I promised I would show the finished product so here is the bike that I built to help with my weight control. I have only ridden it up and down the driveway with no power so far but it does fine balance wise.
The motor is 350 watts... the drive is a coaster brake hub run by a bike chain to the motor. I have jbweld and sand on it. I had to weld the sprocket onto the motor but it seems to be okay. I did test it with some old batteries and it didn't fly apart.
The rack on the rear is for the batteries. The total additional weight will be about twenty pounds. Considering I weighed fifty pounds more when I started the bike riding, it is still light.
The batteries on the way are twelve amp hour. If I ran the bike wide open they would run 34 minutes. By being battery conscious and with the freewheel hub I should be able to stretch that some. I have no idea what the speed will be I'll have to come back and let you know.
I have a two speed switch on the handle bars. 12 volt on one leg 24 on the other and of course off. So I have pedal only, I have 12 volt helper 1/2 throttle and 24 volt helper full throttle.
Shoes is going to make a custom cover for the batteries. So there should be one more picture when it is all together.