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Schraeder Valve Presta Valve
Tire pressure is given either as maximum pressure or as a pressure range. How a tire
performs under different terrain or weather conditions depends largely on tire
pressure. Inflating the tire to near its maximum recommended pressure gives the
lowest rolling resistance; but also produces the harshest ride. High pressures work
best on smooth, dry pavement. Very low pressure, at the bottom of the recommmend-
ed pressure range, gives the best performance on smooth, slick terrain such as
hard-packed clay, and on deep, loose surfaces such as deep, dry sand. 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 suffciently to pinch the inner tube between the rim
and the riding surface.
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. The tire valve allows air to enter the tire’s inner tube under pressure, but doesn’t let
it back out unless you want it to. 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 is like the valve on
a car tire, this is the type of valve stem you should have on your bike. To inflate a
Schraeder valve tube, remove the valve cap and push the air hose on you bike. To
inflate a Schraeder valve tube, remove the valve cap and push the air hose or pump
fitting onto the end of the valve stem. To let air out of a Schraeder valve, depress the
pin on the end of the valve stem with the end of a key or other appropriate object.
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