Presta valves are the most commonly used valves on mountain bikes despite the fact they are far from user-friendly. Presta valves are fiddly, delicate, frequently get clogged with sealant, and have an annoying habit of valve cores unscrewing themselves when removing pumps and undoing all your hard work.
Despite all these common issues, there is one reason why Presta valves were adopted in cycling. It wasn’t the result of a big Presta lobbyist but rather the smaller valve hole in the rim improved rim strength. Rim manufacturers all adopted the smaller Presta valve and squeezed out the old-reliable Schreader.
