It sucked. Seriously.
My chain broke at mile 7 (in pitch dark, since I left at 4:00 am), and because I wasn't sure what happened and kept pedalling, it got caught up in the derailleur and took that off as well. A volunteer who had been bringing supplies out to a rest stop gave me a ride back to the starting point, where the mechanic took one look at it and said, "I can't fix that." So, my death ride was 7 miles long and about 200 feet of climbing.
Once it got a bit lighter, I noticed that the chain also took a chunk out of my seat stay, so I'm probably looking at some pretty expensive repairs in addition to the frustration of spending 6 months getting ready for a ride I never did.
My TnT teammates did much better, on hot, tough day. Many did all 5 passes, and all rode a good race.
Still, I'm frustrated and upset. I'm also trying to figure out a backup plan since I'm now bike-less.