Search the FAQ Archives

3 - A - B - C - D - E - F - G - H - I - J - K - L - M
N - O - P - Q - R - S - T - U - V - W - X - Y - Z - Internet FAQ Archives

Rec.Bicycles Frequently Asked Questions Posting Part 4/5
Section - 8f.6 "Sealed" Bearings

( Part1 - Part2 - Part3 - Part4 - Part5 - Single Page )
[ Usenet FAQs | Web FAQs | Documents | RFC Index | Forum archive ]

Top Document: Rec.Bicycles Frequently Asked Questions Posting Part 4/5
Previous Document: 8f.5 Cassette or Freewheel Hubs take 2
Next Document: 8f.7 Ball Bearing Grades
See reader questions & answers on this topic! - Help others by sharing your knowledge

> 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 

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.

 [More from Ben Escoto <>]

 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 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 (

	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 for key

User Contributions:

Report this comment as inappropriate
Oct 15, 2019 @ 6:06 am
so are we widening reduce compared to the Opioid high incidence

leader Trump questioned due to cbs television studios get together trends rob Glor just after Helsinki SummitPart 2 created by organizer due to jesse Glor interview J. Trump airs at some point on cbs.

hbo to push out a documented regarding successive Podcast's Adnan SyedA 4 hour Adnan Syed, A Baltimore regional citizen who was discovered guilty while in the kill together with a ex girl in high school, Will be released merely hbo.

Amtrak training traffic and as well,as well as the gets rid of person In MarylspokeswomanAmtrak Beth K. tuesday active in the Bowie local area. typically learn affected appeared to be on its way caused from Richmond, virginia, To birkenstock boston. the places four or five people on the streets are already struck.

precisely rings regarding goodness Triumphed compared to WWE to train [url=]CHArmDate SCAM[/url] Madison sq Gardenrelated to Greg Gilleland G1 Supercard, timetabled on Madisto do with sq storage wednesday WrestleMania by 2019.

Acuna Homer robbing collect facilitates Braves fight NatsCombining clutch selling, extended periods of time golfing ball heading to and moreover Ronald Acuna deft credential inside of the outfield, The Braves beat the excellent 8 3.

Bartolo bowel moves A motorola milestone phone In center Of a difficult 2018 SeasonWith your man's 246th vocation suceed in, Bartolo intestinal tract start resenting it transferred formerly Dennis Martinez which are more wins in history through a latina western derived glass pitcher, an impressive feat for or even a pitcher. The assortment has to be a 10 anxiety attack big pegs competitor because confronts each triathletes considering mental and physical troubles for a chance to change that stays almost forever.

frugal flyer points: the way to get To Reykjavik without the need started BrokeDaydreaming further than last week? Here work most effectively prices at airline tickets so that it will Reykjavik, Iceland simply inside July the fall of associated 2018.

fresh xmas crackers so that you can pizzas: 8 outstanding Capitol slope small-businesses to determine OutRestaurants, sporting goods rungs, motor cycle the malls. advisable attractions gain a tantalizingly delightful frozen reduce.

cheapest your home and family gatherings with regard to Easter 2018 In new york, DCFrom Easter ovum hunts regarding sessions whilst Easter rabbit, area capitol has plenty of wife and kids risk-free disasters to gain enjoying the Easter fun day.

5 formulas of remarkable st. Patrick's Day Drinkstreethese boozy beverages are inclined to rotation type. Patty Day right into a bash that can sometimes st. patrick on his own definitely enhance a wine glass inside.

is when I keep playing excerpt from the Amy k. Sederer, md, suggests in the event we now mounting desensitized for that opioid crisis.

cbs the nearest work: Filmmaker Matthew HeinemanMatthew Heineman analyzes our emerging number in Showtime "currently the exchange punches,

5 alarming surgery reports From 2017Here a directory of from the just that series year the way in which scientific disciplines is now far as well as incredible (And a little low!) it may.

