esoria said:
we go often at 95-100kmh at 10-11kw continous withouth problem
Esoria,
Be more careful in using the work "continuous". You guys don't carry enough battery for continuous operation at that power level. It's great to hear that the V2 has a better stator, so it can run more efficiently at higher rpm.
Peter,
You can't really compare your off road riding at much lower speeds and a constantly varying throttle position to our friends in Italy cruising along at good speed on flat roads without even being slowed by stop signs and traffic lights. Plus you're talking about lightweight guys on stock mountain bikes pushing low enough torque that they don't flip over backward. Not only does the V2 motor run at higher efficiency, but hubbies dissipate heat much better at higher rpm and with higher speed external air flow. More importantly though, they are running the motors in their prime band of operation.
The cause of most heat problems are too many full stop or low speed takeoffs, where every acceleration starts at 0% or very low efficiency, running too long at high load and low speed, and/or running current limits too high.
Also, don't underestimate the value in measuring the temperature of the outside shell, especially when you include checking the what temperature does after you stop. Yes, the stator is hotter than the outside shell and that differential will vary with different motors, but Justin's thorough testing of hubbie cooling showed pretty clearly that if the outside shell stays below 60-70°C that the motor is safe from all but a bogged down condition which can burn up a motor in low tens of seconds.
There are an awful lot of claims thrown around ES without any context, and when it comes to performance of an ebike context is everything. Without the total load, terrain, and type of riding, performance measures are meaningless. The term that cracks me up the most is "wheelie machine". Some bikes are wheelie machines even with no motor. In fact, any bike that can be wheelied using the pedals should easily lift in front with any electric motor. I'm quite heavy at over 120kg, and all of my bikes are over 50kg. Plus I live in a mountainous country, so for street riding my equipment is tortured.
What I've found to be the hardest on our systems was quite a surprise to me though. That is riding in bumper-to-bumper stop-n-go traffic. In much of the downtown area of the capital city here, at times there can be no escape from traffic, even on a bicycle. Even with very soft low speed takeoffs, doing many repeated full stop starts can build up heat in a motor quite quickly. With each start beginning at 0% efficiency, even repeating just 100W at the wheel for a few seconds can require thousands of watts, and with the motor not spinning much all that waste heat doesn't dissipate well. If there's ever a time to use your pedals for motion, that's the time.
John
