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A step of 7% corresponds to a 1-tooth change from a 14-tooth sprocket to a 15-tooth sprocket, while a step of 15% corresponds to a 2-tooth change from a 13-tooth sprocket to a 15-tooth sprocket. By contrast, car engines deliver power over a much larger range of speeds than cyclists' legs do, so relative differences of 30% or more are common for ...
The forward speed at which oscillations do not increase, where the weave mode eigenvalues switch from positive to negative in a Hopf bifurcation at about 5.3 m/s (12 mph) in this example, is called the weave speed. Below this speed, oscillations increase until the uncontrolled bike falls over. Above this speed, oscillations eventually die out.
Major changes in bicycle form have often been initiated or accompanied by advances in drivetrain systems. Several early drivetrains used straight-cut gears that meshed directly with each other outside of the hub. [1] [2] Some bicycles have used a double-sided rear wheel, with different-sized sprockets on each side. To change gears, the rider ...
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.
The 14-speed Rohloff Speedhub hub gear, introduced in 1998, has a range exceeding 5 to 1, and is thus comparable in range to 24, 27 and 30-speed derailleur systems (with 3×8, 3×9 and 3×10 cogs front and rear), since the latter have three overlapping ranges often with only about 14 distinct gears. As there is no overlap with the Speedhub, the ...
One problem with roller chains is the variation in speed, or surging, caused by the acceleration and deceleration of the chain as it goes around the sprocket link by link. It starts as soon as the pitch line of the chain contacts the first tooth of the sprocket. This contact occurs at a point below the pitch circle of the sprocket.
For a toothed belt drive, the number of teeth on the sprocket can be used. For friction belt drives the pitch radius of the input and output pulleys must be used. The mechanical advantage of a pair of a chain drive or toothed belt drive with an input sprocket with N A teeth and the output sprocket has N B teeth is given by
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]