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Motorcycle components and systems for a
motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...
are engineered, manufactured, and assembled in order to produce motorcycle models with the desired performance, aesthetics, and cost. The key components of modern motorcycles are presented below.


Chassis

The chassis of a motorcycle includes the frame and suspension, along with the front forks, of the vehicle.


Frame

The frame is typically made from welded
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
or steel (or
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...
) struts, with the rear
suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathematics * Suspension (chemistry), small solid particles suspende ...
being an integral component in the design.
Carbon fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
,
titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...
, and
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
are used in a few very expensive custom frames. The frame includes the
head tube The head tube is the part of a cycle's tubular frame within which the front fork steerer tube is mounted. On a motorcycle, the "head tube" is normally called the steering head. On bicycles the manufacturer's brand located on the head tube is kno ...
that holds the front fork and allows it to pivot. Some motorcycles include the engine as a load-bearing stressed member; this has been used all through motorcycle history but is now becoming more common. Oil-in-frame (Oif) chassis, where the lubricating oil is stored in the frame of the motorcycle, was used for
Vincent Motorcycles Vincent Motorcycles was a British manufacturer of motorcycles from 1928 to 1955. The business was established by Philip Vincent who bought an existing manufacturing name HRD, initially renaming it as ''Vincent HRD'', producing his own motorcyc ...
of the 1950s, and for a while during the 1970s on some NVT British motorcycles. It was widely unpopular and generally regarded as a bad idea at the time. Today it is a used on some " thumpers" (single-cylinder four-strokes) that usually have dry-sump lubrication requiring an external oil tank. It has since gained some cachet in the modern custom bike world too because of the space savings it can afford and the reference to an earlier era. Buell motorcycles employed a similar design with the oil held in the swingarm and fuel held in the frame.


Suspension

Modern designs have the two wheels of a motorcycle connected to the chassis by a suspension arrangement, however ' chopper' style motorcycles often elect to forgo rear suspension, using a rigid frame. The front suspension is usually built into the front fork and may consist of telescoping tubes called fork tubes which contain the suspension inside or some multibar linkage that incorporate the suspension externally. There is another type of front suspension system which is Earles type which highly used in off-road motorcycles. The rear suspension supports the '' swingarm'', which is attached via the ''swingarm pivot bolt'' to the frame and holds the axle of the rear wheel. The rear suspension can consist of several shock arrangements: *Dual shocks, which are placed at the far ends of the swingarm *Traditional monoshock, which is placed at the front of the swingarm, above the swingarm pivot bolt *
Softail A softail (shortened form of ''soft tail'') motorcycle intentionally looks like vintage motorcycles with a rigid hard-tail frame that has a triangle of steel tubes at the rear axle, like on a bicycle frame, but on a Softail these tubes are ...
style suspension, where the shock absorbers are mounted horizontally in front of the swingarm, below the swingarm pivot bolt and operate in extension.


Fuel tank

A fuel tank (also called a petrol tank or gas tank) is a safe container for flammable fluids. Though any storage tank for fuel may be so called, the term is typically applied to part of an engine system in which the fuel is stored and propelled (fuel pump) or released (pressurized gas) into an engine.


Front fork

A motorcycle fork is the portion of a motorcycle that holds the front wheel and allows one to steer. For handling, the front fork is the most critical part of a motorcycle. The combination of rake and trail determines how stable the motorcycle is. The 'fork' on a motorcycle consists of multiple components. The triple trees (also known as yokes) hold the fork tubes (which contain the fork springs), and are fastened to the neck of the frame by the steering stem. At the bottom of the fork tubes are the lower legs, often referred to as sliders. The sliders house the dampening assemblies, which vary based on the brand and type of fork. The front axle is located perpendicular and engages the sliders. The handlebars are clamped to the top triple tree and allow the rider to steer the motorcycle.


Engine

Almost all commercially available motorcycles are driven by conventional gasoline
internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...
s, but some small scooter-type models use an
electric motor An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate for ...
, and a very small number of diesel models exist (e.g., the
USMC The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through co ...
M1030 M1 version of the
Kawasaki KLR650 The Kawasaki KLR650 is a dual-sport motorcycle intended for both on-road and off-road riding. It was a long-standing model in Kawasaki's lineup, having been introduced in 1987 to replace the 1984–1986 Kawasaki KLR600, and remaining almos ...
and the Dutch-produced Track T-800CDI). Motorcycle engines range from less than 50 cc (
cubic centimetre A cubic centimetre (or cubic centimeter in US English) (SI unit symbol: cm3; non-SI abbreviations: cc and ccm) is a commonly used unit of volume that corresponds to the volume of a cube that measures 1 cm × 1 cm × 1 cm. One cub ...
s), commonly found in many small scooters, to 5735 cc, a Chevrolet
V8 engine A V8 engine is an eight-cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration. The first V8 engine was produced by the French Antoinette company in 1904, developed and u ...
, currently used by Boss Hoss in its cruiser style motorcycle. Motorcycles have mostly, but not exclusively, been produced with one to four cylinders, and designers have tried virtually every imaginable layout. The most common engine configurations today are the single and
twin Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
, the
V-twin A V-twin engine, also called a V2 engine, is a two-cylinder piston engine where the cylinders share a common crankshaft and are arranged in a V configuration. Although widely associated with motorcycles (installed either transversely or longi ...
, the opposed twin (or boxer), and the in-line triple and in-line four. A number of others designs have reached mass production, including the V-4, the flat 6-cylinder, the flat 4-cylinder, the in-line 6-cylinder, and the
Wankel engine The Wankel engine (, ) is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. It was invented by German engineer Felix Wankel, and designed by German engineer Hanns-Dieter Paschke. ...
. Exotic engines, such as a radial piston engine, sometimes appear in custom built motorcycles, though two firms
Megola The Megola was a German motorcycle produced between 1921 and 1925 in Munich. Like Bimota, the name is a portmanteau derived loosely from the names of its designers Meixner, Cockerell, and Landgraf. Design The Megola had a unique design, laid down ...
and Redrup put radial-engined motorcycles into production. Engines with more cylinders for the same displacement feel smoother to ride. Engines with fewer cylinders are cheaper, lighter, and easier to maintain. Liquid-cooled motorcycles have a radiator which is the primary way their heat is dispersed. Coolant or oil is constantly circulated between this radiator and the cylinder when the engine is running. Air-cooled motorcycles rely on air blowing past fins on the engine case to disperse heat. Liquid-cooled motorcycles have the potential for greater power at a given displacement, tighter tolerances, and longer operating life, whereas air-cooled motorcycles are potentially cheaper to purchase, less mechanically complex and are lighter. An air-cooled engine contracts and expands with its wider temperature range, requiring looser tolerances, and giving shorter engine life. The temperature range of an air-cooled two-stroke is even more extreme and component life even shorter than in an air-cooled four-stroke. As applied to motorcycles,
two-stroke engine A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of ...
s have some advantages over equivalent
four-stroke engine A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...
s: they are lighter, mechanically much simpler, and produce more power when operating at their best. But four-stroke engines are cleaner, more reliable, and deliver power over a much broader range of engine speeds. In developed countries, two-stroke road-bikes are rare, because—in addition to the reasons above—modifying them to meet contemporary emissions standards is prohibitively expensive. Almost all modern two-strokes are single-cylinder, liquid-cooled, and under 600 cc. In November 2006, the
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...
company E.V.A. Products BV Holland announced that its diesel motorcycle, the Track T-800CDI, achieved production status. The Track T-800CDI uses an 800 cc three-cylinder Daimler Chrysler diesel engine. Other manufacturers, including Royal Enfield, had been producing diesel-powered bikes since at least the 1980s. Also, Intelligent Energy, an English alternative-fuel company, is developing a motorcycle powered by a detachable
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
-powered fuel cell, which it calls an Emissions Neutral Vehicle ( ENV). According to reports, the vehicle can sustain speeds of 80 km/h while making virtually no noise, and can run for up to four hours without refuelling.


