8b.20 Gluing Sew-up Tires

[More up to date copies of Roger's articles can be found at
 http://www.roble.com/marquis/]

 Davis criterium, it's hot, hot, hot.  The pace is fast and the
corners sharp.  Inevitably some riders are going to roll tires,
happens every year.  What can you do to insure that your sew-up
tires stay glued when the mercury rises?

There is no one cause of poor tire-rim adhesion so let's start at
the beginning, new rims and tires.  Most rims are shipped with a
coating of anti-corrosive substances that closely resemble grease.
This has to be thoroughly removed with solvent and a clean rag
before you can put down the first coat of glue.  Fast Tack is not
the best glue to use on a bare rim.  Instead try Clement, Wolber or
one of the other slower drying glues.  Put a thin coat of glue all
the way around and leave the wheel(s) to dry for at least 12 hours.

 While this glue is drying you might check your tires for any latex
that might be covering the base tape.  If there is any latex at all
give it a good roughing up with coarse sandpaper before coating it
with a thin layer of standard glue or Fast Tack.  This too should
be left to dry for a few hours.  If you're a light rider or don't
plan on doing any hard cornering on hot days you can usually leave
out this step but always roughen the latex on the base tape.

 After the base coat of glue has dried it's time for the adhesive
layer.  This should be thicker than the first layer but not so
thick that it can squeeze out from under the tire when you mount it
and get on the rim and sidewalls.  If you are using a traditional
style road glue let it dry for ten to fifteen minutes before
putting your tires on.  Tires should be mounted on Fast Tacked rims
immediately.

 New tires usually need a good stretching before they will go onto
the rim without tending to roll and get glue all over them.  I
usually stretch a tire by pulling it around my knees and feet for
a few seconds and then mounting it on an old rim for a while.  You
might want to try mounting the tire on a dry rim first to see just
how much stretching it will need.

 If you used traditional sew-up glue you should wait at least 12
hours before doing any serious cornering.  If you need to race
right away you can use Fast Tack and corner confidently within an
hour.  Be sure to spread the glue evenly over the surface of the
rim using your finger or a brush.  To get the last section of tire
onto the rim without making a mess grab the remaining 3 or 4 inches
and lift the tire away from and over the rim.  This can be
difficult if you forget to stretch it beforehand.

 Some glues work better than others in hot weather.  Fast Tack works
best followed by Wolber and Vittoria with Clement in the middle and
Tubasti at the bottom of the list.

 When buying Fast Tack be sure you get the real thing.  3-M sells
other trim adhesives in boxes nearly identical to Fast Tack.  These
trim adhesives do not work for bicycle tires!  Be careful that
whatever glue you do use has not separated in its tube.  If it has,
take a spoke and stir it up before you squeeze it out.  I have also
heard of mixing different glues before application.  This is a
dangerous shortcut that yields unpredictable results.  Fast Tack
and Clement are the most popular tire adhesives.  Even though Fast
Tack will dry out you can get a few tire changes between
replications if you have a good layer of traditional glue on the
rim underneath it.  Racing tires though, should be reglued each
time.  Base tapes can come apart from the tire in hot weather and
underinflation can cause tires to roll as well.  Check these things
as well as the tread for wear or cuts before every race and you'll
be able to descend and corner with confidence.

Roger Marquis (marquis@roble.com)