40
Tech
Tires and tubes
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 infl ate
your tires to that pressure. Then, check
infl ation as described in “Mechanical safety
check” on page 5 so you’ll know how
correctly infl ated 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, so it is import-
ant to check your tire pressures before
every ride.
Some special high-performance tires
have unidirectional treads: their tread pat-
tern is designed to work better in one direc-
tion 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 cor-
rect direction.
Tire Valves
There are primarily two kinds of bicycle
tube valves: The Schrader Valve and the
Presta Valve. The bicycle pump you use
must have the fi tting appropriate to the
valve stems on your bicycle.
The Schrader valve (fi g. 4-12 ) is like the
valve on a car tire. To infl ate a
Schrader valve tube, remove the
valve cap and clamp the pump
fi tting onto the end of the valve
stem. To let air out of a Schrader
valve, depress the pin in the end of the
valve stem with the end of a key or other
appropriate object.
The Presta valve (fi g. 4-13 ) has
a narrower diameter and is only
found on bicycle tires. To infl ate a
Presta valve tube using a Presta
headed bicycle pump, remove
the valve cap; unscrew (count-
er-clockwise) 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 infl ate. To infl ate a Presta valve
with a Schrader pump fi 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
fi ts into the Schrader pump fi tting. Close
the valve after infl ation. To let air out of a
Presta valve, open up the valve stem lock
nut and depress the valve stem.
We highly recommend that you carry
a spare inner tube when you ride your
bike. 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 lose
control and fall. Replace a patched tube
as soon as possible.
fig. 4-12
fig. 4-13