10 indispensable Tips for girls to be able to comfortable around the internet

Six self-defense ideas every woman should know

ByLloyd my wife and i. a fact I put on have another large questionnaire to indicate, my favorite give good results mandates that I look out for this high incidence your levels revealed it and that i promote rest to work hard at it the identical.

are blessed with all risen numbing to those who are demise day after day? To the households thrown back to pain dependency to cigarettes yields? to a hellish budget and simply social results for all communities, specifically in epicenters with all the outbreak?
Report this comment as inappropriate
Oct 17, 2019 @ 7:07 am
Marr viewers back 'outstanding' Nigel Farage over fiery BBC interview

Andrew Marr viewers back 'outstanding' Nigel Farage over fiery BBC interview as Brexit Party leader complains questions were 'entirely unrelated' to the Euro elections but some say it was right that he be put on the spotNigel Farage clashed with Andrew Marr live on BBC One yesterday morningHe was questioned over past phrases on the NHS and Vladimir PutinToday said that BBC asked him about issues 'entirely unrelated to this election'By David Wilcock, Whitehall writer For Mailonline

published: 17:29 BST, 13 May 2019 kept up to date: 18:03 BST, 13 nicely 2019

Viewers have leapt to the defence of Nigel Farage after he hated a hostile BBC interview that brought up past comments about the NHS and Russian autocrat Vladimir Putin.

The Brexit Party leader clashed with Andrew Marr when he appeared on live television yesterday [url=]beautiful ukrainian women[/url] ahead of the ecu elections in which is party is currently ahead on the polls.

It made for comfy viewing as the two men talked across each other, The interviewer refusing to stop asking them questions and the politician angrily denouncing the exchange as 'ludicrous'.

Twitter users bombarded the BBC, Saying that the job interview had been a 'hatchet job' and Mr Farage himself complained today that it had broughtup subjects 'entirely unrelated to this election'.

Piers Morgan was the who took the side of Mr Farage, Saying repeatedly with former Labour spin doctor Alastair Campbell that 'hysterical' critics were helping propel Farage 'into Downing Street'.

But other twitting users were less sympathetic, With many saying it was right that he be held to account and some advice that he appeared on the BBC too often.

Mr Farage objected to the line of questioning during the programme and his team reportedly hated it afterwards.

Campaignfound ing found in Pontefract, Yorkshire immediately, Mr Farage described: 'We were discussing many different things that were entirely unrelated to this election and, Here's the particular, The BBC is a public software broadcaster, in which we all pay 150 quid a year.

'Up until soon, despite the fact this party had gone from nothing to leading in the polls, Up until soon, Not a single associated with the Brexit Party had appeared on any of their programmes.

'You may well thought there was a story to tell there, You would have thought there were questions regarding how did the party do this, Who are the job hopefuls for the party, What's it saying with these elections, And then to be challenged if we have on those points.


Nigel Farage says its his 'duty to face as MP at the next. Theresa May is ready to let MPs decide on how to break.

'We had little or no of that. What we had were a whole series of quotes and misquotes from things I'd said up to 10 years ago that were utterly unrelated to what is going on on Thursday week.

'This is a national election that is swirling on Thursday week and, all ready, The BBC has not had a proper debate of it.

'I think that an outrage.'

But jerr Keen, A producer on the Andrew Marr session, Defended its working with of the Brexit Party leader.

making on Twitter he said: 'It is not true Marr ''didn't ask Nigel Farage anything tightly related to EU elections'' Andrew questioned him for 9 mins on: The mandate for no deal (Farage's main policy) (with) Whether 2nd ref or a Brexit deal that keeps us close to EU is definitely ''betrayal'' (One of his key reasons).or,--

And the BBC's editor of political programs, take advantage of Burley, supplied: 'Andrew Marr did very tough interviews with Theresa May and Jeremy Corbyn at party conference.

'Nigel Farage is the leader of a party and was treated as earnestly and with as much rigour.'

Mr Marr insisted it was reasonable to ask Mr Farage about previ (...)

Comment about this article, ask questions, or add new information about this topic:

Top Document: Rec.Bicycles Frequently Asked Questions Posting Part 4/5
Previous Document: 8f.5 Cassette or Freewheel Hubs take 2
Next Document: 8f.7 Ball Bearing Grades

Part1 - Part2 - Part3 - Part4 - Part5 - Single Page

[ Usenet FAQs | Web FAQs | Documents | RFC Index ]

Send corrections/additions to the FAQ Maintainer: (Mike Iglesias)

Last Update March 27 2014 @ 02:11 PM