I think StephenH has hit an important point. It is relatively unusual for large groups to stay together on long bike rides. It is an unusual rando event that attracts more than
20-30 riders. So you end up at the back end of nowhere at 3am with another 12-18hrs to go on the bike by yourself. With luck you might find a compatible group that is willing to
stay together through a 400k or longer ride but so many factors begin to pop up: hunger, fatigue need to sleep, different slump times that staying together can be
extremely difficult. 5 mile long hills also tend to do that as well. Read some of Machka's older posts to get the flavor of riding long rides. (See her website).
And to give you a little incentive read this:
http://www.slowtwitch.com/Features/E...dent__495.html
A truly formidable woman who would probably leave 96% of rando males in the dust . One obit mentions the twins doing a TWIN Ironman (swim some, bike 200, run 52mi).