Bicycle tire
Encyclopedia
A bicycle tire is a tire
that fits on the wheel
of a bicycle
, unicycle
, tricycle
, quadracycle
, bicycle trailer
, or trailer bike
. They may also be used on wheelchair
s and handcycles, especially 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
. They are the second largest source, after air drag
, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle
.
Modern bicycle tires can be classified by several different criteria:
s. In an attempt to soften the ride, rubber tires with a hollow core were also tried.
The first practical pneumatic tire was made by John Boyd Dunlop
, a Scot
, in 1887 for his son's bicycle
, in an effort to prevent the headache
s his son had while riding on rough roads (Dunlop's patent was later declared invalid because of prior art by fellow Scot Robert William Thomson
). Dunlop is credited with "realizing rubber could withstand the wear and tear of being a tire while retaining its resilience". This led to the founding of Dunlop Pneumatic Tyre Co. Ltd in 1889. By 1890, it began adding a tough canvas layer to the rubber to reduce punctures. Racers quickly adopted the pneumatic tire for the increase in speed it enabled.
Finally, the detachable tire was introduced in 1891 by Édouard Michelin
. It was held on the rim with clamps, instead of glue, and could be removed to replace or patch the separate inner tube.
fiber bead that interlocks with flange
s in the rim. A separate airtight inner tube enclosed by the rim supports the tire carcass and maintains the bead lock. An advantage of this system is that the inner tube can be easily accessed in the case of a leak to be patched or replaced.
The ISO 5775-2 standard defines designations for bicycle rims. It distinguishes between
Traditional clincher rims were straight-sided. Various "hook" (also called "crochet") designs emerged in the 1970s to hold the bead of the tire in place, allowing high (80–150 psi (5.5–10.3 bar)) air pressure.
-shaped and attached to tubular rims with adhesive. The rim provides a shallow circular outer cross-section in which the tire lies instead of flanges on which tire beads seat.
or latex
, that provides a relatively airtight barrier inside the tire.
are offered for 100% flat prevention. The desirable suspension quality of the pneumatic tire is lost, and ride quality suffers.
casing covered by a rubber tread. In the case of clinchers, the casing wraps around two beads, one on each edge.
, though cotton
and silk
have also been used. The casing provides the resistance against stretching necessary to contain the internal air pressure while remaining flexible enough to conform to the ground surface. The thread count of the cloth affects the weight and performance of the tire, and high thread counts are generally preferred.
The fibers of the cloth in most bicycle tires are not woven together, but kept in separate plies so that they can move more freely to reduce wear and rolling resistance. They are also usually oriented diagonally, forming a bias plies. Radial ply has been attempted, but found to provide undesirable handling characteristics.
Compound
The tread is made of butyl rubber
that often includes additives such as carbon black
, which gives it its characteristic color, and silicon
. These additives improve wear resistance usually at the expense of traction. Some tires have a dual-compound tread that is tougher in the middle and grippier on the edges. Many modern tires are available with treads in a variety or combination of colors. Road racing
tires with different tread compounds for the front and rear have been developed, attempting to provide more traction in front and less rolling resistance in the rear.
Pattern
Treads fall somewhere along the spectrum from smooth or slick to knobby. Smooth treads are intended for on-road use, where a tread pattern offers no improvement in traction. However, many otherwise slick tires have a light tread pattern, due to the common belief that a slick tire will be slippery in wet conditions. Knobby treads are intended for off-road use, where the tread texture can help improve traction on soft surfaces. Many treads are omnidirectional--the tire can be installed in either orientation--but some are unidirectional and designed to be oriented a certain way. Some tires, especially for mountain bike
s have a tread which is intended either for the front wheel or the rear wheel. A special tread pattern, with small dimples, has been developed to reduce air drag.
Profile
The profile of the tread is usually circular, matching the shape of the casing inside it and allowing the tire to roll to the side as the bicycle leans for turning or balancing. More-squared profiles are sometimes used on mountain bike tires and novelty tires designed to look like automotive racing slicks, as on wheelie bike
s.
Wire
Wire beads are used on inexpensive tires. Though they cannot be folded, they can at least be twisted into three smaller hoops.
Kevlar
Kevlar beads are used on expensive tires, and these are also called "foldable".
Gum wall
Tires with sidewalls made of natural rubber are called "gum wall". The tan colored, natural rubber lacks additives to help protect it from ozone.
