People often ask us why many of our bikes have that weird “skinny” valve. Here’s a short history of both valves and why they exist.
Presta valves, or also known as the Sclaverand valve or French valve is commonly found in road and mountain bikes. The design for the presta valve allows for higher performance riding. It is comprised of a couple of different pieces including: outer valve stem, an inner valve body, and a lock nut. On some presta valves, you are unable to remove the core unlike a schrader valve. There is a small locknut on the top that can be screwed open or closed. To insert air into the tube, simply unscrew the nut, and use a pump or CO2 cartridge to insert air. To keep air pressure from leaving the tube, screw the lock nut down tight. This can also be used for a small release of air pressure by just pressing the unscrewed valve down, allowing for a controlled air pressure release, which is much easier than a schrader valve. The presta valve is much skinnier than a schrader valve and some bike rims are drilled only for a presta valve. A smaller hole means the rim can be stronger and/or narrower than one that fits a schrader valve. A presta valve can fit on any bike when used in conjunction with a size reducer. Presta valves are also lighter weight than a schrader valve. Deeper rims require a longer valve, and presta valves come in many lengths while schrader valves generally only come in one length… short.
Schrader valves, or also know as the American valve, was invented by August Schrader in 1891. This valve is used by automobiles and bikes and features an inner removable core that requires a specialty tool for removal. To release air, simply press down on the pin in the middle of the valve as shown in the animation. A spring in the valve keeps the pin up to close the valve. This is a little more difficult than a presta valve. One benefit to the schrader valve is that it is always possible to remove the core to add sealants (like Slime) to prevent flats. One downside to schrader valves is that they can get gummed up and leak air. It requires a spring and air pressure to keep the air in. (Animation from WikiPedia).
Virtually all modern road bikes and most middle to upper-level mountain bikes have presta valves. Many pumps will work with both valve types. If your pump or compressor is not compatible with presta valves, there is a small inexpensive brass adapter (shown on the left) to make it easier for you. There are benefits to both types of valves. The short answer is to just keep what is on your bike unless you have a good reason to switch.