I think OP means that in big-big, the chain rubs the underside of the "crossbar" of the front derailleur, that spans the 2 sides of the FD cage.
And raising the derailleur to prevent rubbing, results in poor shifting.
Can you post a side view picture of the FD when in big-big ?
Last edited by Homebrew01; 07-10-15 at 07:53 PM.