Yesterday Lynn mentioned that the noise from her wheel was getting worse, but she couldn’t figure out what it was or when it happened exactly. I did a few tests, and heard a knocking when the motor was powering the wheel, but not when the wheel was being pedaled or when coasting. This implies it is between the motor and the motor clutch, which only leaves the epicyclic gears. As it sounded exactly the same as my bike when a nylon gear broke on it, the diagnoses was simple – one or more broken gears in the wheel.
Having done the job once, and having a couple of spare gears lying around, I was confident of getting the job done quickly. 30 minutes to take the wheel out of the bike and remove the clutch and gear carrier from the wheel, and another 30 to replace a cracked gear, regrease the workings, and reassemble. I then spent another 30 rearranging the bike rack and mudguards while I refitted the wheel and tested. A final adjust of the rear brakes and it sounded as good as new. She rode it to work at 6:30 this morning, so it must be ok 🙂
I only have one spare gear so I may have to order a clutch unit with 3 gears already fitted, just in case it happens again.
Coincidentally, Lynn’s bike has done 5,500 kms, which is approximately what my bike had done when I replaced the motor gears. I put mine down to a heavy rider and some serious abuse, but Lynn is 40kgs lighter and quite gentle on her bike, so maybe it is a bit of built in obsolescence on the part of Bafang?