Originally Posted by masi61

I just listened to the video and that sound is pretty “scrapey”. It makes me wonder about 2 possibilities - 1) Could your front derailleur have dropped down a bit due to a loose bolt? If so, the top of the cage could come into contact with some chainring teeth. This would account for an odd noise even though maybe your FD cage is centered properly. Or, 2) Did you recently remove your chain for servicing? If so, is there any chance the chain was run improperly outside the rear derailleur cage? What I mean is that the chain might be running over the top of the little tab on the back of the outer cage plate, as opposed to under it.

I have made both of the above 2 derailleur set-up mistakes at various times over the years. The plot thickens! Once you definitively track down the cause of this silly noise we’ll eagerly await the consolation prize for the correct bike detective!