u/Fair_Resolution7965

Hi everyone,

I need some help diagnosing an issue with my Sur-Ron Light Bee X.

Bike history:

Total mileage: ~8,000–9,000 km

Around 5,000–8,000 km ago I replaced the chain and rear sprocket

Since then, no drivetrain parts have been changed

The front sprocket has never been replaced

Current situation:

I just replaced the chain again at around ~9,000 km.

Immediately after installing the new chain, a new noise appeared.

The noise:

Only appears under throttle / load

Gets louder during strong acceleration (high torque)

Disappears when coasting or no load is applied

Sounds like a metallic “chain/rattle/grinding” type noise

My suspicion:

I inspected the front sprocket and it looks quite worn (hooked teeth).

My theory is:

The old chain was stretched and “matched” the worn front sprocket over time

The new chain does not match the worn sprocket profile anymore

This mismatch is causing the noise under load

What I’m asking:

Could you guys confirm if this level of front sprocket wear is enough to cause this kind of noise?

Or could the issue be something else (jackshaft bearings, chain alignment, etc.)?

I’ve attached pictures of the front sprocket for reference.

Any input would be appreciated before I start replacing more parts unnecessarily.

Thanks

Also if i take chains off sound dissapears upload 2 vids...

I just replaced really used chain with brand new D. I. D 420 chain, ive tried looser and tigther chains and belt but sound is still there, on video u can hear when i use throttle u hear sound without throttle no sound also if i spin rear wheel freely on air it don't sound bad but when i sit on it and drive there is this sound.. is my jackshaft bearings cooked?

So it was time to replace chain, my belt is not too tight i tried tighter and looser, also chain is not too tight or loose but its keeping this sound, much louder before replacing chains. Ive driven like 8000km with this thing so could it be bearings in jackshaft? Should i replace only bearings or whole jackshaft? Also im located at EU so pls dont link usa products. China or eu. Thanks.