I own a cervelo soloist with campy centaur group. The bike is great overall. Although, there is this squeaking noise that's drinving me crazy. I checked pretty much everything: BB, crankarms, pedals, cleats, seatpost, saddle... all of them seem to be ok. So I started checking the cassette and RD and I notice a screw on the RD I've never seen before (see pic). Do you guys know what is it for ? is it to put or release tension on the chain ? Do you think the noise might come from there ?