I've got an oldish frame that was originally 14 spd (2 x 7) and I want to add a triple chainset.

I've fitted a narrow BB and a chainset - the cranks clear the chainstays by an equal distance and although I'd like a lower Q factor it's probably ok.

The problem is the R/H chainstay isn't recessed for inner chainring clearance.

I just wondered how frame builders add this and whether it's possible to add now ?