Originally Posted by
bikinpolitico
I don't think they are fancy for no reason. They are designed to hold high pressure with less air leakage. This is an issue if you are running 110 PSI, less so if you are running 60 PSI. A little air loss with road thin road tires is a BIG deal, on MTB or cruiser tire, not so much. Different applications require different solutions. Pick your equipment accordingly.
Good tubes don't leak through the valve. They leak through the walls of the tube. Rubber simply isn't entirely air tight. The advantage of the presta valve is that it has smaller hole, which means less lost strength on narrow wheels, and you can fill it easier with a simple pump. With a Schrader valve, you need something that mechanically depresses the valve stem's core; a presta valve merely requires that you put more air pressure on it than what's in the tube. The smaller diameter of the presta valve (it's about one quarter the area of a schrader valve) means that you need less force to overcome the pressure in the tire. (That's a huge advantage with the sort of lousy frame pumps that were avaliable decades ago. Modern pumps, not so much.)