The Toecutter said:Thinking of something like a Leafbike motor, but with 0.2 mm laminations, and less mass, perhaps around 7-10 lbs. With the right design, I think peak efficiencies of around 95% are possible without much in the way of added cost, which would allow similar or better peak power when compared to the existing offering from Leafbike that would weigh twice as much.
If it were that cheap and easy, you'd already be able to buy such a thing. The Chinese don't want to buy more material and ship more weight than they have to. I doubt there's that much extra efficiency to be had from thinner laminations, at the speeds hub motors run.
Lightweight, high power motors are temperamental. Keep in mind that no matter how good the peak motor efficiency, every motor starts at 0% and covers the entire range between zero efficiency and whatever its peak efficiency is. Half the motor mass means it burns up twice as fast when it's pushed out of its happy speed and load regime. I'd rather tote a few extra pounds and have a system that is much more fault tolerant.