm desperate. For temperatures in the 30's, and maybe 20's, I wear a polarfleece pullover thing under the outer shell. Combining that with or without polypro (lightweight) sweater or serious duty wool sweater gives a lot of options. Sometimes I add a down vest -- I prefer it *outside* my shell (contrary to usual wisdom) because I usually find it too warm once I start moving and want to unzip it, leaving the wind shell closed for wind protection. I only use the down vest when it's below about 15 F.

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