These seem to have gotten lost and forgotten when we went from having a website + a forum, to being a forum only. Reposting pretty much as they were written long, long ago. If you think anything needs to be amended, please post your thoughts. Taken from http://www.cosportbikeclub.org/club/rules.html:
Rules:
Considering the trigger you hold in your hand, they're really very simple...
- Arrive fully-fueled and ready to ride.
- Wear a HELMET & appropriate riding gear... PLEASE. We put time & miles into some rides and you can run across some adverse weather conditions in the mountains. If you don’t like wearing a helmet, we won't force you to, or stop you from riding with us, but we would be more comfortable if you did.
- Safety first - don't put other people at risk. We’re not on a racetrack, we’re here to have fun.
- Ride in staggered formation on highways. Signal your intent to move to the other side of the lane.
- In the twisties, ride in single file and no passing in the same lane (make sure you leave enough room between you and the rider in front).
- Rider in front has right of way.
- Pass safely using another lane ("safely" varies depending on the individual - the person in front of you may not feel confident/comfortable enough to pass when you would).
- Ride at your own pace. We don't make any turns before everyone's caught up. Everyone's at a different level, so there is no need to feel you have to keep up with the rider in front of you or be at the front of the pack.
- Do NOT leave the group and turn back (or go a different route) unless you've told someone you're going to do so. Since we wait for everyone before making a turn, it would be inconsiderate to delay everyone by making them "wait" for someone who has no intention of catching up.
- Position yourself appropriately in the pack: Faster riders may want to place themselves near the front, and slower riders near the rear. If you’re not sure where you fit, start in the middle or near the back. If you find yourself getting frustrated because the rider in front of you is going slower than you want to go, remember, you can always re-position yourself at the next break-stop. And if you feel that you’re slowing down the rider behind you, feel free to indicate to them to pass you - if they don’t, then you’re fine & don’t worry about them.

Although we haven't adopted it for the club, "The Pace" offers guidelines for safe & fun group riding and we recommend you read it.