Unbelievable Weird Noise Elimination Solution

[dannydibbert]

After all my troubleshooting to find the somewhat random weird grinding noise at high wattage (~900+ watts) on my new e-bike including a Bafang 750 rear hub complete tear down with magnet inspection, nylon planetary gears relube with red lithium, spoke checks, controller evaluation, elimination of brake possibility by riding alternately without front then rear, lots of Q/A on my thread below which all helped a bit; the grinding noise still occurred (not quite as bad but still there).

I took a step back and considered that the issue, since it is not repeatable without a load (i.e. upside down there is no issue ever), may be a dynamic resonance issue somewhere. Realizing that the most likely part susceptible to this may be the spokes I refocused on them. It turns out that my front and rear spokes have a very cheap reflector set. I removed both reflectors and did a bunch of repeated high wattage riding and wouldn't you know it ...... NO MORE GRINDING NOISE AT ALL !!!

Thanks again to all the help on this forum.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=107515

 

[Hickbeard]

Isn't that just bloody typical.

Glad you sorted it and nothing sinister.



Sent from my CLT-L09 using Tapatalk

 

[Balmorhea]

I took a step back and considered that the issue, since it is not repeatable without a load (i.e. upside down there is no issue ever), may be a dynamic resonance issue somewhere. Realizing that the most likely part susceptible to this may be the spokes I refocused on them. It turns out that my front and rear spokes have a very cheap reflector set. I removed both reflectors and did a bunch of repeated high wattage riding and wouldn't you know it ...... NO MORE GRINDING NOISE AT ALL !!!

My formerly quiet cargo e-bike acquired a buzz at a certain RPM recently when I finally fitted proper fenders. It’s the wire stay curved inside the front fender, humming against the plastic fender when the front motor reaches its most resonant speed. So far, it’s not bothersome enough to go after it with silicone sealant or double-stick tape. I like the fenders a lot more than I dislike the noise.

 

[dannydibbert]

I took a step back and considered that the issue, since it is not repeatable without a load (i.e. upside down there is no issue ever), may be a dynamic resonance issue somewhere. Realizing that the most likely part susceptible to this may be the spokes I refocused on them. It turns out that my front and rear spokes have a very cheap reflector set. I removed both reflectors and did a bunch of repeated high wattage riding and wouldn't you know it ...... NO MORE GRINDING NOISE AT ALL !!!

My formerly quiet cargo e-bike acquired a buzz at a certain RPM recently when I finally fitted proper fenders. It’s the wire stay curved inside the front fender, humming against the plastic fender when the front motor reaches its most resonant speed. So far, it’s not bothersome enough to go after it with silicone sealant or double-stick tape. I like the fenders a lot more than I dislike the noise.

Try some nylon washers to dampen it out.

 

[99t4]

Everybody likes a happy ending!

As I recall, most responders were saying the noise appeared to be of a mechanical nature, not electronic. Now it makes sense.

 

[Tommm]

This is why I am against putting stuff on that isn't necessary, and using tape underneath anything that contacts a metal part. Less is more.

 

[dogman dan]

Yep, all kinds of funny noises from all kinds of things can happen when you ride above 15 mph. Can be real hard to get the buzz out of fenders, or other stuff. Always hard to reproduce the noise in the garage, and damn hazardous to try to put a hand on various parts at 30 mph.