Re: A new shift concept for the engineers....
All you need to do is weigh the cost/benefit and logic of that first.
A $150 jackshaft shift kit and 1 drive chain with any geared bike vs. 2 chains and a mortified left hub assembly.
I am all into innovation, and no offense intended to any idea, all I do is share my thoughts on them with a bit of logic which is what forums are for right?
Other than something cheap and easy on the motor if you really want gears AND run two chains with gears on the motor side is...
All I will say is weigh the benefit of a jackshaft and new rear hub shifter single chain cost/benefit against the basic cost/benefit of adding gears to a second chain new left side drive hub or motor that doesn't even exist.