For the most part, the only group rides I do are ones by the cycling club I'm in, and technically there is a ride leader for each ride. The ride leader will also post the route and its distance, though sometimes it will just be decided during the ride depending on who shows up and how far and where they want to ride. It's usually up to the ride leader to "police" the ride rules, though any of the riders might yell at offenders at any time. Each ride group has a description of what general cruising speeds will be expected. An example would be to expect riding speeds of 22 to 30 mph depending on wind, terrain, number of riders, etc. So obviously riders who can't stay in a group going over 20 mph would be better served not to ride with that group.

For the group ride that is a drop ride, if you're off the back then you're SOL, but sometimes one of your buddies will drop back to keep you company or maybe you'll form a grupetto with riders that blew later on down the road. If you're pulling too slow, you'll probably get yelled at to get the heck off the front. It is semi-neutralized up until a certain point and then it's attacks until the sprint line, then finally a neutralized roll in back home.

For the no drop rides, one of the objectives is to stick together; for example, the entire group will usually stop for a flat or mechanical until the rider gets his bicycle back in operating condition. If you are too slow to even just suck wheel the entire ride, you'll most likely get a gentle suggestion to ride with a slower group. Sometimes the no drop group will start to get fragmented by too strong a pull uphill or in crosswinds, and riders who are cognizant of that will ride up and let folks up front know that. There is always a regrouping after any sprint or KOM points during the ride.