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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 cor-
rect 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 fitting appropriate to the
valve stems on your bicycle.
The Schraeder valve (fig. 18) is like the valve on a
car tire. To inflate a Schraeder valve tube, remove the
valve cap and clamp the pump fitting 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 (fig. 19) has a narrower diameter and
is only found on bicycle tires. To inflate 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 inflate. To inflate a Presta valve with a Schraeder pump fitting, 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 fits into the Schraeder pump fitting.
Close the valve after inflation. 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.
Fig. 18
Fig. 19
4. Tech
Summary of Contents for multi-speed bicycles
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