If the crank is a compact triple, 110/74, a road triple doesn't exactly match the curve of the rings, and the further from the standard Shimano road ring design you go, the less the match, especially with a 48 big ring, where the derailer is designed for a 52. I have had issues with this on a prior occasion. The Suntour F derailer I have was designed for a lg. ring of 48 or so, it was pre-Micro-Drive and is a really good derailer, thus I was hoping to stay with it.

The real problem I dealt with, was the Nashbar crank had pinned middle and large rings. The chain would get caught by the pins on the middle ring in certain gear combo's, resulting in a type of chainsuck. That's a chainline issue and I did not desire to hunt down an ISIX b-bracket in a different size, especially owning a good stock of new square tapers. So on went the old crank.