StephenH

A friend has a Da Vinci tandem, and if I remember correctly, it's basically 10 speeds on the back and 4 on the front, so there's 40.
My experience: Mostly use the big ring up front, and only the smaller ring(s) up front towards the low end of the gear range. So really, with a triple on front and 10 speed in back (my Sojourn was that way), there were about 11 gears that I actually used. The others were just there to extend the range, not so much for the extra combinations. Even with that gearing, more often than not, I'd be shifting two gears at a time anyway, as they were really closer together than I needed.


If you get a regular bike going below about 2 mph, you tend to fall over, and above a 53:11 or so range, you really can't push it unless you're going downhill or with a tailwind, so there's not a lot of point to the extra gears.


Now, if you want something different, make it where the left and the right crank rotate at different speeds...