Bicycle pump

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Bicycle floor pump Bike pump.jpg
Bicycle floor pump
Foot-operated bike pump Bicycle Pump foot operated.jpg
Foot-operated bike pump
Frame-mounted bike pump Bicycle pump frame mounted.jpg
Frame-mounted bike pump
Outdoor public air compressor for bicycles. LA2 bicycle pump in Linkoping by night.jpg
Outdoor public air compressor for bicycles.

A bicycle pump is a type of positive-displacement air pump specifically designed for inflating bicycle tires. It has a connection or adapter for use with one or both of the two most common types of valves used on bicycles, Schrader or Presta. A third type of valve called the Dunlop (or Woods) valve exists, but tubes with these valves can be filled using a Presta pump. [1]

Contents

Several basic types are available:

In its most basic form, a bicycle pump functions via a hand-operated piston. During up-stroke, this piston draws air through a one-way valve into the pump from outside. During down-stroke, the piston then displaces air from the pump into the bicycle tire. Most floor pumps, also commonly called track pumps, have a built-in pressure gauge to indicate tire pressure.

Electrically-operated pumps intended to inflate car tires (as available in most service stations) can in principle be used to inflate a bicycle tire if the right type of connection is available. Some such pumps are designed to cut off before a suitable pressure (much higher for a bicycle than a car tire), and will much under inflate the tire. Others may not cut off, but deliver a high rate of flow to fill the larger car tire, with a risk of over inflating and bursting a bicycle tire unless it is stopped with split-second timing.

Inflating tubeless tires requires an initial surge of air to seat the bead, and specialized pumps are available specifically for this task. [2]

History

It is not known when the first bicycle pump was invented, but it is believed to have been in or around 1887, which is when the first inflatable tire or pneumatic tire was produced by John Boyd Dunlop of Scotland. The first bicycle pump consisted of a metal cylinder that had a metal rod running down the middle of it. This would have forced the air out of the cylinder and then sucked in new air when the metal rod was pulled up again. Many modern pumps use a very similar method, while some, such as the electric pumps, use an automated pumping mechanism.

How they work

The bicycle pump compresses air. When the cylinder is compressed, air is pushed down the tube of the pump and then into the tire via the valve, which is forced open by the pressure of the air. When the handle is pulled up again, the valve shuts off automatically so that the air cannot escape from the tire, and new air is forced back into the cylinder so the process can be repeated. Some pumps have a gauge that shows the pressure of air that is forced into the tire. Once the tire is at the correct pressure, the pump valve can be removed from the tire, and the cap can be replaced on the tire valve.

There are two main types of tire valves to which the bicycle tire pump attaches. These are the Presta valve and the Schrader valve. Some pumps fit both types of valves, whereas others do not, but adapters are available that enable the pump to fit any type of valve. "All valves adjustable connecting systems," also known as AVACS, enable the pump to fit any type of valve found on a bicycle, and it also has the capacity to fit onto other universal inflatable products, such as balls, paddling pools, and rubber rings. The AVACS feature is commonly available on pump models and can also be bought as a separate valve attachment. It also works by repeatedly pulling and pushing activities of the Piston.

Types

There are three main types of bicycle pumps

Stand pump

Also known as a floor or track pump. To operate, the user rests the base of the pump on the floor, resting feet at the base, and pulls and pushes full strokes with handles. An additional tube must connect the pump to the fill valve, which may create dead volume.

Hand pump

There are two basic types: tubed and integral. The tubed type requires a separate tube to connect the pump to the valve. These have the advantage that they are cheap, but are inefficient compared to other pumps. They also have a lot of joints from which air can escape.

Integral pumps have a hole in the side with a rubber washer that fits round the valve. This is frequently compressed on to the valve by an extra lever. Because it is well sealed, rigid and has little dead volume, this type of pump is very efficient. An 8″ integral will typically pump faster than an 18″ tubed. These type of pumps will run the risk of shredding the tube valves, especially on those with presta valves.

A simple pump has a cupped fiber or plastic piston. On the forward stroke the air pushes the sides of the cup against the cylinder, so forming a seal; it provides its own valve. Then this piston can push the air out of the hole at the far end.

Some of the most efficient pumps are double action pumps. By sealing the piston in the cylinder at both ends they can force air into the tire on both strokes.

