Hi,
I'd like to mount a 34.8, clamp-on derailleur (SRAM Rival) on an old steel bike with a traditionally-sized seat tube [EDIT: 28.x? Whatever it is...]. Is this going to work if I shim it, or will the derailleur position somehow be off with respect to the chainrings. (I'd expect this to work but just wanted to make sure before I buy something.)

Thanks,
Daniel