It has fully adjustable Break Regen, Automatic Slope Hold and Cruise Control built into the controller.You could just use a freewheel motor output sprocket if you can find one strong enough, that's what I use on my 50V 1860W shifting e-bikes, or in this case an e-Beast.
Nowhere near the power you are talking but it has gears so it might run with you.
I was thinking an easy mechanical disengage of the motor from the drive train.
That would be pretty easy to do with a belt but a chain presents a different problem and a cent clutch seems like a poor solution.
How often do you plan to be pedaling it anyway?
Speaking of braking by motor drag, have you considered a regenerative braking system?
That big electric motor is a heck of a generator, have it charge your batteries.
If you think that motor has drag doing nothing, it would probably lock your back wheel even hurtling downhill even with all that weight on the back wheel if you tried to charge with too much current, but one thing is for sure, it would make for a good brake if you could control it ;-}
Mechanical disengage would have to be simple and I'm guessing heavy duty for this motor. I thought about it for a second.
The magnetic drag is nowhere near strong enough to prevent my or any other wheel from spinning. On this BLDC motor there is one moving part and it doesn't make physical contact with anything while it rotates so there is nothing to lock up.
