8b.21 Another way to glue sewup tires
Description
This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
8b.21 Another way to glue sewup tires
From: "Mike & Joanna Brown" <mjbrown1@airmail.net>
Date: Wed, 06 May 1998 21:49:53 CDT
I have been racing for 6 years now and have tried multiple tire/rim
combinations. I have come to the conclusion that good tubular tires on a
pair of good carbon fiber rims provide the ultimate ride. But many people
dislike tubular tires because of the gluing process and the possibility of
rolling the tire during fast cornering.
I decided to write this article because of the three to four racers who
rolled a tire at the recent Baylor/Mirage sponsored criterium. Rolling a
tire at anytime during race can be catastrophic. Everyone has their "best"
way of gluing a tire. I can assure you, this is by far the best and SAFEST
way to glue a tire to prevent it from rolling during any type of cornering
at any speed. I took this process out of Cycling USA last year and now
follow it religiously when gluing my own tires. This gluing process was
far superior to the manufacturers recommended process in regards to bond
strength at tire/rim interface. We will briefly discuss the following; 1)
The glue 2) Mounting tubulars to new rims 3) Mounting tubulars to used
rims.
Not all glues are the same. Especially in Texas! The temperature outside
may be 90 to 100 degrees, but the surface you are racing on may be 150 to
160 degrees. You definitely want a glue that sets up hard in hot weather.
If not, as the temperature increases the glue/bond gets softer/weaker and
chances of roll off and serious injury increase. The article listed seven
glues in this order of strongest to weakest tire/rim bond; Vittoria Mastik'
One, Continental, Wolbar, SM Fast Track, Vittoria Gutta, Pana Cement and
Clement. I prefer clear glues. That way if you screw up its very
difficult to tell. With colored glues, if you screw up everyone knows.
Also for your information I use Pana Cement. It does not provide the
strongest bond, but it sets up perfectly in all extremes of hot weather and
it takes one hell of a finger bleeding effort to get the tire off the rim.
Gluing tubulars to new rims properly should take about 84 hours. Here's
the process. Test mount the tubular to a dry rim, inflate to 100 psi and
allow to sit 24 hours. This stretches the tire which will make mounting
easier and also allow you to inspect the tube and tire for defects (most
"good" tubulars are hand made). After 24 hours remove the tire. Clean the
rim with acetone, lacquer thinner or alcohol only. Other types of cleaners
may leave a film on the rim that cannot be seen by the eye and will
decrease tire/rim bond strength. Composite rim owners should contact the
manufacturer for recommended solvents. Roughing the rim surface will not
improve the bond strength. Gently scrap the base tape on the tire with a
straight edge to remove any latex. If you scrap a one inch section and the
appearance of the base tape does not change, then you probably have no
latex on the base tape and can stop scrapping. But be sure to visually
inspect the entire base tape just to be sure.
Inflate your tire off the rim until the base tape rolls outward. Apply a
uniform layer of glue over the entire base tape area. It is best to do
several tires at this time. You can store those tires not used and
anticipate that the adhesive bond will remain strong as long as the tire
surface is kept clean. Apply a uniform layer of glue across the entire
width of the tire rim gluing surface. The principle bond is at the rim
edge; therefore, it is critical for performance to ensure that the glue
reaches the edges of the rim. Allow both to dry for 24 hours. Apply an
additional coat after that 24 hour period and allow that 2nd coat to dry
for 12 hours. Apply a third coat. This is the mounting coat. With Pana
Cement, once the third coat is applied to the tire and rim mount the tire
immediately. (One tip I would suggest here is before putting glue on the
rim is to put black electrical tape on the entire outside edge and breaking
surfaces. This makes for very easy cleaning after the tire is put on.
Just peal the tape away and all excess glue comes with it and leaves behind
a nice, clean breaking surface).
Place the rim vertically on a clean, smooth surface with the valve hole at
the top of the rim. Place the valve stem through the hole and ensure that
it is properly aligned-straight through the hole (Another tip\u2026For those
with deep dish rims requiring valve extenders, place a small amount of
loctite on the tube valve stem threads and then screw the valve extender
on. This will prevent any leaking at that junction once the tire is glued
on). Grab the tire 8" away from the valve stem in both directions, pull
outward with a mighty heave and place the section of tire between your
hands on the rim. Slide your hands down another few inches down the tire,
pull and install this section. Once a full 180 degree section of the tire
has been mounted, turn the wheel over and place the valve stem section down
vertically on the ground. This is the point where I have my wife hold the
section of tire I had just put on the rim with two hands at 0 and 180
degrees. I then grab the tire at the top and turn it so the base tape is
facing up. At this point I pull up on the tire and roll it onto the top of
the rim. It's actually very easy with two people.
Once the tire is on the rim, it must be aligned. Inflate the tire to
about 50 psi so it can be easily "turned" to align. You can either align
the tire by the tread or by the base tape. Here, I prefer to align my
tires by the base tape. Higher quality tubulars treads will align
properly. Lower quality tires were not necessarily made straight, so
perfect alignment may not be possible. Once aligned, inflate the tire to
100 psi and allow to dry for preferably for 24 hours.
When gluing tubulars to used rims, do not remove the old tire until you
are ready to begin the gluing process as the old tire keeps the rim surface
clear of debris which would weaken the new tire joint. You must find a
weak point in the joint and begin removing the old tire. On my Zipp 440's,
I use a tire lever so I do not damage the rim surface. On aluminum rims
you can use a flat head screw driver to make it easier. You may glue a new
tire over the old glue on the rim unless it is not contaminated or old, if
there is too much glue on the rim or if the remaining glue covers the rim
only in spots. If one of these conditions applies to your rim, remove the
old glue with heavy duty furniture stripper. Apply the stripper according
to the manufactures recommendations. I always put the stripper on and let
it sit for 30 to 45 minutes and the old glue then wipes away like butter.
DO NOT wipe the glue along the rim. This causes the old glue and stripper
to be pushed down into the nipple holes. Wipe across the rim in small
sections. Once the rim is free of glue, begin the process as described
above in the article. If you leave the old glue on the rim, apply at
least one additional coat before installing the tire. To the tire, apply
at least one coat and let it dry for 24 hours before putting on the
mounting coat.
In concluding, let me state once again everyone has their "best" way to
mount tubulars. I can honestly say I have mounted and raced on tubulars
put on in 24 hours. Those instances are far and few between though. I
always make a 100% effort to follow the procedure written above if all
possible. 84 hours seems like a long time to wait just to mount a stupid
tire. It all comes down to how much you value safety. When it comes to
the safety of the other riders, not to mention the consequences of roll off
to my wife and my job, I want to be damn sure I'm as safe as I can possibly
be because I took the time to do things right!
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