Some analysis of the number of 90 hour starters who finish in under 70 hours might be interesting. Not %age, but numbers. In 1999 I was fairly fit, and was picking up 80 hour riders around Tinteniac.
I think it's a good idea to be just behind the motorbike when you are let go at 25km. So when you fail to stick with the fastest group, you can drop back to form an alliance with riders who match your pace. If you're not familiar with mass starts, that's going to more difficult in the 80 hour start, as everyone is wanting to do the same thing.
My strategy is based on not being able to climb as well as the average rider of my likely finishing time. I have to accept that I will lose any group I'm with in the early sections on the hills, so I want a lot of riders behind me to spur me on.
Once you are off the back of the group you started with, you have a long wait for riders of your speed to appear. All the earliest riders passing you will be too fast to hold onto, so you might as well be on your own.