Skin wall
Tires with very little rubber, if any, covering the sidewall are called "skin wall". This reduces rolling resistance at the cost of less damage protection.
or trainers
. It minimizes the heat build up and excessive wear that traditional tires experience in this environment and is not suitable for use on pavement.
, along with corresponding rim size designations (e.g., "622×19C"). Older English (inch, e.g. "28×1-5/8×1-3/8") and French (metric, e.g. "700x35C") designations are also still used, but can be ambiguous. The diameter of the tire must match the diameter of the rim, but the width of the tire only has to be in the range of widths appropriate for the width of the rim. Diameters vary from a large 910 mm, for touring unicycles, to a small 125 mm, for roller skiing
. Widths vary from a narrow 18 mm to a wide 94 mm for the Surly
Endomorph.
A balloon tire is a type of wide, low-pressure tire that first appeared on cruiser bicycle
s in the 1930s. They are typically 2 inches (50.8 mm) to 4.7 inches (119.4 mm) wide and are used on mountain bike
s and for riding in snow.
One published guideline for clincher inflation pressure is to pick the value for each wheel that produces a 15% reduction in the distance between that wheel rim and the ground between loaded (i.e. with the rider) and unloaded. Pressures below this lead to increased rolling resistance and likelihood of pinch-flats. Pressures above this lead to less rolling resistance in the tire itself, but to larger energy losses in the frame and rider. Bicycle tires are essentially thin-walled pressure vessels and so the circumferential force in the casing is directly proportional to the internal pressure and to the tire diameter, and the force in the longitudinal direction is half of this.
Inner tubes are not completely impermeable to air, and so lose pressure over time naturally. Butyl inner tubes hold pressure better than latex. At least one public bicycle sharing system, Bixi
, is inflating tires with nitrogen
, instead of simple air, which is already 78% nitrogen, in an attempt to keep the tires at the proper inflation pressure longer, though the effectiveness of this is debatable.
is a complex function of the materials and construction methods used and the inflation pressure, with higher pressure (up to a limit), thinner casing layers, wider tires, larger-diameter wheels, and more-elastic tread material all tending to have less rolling resistance. Rolling resistance coefficients may vary from 0.002 to 0.010, and have been found to decrease with inflation pressure and increase with vertical load.
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
that fits on the wheel
Bicycle wheel
A bicycle wheel is a wheel, most commonly a wire wheel, designed for bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels....
of a bicycle
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
, unicycle
Unicycle
A unicycle is a human-powered, single-track vehicle with one wheel. Unicycles resemble bicycles, but are less complex.-History:One theory of the advent of the unicycle stems from the popularity of the penny-farthing during the late 19th century...
, tricycle
Tricycle
A tricycle is a three-wheeled vehicle. While tricycles are often associated with the small three-wheeled vehicles used by pre-school-age children, they are also used by adults for a variety of purposes. In the United States and Canada, adult-sized tricycles are used primarily by older persons for...
, quadracycle
Quadracycle
A quadracycle is a four-wheeled human-powered vehicle. It is also referred to as a quadricycle, quadcycle pedal car or four-wheeled bicycle, amongst other terms....
, bicycle trailer
Bicycle trailer
A bicycle trailer is a motorless wheeled frame with a hitch system for transporting cargo by bicycle. It can greatly increase a bike's cargo capacity, allowing point-to-point haulage of objects up to 4 cubic yards in volume that weigh as much as half-a-ton.-Types:Different types of trailer are...
, or trailer bike
Trailer bike
Trailer bike is a one-wheeled bicycle trailer designed to carry one or more small riders in positions that closely resemble that of a bicycle rider...
. They may also be used on wheelchair
Wheelchair
A wheelchair is a chair with wheels, designed to be a replacement for walking. The device comes in variations where it is propelled by motors or by the seated occupant turning the rear wheels by hand. Often there are handles behind the seat for someone else to do the pushing...
s and handcycles, especially for racing
Wheelchair racing
Wheelchair racing is the racing of wheelchairs in track and road races. Wheelchair racing is open to athletes with any qualifying type of disability, amputees, spinal cord injuries, cerebral palsy and partially sighted . Athletes are classified in accordance with the nature and severity of their...
. Bicycle tires provide an important source of suspension
Bicycle suspension
A bicycle suspension is the system or systems used to suspend the rider and all or part of the bicycle in order to protect them from the roughness of the terrain over which they travel...
, generate the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion
Vehicle propulsion
Vehicle propulsion refers to the act of moving an artificial carrier of people or goods over any distance. The power plant used to drive the vehicles can vary widely. Originally, humans or animals would have provided the propulsion system, later being supplemented by wind power...
and braking
Bicycle brake systems
A bicycle brake is used to slow down or stop a bicycle. There have been various types of brake used throughout history, and several are still in use today...
