can someone explain to me exactly what a motor controller does in an electric powered bike?

ok so i wanna build my first electric powered bike but i would like to do it all from salvaged parts or parts i will make. i am not looking to go 100mph or ride it for days at a time I would just like to built this first one to help me understand how it works. As of right now my biggest hang-ups are what does the controller do and can i make one, and how do i figure out how much power it will need in other words if it weighes 10 pounds and i wanna go 10mph i need a 12v motor (hope that makes sense)
Thanks for any help
Danny

The motor controller adjusts the supply to the motor, so you don't leave rubber everytime you press the start button ! Good ones will even push the energy that is in your forward motion BACK into the battery as you brake.

Power levels ? Hard to calculate - depends on YOUR weight AND the bikes, and how fast YOU want to be accelerated, then on the drag of the whole thing. 

Steve
dannyces (author)  steveastrouk7 years ago
hey sorry i never got back i didnt get an email letting me know i had replys..
so i guess my next question is is there a formula of some kind to figure this out like 210lbs (my weight) 50lbs (bike weight) 20mph (top speed) = 36 volt motor???
i mean is this gonna be a trial and error kinda thing or is there a way to actually know before hand??
Field-diversion or not?

L
Sean_Voodoo7 years ago
it makes the bike go