Most torque converters have a stall speed around 2000 - 2500 RPM. Which also happens to be the RPM range that your vehicle normally runs at cruising speed. At a lower speed you would be simply running a viscous coupling between the engine and transmission.
Then, thereâs the obvious choice: A dynamo attached to one of the bike wheels. (These devices in general are called generators, but when attached to a bike, a generator is traditionally referred to as a dynamo.
A hub gear, internal-gear hub, or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements.