Mid Drive Motors - Crank vs Chainring RPM

Skirmish

100 mW
Joined
Mar 18, 2021
Messages
44
When not using throttle with Tongsheng TSDZ2 and Bafang BBSxx mid-drive motors, do the chainrings spin at the same RPM as the cranks but with additional torque supplied by the motor?
Is it possible to configure the chainring RPM as a function of crank RPM?
 
Tongsheng is programmed as follows
Power Assist Ratio: 36%~300% (with 4 levels of torque sensitivity-to-power-output to choose from)
Maximum Torque: 80/90/100 N.m
Pedal Cadence Assist: speed of chainring
Level 1 90 rpm
Level 2 100 rpm
Level 3 110 rpm
Level 4 120 RPM

I’m not sure how that computes to pedal speed, I’ve seen some posts that say assist disengages at 90 rpm pedal cadence.

Functionally wit 700x50 tires and 11 x 42 gearing 27mph is where I max out.
 
Hillhater said:
The TSDZ2 is Torque sensing,..so by definition the chainring , and hence crank+pedals,... will all be rotating at the same speed.
That can only change if the separate throttle control is used.

Even in PAS mode?

Would that apply to the torque sensing mode of this motor too? https://www.cycmotor.com/x1-pro-gen-2
 
What do you mean by “PAS” mode ?
The TSDZ2 has 5 levels of pedal assist,..basicly increasing amounts of torque assist.
My TSDZ2 (48v, 750W, factory stock). does not have cadence sensing, only speed sensing from wheel rpm.
Maybe there are different versions, or some of the software upgrades give that option, but it would need a cadence sensor ?
 
Back
Top