Originally Posted by
rschleicher
The 2010 Ultegra RD will support all gear combinations of a 50/34 compact crank, and the 11-28 Ultegra cassette (and therefore also works with the 12-27 105 cassette).
You can get an older Ultegra mid cage RD 6500 for a fraction of the price of the newest model. Should work great for this application. I picked up a few of them on sale and I'm running them on both of my main road bikes.
http://www.cambriabike.com/shopexd.a...EAR+DERAILLEUR