Dan, a 5 year bump for great info.
The following is not well discussed in the motorcycle world. I've heard of it and witnessed it.
When a rider or riders are in tow and then they or one of them feels comfortable with the lead rider, then feels the lead rider is perhaps a bit slow, they then pass them and soon after crash.
As for my experience they crash with in 10 or less of passing me. I come upon them in the dirt...4 times in as many years. Really experienced riders, some of them. Really high speed offs too (55, 60, 75 and 90). I have warned the two last ones prior to the start of the ride that they might feel "too comfortable" behind me but to trust my speed. Ahhh, I was too slow for them, but they were too fast themselves...
Moral of the story, trust your lead rider, unless you know you can lead better. But not if you think you can rider faster.
THINK...is 85 more fun then 80? Or what ever numbers you can use.