. They are the second largest source, after air drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle
Safety bicycle
A safety bicycle is a type of bicycle that became very popular beginning in the late 1880s as an alternative to the penny-farthing or ordinary and is now the most common type of bicycle. Early bicycles of this style were known as safety bicycles because they were noted for, and marketed as, being...
.
Modern bicycle tires can be classified by several different criteria:
- how they attach to the rim: clincher or tubular,
- if and how they hold air: tubed, tubeless, or solid,
- what type of tread they have: slick or knobby.
History
The first bicycle "tires" were iron bands on the wooden wheels of velocipedes. These were followed by solid rubber tires on penny-farthingPenny-farthing
Penny-farthing, high wheel, high wheeler, and ordinary are all terms used to describe a type of bicycle with a large front wheel and a much smaller rear wheel that was popular after the boneshaker, until the development of the safety bicycle, in the 1880s...
s. In an attempt to soften the ride, rubber tires with a hollow core were also tried.
The first practical pneumatic tire was made by John Boyd Dunlop
John Boyd Dunlop
John Boyd Dunlop was a Scottish inventor. He was one of the founders of the rubber company that bore his name, Dunlop Pneumatic Tyre Company....
, a Scot
Scottish people
The Scottish people , or Scots, are a nation and ethnic group native to Scotland. Historically they emerged from an amalgamation of the Picts and Gaels, incorporating neighbouring Britons to the south as well as invading Germanic peoples such as the Anglo-Saxons and the Norse.In modern use,...
, in 1887 for his son's bicycle
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
, in an effort to prevent the headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
s his son had while riding on rough roads (Dunlop's patent was later declared invalid because of prior art by fellow Scot Robert William Thomson
Robert William Thomson
Robert William Thomson , from Stonehaven, Scotland, was the original inventor of the pneumatic tyre.-Biography:...
). Dunlop is credited with "realizing rubber could withstand the wear and tear of being a tire while retaining its resilience". This led to the founding of Dunlop Pneumatic Tyre Co. Ltd in 1889. By 1890, it began adding a tough canvas layer to the rubber to reduce punctures. Racers quickly adopted the pneumatic tire for the increase in speed it enabled.
Finally, the detachable tire was introduced in 1891 by Édouard Michelin
Edouard Michelin
Édouard Michelin was a French industrialist. He was born in Clermont-Ferrand, France. Édouard and his elder brother André served as co-directors of the Michelin company....
. It was held on the rim with clamps, instead of glue, and could be removed to replace or patch the separate inner tube.
Attaching to the rim
Two main techniques for attaching a bicycle tire to a rim have developed: clincher and tubular. In an attempt to provide the best attributes of both methods, tubular clinchers have also been offered.Clincher
Most bicycle tires are clincher for use with "clincher" rims. These tires have a wire or KevlarKevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
fiber bead that interlocks with flange
Flange
A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel...
s in the rim. A separate airtight inner tube enclosed by the rim supports the tire carcass and maintains the bead lock. An advantage of this system is that the inner tube can be easily accessed in the case of a leak to be patched or replaced.
The ISO 5775-2 standard defines designations for bicycle rims. It distinguishes between
- Straight-side (SS) rims
- Crochet-type (C) rims
- Hooked-bead (HB) rims
Traditional clincher rims were straight-sided. Various "hook" (also called "crochet") designs emerged in the 1970s to hold the bead of the tire in place, allowing high (80–150 psi (5.5–10.3 bar)) air pressure.
Tubular or sew-up
Some tires are torusTorus
In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...
-shaped and attached to tubular rims with adhesive. The rim provides a shallow circular outer cross-section in which the tire lies instead of flanges on which tire beads seat.
Holding air
Bicycle tires may hold air with a separate, relatively impermeable inner tube; between just the tire and rim, in a tubeless system; or in a few cases, be non-pneumatic.Tubed
A tubed tire has a separate inner tube, made of butyl rubberButyl rubber
Butyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for Isobutylene Isoprene Rubber. Polyisobutylene, also known as "PIB" or polyisobutene, n, is the homopolymer of isobutylene, or 2-methyl-1-propene, on which butyl rubber is based...
or latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
, that provides a relatively airtight barrier inside the tire.
