![]() Not all tires have direction orientation. Directional arrows printed on the sidewalls indicate rotation of wheel. Note directional arrows of tire manufacturer, if any.Presta valve with Schrader adapter sleeve It is possible to use the smaller Presta valve in a rim intended for the larger Schrader by using an adapter sleeve. The rim valve hole should match the valve of the tube. ![]() Longer valve stems are needed for deeper aerodynamic rims. Presta valve tubes are available with different length valves. To inflate the tube, unthread the locknut and tap the valve to insure it is not stuck. To deflate the inner tube, unthread the locknut. At the top of the stem is a small locknut, which must be unthreaded before air can enter the tube. Presta stems are nominally 6mm (1/4″) diameter, thinner than Schrader valves. The Presta valve is common on mid and higher priced road and mountain bikes. Schrader valve core removed for cleaning and inspection with VC-1 A special tool such as the Park Tool VC-1 will remove and or tighten the core. A loose core can also be the source of a slow leak. This is rarely required, but a valve can become stuck and cause a slow leak. The Schrader valve core can be removed if necessary. Schrader-compatible pump fittings press on the internal stem with a plunger, allowing the tube to be filled. Upon release of the stem, the stem spring shuts. To deflate the schrader valve tube, it is necessary to stick a small hex wrench or other object into the valve in order to press on the stem and release the air. ![]() The valve stem is approximately 8mm (5/16″) in diameter and has an internal spring plunger to assist in shutting the valve. The Schrader-type valve is common on American cars and motorcycles. There are three common types of valve stems on bicycles: Schrader (“American” type), Presta (“French” type) and Woods (also known as “Dunlop”). To deflate a Presta valve, unthread the locknut at the tip of the valve stem and pressĦ Valve Types Valve stem types (L-R): Schrader, Presta, Woods ("Dunlop") For best results, press downward on wheel while depressing the valve. Even a small amount of air left in the tube can make it more difficult to get the tire off. Loosen and remove locking nut before deflating. Fully threaded valve shafts may have a locking nut next to rim. Do not use a screwdriver, knife, or other sharp object, which might damage tire or tube. There are currently many different bead diameter standards, and none are interchangeable.īecause tire beads can be a tight fit in the rim, it is commonly necessary to tire levers to pry tire bead up and over rim sidewall. The sizing of the rim bead seat and the tire bead must match. As the inner tube is inflated, the tire bead is pushed against the “bead seat” of the rim, the portion of the rim that is hooked to hold the bead. The common bicycle tire is called a “clincher” tire, and in made with bead on the inside edge of the tire.
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