Originally Posted by bwgride

Collie --

The shim may be the reason. I'd look for a FD that fits the tube correctly. By rub, I assume you mean the chain rubs against the cage side and not the cage bottom. If the bottom is where the rub occurs, then lower the dérailleur a millimeter or two. If the chain rubs against the side, there are at least three things to explore.

First, check the adjustments on the dérailleur to ensure the limit stop is not preventing the dérailleur from retracting completely.

Second, it is possible the bottom bracket you have is not placing the crank set far enough away from your frame. However, if that were the case, the inner chain ring may rub against the frame itself, so this is unlikely to be the cause.

A third possibility may lie with the alignment of the dérailleur; you may need to tilt the cage at a different angle to the chain to allow for clearance.