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Schlumpf Drives are primarily used as an alternative to multiple chainrings. Four models are currently produced, with differing ratios from pedal revolutions to chainwheel revolutions. Speed Drive, this allows a 65% increase in the final drive (ratio 1.65). High Speed Drive, this allows a 150% increase in the final drive (ratio 2.5).
The Schlumpf Mountain Drive and Speed Drive have been available since 2001. [14] Some systems offer direct drive plus one of three variants (reduction 1:2.5, increase 1.65:1, and increase 2.5:1). Changing gears is accomplished by using your foot to tap a button protruding on each side of the bottom bracket spindle.
Patents for built-in systems to change gear ratios appeared as early as 1890. [8] [9] Adler offered a three-speed gearbox bicycle in the 1930s. [10]Several attempts to develop gearbox bicycles during the 2000s for downhill racing, such as the Honda RN-01 G-cross, incorporated complete derailleur gear drive trains in an enclosure.
Before epicyclic gears were used in bicycle hubs, they were used on tricycles. Patents for epicyclic hubs date from the mid-1880s. [5] [6] The first patent for a compact epicyclic hub gear was granted in 1895 to the American machinist Seward Thomas Johnson of Noblesville, Indiana, U.S.A. [7] This was a 2-speed but was not commercially successful.
In mechanical engineering, mechanical efficiency is a dimensionless ratio that measures the efficiency of a mechanism or machine in transforming the power input to the device to power output. A machine is a mechanical linkage in which force is applied at one point, and the force does work moving a load at another point.
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High gear reduction ratios are possible in a small volume (a ratio from 30:1 up to 320:1 is possible in the same space in which planetary gears typically only produce a 10:1 ratio). Disadvantages include a tendency for 'wind-up' (a torsional spring rate) in the low torque region. Strain wave gearing is commonly used in robotics [3] and ...