Bicycle drivetrain systems are used to transmit power on bicycles,

tricycle A tricycle, sometimes abbreviated to trike, is a human-powered (or gasoline or electric motor powered or assisted, or gravity powered) three-wheeled vehicle. Some tricycles, such as cycle rickshaws (for passenger transport) and freight trikes ...

quadracycle A quadracycle is a four-wheeled human-powered land vehicle. It is also referred to as a quadricycle, quadcycle, pedal car or four-wheeled bicycle amongst other terms. Quadracycles have been in use since 1853 and have grown into several fami ...

s, unicycles, or other

human-powered vehicle Human-powered transport is the transport of person(s) and/or goods using human muscle power. Unlike animal-powered transport, human-powered transport has existed since time immemorial in the form of walking, running and swimming. Modern technolo ...

s from the riders to the drive wheels. Most also include some type of a

mechanism Mechanism may refer to: * Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that ...

to convert

speed In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quanti ...

and

torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...

via

gear ratio A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage. Gear teeth are designed to ensure the Pitch circle diameter (gears), pitch circles of engaging gears roll on each other without slipping, pr ...

History

The history of bicycle drivetrain systems is closely linked to the

history of the bicycle Vehicles that have two wheels and require balancing by the rider date back to the early 19th century. The first means of transport making use of two wheels arranged consecutively, and thus the archetype of the bicycle, was the German ''draisine' ...

. Major changes in bicycle form have often been initiated or accompanied by advances in drivetrain systems. Several early drivetrains used straight-cut gears that meshed directly with each other outside of the hub. Some bicycles have used a double-sided rear wheel, with different-sized sprockets on each side. To change gears, the rider would stop and dismount, remove the rear wheel and reinstall it in the reverse direction. Derailleur systems were first developed in the late 19th century, but the modern cable-operated parallelogram derailleur was invented in the 1950s. *

Draisine A draisine () is a light auxiliary rail vehicle, driven by service personnel, equipped to transport crew and material necessary for the maintenance of railway infrastructure. The eponymous term is derived from the German inventor Baron Karl ...

* Penny-farthing *

Safety bicycle A safety bicycle (or simply a safety) is a type of bicycle that became very popular beginning in the late 1880s as an alternative to the penny-farthing ("ordinary") and is now the most common type of bicycle. Early bicycles of this style were know ...

Power collection

Bicycle drivetrain systems have been developed to collect power from riders by a variety of methods.

From legs

Crankset The crankset (in the US) or chainset (in the UK), is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain or belt, which in turn drives the rear wheel ...

Groupset A groupset or gruppo (from the Italian for "group", sometimes misspelled grouppo) is a bicycle component manufacturer's organized collection of mechanical parts. It generally refers to all of the components that make up a bicycle excluding the bic ...

, and

pedals A pedal (from the Latin '' pes'' ''pedis'', "foot") is a lever designed to be operated by foot and may refer to: Computers and other equipment * Footmouse, a foot-operated computer mouse * In medical transcription, a pedal is used to control ...

Treadle bicycle A treadle bicycle is a bicycle powered by a treadle instead of the more common crank. Treadles were one of the mechanisms inventors tried in order to position the pedals away from the drive wheel hub before the development of the bicycle chain or ...

** Vertical foot motion that mimics that of a

climbing Climbing is the activity of using one's hands, feet, or any other part of the body to ascend a steep topographical object that can range from the world's tallest mountains (e.g. the eight thousanders), to small boulders. Climbing is done ...

exercise machine ** Elliptical foot motion that mimicks that of an

elliptical trainer An elliptical trainer or cross-trainer is a stationary exercise machine used to stair climb, walk, or run without causing excessive pressure to the joints, hence decreasing the risk of impact injuries. For this reason, people with some injuri ...

***

ElliptiGO ElliptiGO, Inc. is a manufacturer of stand-up and elliptical bicycles headquartered in Solana Beach, California. Elliptical bikes combine the motion of an indoor elliptical trainer An elliptical trainer or cross-trainer is a stationary ex ...

* ''Swingbike'' and ''Risigo'' that moved the seat and pedals in coordination. File:Rowbike.jpg, A

rowbike A rowbike is an example of a rowing cycle, hybrid fitness/transport machine that combines a bicycle, and a rowing machine. "Rowbike" is a trademark of the Rowbike company. The Rowbike was invented by Scott Olson, the creator of Rollerblade inl ...

File:ElliptiGO Miller Hiwy jeh.jpg,

From arms

Handcycle A handcycle is a type of human-powered land vehicle powered by the arms rather than the legs, as on a bicycle. Most handcycles are tricycle in form, with two coasting rear wheels and one steerable powered front wheel. Despite usually having ...

From whole body

Rowing Rowing is the act of propelling a human-powered watercraft using the sweeping motions of oars to displace water and generate reactional propulsion. Rowing is functionally similar to paddling, but rowing requires oars to be mechanically ...

Hand and foot Canasta (; Spanish for "basket") is a card game of the rummy family of games believed to be a variant of 500 Rum. Although many variations exist for two, three, five or six players, it is most commonly played by four in two partnerships with tw ...

* ''Exycle'': from legs and chest

From multiple riders

Tandem bicycle A tandem bicycle or twin is a form of bicycle (occasionally a tricycle) designed to be ridden by more than one person. The term tandem refers to the seating arrangement (fore to aft, not side by side), not the number of riders. Patents relat ...

Sociable The sociable or buddy bike or side by side bicycle is a bicycle that supports two riders who sit next to one another, in contrast to a tandem bicycle, where the riders sit fore and aft. The name "sociable" alludes to the relative ease with which ...

* Conference Bike * Pedibus

Power transmission

Bicycle drivetrain systems have been developed to transmit power from riders to drive wheels by a variety of methods. Most bicycle drivetrain systems incorporate a

freewheel Freewheel mechanism In mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. An ...

to allow

coasting Coasting may refer to: * Coasting (vehicle), performing a natural deceleration of a motor when the power is removed * Carrying out a part of a spaceflight without orbital maneuver * Sledding * Performing ovarian hyperstimulation without inducing ...

, but direct-drive and fixed-gear systems do not. The latter are sometimes also described as

bicycle brake systems A bicycle brake reduces the speed of a bicycle or prevents it from moving. The three main types are: rim brakes, disc brakes, and drum brakes. Most bicycle brake systems consist of three main components: a mechanism for the rider to apply the b ...

. File:Belt-drive crankset.JPG, A belt-drive

crankset The crankset (in the US) or chainset (in the UK), is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain or belt, which in turn drives the rear wheel ...

File:Stringbike 01.jpg, A

wire rope Steel wire rope (right hand lang lay) Wire rope is several strands of metal wire twisted into a helix forming a composite ''rope'', in a pattern known as ''laid rope''. Larger diameter wire rope consists of multiple strands of such laid rope in a ...

and pulley drive on a Stringbike

Direct

Some human powered vehicles, both historical and modern, employ

direct-drive A direct-drive mechanism is a mechanism design where the force or torque from a prime mover is transmitted directly to the effector device (such as the drive wheels of a vehicle) without involving any intermediate couplings such as a gear train o ...

. Examples include most Penny-farthings, unicycles, and children's tricycles. Another interpretation of direct-drive is that the rider pushes directly against the ground with a foot, as employed in

balance bicycle A balance bicycle, run bike or no pedal bike or dandy horse is a training bicycle that helps children learn balance and steering. It has no foot pedals, no drivetrain, no chain, no gears, no gear shifters, no derailleurs, and no freewheel. Desig ...

kick scooter A kick scooter (also referred to as a push-scooter or scooter) is a human-powered street vehicle with a handlebar, deck, and wheels propelled by a rider pushing off the ground with their leg. Today the most common scooters are made of aluminum, ...

s, and

chukudu The chukudu (or chikudu, cbokoudou, tshukudu) is a two-wheeled handmade vehicle used in the east of the Democratic Republic of Congo. It is made of wood, and is used for transporting cargo. The chukudu generally has an angular frame, two small ...

Rotating

* Chain ** Chainline **

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 ...

Micro drive Micro drive is a type of bicycle drivetrain, mostly BMX and MTB, that uses smaller than standard-sized sprockets. The smallest rear sprocket that fits on a freehub body is an 10-tooth, but with the use of a cassette hub, sometimes called a m ...

* Chainless **

Belt Belt may refer to: Apparel * Belt (clothing), a leather or fabric band worn around the waist * Championship belt, a type of trophy used primarily in combat sports * Colored belts, such as a black belt or red belt, worn by martial arts practit ...

** Shaft **

Wire rope Steel wire rope (right hand lang lay) Wire rope is several strands of metal wire twisted into a helix forming a composite ''rope'', in a pattern known as ''laid rope''. Larger diameter wire rope consists of multiple strands of such laid rope in a ...

as in the Stringbike and

Rowbike A rowbike is an example of a rowing cycle, hybrid fitness/transport machine that combines a bicycle, and a rowing machine. "Rowbike" is a trademark of the Rowbike company. The Rowbike was invented by Scott Olson, the creator of Rollerblade inl ...

Non-rotating

Hydraulic Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counte ...

* Electric, in which turning the cranks generates electricity that then drives an electric motor in the rear wheel.