Transmission

Most motorcycles have a
sequential manual transmission A sequential manual transmission, also known as a sequential gearbox, or a sequential transmission, is a type of non-synchronous manual transmission used mostly for motorcycles and racing cars. It produces faster shift times than traditional ...
shifted by a foot lever. Some (mostly smaller) motorcycles, and many scooters use either a continuously variable transmission, or a hydraulic automatic transmission.
semi-automatic transmission A semi-automatic transmission is a "theoretical" multiple-speed transmission where part of its operation is automated (typically the actuation of the clutch), but the driver's input would be required to launch the vehicle from a standstill and t ...
s are also in use; where the driver's input is still required for shifting gears, but the clutch system is controlled and operated automatically. These systems are mostly found on smaller dirt bikes (e.g.,
minibike A minibike is a two-wheeled, motorized, off-highway recreational vehicle popularized in the 1960s and 1970s, but available continuously from a wide variety of manufacturers since 1959. Their off-highway nature and (in many countries) typically enti ...
s; such as
pit bike A pit bike is a small recreation, stunt or motocross racing motorcycle. Usually defined as having a horizontal air cooled engine and an open cradle frame. Pit bike history The pit bike evolved from the use of custom-built motorized two wheeled m ...
s),
underbone An underbone is a type of motorcycle that uses structural tube framing with an overlay of plastic or non-structural body panels and contrasts with monocoque or unibody designs where pressed steel serves both as the vehicle's structure and body ...
s, many older
moped A moped ( ) is a type of small motorcycle, generally having a less stringent licensing requirement than full motorcycles or automobiles. The term used to mean a similar vehicle except with both bicycle pedals and a motorcycle engine. Mopeds typ ...
s and scooters, and various other types of motorcycles. Engine power can be engaged or interrupted through the clutch, typically an arrangement of plates stacked in alternating fashion, one geared on the inside to the engine and the next geared on the outside to the transmission input shaft.


Final drive

Power transfer from the gearbox to the rear wheel is accomplished by different methods. Chain-drive uses
sprocket A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a roller chain, chain, Caterpillar track, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial ...
s and a
roller chain Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire- and tube-drawing machines, pri ...
, which requires both lubrication and adjustment for elongation (stretch) that occurs through wear. The lubricant is subject to being thrown off the fast-moving chain and results in grime and dirt build-up. Chains do deteriorate, and excessive wear on the front and rear sprockets can be dangerous. In a chain-drive, the power is transmitted into the rear wheel via a cush drive. Conventional roller chain-drives suffer the potential for vibration, as the effective radius of action in a chain and sprocket combination constantly changes during the revolution ("chordal action"). If a drive sprocket rotates at constant RPM, then the chain (and the driven sprocket) must accelerate and decelerate constantly. Most chain-driven motorcycles are fitted with a rubber bushed rear wheel hub to eliminate this vibration issue. Belt-drive and shaft-drive are also used.


