Intro: Electric Motor Bike (revised With Better Description)
I recently saw this mountain bike with a free sign on it, so I snatched it up and took it home and with minimal effort got it running like new again. Then I remembered i had a razor scooter motor and I decided to see if I could power the bike using only the manufacturers wheel and apply friction to the tire. So the scooter was all intact excluding the handlebar assembly. Leaving the metal frame that housed the plastic battery compartment and the supports for the motor and wheel. And the supports for the motor and wheel had two channels of metal that ran approx. 1" above the motor and the wheel, running right to left or vise versa if you were looking down on to the motor from above. So I took and cut those 2 channels in half in the center. I then bent either side up, leaving a 1.25" gap between each opposing support arm. (it is a good gauge metal so it is very strong) Now that I had a total of four support arms sticking straight up approx. 2.5" I then drilled a 1/4' hole in each support arm. The rack on the bike that this motor is attached has a 1.25" metal tube that runs the length of the rack on the bottom side facing the tire. I then drilled two holes into that tubing lining them up with the four holes I drilled in the support arms I bent upwards and had spaced a 1.25" apart. I took some all thread and washers and nuts and mounted the motor assembly to the rack. Now, after finishing the project and I knew this was gonna be a problem, and that is the bike has full suspension, a shock. So I can set it up so that when I ride the bike (190lbs) I know how much the shock will depress when im seated on the bike and that also dictates how much pressure is being applied by the scooter wheel to the bike tire. But if someone else gets on who is 140lbs, well I then have to adjust the height of the rack and so on. If I did it all over again id choose a bike with no rear suspension, fixed frame. But if you look in pic#2 you can see better where I cut that support channel n bent it up, maybe youll get a better idea of why I did it and how I attached the whole thing to the tubing under the rack. I took the battery compartment from out of the scooter and attached it to the top of the rack with two very small bungee like cords.I used the original wiring harness from the scooter to make the connection to the switch and the batteries. Now the Dewalt 18v batteries I connected them in a series, meaning i jumped the negative terminal from battery 1 to the positive terminal in battery 2, then connect the positive feed to motor to the positive terminal in battery 1 and the negative feed to the neg. terminal in battery two, giving me 36v of power instead of 18, (and im going to take it to 54v in the near future) and it does the trick I first tried only 18v, and I woulod have to pedal up to spedd then on a flat surface the bike would maintain a constant speed of approx. 4-5 mph and helped very little going up hills. With 2 batteries. on a flat surface I can hit the switch and from a dead stop the bike will accelerate up to approx. 10-12 mph. But going up hills is now awesome, In a gear Id never ever use to climb a hill in, I can now easily make it up this super steep hill by my house with minimal effort. I mean I have to pedal but its effortless.. And I had no switches laying around except an old ceiling fan pull string switch, yup you guessed it, pull the string 1,time nothing, 2 times nothing, 3 times and its on, lol no joke that's how its powered on.Im also going to play around with adhering a better material to the scooter wheel instead of that smooth hard plastic. Im thinking better traction, means less friction is needed to power the bike meaning increased speed, who knows. Im just a silly plumber with too many gadgets in his barn to play n build stuff out of. Id like to hear from the other fellow on here who did this same thing only his is on the front tire..