Archive for October 10th, 2016

October 10, 2016

Presta Valve

valve stems

Bicycle wheels are comprised of a tough outer tire, a soft inner tube, and a rim (the stiff outermost-edge which is often supported by spokes). The inner tube is inflated means of a valve stem that opens to let air in and then automatically closes and is kept sealed by the pressure in the chamber. The Presta valve (also called the ‘Sclaverand’ or ‘French’ valve) is a valve commonly found in high pressure (100 psi) road style inner tubes. It is comprised of an outer valve stem and an inner valve body. A lock nut to secure the stem at the wheel rim and a valve cap may also be present.

 The outer valve stem is manufactured in various lengths for different applications, and has a narrower diameter at the base (6 mm) than the more common Schrader or American valve (8 mm) and is also used on most automobile tires. Japan, India, Russia, Germany, Britain, and several other countries use a third type of valve for their bicycles, the Dunlop (also called a ‘Woods’ or ‘English’ valve) which also has a wider base than a Presta valve. It is similar enough in size to a Schrader valve to use identically drilled valve holes in rims, but it can be inflated with a Presta valve adapter.

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