Home > categories > Mechanical Parts & Fabrication Services > Valves > What is the purpose of those new valves on bikes that are longer and skinnier and that you?

What is the purpose of those new valves on bikes that are longer and skinnier and that you?

need a different pump for? Is this some improvement on the old valve?


first off they are not new ;-) These two standards have been around a long time. valve stems come in two types, schaeder and presta. Now i sometimes get these mixed up but I think Presta is the narrower valve. If I'm wrong I'm sure someone will correct me ;-) Either way there are these two types. Here we are referring to width/diameter not length. the thicker valves are usually on mountain bikes, some comfort bikes. the thinner narrower valves are usually on road bikes, some cross bikes, the type with skinny tires. Most bike pumps these days whether floor pump to mini pump will work for *both* Schaeder and Presta. The valve end on your pump (unless it's a piece of c*^ from Wallmart) SHOULD simply unscrew, reverses and voila! You can now pump up the tires of your MTB and your road bike or help another rider out! Now, on to your actual question ;-) Sorry for the drift. the long valve stems have to do with Aero wheels. These are rims, usually carbon that are designed to be very narrow and literaly slice the wind for faster acceleration. these are usually road bike rims, the skinny tires. Examples of Aero rims would be like Rolf Elan. Because of the design of the aero rim a longer valve stem is needed or it would literaly be lost within the carbon rim. But you don't have to have aero rims to have a tube with a longer stem. The stems on most tires are available in long, short, medium. I like to have the length match, it's just an aesthetic thing. But the function is exactly the same and the difference in weight is negligable. So to sumarise if you have aero rims you *must* choose tubes with a longer valve stem. If you don't have aero rims you can use them if you like, doesn't really matter, it's all what you like. but you do not need a different pump.
Dita is correct. You do not need a new pump. Most of the new ones (ones you'd find at a bike shop, probably not Wal Mart pumps), will handle both. The newest ones have a smart head where you just plug in the valve, flip the lever, and the pump figures out which valve stem you have. On slightly older pumps, it is a matter of switching the pump head internals around. On the really old pumps (or really cheap ones), you need a brass or alloy adapter that threads onto the presta valve and converts it to schrader.The schrader valve uses a spring to close the valve to prevent air loss. Presta uses the air pressure itself to seal the valve.
There are schrader valves which are bigger diameter and are used also for automotive tires. They have a spring-loaded center pin that gets pushed down and opened when a inflating head is used. The spring is what keeps the air in the tube. The presta valve is the skinnier one. It does not rely on a spring to keep the valve close. The air pressure inside the tube keeps the valve closed. Generally, less expensive bikes use schraders while better bikes use prestas. All decent pumps have pump heads that accomodate both types. Either it is done by manually reversing the inside of the head assembly to change between presta and schrader or the head automatically adjusts or you use the appropriate one when the head has holes for both.

Share to: