A gearbox bicycle is a

bicycle A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist. Bic ...

that uses a

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...

to convert

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 ...

and

rotational speed Rotational frequency (also known as rotational speed or rate of rotation) of an object Rotation around a fixed axis, rotating around an axis is the frequency of rotation of the object. Its unit is revolution per minute (rpm), cycle per second ...

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 A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (con ...

near the crank, and it may be used in addition to or instead of

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 ...

or a

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 ...

. Cited advantages include improved shifting performance, protecting the gearing from damage and exposure to dirt and moisture, as with hub gears, plus locating the additional mass between the two wheels and on the frame where it may be suspended, unlike with hub gears.

History

Patents for built-in systems to change gear ratios appeared as early as 1890. Adler offered a three-speed gearbox bicycle in the 1930s. Several attempts to develop gearbox bicycles during the 2000s for downhill racing, such as the Honda RN-01 G-cross, incorporated complete derailleur gear drive trains in an enclosure. Around the same time Schlumpf Innovations and Hammerschmidt offered

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 ...

s with two different gear ratios and just one chainring. Pinion launched their spur-gear system in the 2010s.

Methods

At least three different gearing techniques have been employed. * Epicyclic gears, as in hub gears. * Spur gears, as in most automobile transmissions. *

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 ...

, as on many bicycles, but fully enclosed.

Gallery

File:Pinion P1.18 interior.jpg, Pinion P1.18 gearbox interior File:Schlumpf Speed Drive bottom bracket.JPG, Schlumpf Speed Drive File:Britannica Bicycle Sunbeam Two-Speed Gear.jpg, Diagram of the Sunbeam two-speed gear for a bicycle (part of the crank) assembly from the 1911 Encyclopædia Britannica, Vol. 3, p. 916 File:L-Variand.png, Image from the Lexikon der gesamten Technik (dictionary of technology) from 1904 by Otto Lueger File:Adler geared bottom bracket 1936.jpg, Adler gearbox with 3 gears from 1936 File:Motaped2.jpg, Mutaped gearbox external view File:Mutaped.jpg, Mutaped gearbox internal view

References

{{Reflist Cycle types

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

History

Methods

See also

Gallery

References