Around where I live we don't have any mountains, but I normally do go up to the hills about once a week. Normally about 2,00 ft of climbing over a 40 mile ride. I have ridden "climbing bikes" such as the Fuji SL, but never in the hills before. Really I don't think there is a big difference. Obviously the lighter the weight, the better in the hills. You're going to be paying to drop weight no matter which route you go. But by no means is a 17 lb transonic any worse at climbing then a 17 lb altimira.