!
WARNING
: There is a safety risk in using gas station air hoses or other air compressors. They are not made for bicycle tires. They move a large
volume of air very rapidly, and will raise the pressure in your tire very rapidly, which could cause the tube to explode.
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 pressures, at the
bottom of the recommended pressure range, give 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 sufficiently 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, ac-
curate 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 inflate your
tires to that pressure. Then, check inflation as described in Section 1.C 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.
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 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.
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