Originally Posted by
Cypress
Bozeman area? I lived there for 7 years. A 39x28 will clear most things in that area save for the nastier bits like Jackson Creek. If you need more, you'll have to switch to an Ultegra RD with a Ultegra cassette and a new chain. If it's newer Shimano stuff, you can also throw a 36t chainring on the front due to their proprietary bolt pattern. I run a 53/36 x 11-30 here in Oregon due to the roads not needing to be graded for snow travel (very steep stuff). A 36x28 is pretty darn climby and even moreso if you can get a 30 on the back.
Actually Big Sky. So dealing with nothing but up and down
Sounds like from most comments I need to get rid of the Dura Ace and switch to Ultegra. If money isn't a big issue, wouldn't that be easier just to change out front and back to Ultegra?