Question how Mid-drive / Class 2 works

[TWBKR]

Hi All,

Newbie question here. I am trying to understand how a mid-drive that can be class 2/throttle only works. If one uses throttle only, is it possible to not pedal, given that it is a mid-drive that is turning the crank that the pedals are attached to. Is there a way that it can disengage, otherwise how can it be a class 2. For a rear drive class 2 situation, easy to understand that one doesnt have to pedal, since the rear hub motor is driving it separate from the pedal crank, but how does this work for a mid-drive? Thanks.

 

[AlanDB]

It is something I have wondered as well. And is there some kind of throttle safety cutoff based on gear you are in and torque required to drive the bike? It seems like you could burn up the motor if you tried to throttle in a high gear under load.

 

[rich c]

The chainring on the Bafang mid drive is mounted on a freewheel.

 

[TWBKR]

Thanks. Yes I would be curious about that too. I guess one has to more actively manage the gears to help the motor, so shift into a low gear, when starting out, or going up hills, so as not to strain the motor and make it the most efficient.

 

[JohnT]

The mid-drive version of the Pedego City Commuter is Class 2 and has throttle and pedal assist. When throttling but not pedaling, the motor spins the chainring but not the pedals. There’s a speed sensor, and since it’s Class 2, the motor will cut at 20 mph.

And, yes, gear selection is important with mid-drives. The City Commuter was only released this year, and I haven’t heard of problems yet, but I have heard that people sometimes run the Bafang BBS-XX mid-drives in too high of a gear going up hills and strain the motor causing damage. I don’t recall what fails.

 

[ymarty]

I have a class 2 mid drive with thumb throttle. I can use the throttle with no impact to the pedals. Throttle will maintain a speed of 20 mph. I primarily use throttle only to get through busy intersections. For steep hills, I will use the throttle but I also shift gears to reduce the load on the motor.