Well that sums up quite nicely what does happen regularly. The first miles on my ride I have to go accross a lot of bumps - which I tend to go over while standing on the pedals and not pedalling for a while. When doing so, the chain hits the frame and I noticed contact/scratch marks on the horizontal chainstay. Not too bad, however is there a way to overcome this chain slapping without pedalling while crossing bumps? If not I may stick some protective tape on the chainstay, but I prefer to keep the frame as clean as possible.