Originally Posted by Boosta

I agree with that to a point but think that it's a case of the brushes on the comm generate the heat which is transfered to the can/mags then the temp of the can and mags get to a point that they can't disepate any more heat any quicker (the surface of the can is only able to get rid of a certain amount at any given time) which in turn means more heat builds up at the comm/brushes which in turn results in fade. It's kind of like a tap on a water tank you can open the tap all the way but it will only allow a certain amount of water to flow through it, so if the water tank was being filled (heat building up at the comm/brushes as you race) at a higher rate than the tap can release it, it would eventually over flow (more heat building at the comm/brushes = motor fade).
Hope that made sense