I wore out my old derailleur and when trying to put the new one on, I noticed that the back of the front derailleur wasn't aligning with the chainrings. It would be as if the seat tube was bent backward about 5 degrees toward the rear axle. I fiddled with it for a couple hours, then took it to my LBS who I've been very happy with. They also couldn't get it to work. They ordered a new one, slapped it on, same problem.

My Cannondale is a 1994 R300 that I built up with mostly 105 and Ultegra parts. I have been running 9 speed, but went for the 10 speed front derailleur as I was told it would work. Anyone had a similar problem? Any general thoughts on what might've cause the frame geometry to not match the derailleur?