Carbon bars on my good bike are marked (more than cosmetically) where the crappy lightweight stem I was running clamped them. Guess they are bin fodder :cry:
I file all the sharp edges off bars, shifters, stem, tiny small radius curve to try & prevent this very thing.
sometimes it can be the stems fault. the old control techs were very popular, yet the bar clamp section of the stem was normally welded at an angle to the main stem extension, or as curly told me "on the piss". what this means is that the right side of the bar was 5mm lower than the left side.... tho pace bars were always sh,te & bound to snap sooner or later anyway