Hi all, I have a problem with my rear derailler rubbing against my cassette. I have a full Sora groupset on an EMC2 road frame and havent had any problems with it.

I have learnt to be able to adjust most components, including the rear derailler since i have had this bike. The upper and lower limits appear to be correct, and the cable tension also appears to be correct. I have no problem changing the gears up or down, apart from the noisy rubbing. The chain doesnt measure as stretched.

You might say the "B-limit screw must be out of whack!". In this case, the B-limit screw is all the way in. My question is, how can I "lower" the derailler cogs further?? Please dont suggest the LBS, as Im happy to take it there, but i'd like to learn myself with your help how to diagnose and correct these problems!