Need help with Bafang m600

[cry0]

I have this weird behaviour on my M600, it only happens when the chain is on one of the outer half cogs of the cassette and I am putting force on the motor, either by pedaling or by using the scooter mode switch and braking at the same time, as in the video below. I have disassembled the motor completely, but can see no signs of wear on any of the gears.

Any ideas?

Bafang m600 issue

www.youtube.com

 

[TeoElFeo]

Are you sure the issue is coming from the motor and not the freehub of the wheel or the chain? I could see the chain jerk.. have you checked if the chsmain is trying to shift to the next sprocket?

 

[cry0]

Are you sure the issue is coming from the motor and not the freehub of the wheel or the chain? I could see the chain jerk.. have you checked if the chsmain is trying to shift to the next sprocket?

initially I thought that would be the problem, so I replaced the chain and rotor, these were too old anyway. I guess I can rule that out now, however the freehub is a good hint, will check it asap. Thanks!

 

[TeoElFeo]

It's not so much the question of wear of the chain but rather derailleur adjustment.. watch carefully what the chain does on the cassette when the thud appears. Is trying to jump somewhere? If that's not the case check the freewheel

 

[etlsnll]

I have this weird behaviour on my M600, it only happens when the chain is on one of the outer half cogs of the cassette and I am putting force on the motor, either by pedaling or by using the scooter mode switch and braking at the same time, as in the video below. I have disassembled the motor completely, but can see no signs of wear on any of the gears.

Any ideas?

Bafang m600 issue

www.youtube.com

Hi I have watched your video and have exactly the same problem with my m600 motor. I am also reasonably experienced bike mechanic and whilst it seems the same its not the chaln jumping or derailleur. That was my initial suspicion because it happens after changing down to an easier gear, for me typically when beginning to tackle a steep section of trail. I have even replaced the final drive gear which has a clutch in the motor and inspected the internals but no difference.

I'm starting to think it's to do with the torque sensor incorrectly adapting to changes in torque through the axel in these lower gear ranges and the jumping action is electronics engaging and disengaging the motor very quickly. If stay in the higher few gears on the bike I can stomp down on the pedals as much as I like and it seems fine.

Please share here the solution if you did fix it. Will do the same if I do too...it seems a slightly rare kind of failure...
Here is a video of my motor failing: https://1drv.ms/v/s!Aj7IohvhuRcwtEgjA0evXcy5C0gJ