I thought David was taking advice on it first? Just because another manufacturer has said they are legal doesn't make it so.
This is turning into such an old chestnut! Take any motor (even a sewing machine motor), and stick a label on it, and that's the rating. What the in-use rating depends on is duty cycle, cooling, internal shaft and bearing sizes, applied voltage, control equipment if appropriate, etc. - you name it, all of those things come into the equation.
So, you could take a motor and connect it to a 24 volt supply and find it won't draw more than 250 watts in use - the same motor on 36 volts might draw 500 watts under load - and the same motor on 48 volts might draw 1kW, and because of the dirty great heat sink fins it'll do that all day, as long as the batteries hold out. What's the rating? Stick a label saying 24V 250 watts on it, and nobody could argue. You want to run it on 48 volts? Go ahead! We (the mythical manufacturers) don't specify it at that voltage in this application, so it's perfectly OK for granny's shopper.
That's the 'problem' from the engineering viewpoint, put as simply as possible. You might be in with a chance if you specified a particular controller and supply voltage, but you still leave the door open for serious overdriving of one kind or another, by upping the supply voltage and/or mix 'n' matching a suitable controller, as long as the motor is up to it.
The danger from our viewpoint would be if someone produced an e-bike which obviously exceeds 15mph by a wide margin on the flat with no pedalling, which would get 'noticed'. Generally, though, unless and until battery technology makes a quantum leap in terms of capacity versus weight, it's all fairly self-regulating, as you can easily 'do' 30mph like that with present technology, but the range will be impracticably short. It's not linear either - double the speed, divide the range by four or five. That sort of thing. Also, how long would your battery survive that sort of treatment? Don't go there. I know these bikes exist - but they're a very minority market. Personally, I hope for all our sakes that the present design boundaries don't get pushed too far.
Rog.
£295?
