I've got a bit of a problem with chain slap on my commuter. It's a 2010 Jamis Aurora Elite, with a Tiagra FD, and a Shimano Deore XT RD, and a SRAM 991 chain. It has a 50/39/30 on the front and an 11-32 on the rear. I recently had the drive train overhauled (new chain, new cassette, etc) at a LBS, but in less than 200 kilometers after getting the bike back, the chain broke on me while commuting in to work. I took the chain (sans bike) into the bike store to complain and they repaired it. I took the chain home and put it back on my bike using a SRAM PowerLink. After installing the chain on my bike, I re-oiled it. In the process of removing the excess oil from the chain (i.e holding a rag against the chain while moving the pedals in reverse) I noticed a lot of chain slap. To be clear, I found that the chain between the front derailler and the cassette (e.g. top chain) was becoming extremely slack and slapping against the chainstay). I initially thought that this may be due to my wiping up excess oil causing too much drag against the chain, so that the cassette wasn't able to wind it up quickly enough. So I stopped holding the rag in place and continued to move the pedals in reverse- but the chain slap persisted. For sake of comparison, I tried moving the pedals on my other bike also in reverse at a much higher speed and observed no chain slap; however, in that case it is a 53/39 on the front and a 12-23 on the reverse and a 10 speed. Also note that there seems to be some rubbing between the FD and the chain, which makes me wonder if the LBS did a lousy job of adjusting the FD.

It seems like excessive chain slap to me, but what do I know. So my questions are 1) is this a potential problem? 2) How do I fix it?

Thanks,
Brad