Bicycle Mechanics - About Presta valves.

Hello Everyone,
I have Presta type valves. I bought a couple of Schader adapters, so that I can use my current air chuck, pressure gage and so forth. I would like to know if they need to stay "screwed shut" or if when I open them to check the pressure and to put air in the tire, can I just leave them open so that I don't have to continuously remove the adapters from the valves and put them back on.

Thanks for any help on this matter. Best -

i keep mine screwed shut. i dont think it really matters much, it's just a habit i've developed.

Screw them shut , when you remove the adapter to unscrew before you pump up, unscrew the sleave & depress the valve momentary to let a little air out ,this seems to make it easyeir for the pump to unseat the valve & pump up the tyre !

They also leak(sometimes) if not screwed down

Keep 'em screwed for sure! Like Grey says, any little brush against will make the air come out... to see how 'open' the valve is, unscrew a flat tube, and you should be able to blow air in through the value with your mouth! So keep 'em screwed! :)

Joe

Like everyone has said, keep them screwed shut. I also use the same adapter so I can use my compressor, and I leave it on the valve as you do so that if I need to pump some air into it at a gas station I can. But this takes practice and you could easily blow a tire if your not; but the gas stations around where I live have those blasted coin operated air machines and the volumn of air is not that great anyway. But also something I discovered, is that if by chance you rip your bikes pump rubber gasket while using it to repair a flat on the road and now the thing won't seal, you can simply take the seal out, turn it around for Schader use and use the converter! This is assuming of course your pump can handle both-most do.

the reason i switched to presta is because you can screw them shut.

Years ago after returning home from a century, I noticed I had forgotten to screw both my valves down when I aired up that morning. Checking the air pressure I found both tires still at proper PSI. Maybe I got lucky.

I agree with the other posters, screw 'em tight.