Originally Posted by
cyccommute
In terms of pressure, neither valve has an advantage over the other. They seal much the same internally. The Schrader just uses an internal spring to pull the poppet into place.
I agree that the Presta adapters are a hassle which is why I don’t use them. Use the proper chuck and there isn’t a hassle at all.
I don’t know how you can lose are while closing the lock screw on a Presta valve. You shouldn’t be pressing down on it at all. Even when I’ve bent the stem, I’ve never released air from a Presta when closing the lock screw. You could probably even leave the screw open without any negative effect. It doesn’t really need to be screwed down as it will stay closed as long as the pressure in the tire or tube is higher than atmospheric pressure.
The problem with Schrader valves and losing air isn’t when removing the chuck. People often can’t get the angle of a Schrader chuck correct when using a compressor for filling tires. They don’t angle it right and just spray air out of the hose. Since the Schrader has to hold the valve open to fill it, any air leakage is air lost from the tire. A Presta valve can be filled with a compressor as well but the adapter used doesn’t press down on the stem so any air lost out of the hose has no impact on the pressure in the tire.
When using a hand pump, seals aren’t always in the best of shape either so some air leaks around the seal. For a Presta valve, this isn’t a problem. But, again, for a Schrader any leakage is leakage from the tire.
Before I had a floor pump, I used my compressor and that only has the shrader chuck. So i learned to hate those adapters :-) I assume there are chucks that do Shrader and Presta. But iIimagine if I'm some where and have no pump, some car infrastructure (gas station, car driver has compressor etc.) is more readily available.
Maybe this is user error and I just do it wrong. but the few times I had Presta when tightening the nut I move it a bit laterally, which lets some air escape. Those were tubes with non-replaceable cores. Not sure if that is typical since the Presta valve only opens when pressurized from the outside. which is a good idea compared to Shrader.
I'm sure half my Presta hate is based on not being experienced with it so the little exposure I had wasn't great.
As I said, both work and are fine. Just preference. For me also based on always having had Shrader and keeping things consistent made sense.
I grew up with dunlop valves that had their own pump. then came bikes with Shrader valves and i all of sudden could use the pump AND car compressors (I lived across a gas station and compressed air is free) and this seemed the best idea ever to me. I never had road bikes or other bikes where the diameter of the valve matters for the rim. so that is just me, and I totally understand when someone prefers Presta.