Originally Posted by
paisan
...The seattube junction with the Bottom Bracket is this huge square layup of carbon so the knuckle/spring of the triple FD would hit the seat tube before it could drop the chain to the inner ring using the 109mm Ultegra BB. ...
It took me a bit to picture your problem with the FD but I think can picture it now (I had to go look at my bike
). You just had a tolerance stack up issue.
You probably could have gotten away with the Ultegra FD on my Colnago or Calfee. They both have more traditional seat tubes and that knuckle has lots of room. I went through all those chain alignment issues with my tandem but even then they weren't as difficult as yours.