A front freewheel or freewheel crank is a

freewheel image:Freewheel en.svg, Freewheel mechanism In mechanical engineering, mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission (mechanics), transmission that disengages the driveshaft from the driv ...

mechanism used on some bicycles which enables the drivetrain of the bicycle to continue spinning while the rider rolls, but stops pedaling, or ''coasts''. Unlike regular bicycles, a front freewheel can make it possible to shift gears using a derailleur while the rider is coasting if paired with a fixed rear hub or a freehub with a slight resistance in the freewheel mechanism, which causes the chain to continue spinning with the wheel rotation. Freewheels in bottom brackets have been used on some

pedelec A Pedelec (from pedal electric cycle) or EPAC (''electronically power assisted cycle''), is a type of low-powered electric bicycle where the rider's pedalling is assisted by a small electric motor. However, unlike some other types of e-bikes, p ...

and are necessary parts for all mid-drive systems to allow the electric motors to work inside their optimal

rotational speed Rotational frequency, also known as rotational speed or rate of rotation (symbols ''ν'', lowercase Greek nu, and also ''n''), is the frequency of rotation of an object around an axis. Its SI unit is the reciprocal seconds (s−1); other com ...

ranges. A mid-mounted motor is mounted near the crankset, as opposed to a front-mounted motor, which sits in the front hub, or a rear-mounted motor, which sits in the rear hub.

History

The

Shimano , originally and later , is a Japanese multinational corporation, multinational manufacturing company for cycling components, fishing tackle and rowing (sport), rowing equipment, which also produced golf supplies until 2005 and snowboarding gear ...

Front Freewheel (FFS) was a proprietary

bicycle A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered transport, human-powered or motorized bicycle, motor-assisted, bicycle pedal, pedal-driven, single-track vehicle, with two bicycle wheel, wheels attached to a ...

drivetrain design of the 1970s that placed a freewheel between the pedal cranks and the front

chainring The crankset (in the US) or chainset (in the UK) is the component of a Bicycle drivetrain systems, bicycle drivetrain that converts the reciprocating motion of the rider's human leg, legs into rotational motion used to drive the bicycle chain, ...

senabling the rider to shift gears while coasting. FFS rear freewheel is different than a standard freewheel because it's "stiff" with more friction than a normal rear freewheel. It will slip if necessary however, to stop the chain in the event of, for example, a clothing tanglewhich could otherwise lead to injuries of the leg by the drivetrain, crashing of the bicycle, or both. FFS marketing followed Shimano's then-current path of beginning with lower-cost implementations of the system using low tech and usually heavier materials. The resulting system was substantially heavier than the standard freewheel and, in any event, did not penetrate the market noticeably, although

Panasonic is a Japanese multinational electronics manufacturer, headquartered in Kadoma, Osaka, Kadoma, Japan. It was founded in 1918 as in Fukushima-ku, Osaka, Fukushima by Kōnosuke Matsushita. The company was incorporated in 1935 and renamed and c ...

, Ross,

Schwinn The Schwinn Bicycle Company is an American company that develops, manufactures and markets bicycles under the eponymous brand name. The company was founded by Ignaz Schwinn (1860–1948) in Chicago in 1895, and in the 20th century became the domi ...

, and

Raleigh Raleigh ( ) is the List of capitals in the United States, capital city of the U.S. state of North Carolina. It is the List of municipalities in North Carolina, second-most populous city in the state (after Charlotte, North Carolina, Charlotte) ...

briefly equipped bicycles with FFS. The late Sheldon Brown called FFS a "solution in search of a problem." Non-proprietary front freewheels can currently be found on bikes used for bike trials riding, such as the Honda RN-01 G-cross. Such a system allows for the use of cheaper fixed-gear rear hubs instead of cassette hubs, lower gear ratios, and increased ground clearance at the bottom bracket.

References

{{reflist Bicycle parts