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.

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?