This is just about as epic as doubletrack can get. Starting at about 7,000 feet, the road steadily climbs up, up, and up. This initial paved portion is probably the least interesting part of the ride, but a beautiful forest full of the oldest living organisms (Bristlecone pines), fairly interesting terrain, and a grand sense of adventure should kept you engaged.
Soon the pavement will end, however, and a 17 mile stretch of easy-going doubletrack will present itself. The constant climbing and descending of this section will be sure to give your legs a go.
Then, you will meet the Barcroft Gate. If a sadistic 70 mile bikepacking journey through water-lacking terrain isn't sounding appetizing, drive up to this point for a strenuous 14 mile out and back. You will still have 2,000 feet of climbing ahead of you, so don't bring your downhill bike looking for a run. This is where things get good.
Emerging above the treeline, the doubletrack soon becomes some conveniently stacked rocks. Flat riding on this terrain can be difficult; that said, be prepared even if you opt for the 14-miler. The windswept peak looming above you, continue through this unforgiving terrain on a seemingly endless climb. Before you know it, you'll have traversed the moonscape and be sitting pretty at 14,233 feet. Make sure to enjoy every vertical foot of your plummet back down!