New answers tagged

1

Since the Presta valve closes after each pump-stroke the pressure in the hose is equal to the pressure in the inner tube. The chuck does not mechanically open the valve as with Schrader (car-type) valves. You will have to overcome this pressure with the following pump-stroke to get more air into the tube. The maximum pressure obtained in the inner tube ...


0

Presta Valves, or any valve for that matter do not leak after you have taken the pump head off. The valve should automatically close even without you having to screw down the valve. Doing that only applies pressure on the valve to reduce leakage over time even further. If the valve keeps leaking till you screw it down means that there is some damage in the ...


6

In my experience there is always some air loss when you remove the pump from a Presta valve, but that air is lost from the pump side of the valve. It's easier to see with a floor pump, since there's the hose to hold air. In a floor pump there's a check valve is at the pump end of that hose, and that will hold the air in the hose at high pressure even after ...


0

You should never exceed the maximum pressure that the tire says. But the tube shouldn't leak any air when the Presta core is unscrewed before or after you connect the pump; at that point you should have to push on the little knob that you unscrew to make air come out. I did some web searching, and your problem with air leaking out of the valve seems ...


-1

Had the same problem—the trick is that the threaded sleeve at the very tip of the valve needs to be unthreaded and floating free in order for the valve to work under the pressure of incoming pumped air. So the order of operation is: valve cap off ensure the valve stem collar nut is seated snug against the surface of the wheel spin the tiny threaded sleeve ...



Top 50 recent answers are included