[springbrk200]

So I am attempting to modify my mountain bike by adding an electric motor inside the rear wheel, or maybe the front wheel.

I have checked ebay for kits to do just this, but they are at least in my mind overly expensive.

I am planning on building a multi phase brushless DC motor. This doesn't sound that complicated, and I can use a few old motors I have for some of the parts.

My goal power output of the motor is 1 hp =~ 745 watts, and high efficiency is important.

My problem is the speed controller. I can cheaply buy a hall effect sensor, and a speed controller that supports up to 20Amps. My question is could I just take the output of the speed controller and run it through a big mosfet. I know I could wire this up, but will the mosfets effect the sensor input to the speed controller, or will this be a non issue if I am using the hall effect sensor instead of a feed back sensor?

[daniel_b2380]

springbrk200,
may be something here of which you speak:
http://www.google.com/search?num=50&...motor+controls
http://en.wikipedia.org/wiki/Electric_motor

[jackdw]

You aren't going to get a multi-phase motor to work on the move unless you have some big batteries and some even bigger inverters... Either that or have a cable trailling after you.

You need a DC system.