A schrader valve (with cap) on a bicycle tire.

Unusually tall schrader valve

The Schrader Valve is a valve stem invented by August Schrader and is used on all automobile tires and lower pressure bicycle tires. It is a poppet valve assisted by a spring. Schrader valves are also used on the fuel rail of some direct fuel injection engines and on some automotive air conditioning systems, in a diameter larger than those used on tires, to allow recharging with refrigerant.

It uses air pressure inside the tire to help shut the valve, but has a spring to assist in keeping the valve shut (especially important at lower pressures). The size used in bicycle tires has a greater diameter than the Presta valve. The spring pressure makes it better than the Presta valve for low pressure tires but the larger diameter hole it requires can weaken the rim.

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