If you look at some of the new xc bikes out there they mount the suspension so it doesnt take up most of the frame and there is still space for a motor, also you could mount a shift kit on top of the suspension and you wouldn't have chain tension issues. Just a thought. For exampl this bike http://www.giant-bicycles.com/_generated/_generated_us/bikes/models/images/2000/2012/Anthem_X_1.jpg