I just happened across this new product for bicycles:
and I immediately thought of Schlumpf/GUNI.
A few slight problems with the application to unis:
- ratios are 1:1 and 1:0.7, for unis you’d want 1:1 and 1:1.5
- it’s all bike tech, through axle and space for 11-speed cassette.
Cool tech though, and likely to be made in much greater quantities than the Schlumpf. I’m no kind of engineer, so I won’t be modding one of these myself.