Originally Posted by
Leisesturm
Just reading the pressure with a stand alone pressure gauge will cause a loss of pressure. On a car or truck tire the loss is negligible but I don't think its worth the hassle on a bike tire.
The loss of pressure with a pressure gauge on a bicycle is equally negligible. The chamber of the pressure gauge is small and the pressure in the tire is large. Don't check the pressure a hundred times but checking it once isn't going to release that much pressure.
I agree with getting a floor pump by the way.
Originally Posted by
jshorr
Check valve?
A check valve is a one-way valve that allows air to flow
to the tire but not back to the pump. This makes it so that you can pull the plunger back without taking air out of the tire.
Presta valves are a check valve in that the internal tire pressure closes them when the pressure from the pump lowers but schrader valves are held open so that air can be put into them. Thus when you hear air leaking from the pump with a presta valve, you aren't losing air but when you hear air leaking from a schrader valve, the tire is losing pressure.