Tech
cont’d
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 sufficiently to pinch the inner tube
between the rim and the riding surface.
Ask a certified bike mechanic to recommend the best tire pressure for the kind of
riding you will most often do, and have them inflate your tires to that pressure. Then,
check inflation. So you'll know how correctly inflated 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 important to check your tire pressures before every ride.
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.
Tire Valves
There are primarily two kinds of bicycle 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. 18a) 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. 18b) 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 locknut; and
push down on the valve stem to free it up. Then push the pump head on the
valve head, and inflate. To inflate a Presta valve with a Schraeder pump fitting,
you'll need a Presta adapter (available through KETTLER Parts & Service —
866-804-0440/[email protected] or at your local 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.
Another valve that is used on bicycles, especially in Germany, is the
Dunlop (fig. 18c) valve. It has a wider base than a Presta valve, similar enough
in size to a Schrader valve to use identically drilled valve holes in rims, but it can
be inflated with a Presta valve adapter. The inner mechanism of the valve can
be replaced easily, without the need for special tools.
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.
Fig. 18a
Fig. 18b
Fig.
39
WARNING
: It is highly recommended 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 loose control and fall. Replace a patched tube as soon as
possible.
Содержание KC720-220
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