The base functionality of the Company’s VDP-CVT is identical to that of a conventional VDP-CVT. A key difference is the makeup of the pulley sides which are segmented into separate ring sectors rather than being made of a single continuous surface element.
The working principle of our segmented bicycle VDP-CVT is based on a series of equal width pulley ring sectors moving into contact with the V-belt from a retracted position such that only the pulley diameters needed for a chosen gear ratio are engaged, while other diameters are out of the way of the belt when it is moved between gear settings.
This achieves the following:
- A comparably narrow and fixed pulley width that can be incorporated into a bicycle crank set without exceeding well established limits of acceptable Q-factors (human stance width applied to a bicycle); and
- The system gear ratio is only limited by how large a sensible largest diameter of drive and driven pulley can be incorporated into given space constraints because pulley width remains constant at any diameter.
An electric motor located in the bicycle crank changes the diameter of the front (drive) pulley through a planetary gearing system. The electric motor is controlled wirelessly through a switch located on the handlebars.
Importantly, the gear ratio setting of the Company’s VDP-CVTs can be achieved by manipulating the active drive pulley diameter only, the passive driven pulley diameter simply reacts by automatically adjusting its diameter. This avoids the irritating, confusing, and inefficient annoyance of a conventional chain and derailleur transmission, where the cyclist has to select the front crank chain ring and the rear wheel sprocket separately and independently from each other to arrive at a desired gear ratio.