At what point can we just return to 1990s wheel sizes, add the motor to the wheel, and have the same unsprung mass as we have with today's gigantic wheels?
replies(5):
However it does have some limitations as well. For the "general case" it may not be ideal.
Top of the list is protection. The motor is an expensive part, the wheel is an exposed part - bumping a curb for example could get expensive quickly.
Cooling is also an issue. In-wheel motors suggest air cooling, whereas a bigger (single) motor can be liquid cooled.
Currently in wheel motors end up being quite a bit more expensive (because 4 motors not 1).
On paper, in-wheel motors save space, allow for concepts like "4 wheel drive with different lock", save weight and cleaner design (no drive shafts etc), but it's not clear that the end product is better for "every day" users.