I don't [technically] have the derailleur yet, but will in a few days. I'm hoping that by adjusting the axle position and the B-screw, I can make it work. Also, this model has a slightly longer neck than its older twin brother, so that may help.

I've ridden 13-26T before with 52-42 up front, and that didn't give a very low gear for long climbs. I may have to go that route on this bike, though.

The stock crankset is 53 42, so I know that I could live with the 26T if need be.

The ARx has plenty if clearance for the 28T, by the way...