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Tire pressure that is too low for your weight and the riding
conditions can cause a puncture of the tube by allowing the
tire to deform sufciently to pinch the inner tube between the
rim and the riding surface.
!
CAUTION: Pencil type automotive tire gauges can be
inaccurate and should not be relied upon for consistent,
accurate pressure readings. Instead, use a high quality dial
gauge.
Ask your dealer to recommend the best tire pressure for
the kind of riding you will most often do, and have the dealer
inate your tires to that pressure. Then, check ination as
described in Section 1.C so you’ll know how correctly inated
tires should look and feel when you don’t have access to a
gauge. Some tires may need to be brought up to pressure
every week or two.
Some special high-performance tires have unidirectional
treads: their tread pattern is designed to work better in
one direction than in the other. The sidewall marking of a
unidirectional tire will have an arrow showing the correct
rotation direction. If your bike has unidirectional tires, be sure
that they are mounted to rotate in the correct direction.
2. Tire Valves
There are primarily two kinds of bicycle tube valves: The
Schraeder Valve and the Presta Valve. The bicycle pump you
use must have the tting appropriate to the valve stems on
your bicycle.
The Schraeder valve (g. 18) is like the valve on a car tire.
To inate a Schraeder valve tube, remove the valve cap and
clamp the pump tting onto the end of the valve stem. To
let air out of a Schraeder valve, depress the pin in the end
of the valve stem with
the end of a key or other
appropriate object.
The Presta valve
(g. 18) has a narrower
diameter and is only
found on bicycle tires.
To inate a Presta valve
tube using a Presta
headed bicycle pump, remove the valve cap; unscrew
(counterclockwise) the valve stem lock nut; and push down
on the valve stem to free it up. Then push the pump head
on to the valve head, and inate. To inate a Presta valve
with a Schraeder pump tting, you’ll need a Presta adapter
(available at your bike shop) which screws on to the valve
stem once you’ve freed up the valve. The adapter ts into
the Schraeder pump tting. Close the valve after ination.
To let air out of a Presta valve, open up the valve stem lock
nut and depress the valve stem.
!
WARNING: Patching a tube is an emergency repair. If you
do not apply the patch correctly or apply several patches,
the tube can fail, resulting in possible tube failure, which
could cause you to loose control and fall. Replace a patched
tube as soon as possible.
5. Service
!
WARNING: Technological advances have made bicycles
and bicycle components more complex, and the pace of
innovation is increasing. It is impossible for this manual to