An electric assist bicycle drive with automatic continuously variable transmission

An automatic hybrid bicycle drive, combining human power and electric assistance via an electronic continuously variable transmission (ldquoe-CVTrdquo), is investigated. A trial design is given for a drive combining two planetary gears and two motor/generators in the rear hub. The motors are nested coaxially and the fixed chain ratio is selected so that the motor volumes are in proportion to their rated torques. As well as requiring no gear-changing, the system should achieve high regenerative braking capability, high efficiency and low maintenance.