Tubeless
Tubeless tires are primarily used on mountain bikes due to the their ability to use low air pressure for better traction without getting flats.Solid
Besides solid rubber tires before the pneumatic tire was invented, solid tires, usually of polyurethanePolyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
are offered for 100% flat prevention. The desirable suspension quality of the pneumatic tire is lost, and ride quality suffers.
Construction
Bicycle tires consist of a clothTextile
A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...
casing covered by a rubber tread. In the case of clinchers, the casing wraps around two beads, one on each edge.
Casing
Bicycle tire casing is made of cloth, usually nylonNylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
, though cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
and silk
Silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...
have also been used. The casing provides the resistance against stretching necessary to contain the internal air pressure while remaining flexible enough to conform to the ground surface. The thread count of the cloth affects the weight and performance of the tire, and high thread counts are generally preferred.
The fibers of the cloth in most bicycle tires are not woven together, but kept in separate plies so that they can move more freely to reduce wear and rolling resistance. They are also usually oriented diagonally, forming a bias plies. Radial ply has been attempted, but found to provide undesirable handling characteristics.
Tread
The tread is the part of the tire that contacts the ground.Compound
The tread is made of butyl rubber
Butyl rubber
Butyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for Isobutylene Isoprene Rubber. Polyisobutylene, also known as "PIB" or polyisobutene, n, is the homopolymer of isobutylene, or 2-methyl-1-propene, on which butyl rubber is based...
that often includes additives such as carbon black
Carbon black
Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of amorphous carbon that has a high surface-area-to-volume ratio, although its...
, which gives it its characteristic color, and silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
. These additives improve wear resistance usually at the expense of traction. Some tires have a dual-compound tread that is tougher in the middle and grippier on the edges. Many modern tires are available with treads in a variety or combination of colors. Road racing
Road bicycle racing
Road bicycle racing is a bicycle racing sport held on roads, using racing bicycles. The term "road racing" is usually applied to events where competing riders start simultaneously with the winner being the first to the line at the end of the course .Historically, the most...
tires with different tread compounds for the front and rear have been developed, attempting to provide more traction in front and less rolling resistance in the rear.
Pattern
Treads fall somewhere along the spectrum from smooth or slick to knobby. Smooth treads are intended for on-road use, where a tread pattern offers no improvement in traction. However, many otherwise slick tires have a light tread pattern, due to the common belief that a slick tire will be slippery in wet conditions. Knobby treads are intended for off-road use, where the tread texture can help improve traction on soft surfaces. Many treads are omnidirectional--the tire can be installed in either orientation--but some are unidirectional and designed to be oriented a certain way. Some tires, especially for mountain bike
Mountain bike
A mountain bike or mountain bicycle is a bicycle created for off-road cycling. This activity includes traversing of rocks and washouts, and steep declines,...
s have a tread which is intended either for the front wheel or the rear wheel. A special tread pattern, with small dimples, has been developed to reduce air drag.
Profile
The profile of the tread is usually circular, matching the shape of the casing inside it and allowing the tire to roll to the side as the bicycle leans for turning or balancing. More-squared profiles are sometimes used on mountain bike tires and novelty tires designed to look like automotive racing slicks, as on wheelie bike
Wheelie bike
A wheelie bike, also called a muscle bike, high-riser, or banana bike, is a type of stylized children's bicycle designed in the 1960s to resemble a chopper motorcycle and characterized by ape hanger handlebars, a banana seat with sissy bar, and small wheels. Notable examples include the Schwinn...
s.
Bead
The bead of clincher tires must be made of a material that will stretch very little to prevent the tire from expanding off of the rim under internal air pressure.Wire
Wire beads are used on inexpensive tires. Though they cannot be folded, they can at least be twisted into three smaller hoops.
Kevlar
Kevlar beads are used on expensive tires, and these are also called "foldable".
Sidewall
The sidewall of the casing, the part not intended to contact the ground, may receive one of several treatments.Gum wall
Tires with sidewalls made of natural rubber are called "gum wall". The tan colored, natural rubber lacks additives to help protect it from ozone.
Skin wall
Tires with very little rubber, if any, covering the sidewall are called "skin wall". This reduces rolling resistance at the cost of less damage protection.
Puncture resistance
Some tires include an extra layer between the under the tread (as shown in the cross section pictured above) to help prevent punctures either by being tough or simply by being thick. These extra layers are usually associated with higher rolling resistance.Studs
Metal studs may be embedded in the tread of knobby tires to improve traction on ice.Reflective
Some tires have a reflective strip on their sidewalls to improve visibility at night. Others have reflective material embedded in the tread.Aerodynamics
In addition to the dimple tread pattern mentioned above, at least one tire has an extra "wing" to cover the gap between the tire sidewall and the wheel rim and reduce drag.Indoor use
At least one modern bicycle tire has been designed specifically for indoor use on rollersBicycle rollers
Bicycle rollers are a type of bicycle trainer that make it possible to ride a bicycle indoors without moving forward. However, unlike other types of bicycle trainers, rollers do not attach to the bicycle frame, and the rider must balance him or herself on the rollers while training...
or trainers
Bicycle trainer
A trainer, or turbo trainer, is a piece of equipment that makes it possible to ride a bicycle while it remains stationary. They are commonly used to train for races, or when riding conditions outside are not favorable...
. It minimizes the heat build up and excessive wear that traditional tires experience in this environment and is not suitable for use on pavement.
Sizes
The modern tire-size designations (e.g. "37-622", also known as ETRTO) are defined by international standard ISO 5775ISO 5775
ISO 5775 is an international standard for labeling the size of bicycle tires and rims. The system used was originally developed by the European Tyre and Rim Technical Organisation . It is designed to make tire sizing consistent and clear. It replaces overlapping informal systems that ambiguously...
, along with corresponding rim size designations (e.g., "622×19C"). Older English (inch, e.g. "28×1-5/8×1-3/8") and French (metric, e.g. "700x35C") designations are also still used, but can be ambiguous. The diameter of the tire must match the diameter of the rim, but the width of the tire only has to be in the range of widths appropriate for the width of the rim. Diameters vary from a large 910 mm, for touring unicycles, to a small 125 mm, for roller skiing
Roller skiing
Roller skiing is a non-snow equivalent to cross-country skiing. Emulating skis, elongated inline skates, with wheels at the ends, are used on tarmac. The skating/skiing action is very similar to actual cross-country skiing on snow....
. Widths vary from a narrow 18 mm to a wide 94 mm for the Surly
Surly Bikes
Surly Bikes is a designer and importer of bicycles, frames, parts, and accessories based in Bloomington, Minnesota, established circa 1998. Surly is owned by and shares facilities with Quality Bicycle Products ....
Endomorph.
Balloon
A balloon tire is a type of wide, low-pressure tire that first appeared on cruiser bicycle
Cruiser bicycle
Cruiser bicycles, also known as beach cruisers, combine balloon tires, upright seating posture, single-speed drivetrains, and straightforward steel construction with expressive styling...
s in the 1930s. They are typically 2 inches (50.8 mm) to 4.7 inches (119.4 mm) wide and are used on mountain bike
Mountain bike
A mountain bike or mountain bicycle is a bicycle created for off-road cycling. This activity includes traversing of rocks and washouts, and steep declines,...
s and for riding in snow.
Inflation pressure
The inflation pressure of bicycle tires ranges from below 30 psi (2 bar; 207 kPa) for tubeless mountain bike tires to 220 psi (15 bar; 1,517 kPa) for tubular track racing tires. The pressure rating of tires is usually stamped somewhere on the sidewall. It may be indicated as "Maximum Pressure," or "Inflate to . . . " and is usually expressed as a range (for example, "90 –". Inflating to the lower number in the pressure range will tend to increase traction and make the ride more comfortable. Inflating to the higher number will tend to make the ride more efficient and will decrease the chances of getting a flat tire.One published guideline for clincher inflation pressure is to pick the value for each wheel that produces a 15% reduction in the distance between that wheel rim and the ground between loaded (i.e. with the rider) and unloaded. Pressures below this lead to increased rolling resistance and likelihood of pinch-flats. Pressures above this lead to less rolling resistance in the tire itself, but to larger energy losses in the frame and rider. Bicycle tires are essentially thin-walled pressure vessels and so the circumferential force in the casing is directly proportional to the internal pressure and to the tire diameter, and the force in the longitudinal direction is half of this.
Inner tubes are not completely impermeable to air, and so lose pressure over time naturally. Butyl inner tubes hold pressure better than latex. At least one public bicycle sharing system, Bixi
BIXI
Bixi is a public bicycle sharing system developed by the Public Bike System Company , which itself was set up by the parking authority of Montréal to create a modular bicycle sharing system for Montréal....
, is inflating tires with nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, instead of simple air, which is already 78% nitrogen, in an attempt to keep the tires at the proper inflation pressure longer, though the effectiveness of this is debatable.
