BBS02 - motor spins in cold weather, doesn't deliver power.


New member
Local time
2:35 PM
Apr 18, 2023
upstate NY
My BBS02 motor has intermittently not been delivering power to the crank, when it gets cold. The motor revs up high, but doesn't deliver power.
It was happening some at 20F, more at 10F. Then when I shift, so the shift sensor temporarily turns the power off, the motor may engage, or it stops engaging. This happens using both the throttle and pedal assist.

The motor only has about 750 miles on it. I accidentally disconnected and reconnected the display/programming cable while the battery was plugged in a couple times, so possibly this damaged something. But it doesn't have problems in warmer weather.

So what's going on? I have been using it at a low power level, maybe increasing the power would warm up the motor more and make it work better. Does it just need more grease maybe? I've been using Mobil 28.
Well, I was riding along a few days later at 13F, and the motor stopped working completely. Luckily I wasn't far from home - it was very difficult to pedal. Same at home, after the bike had warmed up: no response to either the pedal assist or throttle.
I told the seller about it. They told me to disconnect everything except the motor, battery and display, and try to start the motor in the mode that's supposed to help you walk the bike along.
When I did that, the display didn't light up at all, when I tried to turn it on. And there was smoke when I put the battery in, even with the display turned off - like the motor had a short in it.
The seller said it sounded like a controller problem. They sent me a replacement motor under warranty, and the bike is working fine again.
The initial problem with the clutch slipping might have been a controller problem actually - I read online that if the controller is bad, it can lose synch with the motor and make it go backwards, so the clutch slips. That seems likely given the controller problems a few days later.