What is the difference between schrader and presta valves

Spring closure makes them simpler to use because one needs only to press the inflation chuck onto them at an automobile service station. For hand pumps, a screwed or lever chuck provides the valve depressor.

The depressor not only makes inflation easier but is necessary to read back pressure in the tire. Use of a service-station hose to inflate bicycle tires is risky; see Sheldon's article about flat tires. Although Presta valves have been made with removable cores, demand is so small that they are uncommon. Removable Presta cores can be identified by two wrench flats on the coarse valve cap threads. Reports of the demise of this Web site are greatly exaggerated! The Presta valve is thin, narrower than the other valves 6 mm instead of 8.

Its small diameter allows a smaller hole in the rim. This is adapted to the narrow rims of racing bikes. It is also lighter than the Shrader valve or the Dunlop valve of about 4 to 5 grams. The Presta valve has 2 caps : one plastic, and a small metal screwed on a small threaded rod fixed in the body of the valve. To deflate, unscrew and press on the metal cap.

It usually has the same circumference over the entire length. Often wrapped with rubber. The outer wall is threaded to tighten a valve cap or the head of a pump. The pin in the middle is a non-return valve that regulates the airflow in and out of the tire using a spring. Check valves are designed to allow airflow in one direction only; the Schrader valve requires pressure on this inner pin to allow air in.

Presta : about half the width of a Schrader valve and made entirely out of metal. They run slightly tapered upwards and some have threads down.

The valve opens by unscrewing a serrated nut at the top. Unlike a Schrader valve, the Presta does not have a check valve — it closes completely based on pressure in the inner tube or tubeless strap.

Many Presta valves, including those for use in tubeless tires, allow you to remove the entire core of the valve. Be careful when unscrewing the knurled nut so that you do not accidentally unscrew the whole core. This will allow all the air to come out of the tire at once. Dunlop : We often see the Dunlop valve on city bikes. They look a bit like a thick Presta valve. On sporty bikes you never really see them. On your tires, of course.

Particularly on the inside of the rim. But you can also find Schrader valves on dampers: those of a suspension fork or rear silencer of a full-suspension mountain bike. Compared to Schrader valves, Presta valves are ideal for bicycle tires for many reasons:. You can place a Presta valve in a rim made for a Schrader valve, but only as an emergency solution.

Your inner tube and outer tube tend to move slightly over the rim. In the wider Schrader hole, a Presta valve can move a lot, so the edge of the rim will eventually damage the valve at the point where it turns into the tire. If you need to put a Presta tire in a Schrader rim to get home, use the small nut to tighten it against the rim.