Originally Posted by
Chesterton
The other possibility I considered is just swapping the 42 for the 34, but would 52/34 be too big a jump for the derailleur to handle smoothly?
I think your first plan is better. Even modern compact cranks only support 16 tooth difference of 34/50. I doubt you will get any joy trying to get a 1990 FD to make that shift.
Also, the new big/outer rings have a lot of metal bits and grooves to help the chain up. Your current 52 is smooth on the inside.
You could *try* a new 48 or 50 outer ring, but big rings are more expensive, so it depends how much $$$ you want to throw at it.