Valve stem

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A valve stem is the port on a wheel that allows the tire to be pressurized. They are typically spring-loaded devices that admit air when the external pressure is greater than the internal tire pressure to allow filling.

1 Types of valve stems
2 External links

[edit] Types of valve stems

[edit] Schrader

The Schrader valve is used on both automobiles and bicycles.

Schrader valves are further classified by their material, diameter, length, and shape:

TR-4 - Straight metal stem (8 mm dia.)

TR-6 - Straight metal stem (8 mm dia.)

TR-13 - Straight rubber stem (11.5 mm dia.)

TR-15 - Straight rubber stem (16 mm dia.)

TR-87 - Short 90° metal stem (10 mm dia.)

TR-87C - Tall 90° metal stem (10 mm dia.)

[edit] Presta

The Presta valve is thinner and is typically only found on road bikes and more expensive bicycles because they can take more pressure.

[edit] Dunlop (or Woods)

Dunlop valves were once popular in Great Britain and Asia. They are still widely used on 28 and 27 inch tires in many country's ( the Netherlands, Germany, Third World ) on single speed bikes for comfort riding in flat terrain.

Their bases are wider than Presta valves, but they can be pumped with Presta pumps. Pumps with a pincher-type connection however are the most common type used: the classic black pumps mounted on a wooden base. The classic pump does not allow for high pressures, 50 psi max.

Due to the construction, the Dunlop valve does not allow to check the pressure. But it retains pressure very well and outperforms both Schrader and Presta/Sclaveland. The actual valve can be easily replaced, without the need for special tools as with Schrader. This also allows to use the wide stem to fill the tube with a sealant that cures leaks while cycling.