I did the RTR a few years ago with about 500 miles of flatland training prior to going out. I didn't find the climbs to be a problem. Most of the climbs out west are long, but gradual. Just relax and spin your way up and don't worry about being slow. The elevation wasn't a problem either, but I adjust to elevation well. The biggest challenge I found was the wind. It can be nasty out there. Bottom line - if you have been riding regularly you will be find. One hlep with the elevation is to start taking an asprin a day a few days before going out then continue it while at elevation.