I just recently changed the chain on my 2001 bianchi eros. The drivetrain is Campy mirage 9 speed, the old chain was a "Z" (I believe), and the new chain is a SRAM 9 speed. Since I put the new chain on, I noticed the paint was scraped down to the metal on the driveside seatstay. In the meantime, I have stopped using my smallest cog (the only position where it could possibly rub). Any suggestions on how to remedy this problem?