- Front freewheel
Shimano front freewheeldesign was an innovative bicycledrivetrain design of the 1970s. To improve the normal bicycle with a freewheelbetween the rear sprocket cluster and wheel hub, Shimano inserted a freewheel between the pedal cranks and the front chainrings that enabled the rider to shift gears while coasting. For safety reasons, however, the normal rear freewheel also had to be retained to stop the chain if clothing got tangled in it, which would otherwise lead to injuries of the leg by the drivetrain, crashing of the bicycle, or both. In addition, the marketing followed Shimano's then-current path of beginning with lower-cost implementations of the system using low tech and usually heavier materials. For one or both of these reasons, the resulting system was substantially heavier than the standard freewheel and, in any event , did not penetrate the market noticeably, although some Panasonicbicycles were briefly equipped with it. It is now often seen as a solution in search of a problem.
Front freewheels can currently be found on bikes used for
bike trials riding. Putting the freewheel on the crank allows some weight to be taken off the rear hub, centering the weight of the bike a little more, making it easier to lift the back wheel as well as simplifying the rear hub, allowing the bearings to sit as far outboard as possible, reducing bending on the hub axle. Because bikes with this set up are almost always singlespeednone of the gear shifting issues that arose in geared systems are problems with this arrangement. The reason for the adoption of front freewheels is likely to be due to the availability of extremely strong screw-on BMX freewheels before the advent of specific components for trials bikes. In fitting the freewheel to the cranks rather than to the back hub a smaller chainring size was possible at the cranks with a gear ratio suitable for trials, increasing the ground clearance of the bike. BMX freewheels could also carry more torque and were cheaper than mountain bike designed systems at the time front freewheels were introduced.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Freewheel — For information about the bicycle component, see Cogset. Freewheel mechanism … Wikipedia
freewheel hub —  A type of hub fitted to the front axle of some four wheel drive vehicles, in which the drive to the front wheels can be disconnected when the front axle is not being driven.  Older type of a bicycle rear hub designed to accept the… … Dictionary of automotive terms
Shimano — Shimano, Inc. Type Public Industry cycling components, fishing tackle, snowboarding equipment Founded February, 1921 … Wikipedia
National (brand) — National was a brand used by Panasonic Corporation (formerly Matsushita Electric Industrial Co., Ltd.) to sell home appliances, personal appliances, and industrial appliances and was the first name used by Konosuke Matsushita s electric firm to… … Wikipedia
Fixed-gear bicycle — A fixed gear bicycle or fixed wheel bicycle, is a bicycle without the ability to coast. The sprocket is screwed directly on to the hub and there is no freewheel mechanism. A reverse thread lockring is usually fitted to prevent the sprocket from… … Wikipedia
Quattro (four wheel drive system) — quattro (meaning four in Italian), is the name used by Audi AG to indicate that four wheel drive (4WD) technologies or systems are used on specific models of the Audi automobiles.Audi.com Glossary [http://www.audi.com/audi/com/en2/tools/glossary/e… … Wikipedia
Bicycle brake — Animation of a single pivot side pull calliper brake for the rear wheel of a steel framed road bike. 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… … Wikipedia
Flip-flop hub — Flip flop hubs, also called double sided hubs, are rear bicycle hubs that are threaded to accept cogs and/or freewheels on both sides. There are several different types of flip flop hubs available for different applications. Their main purpose is … Wikipedia
Bicycle — For other uses, see Bicycle (disambiguation). A mountain bike, a popular multi use 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… … Wikipedia
Bicycle wheel — For the Marcel Duchamp installation, see Bicycle Wheel. The front wheel from a racing bicycle made using a Mavic rim … Wikipedia