CCCorlew, on my LHT loaded (32 lbs bike, 30 lbs pack and 205 lbs me), I used the 26-34 on many occasions touring in Western US. Yes, a heavy bike with a heavy load. The unknown will be the Roubaix on climbs such as these, with a hopefully lighter me and no pack besides the bare necessities. Changing the cassette would appear to me to be the easiest solution. Adding a third chainring would include replacing the front derailleur I assume.