I'm confused. I installed a new 9-speed Shimano CS-6600 cassette 12/27 - my previous cassette was 12/26. With my previous cassette, the B-tension screw was fully tightened. I always thought that was weird there was no more room for adjustment away from the cassette - but it allowed the pulley to just clear so I didn't investigate further. Anyway, with the slightly larger 27 sprocket, it is now barely hitting and "clicking". Unfortunately, I didn't realize this until I put a hundred miles on it. I don't see any damage. Anyway, in an attempt to see if a longer B-tension bolt would actually get the pulley away from the sprocket, I put a test spacer in between the end of the bolt and the "claw" on the hanger. It seems to pull it away. Can anyone give me a sanity check here?? Now I'm really confused why the B-tension is fully tightened.