Bicycle gears Pinion P1.18, Nuvinci, Rohloff.

Pinion

This is a very interesting approach, linear gears at the centre of effort of the pedalling motion (and near the ideal centre of gravity). very wide range of gear ratio and the use of a belt drive train. Seems like the ideal system. The only negatives might be the unproven reliability, the high price and the non standard frame.
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Nuvinci drive

The Nuvinci drive is a continuous variable drive, using canting spheres and a force conducting fluid. The gear is part of the rearwheel hub. Main characteristic is continuous variability.
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Rohloff gear

The Rohloff gear paved the way for many of the others they were the first commercially available multi gear rearwheel gearhub.They have proven technology which has shown its merits in the toughest of bicycle applications.
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