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The front fork holds the front wheel and is movable. The wheels: wheels include a hub, the spokes, metal rim and rubber tyres. The brakes: they include the actuators on the handlebar, brake cables, brake pads and calipers. The chain and gears: they consist of the front chain wheels, the rear freewheel, the shift levers on the handlebars and the cables. Other bicycle parts include the seat, seat posts, handlebars, handlebar stem, bicycle lights, dynamos, cranks, and pedals. Gears and ball bearings Most racing bicycles have gears. Gears basically serve the purpose of reducing the size and diameter of the wheel. Gears adjust the direction of rotation. Multiple gears on a bicycle helps change the distance the bicycle moves forward with each stroke of the pedal. A mountain bike has 24 gears. Chain wheels are the gears at the front. Most bikes have 2-3 chain wheels. The freewheel, at the rear, has 5-9 gears on it. It spins freely in one direction and locks in the other. This enables the bike to coast, when not pedaling. There are front and rear derailleurs to change the gears. Ball bearings in a bicycle serve to reduce friction. Ball bearings are found in the front and rear hubs for the wheels, the pedals, the fork tube, the bottom bracket and in the freewheel. These bearings need to be periodically cleaned and greased. Expensive bicycles have sealed bearing cartridges that dont need lubrication. Materials used Bicycles need to be strong and lightweight. Alloy steel is used for making the frames and fork tubes. The handlebars, seat posts and brake levers are made of aluminum alloy. Aluminum alloy frames are affordable. Carbon frames, titanium and advanced steel alloys frames are also available. |
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