Well, if I had it to do all over again, I would have gone with a rear hub motor. As it stands, I am over 16000 miles on my front hub motor, a generic hub motor from yescomusa. However, I am on my third frame and 4th fork. I should be on my 5th fork except that I have been riding on a front alloy fork with a cracked dropout for 14 months now. My low cost front fork dropouts are so good I don't even need to buy a new fork. (And for that northern California snob, even Grin has been developing inside the dropout torque arms.
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Here is the skinny on front hub DD motors, if you use a front hub motor on a mountain bike frame.
I used a non-suspension fork for months, but every time I hit a pot hole at speed it felt like bomb is exploding underneath me. I have run 2.5 inch tires with that steel fork and the big tire didn't help much. I went to a suspension fork and it helped a lot. (The explosions became big bumps instead because the springs kind of helped). However the motor keeps extending the suspension fork instead of letting the fork compress so suspension forks are not the panacea. And, before I could even use the motor on a suspension fork, I had to customize the fork dropout width to make the motor axle fit in a perfect line. It has to fit perfectly so the dropouts don't crack apart, which they might do anyway on a very cold nights ride. ....(Are you great with a file to make a perfect dropout adjustment?) It can be done, just don't think it is going to be fast. You got to go slow to make it perfect.
Even then, the motor is heavy and it affects the ride. It takes a bit of experience to keep from washing out on fast turns in slick conditions....Not to mention those unexpected situations where the wheel can wash out.
On the other hand, it might be more efficient because it is constantly pulling. And, you never have to worry about chain and sprocket issues.
I would say this. If you already have a big beach cruiser with big tires and want to have a slow ebike that is easy to install on your steel front forks, then a front hub motor is fine. If you want speed and handling and a suspension fork, go with a rear hub motor.