How can you tell how far apart your chainrings are? I just replaced my cassette and my crank with one from the LBS that the guy said would work. I've had no problems with the cassette, but the crank is too wide so that my front derailleur does not reach the 3rd chainring. So here's my question:

Is there a specification on cranks that show the length each chainring is away from each other, and for that matter how far it sits from the frame as well? This way I can look at the one I used to have on and find one with similar measurements.
It's possible that you just need to adjust your front derailleur a bit to accommodate your new setup. There are many threads here and videos online about how to do this.

The crank may not be the exact same distance from the frame as your old one, but that doesn't mean it doesn't work.