Maybe a shift lever could be designed to replace the the clutch cable. Did you explore the coged belt concept. I would think they would be redily availble in Europe.
I considered a lever or a pedal too; like an old Indian or Harley, and to be honest looks like the most convenient option.
The reasons why I've been trying to get it working on a 2 stroke clutch lever are directed to a practical nature; by operating the clutch with the hands, I'd be able to keep both the toes on the bicycle's pedals.
Being gas bikes banned here, I'd keep a more classic pose and I'd blend into the traffic a little better, in addiction I'd be more comfortable being able to instantly pedal the bike, should anything of unexpected happen, without risking to loose my balance and fall.
I got a little update on the prototype transmission; I more or less figured a decent clutch mechanism for a "neutral by default" mode:
The swinging arm is to be connected to a weak expansion spring, whose direction (red line) more or less matches the radius of the arm; the cable from the clutch lever would enter into a properly placed and oriented J guide, and would slide through the spring, to connect to the arm.
As the clutch mechanism engages, the spring would act as a dampener, reducing the strain onto the cable.
If I had proof which this type of clutch system would work even with the roller swinging downwards, the spring could be changed with a longer and harder one, and the principle would reverse; it would stay in gear by default, and the cable would fight against the spring to lift back up the roller and set back to neutral.
