Understanding Motors and Batteries for Electric Bikes


Staff member
Hey guys, I thought you might enjoy this. The last time I visited Optibike in Boulder, CO I got to spend some time with Jim Turner (the founder) and ask some questions about ebikes. He's got a masters degree in mechanical engineering, has been in the space since 1996 and grew up riding motocross bikes so his perspective is really cool (and he has a free ebook you can check out on Amazon).

Here's the video of Jim talking about different kinds of electric bike motors: geared and direct drive hub as well as mid-drive or center motors.

Here's the video of Jim talking about the different kinds of battery chemistries: lead acid, nicad, lithium-ion and lithium-phosphate. He also talks about how to care for ebike batteries towards the end.



Well-Known Member
Jim hits the nail on the head about motor drag (cogging torque) on ddhub. Regen is not free (harder to pedal without assist) and regen is has a very limit usefulness at 2-3%. MAybe ok for a heavier bike/rider with higher power, and stop/go application. Batteries wear out faster with regen. and you CAN damage a battery if regen is done full without a good bms. ubs benefit from silence, less gear changes, easier to use....

The Opti MBB has two clutches for a real freewheel effect - no drag when pedalling or coasting. The Bosch, Yamaha, Impule, BBS01/02 turns gears when pedalling and there is resistance when pedalling un-assisted. Not a lot of resistance, but some. Is this not true?