I am considering it too, but have no experience with long climbs and steep grades at 11k feet.

I ride over 100 miles a week (individual and group rides on weekends), but at near sea level altitude. Lots of hills, but... they are hills not mountain tops. Averaging 19mph over 45k on my own through flat land is not a problem.

Would like to hear from anyone about the challenges of high altitude riding or just the fitness levels required to complete the Amateur (15-17mph) route? And by complete, I mean hit the 3 stops and stay in front of the sag wagons.