Here's one-
If your new to a group of riders and you get uncomfortable with there riding style or ability, smile thank them fo rhte ride and leave.
I rode with a group of 20-30 down here one day, and they all assured me before the ride that they all followed general curtosy and speed rules. 150 mph was the average of the group, they left me way behind, they went almost 30 miles in 18 minutes. Beyond the fact that when they all started they all wanted to jokey for position, it was like a superbike race on a back road. It was the scariest thing I ever experinced. 20 crap munchers flying by me doing wheelies right next to me cut me off, all to try to prove something.
I refuse to ride with any of them after that. I made it to the gas station asked where they were going next. They said left, I went right and had one of the best riding days I've had since moving here. so take all this for what it's worth.