Pumps can be fitted to a bracket on the bike frame, either a clamp on, screw on, or a braze-on peg, or they can be carried in a pannier or other bag on the bike, or they can be carried by the rider in a backpack, pocket, etc.

Mini pump

Mini pumps (or compact pumps) are usually hand pumps that have been made very small and light, so that they can readily be carried on a bicycle for emergency use; they can fit in pockets, saddle bags, or even include a water bottle bracket. Because of their small size, the volume of air that these pumps can provide is somewhat limited compared to a floor pump, so quite a lot of pumping may be needed.

Foot pump

These pumps are often not specifically designed for bicycle use. They do not generate very high pressures so do not work well for narrow road-bike tires, but are fine for large low-pressure tires as found on mountain bikes.

Because they are designed for cars they fit Schrader valves. If the bicycle has Presta valves a small brass reducer is required in order to use the pump.

CO2 inflators

Gas-filled cylinders for bicycles have an unclear history but appear to have appeared between the two World Wars. One story says they were made "by a rider after watching a café proprietor charge up the glass of beer he had ordered from a bottle of carbon dioxide." [3]

The pumps generally used liquefied gas that could not be replaced at home. A later version, which had more success, used a cartridge sold originally for drinks siphons. A lever broke the cartridge and enough gas escaped to inflate a tire.

Modern gas pumps are often used by mountain bike or road bike racers who need to save weight, and to save time if they puncture during a race. They can be a one-time pump or a pump that can be fitted with a replacement cartridge. Most pumps use carbon dioxide and standard-threaded 16g CO2 canisters. Carbon dioxide leaks out of a rubber inner tube more rapidly than air - despite its larger molecule size, the CO2 molecule is significantly more soluble than Oxygen and Nitrogen in rubber and as such can cause a tire to deflate far quicker than if filled with air.

Electric pump

Twelve-volt air compressors made for automobile tires are also compatible with bicycle tires. A portable jump-starter for automobiles can sometimes be used to power these types of pumps. Even non-standard do-it-yourself (DIY) 12-volt electric systems that are primarily for bicycle lighting are sometimes used to power these pumps when cigar lighter receptacles are installed. A main advantage to electric pumps is that recent ones take up less space than hand or foot pumps, which makes them suitable for well-equipped bicycles with DIY 12-volt electric systems to use when basket space is of the essence.

Tire pressure

The pressure rating of tires is usually stamped somewhere on the sidewall. This may be in psi (pounds per square inch) or bar. The pressure rating could be indicated as "Maximum Pressure," or "Inflate to . . . " and will usually give a range (for example, 90-120 psi, or 35-60 psi). Inflating to the lower number in the pressure range will increase traction and make the ride more comfortable. Inflating to the higher number will make the ride more efficient and will decrease the chances of getting a flat tire but a firmer ride must be expected.

Pressure output

The maximum pressure, or how much air the pump can force into a tire, is an important consideration. The pump needs to match or exceed the stated air pressure the tires can handle. If the maximum air pressure is too low, it will not be able to adequately inflate the tires, no matter how hard it is used.

See also

Related Research Articles

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<span class="mw-page-title-main">Air compressor</span> Machine to pressurize air

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<span class="mw-page-title-main">Valve stem</span> Type of valve

A valve stem is a self-contained valve which opens to admit gas to a chamber, and is then automatically closed and kept sealed by the pressure in the chamber, or a spring, or both, to prevent the gas from escaping.

<span class="mw-page-title-main">Schrader valve</span> Motor vehicle and bicycle tube valve

The Schrader valve is a type of pneumatic tire valve used on virtually every motor vehicle in the world today. The Schrader company, for which it was named, was founded in 1844 by August Schrader. The original Schrader valve design was invented in 1891, and patented in the United States in 1893.

<span class="mw-page-title-main">August Schrader</span> German-American inventor (1807–1894)

August Schrader (1807–1894) was a German-American inventor and mechanic. He is known for inventing the Schrader valve.

<span class="mw-page-title-main">Presta valve</span> Bicycle tube valve

The Presta valve is a tire valve commonly found in high pressure road style and some mountain bicycle inner tubes. It comprises an outer valve stem and an inner valve body. A lock nut to secure the stem at the wheel rim and a valve cap may also be present.

