Originally Posted by
bark_eater
I was hopeing to leave the deraileur height alone as this might be a temporary change. The new large ring will have 4 less teath. Im not sure how much that changes the radius..
From your above posting your big chainring is going to be 6 teeth smaller (54T to 48T) and that is a huge change in radius. Lowering the front derailleur will be essential to get decent shifting.