A valve stem is a self-contained

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or Slurry, slurries) by opening, closing, or partially obstructing various passageways. Valves are technically Pip ...

that opens to admit gas to a chamber (such as air to inflate a

tire A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineeri ...

), and is then automatically closed and kept sealed by the

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

in the chamber, or a spring, or both, to prevent the gas from escaping. There are many types of valves, and they are most commonly used on

automobile A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, peopl ...

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

, and

bicycle tire A bicycle tire is a tire that fits on the Bicycle wheel, wheel of a bicycle or similar vehicle. These tires may also be used on tricycles, wheelchairs, and handcycles, frequently for Wheelchair racing, racing. Bicycle tires provide an importa ...

s, but also for many other applications. The most common type is the

Schrader valve The Schrader valve (also called American valve (AV)) is a type of pneumatic tire valve used on virtually every motor vehicle in the world today. The original Schrader valve design was invented in 1891 and patented in the United States in 1893.G ...

, but some

road bicycle The term road bicycle is used to describe bicycles built for traveling at speed on paved roads. Some sources use the term to mean racing bicycle. Other sources specifically exclude racing bicycles from the definition, using the term to mean a ...

s with skinny tires instead use the Presta valve.

Schrader

Schrader valves consist of a valve stem into which a

poppet valve A poppet valve (also sometimes called mushroom valve) is a valve typically used to control the timing and quantity of petrol (gas) or vapour flow into or out of an engine, but with many other applications. It consists of a hole or open-ended ch ...

is threaded with a spring attached. They are used on virtually all automobile and motorbike tires and on wider-rimmed bicycle tires. In addition to tires, Schrader valves of varying diameters are used in

refrigeration Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature).IIR International Dictionary of ...

and air conditioning systems,

plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses piping, pipes, valves, piping and plumbing fitting, plumbing fixtures, Storage tank, tanks, and other apparatuses to convey fluids. HVAC, Heating and co ...

, engine fuel injection, suspension systems, and SCUBA regulators, allowing the user to remove and attach a hose while in use. The Schrader valves in the fuel injector rail of many automobiles are used as a quick and easy point to check fuel pressure or connect an injector cleaner cartridge.

Presta

Presta valves (also called Sclaverand valves or French valves) are normally only used on bicycles. The stem has a narrower diameter (nominally 6 mm) than the thinnest (nominally 8 mm) Schrader type, and so the bore of the hole in the rim through which the stem passes can be smaller. Has a locknut that needs to be opened to inflate/deflate.

Dunlop (or Woods)

Dunlop valves (also called Woods valves or English valves) were the dominating bicycle valves in the European region and many other countries. As of 2021, Presta valves are just as common in these regions. Dunlop valves are still widely used especially on low to medium-priced bicycles (city and trekking bikes). They can be pumped up with a Presta bicycle pump.

Regina

The "Regina Valve" is very similar to the Presta and mostly used in Italy. The central threaded pin is so short that it does not protrude from the valve tube and therefore cannot be bent. In order to close the valve tightly, a small, loose nut is placed on this threaded rod with a diameter of only around 1.5 mm and screwed on by hand. A threaded rod is enough. By tightening the nut, the valve disc with the conical sealing body is pressed against the valve seat. Rim drilling:⌀ 6.5 mm Thread DIN 7756 • outside VG 6×32 •outside VG 5.2×24 at the upper end Maximum pressure 15 bars.

Others

Many other valves are used only in certain regions or for limited purposes. Invisible tire valves are different in design from traditional tire valves. An inflator stem is not used; instead, a removable cap on a valve stem embedded in the tire rim is fitted, with only the cap visible. When inflating the tire, the cap is first removed, typically with a coin, and then a "portable" dedicated inflator stem is screwed onto the valve stem. Through the inflator, the tire is inflated as usual.

References

External links

summary of bicycle valve types
by Sheldon Brown
common types of valves used for bicyclesadvantages Of tire monitoring valve cap
{{Bike equipment Tires Valves Bicycle parts