> Not quite right. There are 2 different valve stems for bicycles. I
don't remember the name but the serious cyclists have something else
available due to the very high pressures they run compared to autos. Forgot
what it's called but I believe both the internals and externals are
different.
The fancy version on a bicycle is called a "Presta" as opposed to the
automotive-style "Schrader" valve. I don't believe it is so much a result of
the higher pressures, I have run the 27x1" tires at over 100 pounds of
pressure with no leakage problems with my schrader valves. The real reason
for the presta valves IMHO is their smaller diameter which is easier to fit
in a narrow rim as well as the usual desire to affect the european
mannerisms in bicycling.
Yes the internals are different as well. Rather than a spring-loaded valve
inside, the valve is operated by the air pressure in the tube and held in
place by the little head on it which screws down and holds the valve up.
David Lieb
Raleigh Gran Prix
Raleigh Gran Record
Roland Tandem
Schwinn Twinn tandem, heavily modified but still heavy
etc.
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