I've biked through Keystone several times. good MUPs and roads. There were slippery spots on the west side of Vail Pass. Start training hard, anaerobic thresh-hold stuff, time trials, 5 hour centuries. When I was there I was 20-30 years younger, was doing 200+ miles a week and lived at 5,500 feet west of Denver. Stay in Denver for a day the sit in Keystone a day before even trying any hard riding. Adapt to the altitude carefully. Get some gears lower then anything you see where you are now. Pedal up Loveland Pass slowly; no headache? Good to go.