Rolling resistance
Rolling resistanceRolling resistance
Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when a round object such as a ball or tire rolls on a flat surface, in steady velocity straight line motion. It is caused mainly by the deformation of the object, the deformation of the surface, or...
is a complex function of the materials and construction methods used and the inflation pressure, with higher pressure (up to a limit), thinner casing layers, wider tires, larger-diameter wheels, and more-elastic tread material all tending to have less rolling resistance. Rolling resistance coefficients may vary from 0.002 to 0.010, and have been found to decrease with inflation pressure and increase with vertical load.
Manufacturers
Notable bicycle tire manufacturers include:- Bontrager (owned by TrekTrek Bicycle CorporationTrek Bicycle Corporation is a major bicycle and cycling product manufacturer and distributor under brand names Trek, Gary Fisher, Bontrager, Klein and until recently, LeMond Racing Cycles...
) - Cheng Shin RubberCheng Shin RubberCheng-Shin Rubber Ind. Co.,Ltd. is the tenth largest tire company in the world . Established in 1967, at the city of Yuanlin, Taiwan-Overview:At first, Cheng Shin Rubber, operating as Maxxis International, only produced bicycle tires...
(also branded as Maxxis and CST) - Coker TireCoker TireCoker Tire Company is a Chattanooga, Tennessee-based company that manufactures and sells vintage-style Michelin, Firestone, BF Goodrich and Uniroyal bias-ply and radial whitewall tires for collector automobiles...
- ContinentalContinental AGContinental AG, internally often called Conti for short, is a worldwide leading German manufacturer of tires, brake systems, vehicle stability control systems, engine injection systems, tachographs and other parts for the automotive and transport industries. The company is based in Hanover, Germany...
- Hutchinson
- KendaKenda Rubber Industrial CompanyKenda Rubber Industrial Company is a manufacturer of pneumatic tires in Taiwan since 1962 with manufacturing facilities in Taiwan, China, and Vietnam. They make tires for bicycles, motorcycles, ATVs, trailers, automobiles, and industrial equipment....
- MichelinMichelinMichelin is a tyre manufacturer based in Clermont-Ferrand in the Auvergne région of France. It is one of the two largest tyre manufacturers in the world along with Bridgestone. In addition to the Michelin brand, it also owns the BFGoodrich, Kleber, Riken, Kormoran and Uniroyal tyre brands...
- Nokian
- SchwalbeSchwalbeSchwalbe is a brand name of Ralf Bohle GmbH, a German manufacturer of bicycle, Scooter and wheelchair tires. The company is a third generation, family owned Mittelstand business with global reach. Schwalbe produces a wide range of tires for different cycling applications, but is best known for its...
- Specialized Bicycle ComponentsSpecialized Bicycle ComponentsSpecialized Bicycle Components, more commonly known simply as Specialized, is a major American brand of bicycles and related products. It was founded in 1974 by Mike Sinyard and is based in Morgan Hill, California-History:...
- VittoriaVittoria S.p.A.Vittoria S.p.A. is an Italian bicycle tire manufacturer established in 1953. The company has more than 1000 employees around the world, produces 5 million tires and runs production of Geax mountain bike tires Their facilities around the world include:...
- VredesteinVredesteinVredestein Banden B.V. is a Dutch-Indian manufacturer of tires for cars, commercial vehicles, tractors and bicycles. The company is independent of other large tire manufacturers and describes itself as "middle-sized". The corporate slogan is "Designed To Protect You"...
- Wilderness Trail BikesWilderness Trail BikesWilderness Trail Bikes is a privately owned company based in Marin County, California, USA. Founded in 1983 as a company that specialized in mountain bicycle parts, today WTB sources and sells its product worldwide supplying bike manufacturers and bike shops with bike components such as tires,...
See also
- Camber thrustCamber thrustCamber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire due to its camber angle and finite contact patch...
- Contact patchContact patchContact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
- Cornering forceCornering forceCornering force or side force is the lateral force produced by a vehicle tire during cornering.Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at which cornering force builds up is described by relaxation length...
- Motorcycle tire
- Pneumatic trailPneumatic trailPneumatic trail or trail of the tire is a trail-like effect generated by compliant tires rolling on a hard surface and subject to side loads, as in a turn...
- Relaxation lengthRelaxation lengthRelaxation length is a dynamic property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value....
- Self aligning torqueSelf aligning torqueSelf aligning torque, also known as aligning torque, SAT, or Mz, is the torque that a tire creates as it rolls along, which tends to steer it, i.e. rotate it around its vertical axis...
- Slip angleSlip angleIn vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing...
- Steering ratio