Originally Posted by pallen

I don't really know a good way around just going out and trying it. I ride with a group that averages 17-18mph, but its pretty easy to get dropped on the 30mph sprints and small hills where everyone suddenly starts hammering. They are a great group though and regroup after hard efforts and I've never seen them leave anyone behind unless the person getting dropped tells them to go on. Every group has its own dynamics - published numbers are only a small part of it.