Originally Posted by merlinextraligh
What's the steepest sustained grade? I'd like to do it in a 38x27 (just for practical reasons) but I think that my be a bit ambituous.
Uhh, yeah, probably just a
bit 
OC can help me confirm, but I remember something around 15-17% for several hundred yards, at least. And this was at the end of the first day, at ~8,500', after having already climbed some 15,000'. So you might want to re-think that gear choice.
That's not to say that it can't be done in 38x27. If you're a very strong climber already (like: you are winning Cat 1/2 hillclimb races on a regular basis), you may be okay with that.
Personally, I was running 34x27 like OC, and it was simply not enough in several places. I am looking into running a 11-32 cassette next time, yes, with my 34 chainring. Ridiculous, perhaps, but for this race, it's better to have and not need than to need and not have. I'm not in a hurry to re-injure my knees and spend 3 months off paying for my mistake again.
Edit: these are the gearing recommendations from the ride organizer:
Gearing recommendations: pro 39/25-27, CAT 1-2 39/27-30, CAT 3 34-39/34, CAT 4-5 30-34/34, Public 26-30/34
And here's what they say about the max % of each of the climbs:
Day One Climbs: Mosquito Flat (10,250') - 22 miles, ave grade 5%, max grade 12%; Pine Creek - 8 miles, 7% average grade, 11% max grade; South Lake - 20.4 miles, ave grade 6%, max grade 17.5%
Total elevation gain - 15,465' over 100 miles
Day Two Climbs: Glacier Lodge - 9 miles, ave grade 8%, max grade 12%; 2/3 of Waucoba Canyon - 8.5 miles, ave grade 5%, max grade 7%; Bristlecone Forest - 21 miles, ave grade 6%, max grade 15%, total gain 6,573'.
Oh yeah and one other thing I just thought of; not training but for the actual race: do not blow the opportunity to put a nice big WARM coat and other clothes in the coat box, to be transported to the top of the last climb each day. In late September at 10,000' in the Eastern Sierras, even when it's sunny, it is COLD. Not to mention your body being in somewhat of a state of shock. They have a small supply of (stinky) blankets and they're in high demand. Also, you have to ride down 20+ miles with little opportunity to warm up.