Two-wheel drive

In 1991, a two-wheel drive bicycle was marketed under the Legacy name. It used a

flexible shaft A flexible shaft, often referred to as a flex shaft, is a device for transmitting rotary motion between two objects which are not fixed relative to one another. It consists of a rotating wire rope or coil which is flexible but has some torsional s ...

and two bevel gears to transmit torque from the rear wheel, driven by a conventional bicycle chain with derailleurs, to the front wheel. In 1994, Steve Christini and Mike Dunn introduced a two-wheel drive option. Their AWD system, aimed at mountain bikers, comprises an adapted differential that sends power to the front wheel once the rear begins to slip. In the late 1990s, 2WD 'Dual Power' mountain bikes were sold in Germany under the Subaru name. They used one belt to transfer power from the rear wheel to the head tube, a small gearbox to allow rotation of the front fork, and then a second belt to transfer power to the front wheel.

Speed and torque conversion

1888 Geared Facile Bicycle Coventry Transport Museum

A cyclist's legs produce power optimally within a narrow pedalling speed range. Gearing is optimized to use this narrow range as best as possible. Bicycle drivetrain systems have been developed to convert speed and torque by a variety of methods.

Implementation

Several technologies have been developed to alter gear ratios. They can be used individually, as an external derailleur or an internal hub gear, or in combinations such as the SRAM Dual Drive, which uses a standard 8 or 9-speed

cassette Cassette may refer to: Technology * Cassette tape (or ''musicassette'', ''audio cassette'', ''cassette tape'', or ''tape''), a worldwide standard for analog audio recording and playback ** Cassette single (or "Cassingle"), a music single in th ...

mounted on a three-speed internally geared hub, offering a similar gear range as a bicycle with a cassette and triple chainrings. *

Derailleur gears Shimano 600 front derailleur (1980) A derailleur is a variable-ratio bicycle gearing system consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another. Modern front and rea ...

Cogset On a bicycle, the cassette or cluster is the set of multiple sprockets that attaches to the hub on the rear wheel. A cogset works with a rear derailleur to provide multiple gear ratios to the rider. Cassettes come in two varieties, freewheels ...

Hub gear A hub gear, internal-gear hub, internally geared hub or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the ...

** Continuously variable *

Gearbox bicycle A gearbox bicycle is a bicycle that uses a gearbox to convert torque and rotational speed from the power source, usually the rider's legs, to what is desired at the drive wheel. The gearbox is usually incorporated into the frame near the crank, ...

Retro-Direct Retro-direct is a gearing mechanism used on some bicycles in the early 20th century, which provides a second gear ratio when pedaled backwards. History Retro-direct was developed by French inventor Paul de Martin de Viviés (1833–1911). An ea ...

Lever A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or '' fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is d ...

and

cam Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bin ...

mechanism, as in the Stringbike

Control

* Shifters **

Electronic Gear-Shifting System upElectronic front derailleur (Shimano Di2) An electronic gear-shifting system is a method of changing gears on a bicycle, which enables riders to shift with electronic switches instead of using conventional control levers and mechanical cables. ...

Autobike An autobike or automatically geared bicycle is a bicycle with an automatic transmission that shifts gears without intervention from the rider. History In 2011 the company Autobike was founded by Mark Simpson. In the company applied for a pate ...

Theory

* Bicycle gearing **

Gear ratio A gear train is a mechanical system formed by mounting gears on a frame so the teeth of the gears engage. Gear teeth are designed to ensure the Pitch circle diameter (gears), pitch circles of engaging gears roll on each other without slipping, pr ...

Gear inches Gear inches is one of several relative measures of bicycle gearing, giving an indication of the mechanical advantage of different gears. Values for 'gear inches' typically range from 20 (very low gearing) via 70 (medium gearing) to 125 (very high g ...

Single-speed

Single-speed bicycle A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle. There are many types of modern single speed bicycles; BMX b ...

** Fixed-gear bicycle

Integration

While several combinations of power collection, transmission, and conversion exist, not all combinations are feasible. For example, a shaft-drive is usually accompanied by a hub gear, and derailleurs are usually implemented with chain drive.

Gallery

File:ElliptiGO Miller Hiwy jeh.jpg,

uses motion similar to that of an

for motion on a modern

treadle bicycle A treadle bicycle is a bicycle powered by a treadle instead of the more common crank. Treadles were one of the mechanisms inventors tried in order to position the pedals away from the drive wheel hub before the development of the bicycle chain or ...

File:Rainbow h.jpg, Hand crank on a tricycle File:Hildick chainless.jpg, Hildick Chainless Bicycle Gear 1898 File:Snek roeifiets.JPG, Cable of a row bike

References

{{Bike equipment Propulsion Mechanical power control

Drivetrain A drivetrain (also frequently spelled as drive train or sometimes drive-train) is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering, the drivetrain is the components o ...

drivetrains