Chain lubrication

Small budget motorcycles may have a totally enclosed drive chain, but this is rare on larger motorcycles, an exception being the Norton rotary bikes. To prevent rapid wear of the chain and sprockets, it is customary to apply a greasy chain-lube via an aerosol. Many riders also fit aftermarket chain-oilers to feed a regular supply of oil to the chain at the rear sprocket. These chain oilers vary in sophistication, but all add significantly to the life of the chain. The custom of lubing by immersing the chain in a tin of hot grease ceased in the early 1970s, once most chains had rubber "O'-rings. The original Suzuki RE5 of 1975 came with a rear chain oiler, but the 1976 model had a sealed chain, and its oiler was deleted as "unnecessary". A belt-drive is still subject to stretch but operates very quietly, cleanly, and efficiently. A toothed belt is frequently used. However, they are not as durable when subjected to high horsepower as a chain. You can not alter the length and change final drive ratios as easily as chains. They also can not wrap as closely around chains. And require larger pulleys compared to chain sprockets to get an effective final drive ratio. Replacing a drive belt typically requires removal of the swingarm, since belts cannot be split the way a chain with a
master link Figure 2: Schematic of a modern master link. Figure 3: A SRAM Powerlink, joining two ends of a chain. Figure 4: A master link with a slightly raised profile. Note that the embossed arrow should point toward the ''inside'' of the chain-loop. N ...
can. A shaft-drive is usually completely enclosed; the visual cue is a tube extending from the rear of the transmission to a bell housing on the rear wheel. Inside the bell housing a bevel gear on the shaft mates with another on the wheel mount. This arrangement is superior in terms of noise and cleanliness and is virtually maintenance-free, with the exception of occasional fluid changes. They are the most durable and usually last the life of the motorcycle. However, the additional gear sets are a source of power loss and added weight. A shaft-equipped motorcycle may also be susceptible to shaft effect. Virtually all high-performance racing motorcycles use chain-drive because they are the most mechanically efficient transmitting power to the rear wheel.


Wheels

The wheel rims are usually steel or aluminum (generally with steel
spokes A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface. The term originally referred to portions of a log that had been riven (split l ...
and an aluminum hub) or
mag Mag, MAG or mags may refer to: Arts, entertainment and media * ''MAG'' (video game), 2010 * ''Mag'' (Slovenian magazine), 1995–2010 * '' The Mag'', a British music magazine Businesses and organisations * MacKenzie Art Gallery, in Regina, Sask ...
-type
cast Cast may refer to: Music * Cast (band), an English alternative rock band * Cast (Mexican band), a progressive Mexican rock band * The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis * ''Cast'', a 2012 album by Trespassers William ...
or machined aluminum. Cast
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
disks, produced by one-step hot forging from magnesium
alloys An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility ...
ZK60 and MA-14, are also used for many motorcycle wheels. At one time, motorcycles used
wire wheels Wire wheels, wire-spoked wheels, tension-spoked wheels, or "suspension" wheels are wheels whose rims connect to their hubs by wire spokes. Although these wires are generally stiffer than a typical wire rope, they function mechanically the same ...
built up from separate components, but, except for dirtbikes, one-piece wheels are more common now. Performance racing motorcycles often use
carbon-fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
wheels, but the expense of these wheels is prohibitively high for general usage.


Tires

Motorcycles mainly use pneumatic tires. However, in some cases where punctures are common (some
enduro Enduro is a form of motorcycle sport run on extended cross-country, off-road courses. Enduro consists of many different obstacles and challenges. The main type of enduro event, and the format to which the World Enduro Championship is run, is ...
s), the tires are filled with a tire mousse which is unpunctureable. Both types of tire come in many configurations. The most important characteristic of any tire is the contact patch, the small area that is in contact with the road surface while riding. There are tires designed for dirt bikes, touring, sport and cruiser bikes. Dirt bike tires have knobbly, deep treads for maximum grip on loose dirt, mud, or gravel; such tires tend to be less stable and noisier on paved surfaces. Sport or performance tires are designed to provide maximum grip for street use on paved surfaces but tend to wear faster. Touring tires are usually made of a harder rubber compound for greater durability, these may last longer but tend to provide less outright grip compared to sports tires at optimal operating temperatures. Touring tires typically offer more grip at lower temperatures and can be more suited to riding in cold or winter conditions where a sport tire may never reach its optimal operating temperature. Cruiser and sport touring tires are designed to compromise between grip and durability. These tend to have stronger sidewalls as they are typically fitted to heavier machines. Motorsport or racing tires offer the highest of levels of grip. Due of the high temperatures at which these tires typically operate, use outside a racing environment is unsafe, typically these tires do not reach their optimum temperature which provides less than optimal grip. In racing situations, tires are normally brought up to temperature in advance based on application and conditions through the use of tire warmers.


