Re: Frame vs rear mount?
I have a rack mounted motor kit. Right now it is bugging me because my frame is a bit unusual and the kit isn't attached in the optimum way. If I had a normal frame it would be trouble free.
Mounting a motor in the center of a frame looks cool. It turns your bicycle into a motorcycle visually. Having a rack mount means easy installation and removal.
I'd be afraid of damaging parts with a motor mounted in the center of the frame so close to my fast moving feet. I pedal my moped whenever I run out of gas. Sometimes that is more than a mile away from a gas station. I also pedal for starting and going up hills. Often I pedal to assist the motor going into strong winds. I can't have anything interfering with pedaling.
If you have a powerful motor you won't need to pedal as much. If you just like to pedal for fun without the motor running then a rack mounted kit that disconnects from the motor drive would be best for you.