Can we assume that the chain is rubbing on the INSIDE of the cage when you're in the largest cogs on the cassete? Otherwise, the problem is not the limit screw. That said, you can just get down on your knees and look at the derailleur from the rear and you will be able to see which screw is which.Douger said:My chain is rubbing on the front derailleur when it's on the small chainring. I looked up how to adjust the limiting screws but the H & L on my Campy derailleur is unmarked. I'm wondering which is which.