lots of versions of this prototyped over the years.
Are derailleur and gearbox drivetrains the pinnacle of what’s possible? Or will bicycle drivetrains of the future be digital?
www.cyclingabout.com
the issue remains efficiency : for every 100 watts of pedaling you do, a derailleur drivetrain puts about 95 into the wheel. with current and soon-feasible technology the electric drive system is going to be more like 55-60 watts from that 100. (100 x .8 = 80 watts generated, 80 x .8 = 64 watts of propulsion at the motor, lose another 5-10 from gearing of some kind to keep the motor speeds in a practical range)
that’s a lot of energy to throw away for a human rider. it would feel sluggish to say the least - even the small difference in efficiency between a derailleur and IGH is noticeable to many people, and this is an order of magnitude worse….