I don't really know thing one about how the bottom bracket works, but yesterday I had my bike in at my LBS and they "re-taped" my BB. Well, now the crank arm on the right side very slightly clips my chainstay when I really hammer with my left leg (due to flex). When there's no load on the pedals the crank arm clears the chainstay, but under heavy pedaling something (either the frame or the BB) flexs enough that it hits. Thing is, this didn't happen before and upon close inspection I realized that the crank arm on the left has more clearance than the crank arm on the right.
It would seem to me that the whole problem could be solved by properly centering the BB, but again, I have no idea how these things work. Is it possible to adjust the BB slightly from left to right, thereby evening out the clearance on both sides?
They may have shaved some metal off the right side BB on the frame or you have square taper BB and when they put the right crank arm back on it squeazed down the spindle a liitle more. The more you take off old style square crank arms every time you put them back on they wear(aluminium) a bit each timecausing them to hit the chainstays. Although you can get a 1mm BB spacer to space the right cup out, it goes between the frame and BB. Best Luck! Buzz