Brakes (disc/drum)

There are generally two independent brakes on a motorcycle, one set on the front wheel and one on the rear. However, some models have "linked brakes" whereby both can be applied at the same time using only one control. Front brakes are generally much more effective than rear brakes: roughly two thirds of stopping power comes from the front brake—mainly as a result of weight transfer being much more pronounced compared to longer or lower vehicles, because of the motorcycle's short
wheelbase In both road and rail vehicles, the wheelbase is the horizontal distance between the centers of the front and rear wheels. For road vehicles with more than two axles (e.g. some trucks), the wheelbase is the distance between the steering (front ...
relative to its center of mass height. This can result in brake dive. Brakes can either be drum or disc based, with disc brakes being more common on large, modern or more expensive motorcycles for their far superior stopping power, particularly in wet conditions. There are many brake-performance-enhancing aftermarket parts available for most motorcycles, including brake pads of varying compounds and steel-braided brake lines. Harley-Davidson replaced drum brakes with disc brakes on Big Twin models starting in 1972, and on Sportster models starting in 1973. In 1981, BMW introduced an
antilock braking system An anti-lock braking system (ABS) is a safety anti-skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses. ABS operates by preventing the wheels from locking up during braking, thereby maintai ...
(ABS) on a motorcycle. Other manufacturers have since also adopted this technology. ABS is normally found on motorcycles of 500 cc or greater engine capacity, although it is available on motor scooters down to 49 cc.


Instruments

Most road motorcycles have an instrument panel, usually consisting of speedometer, odometer and
tachometer A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analo ...
.
Fuel gauge In automotive and aerospace engineering, a fuel gauge is an instrument used to indicate the amount of fuel in a fuel tank. In electrical engineering, the term is used for ICs determining the current State of Charge of accumulators. Motor vehi ...
s are becoming more common, but traditionally a reserve tank arrangement is used with a
petcock A petcock is a small shut-off valve used to control the flow of liquid or gas. Historically, petcocks were threaded valves controlled by a butterfly handle; modern petcocks are typically ball valves. Compared to the progressive control of a ga ...
(petrol tap) on the side of the motorcycle allowing the rider to switch to a reserve fuel supply when the main fuel supply is exhausted. There is not actually a separate reserve tank: The intake for the petcock has two pipes, one extending higher into the fuel tank than the other. When fuel no longer covers the longer pipe the engine will lose power/splutter and the rider switches the petcock to the "reserve" setting, which accesses the shorter pipe. Riders whose bikes lack a fuel gauge (most machines prior to the past few years) usually learn how far they can go with a full tank of fuel, and then use a trip meter if available to judge when they must refill the tank.


Lighting system

The lighting system consists of
Headlight A headlamp is a lamp attached to the front of a vehicle to illuminate the road ahead. Headlamps are also often called headlights, but in the most precise usage, ''headlamp'' is the term for the device itself and ''headlight'' is the term for ...
, tail light, and turn indicator lights.


Ignition key switch

An ignition switch, starter switch or start switch is a
Key switch A key switch (sometimes called a keyswitch or lock switch) is a key-operated switch. Key switches are used in situations where access needs to be restricted to the switch's functions. Key switches are available as components with solder connecti ...
in the control system of a motor vehicle that activates the main electrical systems for the vehicle.In vehicles powered by internal combustion engines, the switch provides power to the starter solenoid and the ignition system components (including the engine control unit and ignition coil), and is frequently combined with the starter switch which activates the starter motor.


See also

*
Bicycle and motorcycle dynamics Bicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics falls under a branch of physics known as classical mechanics. Bike motions of interest ...
* Shaft effect


References


External links


How Motorcycles Work
by Bill Harris
Motorcycle Glossary
- definitions of motorcycle terms {{Motorcycle components
Construction Construction is a general term meaning the art and science to form Physical object, objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Pr ...
Construction Construction is a general term meaning the art and science to form Physical object, objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Pr ...