for the north group

GREAT IDEA!!  I'm totally up for it, I don't know the area much though.  COgirl knows some.   

I heard that Louisville Cyclery does a Sat or Sun ride, has anyone done this? 

Anyway, just a bit of lead time and the wheres, I'll be there.

I've been meaning to ride with them, but I don't have my legs under me yet and don't like getting dropped, so I haven't.

That's actually what made having breakfast 10 miles in so nice.  The ride would splinter into the fast group and the slow group within the first few miles; the fast group (and those chasing) would kill temselves before breakfast, then we would all regroup, eat and head back out.  After breakfast, those who weren't quite ready for 40 miles would take a shorter 5 mile route back, while everyone else was too full to pull stupid stuff.  Once warmed back up a little, there would always be a few attacks, but there would always be a group left together... it was the faster riders goofing around that would end up strung out.  We would also regularly have 20+ riders, so you were pretty much guarenteed to be riding with at least 4 other people of your ability (or willing to go your pace).

Indiana actually has a group called the Central Indiana Bicycling Association (CIBA) that was a non-profit pro-bike group that provided an easy foundation for organizing rides like this.  You paid some nominal yearly membership fee, and they provided webspace to promote the ride, waivers, etc.  Does colorado have a body similar to this?

What with the 'pace line' talk and what not, I think y'all should gimme something to look at 'rules' wise before I make an outta myself.  Gotta link? 

And dittos for me too,COskigirl, re: drop off if I can't keep up.

Riding in a pace line is much easier then a lot of people think.  If you can hold a line, you can pace line.  The biggest 'skill' involved is trusting your fellow riders to not do anything stupid, and getting over the 'panic' of riding that close to someone.  Really single file is easier to learn, as you are only really worried about one rider ahead of you.  Side by side takes a little getting used to, especially the first time someone comes in really tight.

We should have a riding skills 'clinic' today.  Lets all ditch work.  I'm game

25 mph in an organized rotating pace line really isn't that hard.  I'd say it's about the same effort as holding 20-21 solo.  You'd actually be surprised how fast a good group can move and how little energy it takes.