Rotafix
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Rotafix
The Rotafix is a method of tightening or loosening a sprocket on a track bike or fixed gear bicycle. Method The Rotafix enables the securing of a sprocket ("cog") to a track hub without the use of a chain whip. The chain is removed from the chainring and rests around the bottom bracket shell and on the sprocket with the rear wheel in the horizontal track ends. The chain is folded over itself such that the bottom half of the chain is trapped between the sprocket and the upper half. The sprocket is then prevented from turning because the chain is wrapped around the bottom bracket. It is essential to take steps to protect the paintwork on the bottom bracket shell from damage by the chain. The sprocket is then tightened onto the hub by turning the wheel backwards until it is too tight to turn any more. This method can tighten the sprocket to very high torque because of high mechanical advantage Mechanical advantage is a measure of the force amplification achieved by using a t ...
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Fixed Gear
A fixed-gear bicycle (or fixed-wheel bicycle, commonly known in some places as a fixie) is a bicycle that has a Bicycle drivetrain systems, drivetrain with no freewheel mechanism. The freewheel was developed early in the history of bicycle design but the fixed-gear bicycle remained the standard track racing design. More recently the "fixie" has become a popular alternative among mainly urban cyclists, offering the advantage of simplicity compared with the standard multi-geared bicycle. Most bicycle hubs incorporate a freewheel to allow the pedals to remain stationary while the bicycle is in motion, so that the rider can coast, i.e., ride without pedalling using forward momentum. A fixed-gear drivetrain has the drive sprocket (or cog) threaded or bolted directly to the hub of the back wheel, so that the pedals are directly coupled to the wheel. During acceleration, the pedal crank drives the wheel, but in other situations, the rear wheel can drive the pedal cranks. This direct c ...
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Chain Whip (bicycle Tool)
A strap wrench is any of various types of wrench that grip an object via a strap or chain being pulled in tension around it until it firmly grips. High static friction keeps it from slipping. Many strap wrenches have built-in handles. Others are made to receive the square drive of a ratchet wrench. The strap or chain can have various forms. Some straps are made of polymers, and are smooth, highly flexible, non-marring, high-friction straps. (Before the era of commercial polymers, the straps were of leather or rubber.) Other straps are bands of spring steel, moderately flexible, slightly firmer and more likely to mar than the polymer variants. The chains tend to be of the roller chain type (like a bicycle chain). Types Oil-filter wrenches Many oil-filter wrenches are actually strap wrenches. Others are of the socket type or the pliers type. Chain whips (e.g., for bicycle work) A chain whip is a tool used to tighten and loosen threaded sprockets on a bicycle. It is called a cha ...
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Sprocket
A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth except for timing pulleys used with toothed belts. Sprockets are used in bicycles, motorcycles, tracked vehicles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc. Perhaps the most common form of sprocket may be found in the bicycle, in which the pedal shaft carries a large sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel. Early automobiles were also largely driven by sprocket and chain mechanism, a practice la ...
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Track Bike
A track bicycle or track bike is a bicycle optimized for racing at a velodrome or outdoor track. Unlike road bicycles, the track bike is a fixed-gear bicycle; thus, it has only a single gear ratio and has neither a freewheel nor brakes. Tires are narrow and inflated to high pressure to reduce rolling resistance. History The first bicycle race is popularly held to have been a 1,200 meter race on the 31 May 1868 at the Parc de Saint-Cloud, Paris. It was won by expatriate Englishman James Moore who rode a wooden bicycle with iron tires. The machine is now on display at the museum in Ely, Cambridgeshire, England. The Union Cycliste Internationale was founded on 14 April 1900 by Belgium, the United States, France, Italy, and Switzerland to replace the International Cycling Association, which had been formed in 1892, over a row with Great Britain as well as because of other issues. Frame design A track frame is specific to its intended use, with emphasis on rigidity and lightne ...
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Chainring
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. It consists of one or more sprockets, also called ''chainrings'' or ''chainwheels'' attached to the '' cranks'', ''arms'', or ''crankarms'' to which the pedals attach. It is connected to the rider by the pedals, to the bicycle frame by the bottom bracket, and to the rear sprocket, cassette or freewheel via the chain. Parts Cranks The two ''cranks'', one on each side and usually mounted 180° apart, connect the bottom bracket axle to the pedals. Lengths Bicycle cranks can vary in length to accommodate different sized riders and different types of cycling. Crank length is measured from the center of the pedal spindle to the center of the bottom bracket spindle or axle. The larger bicycle component manufacturers typically offer ...
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Mechanical Advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for this is the ''law of the lever.'' Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal machine does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal. Lever The lever is a movable bar that pivots on a fulcrum attached to or positioned on or across a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot. The location of the fulcrum determines ...
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