Cracking noise under hard acceleration

I’m using qs 205 hub motor 2000w 72v with votol em100 controller. The motor run fine, but on no load when it’s under hard acceleration or deceleration it makes a one cracking noise. I’ve tried to spin to see whether the hub is rubbing, and the hub have nothing rubbing against it.

Any idea what cause the problem

Any help is appreciated...

Ya know, cracked chainstays tend to do that.. in those conditions.. you may want to look the rear of the frame over.. especially if you have a dual suspension bike.

neptronix said:

Ya know, cracked chainstays tend to do that.. in those conditions.. you may want to look the rear of the frame over.. especially if you have a dual suspension bike.

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The bike do not have any chain. It’s a hub motor. I’ll will recheck And tighten the bolt and the torque arm. Thank u for you reply.

My friend, chainstay is the bottom half of the swingarm on bicycles, maybe you have crack or damage there?

Here is the video of the noise.

https://youtu.be/kAzIKoGF0uw

Any help is appreciated