Originally Posted by
never_recover
Actually maybe I'm missing something but I've had issues (rubbing) running fat chains through a 9sp RD, so I'd say the LBS is right. Of course, the obvious solution is to run a good 9sp chain (I have a stack of 6500/XT chains which can be had very cheap around here)...
Yeah, this is why I hesitated on saying that it would work. The indexing will work fine, but the chain might not play nice. 9 speed chains only cost $5 more than a 6/7/8 but he wants to use his NOS 6 speed chain. I know FDs in particular don't play nice with different width chains.