A little math show that the low gear ratio on the Roubaix is 34/30 = 1.133 and the low gear on the LHT is 26/34 = 0.765 so the Roubaix low gear is 48% larger than the low gear on the LHT (assuming the same wheel/tire size). That means to go the same speed on steep grades, you will be pedaling the Roubaix with a much lower cadence - approx 67.5% of the LHT cadence. Sounds like you should bring the LHT to Colorado.