I have just heared off an old friend at a Research institute I once worked at.
They have a recumbent with an ATC NuVinci Variable gear ration hub operated by a stepper motor.
The rider's cadence is measured and a small ECU sends signals to the stepper motor to adjust the gear.
Program in 90 rpm and the ECU adjusts the ratio so you always pedal at 90 rpm, up hill or down dale.
I have asked for a test ride,,,
They have a recumbent with an ATC NuVinci Variable gear ration hub operated by a stepper motor.
The rider's cadence is measured and a small ECU sends signals to the stepper motor to adjust the gear.
Program in 90 rpm and the ECU adjusts the ratio so you always pedal at 90 rpm, up hill or down dale.
I have asked for a test ride,,,