Before i get into this i am not trien to argue with you on this subject. just letting you know what problems we had.

its not about the torque applied, its the pulses of torque applied that launches your derailluer. not to mention the torque you are producing at the wheel from the engine is much higher then you might think. you have alot of gear reduction going in in your set up. the gear reduction in the diferential used 7:1 reduction (i could very easily be wrong on this).

The derailluer worked fine for many monthes(this bike was my rider at the time). but one fateful day at the sturgis bike rally, i was climbing the last hill into deadwood from sturgis when suddenly my rear wheel locked up. i somehow kept the bike from going over and when i stopped i noticed about 1/4 of my 12 gauge spokes snapped, and what was left of the derailluer was intangled in the remaining spokes.

We took that same bike, got it a new rim with a nexus 8 spd internal hub and the thing still runs today. i am just trien to let ya know that expecting your derailuer to handle all of that is just asking for trouble.