Yes, the FD cage.

The point I'm making is that once the chain is on the middle front, and adjusted to an optimum position, I don't then want to continue readjusting the chain position on the middle front as I move up and down the rear rings. This works perfectly with my current 5 speed freewheel, but not it seems if it's going to entail the thicker freewheel/cassette of an 8 speed.