Use a belt and do what I did. But go roller instead of wheel sheave (pulley) . You guys remember my HF belt driven duel pulley 2 speed on that Mongoose ! Still running trouble free.
Thanks Happy! Those are pretty fun to build, I have one nearly finished as a pedal only. Not getting much exercise on my MBs.Wow that is impressive, even before the motor add. I like the style and the wood trim.