I'm fitting out a new frame I got for Christmas with many of the parts from my old bike.
2003 Allez Elite Triple moving to Allez Comp. I couldn't use my old 105 front derailleur as it was a clamp on and the new frame is a braze on. So, I bought a new 105 triple for the front. The old 105 handled a 52, 42, 30. The new one cannot handle that span of 22 teeth, and requires at least an 11 tooth difference between the big and middle rings. So it's either buying another derailleur or getting two new chain rings to have a 50, 39, 30.

With that said, what is the difference (besides price) between the 50, and 42 rings for a double and those for a triple front?

If this has been answered before, please tell what to search for, or post a link to the the discussion.