I had the wrong model. I was envisioning the rotor running in a planetary outer bearing race but with the hub connected to the wheel. But that's wrong because it couldn't be direct drive, the wheel does not turn at 18K rpm of course. I'm going to have to go research the per-wheel drive train.

I had the wrong model. I was envisioning the rotor running in a planetary outer bearing race because the rotating field coil magnetic fields would induce energy into any central metal bearing, which will heat up from the induction.