This is now the second bike I have that makes this annoying sound. I seems like the rollers on the chain links are hitting the pulleys on the derailleur. I have tried different chains but nothing works. I have checked chain stretch and they come out @ 12" - 12.03125" or so. Some chains are louder. At first I thought the chain was rubbing against the cage but not so. It is a 7400 Dura Ace 8 speed. Any one got any clues? Thanks!!!