I am a ride leader for the Appalachian Mountain Club and I also ride with another large club. I went through a 2 night plus a weekend outdoor leadership skills training course, that while it is geared toward hiking leaders, is required for all activities in AMC. We have 2 kinds of rides: show and go and those you sign up for and the leader screens for. It is much different than a regular bike club and I am glad. I have led both types of rides; the difference is on our weekly show and go rides, different leaders sign up for the season and there is a coordinator who reports to the cycling committee of the chapter who keeps track of who is leading which date. The routes are set by the leaders and are not the same, though on these show and go rides, they tend to rotate through a set number of loops. DH and I led about 5-6 Friday morning series rides a couple of years ago; however, they got so fast that people stopped coming and it was hard to find leaders.
I prefer leading the "day trip" type rides that I plan and people call me to sign up. I screen them for ability and even so, there will be someone who lies to me and ends up struggling. Since our policy is there must be a leader and a sweep, unless someone tells me they are off the ride and absolves me of my responsibility, the sweep has to stay behind them. We are forced to keep the group together somewhat, because of our liability rules. But, I am glad I went through the training; it makes it feel professional and i have had more than one person comment how they felt welcomed and how AMC was not like "the other clubs." We have rides that are rated "beginner" with a 10-12 mph average and intermediate, with an average of 13-16. We give everyone cue sheets.

The other group I ride with is part of a large club, but is a very distinct group. It's strictly social, average about 13-14, with a faster group sometimes splitting off, which averages about 15 or so. Every week a different person leads, with a lunch stop involved. The rides get progressively longer as the season goes on, although the group rides all year long, only a few ride through the winter. There is always an alternative x country ski, snow shoe or hike in the winter. They use a human arrowing system, no cue sheets, which is a bit daunting if you haven't experienced it. Someone right behind the leader volunteers to take a turn, stop, and position their bike toward the direction of the turn. You have to stay there until the sweep passes, and with 30-50 riders, it's a job. Then you ride to catch up. I'll do it if I'm around here, but not in an area where I don't know where I am. The leaders in this group can be anyone, but some are not what i'd call the best. They are nice people and very experienced riders, but after going through the leadership training, I have rather strict ideas of what a leader needs to do.