Pay attention to the hand signals. You'll figure out what they mean pretty easily. I have no idea whether the hand signals are universal or whether every area has it's own "accent" or "dialect". Remember it's your responsibility to relay them too. The guy behind you isn't a mind reader - he won't know you're going to stop unless you signal that you're going to stop. Fail to signal and it's your fault if he slams into the back of you when you hit the breaks.

On my first ever group ride the guy in front of me put his hand out flat to the ground and started waving it back and forth. I'm like "What the heck does that me..." bump bump bump bump bump... "oh... uneven surface".

If someone could point to a web page with "group ride hand signals" that would be pretty cool.

But like ********** said, you'll probably get a bit bored. We have casual conversations riding out between 20mph and 24mph in some groups.