User Guide

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Snakebite
You are probably familiar with this sce-
nario. With your tire pressure set on the
soft side to enhance traction, you run over
a sharp object, like a rock. The soft tire is
compressed between the rock and the rim,
another hard spot. Caught in the middle of
this squeeze play is the tire and the lowly
inner tube, made of soft rubber. The tire can
resist the compression because it is fairly
thick, and has reinforcing threads running
through it. The poor inner tube has nothing.
Under pressure, the inner tube rubber sepa-
rates and gets treated to the mountain bik-
ers’ nemesis: snakebite, denoted by a pair of
matched holes in the inner tube.
A cure for snakebite
Until recently, the only cure for snakebite
was to increase the air pressure in the tire.
Unfortunately, this solution causes its own
problem; reduced traction. To solve this prob-
lem, a consortium of rim and tire builders
came up with a novel approach; why not
eliminate the tube? Following this path they
came up with a design using a dedicated
tire to seal to a dedicated rim and hold air
without a tube, dubbed UST.
The downside of UST
The UST ‘solution’ has a host of its
own problems. First, its very expensive. The
key to UST is a rim without spoke holes
through its outer wall. This design requires
a special method of rim manufacturing and
spoke installation. Second, this special wheel
doesn’t use conventional spokes, so to get
UST benefits the rider has to buy an entire
wheel. Third, a UST rim will not work with
a standard tire. And lastly, there is a limited
selection of tires and tread patterns that will
fit this special rim.
A second opinion
We considered the pros and cons of UST
tubeless technology and saw that there was
room for improvement. By finding a different
method of containing the air, we are able
to use conventional wheel building practices.
Not only does this make it less expensive
to buy into the system, it also means the
wheels are fully serviceable at your local deal-
er; a real plus for the rider. Second, our rim
design is compatible with standard moun-
tain bike tires, given that the rider use an
inner tube. With both UST and our Tubeless
Compatible system, going tubeless requires a
special tire that has a sealing layer on the
inside of its casing to prevent the air from
simply rushing out. Conventional tires don’t
have this layer. But again, you can use a
conventional tire on our tubeless compatible
rims, you just have to use a tube. In addition,
with our system you can use the UST tube-
less tires.
How did we do it?
The key to our Tubeless Compatible system
is a special rim and its mated rim strip. This
rim strip is made of a thermoplastic rubber
material, so its impervious to air. Installed
correctly in the special mated rim, it seals
tightly to prevent air escaping through the
spoke holes. The rim’s hook allows greater
contact with the tubeless tire’s smooth,
enlarged bead so these two surfaces also seal
up tight. The inside of the tubeless tire has
a special coating to prevent air from escap-
ing through the tire casing. When these fea-
tures are all in order, no tube is needed. Just
install a special presta valve stem into the
rim, and inflate.
Does the system eliminate air leakage?
Have you ever noticed that you occasional-
ly have to pump up your tires (well, really its
your tubes), even if they don’t have a punc-
ture? In a similar fashion, a properly mount-
ed tubeless tire can ‘bleed’ air. We expect that
this will amount to about 4 PSI (1/4 ATM)
per day.
For display purposes, 2003 complete bikes
with tubeless tires include an installed inner
tube. Since inner tubes have a slower bleed
rate, the dealer won’t have lots of bikes sit-
ting on the sales floor with soft tires.
What if a tubeless tire runs over a nail?
A tubeless tire functions like a tire with
a tube in it. Its just that the tire holds the
air, not the tube. So if you run over a large,
sharp object that can penetrate the tire cas-
ing, it will probably flat the tire just like with
an inner tube.
Also like an inner tube, you can probably
patch the hole (from the inside of the tire).
The difficulty lies in determining where a
tire is punctured. An inner tube is basically
fully enclosed. A tubeless tire is not. If the
source of the air leak is not immediately obvi-
ous, you may have a problem getting the
TUBELESS COMPATIBLE TECHNOLOGY