Well, if you put it on a higher setting on a true 10% slope (10ft rise per 100 distance, right?) and pedal hard with it, I'm guessing maybe 10-13 mph, but that is just a rough guess. I checked Google elevation gain on the steepest hill in our city (Carnahan Rd) and it is 10% exactly for about 1/2 mile (between about 900 S and 1700 S). I should go try it sometime and see what it will do speed-wise. Maybe I'll do that in the next few days when I ride and let you know. As far as motor overheating, I would maybe cut back the assist to a little lower setting on really hot days just to be sure. But you could just try it at the highest setting and if the motor gets too hot it will shut down before damage occurs.
One other thing- I've studied the available battery chemistries a bit and it seems like the Lithium Manganese (LiMn) are the safest and best ones, and they happen to be a lot lighter per energy than the more common Lipo's. Lipo (Lithium Poly Iron Phosphate I think) are cheaper and are rated to give more total cycles per life than the LiMn but are heavier and potentially not as safe. When you would be stressing the battery pretty hard on hot days on that hill I would really consider going with the safer chemistry, just to drastically reduce the chance of any kind of overheating and battery fire. Most likely with a good quality motor and controller the motor would shutdown before the battery got to that critical point, but it would just give you extra insurance against ever having something catastrophic happen out there. Falco's batteries are all LiMn for this reason but you can get LiMn from other manufacturers as well.
