When I first heard about CVTs and bikes, the very first thing that came to my mind was using some sort of a grip shift. It seems like the most natural and intutive way to control it. Anything else would, to me, seem like an overly complex system for what should be a very natural and intutive device.

The only other thing that comes close would be something like the old style stem mounted shifter, something that you could just grab and adjust.

I think that the design would have to provide the ability to move with one action thru the entire range of ratios and allow for fine tuning using the same type of action. A grip shift or friction type lever fits that description.

TWIW, I do like the idea of the old style top tube mounted shifter, had one like that back when I was a kid on my krate, but I suspect that the liability lawyers would never let it out the door today.

Steve W