This invention relates generally to power assist devices for human powered vehicles, such as bicycles; more particularly it concerns a unique power assist package easily connectible to a bicycle and operable to provide power-assist, when needed or wanted.
There have been many design approaches for coupling a battery-powered power assist device to a bicycle, but so far to my knowledge none has provided, in a convenient, economical way, a complete system add-on device that one can install quickly onto bicycles having various types of tires, brakes, gears, etc. To avoid the complexity of needing to couple somehow to the bicycle drive system (tires, wheels, sprockets, chain, cranks; components with geometry that vary from bicycle to bicycle) the power assist needs to power its own wheel or wheels. Various sidecars towed units have been developed to provide self-contained, add-on drive of an integrated wheel or wheels, but none to my knowledge have been highly successful in the modern marketplace.
The geometry challenge is 1) to have the desired force pressing the wheel to the ground at all times, 2) the device never tangling with the rider's body, legs, or feet, 3) the device not inhibiting parking in a small space or backing up, 4) the device not preventing the rear bicycle rack from carrying packages, basket, or even a passenger, 5) the device not having a significant affect on the vehicle's dynamics, 6) the device combining all the batteries, motor, and drive wheel in a package that can be rolled or carried for recharging or storing; and the device avoiding scrubbing. For a practical battery-powered assist, the batteries, motor, and drive wheel should be part of a single unit.