Gearless Direct-Drive Technology:
Some History: Heinzmann of Germany had a wonderful geared direct drive motor which was really popular in the late 1990s. Lee Iacocca used it in his ambitious electric bike venture.
In Canada, BionX launched a gearless motor in the late 1990s. The earlier system was quite cool and sophisticated. In the meanwhile, in Netherlands, Sparta of Accell group was having a great success with a small gearless brushless Chinese motor called toprun.
BionX and Accell group essentially pioneered the torque sensor technology and for the first time redefined a unique electric bike experience. That experience has been a cornerstone of a number of future developments.
However, direct drive technologies suffered some serious setbacks. There were a number of quality issues and generally customers had to wait a long time get their problems sorted out. And most importantly, there was a reduction in torque during a long hill climb due to internal overheating of the motor. This was a serious issue in hilly areas.
How the Direct-Drive eBike Technology Works:
Figure 2 - Direct Drive eBike Technology
Figure 3 - Direct Drive eBike Technology
Figure 2 and 3 illustrate the use of direct drive technology in a bicycle. Essentially the motor drives the wheel directly. The motor torque and power are transferred without any intermediary stages directly to the wheel.
Takeaway: Direct drive directly drives a bicycle wheel.