New chain flapping making noise

[james4555]

Just got my bike back from the lbs and the chain is flapping near the chainring.

Video of it happening below

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Had a new chain and cassette fitted.

 

[james4555]

I'm beginning to think there is something else going on. Before you start replacing all the parts, as this can get expensive, and may not solve it. I would get a good bike mechanic to look at it.

Got it booked in Thursday in another lbs hopefully they will be able to diagnose it. Thanks for the help and suggestions.

 

[james4555]

I'm beginning to think there is something else going on. Before you start replacing all the parts, as this can get expensive, and may not solve it. I would get a good bike mechanic to look at it

Ended up ordering a new derailleur same model just in case the lbs asks to replace it and when comparing the new one against the one on my bike now it's been modified.
Large bolt on the one installed on my bike by lbs

Compared to the brand new one.

Have you ever come across that before. Why would they do that ?

 

[Paulquattro]

I'd imagine a 15t chainring (15t, that's tiny) wouldn't last long before being totally shagged out, and it's going to eat chains for breakfast being such a tight radius.

All The old bosch motors used to run small chainrings as they were geared 2.5 times in the motor
And in all fairness they didnt wear terribly at all