Presta valve

Presta valve

The Presta valve is a valve commonly found in high pressure road style and better mountain bicycle tires, although it is now used on all UST or "tubeless" mountain bike tires. Its three components are the valve body, a threaded valve stem, and a lock nut. The valve body is available in various lengths. Air inside the tire holds the valve shut. A threaded stem extending out of the valve can be screwed down to ensure the valve remains closed.

The Presta's narrow diameter helps the strength of narrow rims because the weakest point on a rim is the valve hole.

The Presta valve must be unscrewed to permit airflow in either direction. The screw, at the tip of the valve, remains within the valve housing even after it is unscrewed; unscrewing the valve permits the plug to move up and down within the housing. It must be unscrewed before attaching a pump. Once the pump is removed, the valve is screwed down to prevent accidental air leakage. A screw cap provides protection to the valve top and prevents the valve from puncturing the tube when it is rolled for storage, but it is not necessary to keep air from leaking.

The standard Presta valve has an external thread.

ee also

* Schrader valve
* Dunlop valve

External links

* [http://www.howcast.com/videos/11998-How-To-Use-a-Presta-Valve How to use a Presta Valve video tutorial]


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