Thanks for the replys and advice. I'm just going to give it a shot since it seems possible. I'll post the results one way or the other. As to the question of sanity, I agree it's not the most normal idea - I just get a kick out of thinking about it. I love 3 speeds, and I have a dual drive on another bike that I really love. So I got a new dual drive, and I'm going to combine two things I like to make an old worn in bike shift like a champion.