mechhead said:
It is a very fine balance with tyre pressure between too little and motor slip and too much and motor slip, too little and there is inadequate pressure against the motor can and too much and there is too little tread wrap surface area against the tyre. The best i can get is around 800 watts with a slick 2"x26 tire. i think the closer to over centre the lever angle of the motor the better the partial power performance is bit the less deeply it bites in to the tyre and the less possible tread wrap you will get. i have not tried grip tape on the motor yet i rekon this could give higher power levels but would shread the tire fast. I think Im doing well to get 800w into the tire as Kepler says he only gets around 400 to 500 max (Kepler please correct me if im wrong ) but his bike is a racer with skinny tires maybe a fatter 2.25 or 2.5" would get more power
The optimum tire bite is if you draw an imaginary line from the pivot point on the swing arm, through the centre of your motor, and through your wheel hub. I tend to set them up with a few degrees less with lower powered systems I think you get a smoother action this way. I agree 800W is about the limit. But thats not the design intent. Its all about ultra light weight which means small battery which in turn means low power if you want to get any reasonable range out the pack.
I think the sweet spot in 250 Whr battery and a switchable between 200W and 400W.
With grip tape using a 6374 motor and a hard compound 2" tire, I have run 1500W without any slip. It worked fine but I really dont see the point.