What's that sound? Geared hub chirping


New member
Local time
8:07 AM
Jun 14, 2023
My 1kw ebike motor has begun making a chirping noise.

It's not the brake (it's disconnected in the video) and it only makes the noise when the motor throttle is activated.

Sounds like a seal somewhere, making noise with each revolution of the wheel..
I can see that your wheel is out of true (& likely out of round, too).
I’d worry about it being a bearing going dry. Is there any lateral play in the hub? I’d tear it down and fix it before a bearing let’s loose and ruins the axle or bearing seat in the hub.
It's only making the noise when the motor is active. Riding with motor off doesn't produce the squeak.

This leads me to believe it is electrical rather than mechanical
I have stripped the motor from the wheel - pulled the planetary gears and casing off.
All that noise is coming from a bearing which isn't audible anymore but I can feel it is going bad. It must be reverberating through all the metal to make all that noise!

Anyhow I need another bearing which is 15x28x7mm

Does anyone know if there is a specific bearing I need? The one in the motor is sealed but I don't know if I need one which fits the spec (load and weight etc)

Picture of the failed bearing attached. There is actually 2 in there but the other is fine.


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From the pic it looks like a metal shielded bearing. Which is fine since it’s inside the hub and protected from the elements. Rubber sealed bearing only tolerate a little over 200 degrees F. 250 degrees max for short periods. While I’m not sure how hot it gets in there, I would replace with same type. It doesn’t see high rpm so just any good name brand bearing will do. Should be a 6902ZZ bearing for both sides with metal shield. If it’s rubber sealed then the number should be 6902-2RS for both sides with rubber seals.
Here’s some on Amazon.

2PACK NSK 6902ZZ 6902-2Z Made in Japan 15X28X7MM Double Metal Sealed Bearings https://a.co/d/cJHNBF0

(2 Pack) NSK 6902-2RS Double Rubber Seal Bearings 15X28X7MM Higher Speed Bearings https://a.co/d/buPFZVx
Links to Amazon may include affiliate code. If you click on an Amazon link and make a purchase, this forum may earn a small commission.
FIL's bike had that chirp in a Lectric. It went away but is noticably slower than the other Lectric, They wouldn't and won't honor a warranty claim.
FIL's bike had that chirp in a Lectric. It went away but is noticably slower than the other Lectric, They wouldn't and won't honor a warranty claim.
You better open the hub up and replace the bearings before you cut a groove in the axle. When a bearing loses its lubricant the inner race seizes to the bearing assy, then the noise goes away because the inner race is sliding on the greased axle OD. But it’s slowly grinding away at the axle. Once the grease that spilled out of the bearing goes away the axle will get torn up quickly. I don’t think axles for electric hubs are easily obtainable. So the only fix at that point is welding up the groove and machining the weld down to the original diameter which is not cheap, even if you can find someone to do it.