<span class="mw-page-title-main">Air pump</span> Pump for pushing air

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<span class="mw-page-title-main">Hydraulic cylinder</span> Mechanical tool for applying force

A hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment, manufacturing machinery, elevators, and civil engineering. A hydraulic cylinder is a hydraulic actuator that provides linear motion when hydraulic energy is converted into mechanical movement. It can be likened to a muscle in that, when the hydraulic system of a machine is activated, the cylinder is responsible for providing the motion.

<span class="mw-page-title-main">Flat tire</span> Deflated pneumatic tire

A flat tire is a deflated pneumatic tyre, which can cause the rim of the wheel to ride on the tire tread or the ground potentially resulting in loss of control of the vehicle or irreparable damage to the tire. The most common cause of a flat tire is puncturing of the tire by a sharp object, such as a nail or pin, letting the air escape. Depending on the size of the puncture, the tire may deflate slowly or rapidly.

A tubeless tire is a pneumatic tire that does not require a separate inner tube.

The Dunlop valve, is a type of pneumatic valve stem in use—mostly on inner tubes of bicycles—in many countries, including Japan, Korea, India, Pakistan, Sri Lanka, most European countries, and a number of developing countries. The Dunlop valve has a wider base than a Presta valve, similar enough in size to a Schrader valve to use identically drilled valve holes in rims, but it can be inflated with a Presta valve adapter. The inner mechanism of the valve can be replaced easily, without the need for special tools.

<span class="mw-page-title-main">Bicycle tire</span> Tire that fits on the wheel of a bicycle

A bicycle tire is a tire that fits on the wheel of a bicycle or similar vehicle. These tires may also be used on tricycles, wheelchairs, and handcycles, frequently for racing. Bicycle tires provide an important source of suspension, generate the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion and braking. Although the use of a pneumatic tire greatly reduces rolling resistance compared to the use of a rigid wheel or solid tire, the tires are still typically, the second largest source, after wind resistance, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle.

<span class="mw-page-title-main">Tubular tyre</span>

A tubular tyre, referred to as a tub in Britain, a sew-up in the US, a single in Australia, or just a tubular is a bicycle tyre that is stitched closed around the inner tube to form a torus. The combination is then glued onto a specially designed rim, referred to as a "sprint rim" in Britain, and just a "tubular rim" in the US, of a bicycle wheel.

<span class="mw-page-title-main">Reciprocating pump</span>

A reciprocating pump is a class of positive-displacement pumps that includes the piston pump, plunger pump, and diaphragm pump. Well maintained, reciprocating pumps can last for decades. Unmaintained, however, they can succumb to wear and tear. It is often used where a relatively small quantity of liquid is to be handled and where delivery pressure is quite large. In reciprocating pumps, the chamber that traps the liquid is a stationary cylinder that contains a piston or plunger.

High-density solids pumps are hydrostatically operating machines which displace the medium being pumped and thus create a flow.

<span class="mw-page-title-main">Booster pump</span> Machine to increase pressure of a fluid

A booster pump is a machine which will increase the pressure of a fluid. They may be used with liquids or gases, but the construction details will vary depending on the fluid. A gas booster is similar to a gas compressor, but generally a simpler mechanism which often has only a single stage of compression, and is used to increase pressure of a gas already above ambient pressure. Two-stage boosters are also made. Boosters may be used for increasing gas pressure, transferring high pressure gas, charging gas cylinders and scavenging.

<span class="mw-page-title-main">Outline of tires</span> Overview of and topical guide to tires

The following outline is provided as an overview of and topical guide to tires:

<span class="mw-page-title-main">Inner tube</span>

An inner tube is an inflatable torus that forms the interior of some pneumatic tires. The tube is inflated with a valve stem, and fits inside of the casing of the tire. The inflated inner tube provides structural support and suspension, while the outer tire provides grip and protects the more fragile tube.

References

  1. Sheldon Brown's Bicycle Glossary W
  2. Mike Yozell (April 27, 2016). "This Floor Pump Makes Installing Tubeless Tires Simple". Bicycling . Retrieved October 25, 2017.
  3. The Bicycle, UK, 30 September 1942, p6