Thanks guys. The bike came with an 12-27 cluster and I changed it to an 11-27, (by adding an 11T and removing the 16T). The largest Dura-Ace rear sprocket available is a 28T. Not worth the cost for one extra tooth. Maybe it's time to go with a 50-34T compact crank.

Is the right-hand crank easy and quick enough enough to swap back and forth, (depending on the ride I'll be doing), between the 53-39T and a 50-34T?