hub motor

There are two basic types of motors in wide use today for electric bikes, direct drive and geared. The direct drive has no internal gears or other moving parts except the actual case which rotates around the axle on sealed bearings. The coils are wound around an assembly that is fastened to the axle and remains stationary. The outer ring of the case has a ring of magnets that rotate in close proximity to the electromoagnets formed by the coils. As the coils are energized in a specific pattern by the motor controller, the magnets are attracted and repelled causing the wheel to rotate.

While nearly at work this morning the hub motor on the Gelato started to make an odd groaning/grunting noise at low speed. At higher speeds the sound stopped. The sound made it seem like it was working hard to get started. Luckily it was less than 100 yards from work.. I put the bike on its stand so the back wheel was not on the ground and turned the throttle. It still made the same noise. At one point the wheel did not even turn without some urging. Once it was going it turned without a problem. All of this was after about 4 miles of riding.