When I was in Calgary doing my intern at Solarbotics, I when to this store called Power in Motion that specialize in urban electric transportation. They had this neat demo wheel of the inside of a hub motor.
Here are the hall effect sensor. There is 3 sensors.
Here you can see the slot inside the shaft where the wires can travel.
There was also this neat battery. 48V 10.5Ah lithium battery. It weight 3.4Kg (7.5Lbs)
That could fit in my scooter. The only draw back of those specific battery is the continuous current discharge. It is very low. I think it is 2C so 20Ah… the motor consume about 4Ah with no load and I get surge current of 70Ah.