Well, I actually tried the RIDESB100 this weekend. There where four routes: 39 miles, 100 km, 100 km with Gibraltar, and the century. I did not finish the ride. At around 43 miles and two miles to the top of Gibraltar, my legs gave out. The last climb before the top was just a killer. The final climb before the top was too much. At two miles away from the top, I just did not want to do the last climb. Also, my bike decided that it would not go into the lowest gear.
What I learned:
Have my bike checked out before the ride.
Have two water bottles on the bike.
Have some hydration tablets to put in the water.
Have some sort of concentrated calories that is easy to fit in the jersey pocket.