Inner tube valve stems allow you to refill your bike tires with air. They have to withstand the air pressure within the tube reacting against your seated weight pushing the bike into unyielding ground. Three types of valve stems are common on bikes around the world, and each has its purposes and advantages.
Schrader Valve
Schrader valves, also spelled Shrader or Schraeder and sometimes called auto valves, are thick, round valves meant for use with fatter tires, although you can find them on most types of tires. The Schrader is a basic valve that is also used on car tires, so you can refill your bike tires at a gas station using the pump meant for cars if you don't have your bike pump with you on the road. Schrader valves have an interior pin or spring that allows air out of the tube when it's pressed down. The stem is removable, allowing you to add sealant into the tube if needed, although this could affect your warranty.
Presta Valve
Presta valves are also called French, high pressure and Sclaverand valves. These are narrower valves that have a cap that you partially unscrew before you attach a bike pump. The narrow profile of the Presta allows it to fit a little better on narrower tires and is more common on racing or high performance tires. Presta valves are more fragile than Schrader valves, and having a spare valve is recommended. Prestas may or may not have a removable center that allows you access to the tube if you need to add sealant. Remember to tighten the cap after filling the tire with air, because it is possible for air to leak out if the cap is left loose.
Woods or Dunlop Valve
The Woods or Dunlop valve, sometimes called a traditional valve, is a multi-part valve used on older bikes in Asia and the United Kingdom. The British website Why Cycle? says the Woods valve is being replaced by the Schrader in the U.K., but it is still common worldwide. Woods valves look like a cross between the Schrader and Presta, and Sheldon Brown of Harris Cyclery writes that Presta bike pumps work on Woods valves.
Member Comments