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A single-speed bicycle is a type of bicycle with a single gear ratio and a freewheel mechanism. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle. Adult single-speed bicycles typically have a gear ratio of between 55 and 75 gear inches, depending on the rider and the anticipated ...
When "safeties" replaced "ordinaries", chains and sprockets allowed small wheels to be turned faster than the pedal cranks. As result, a 28-inch wheel could be made to move a bicycle at the same speed as a 60-inch wheel. Such a bicycle was then said to be geared at 60 gear inches and pedalled similar to an ordinary with a 60-inch wheel.
Careful sprocket selection can allow the available gear ratios when using one sprocket to fall half-way between those available when using the second sprocket, providing half-step gearing, as on the Brompton 6-speed folding bicycle. This concept is used and extended in the SRAM Dual Drive system, where a conventional multi-speed cassette is ...
The ratio of the force driving the bicycle to the force on the pedal, which is the total mechanical advantage of the bicycle, is the product of the speed ratio (or teeth ratio of output sprocket/input sprocket) and the crank-wheel lever ratio.
A multi-speed bicycle, by providing two or three different-sized driving sprockets and up to 12 (as of 2018) different-sized driven sprockets, allows up to 36 different gear ratios. The resulting lower gear ratios make the bike easier to pedal up hills while the higher gear ratios make the bike more powerful to pedal on flats and downhills.
A track bicycle or track bike is a form of fixed-gear bicycle optimized for racing at a velodrome or at an outdoor track. Some road racing and club cyclists use a fixed-gear bicycle for training during the winter months, generally using a relatively low gear ratio, believed to help develop a good pedalling style. [5]
Several technologies have been developed to alter gear ratios. They can be used individually, as an external derailleur or an internal hub gear, or in combinations such as the SRAM Dual Drive , which uses a standard 8 or 9-speed cassette mounted on a three-speed internally geared hub, offering a similar gear range as a bicycle with a cassette ...
Shimano 600 front derailleur (1980). A derailleur (French pronunciation:) 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.