Sooner or later you'll be tempted into a paceline. The buzz of riding along in a group 5 klms faster than you are already riding is addictive. There are a few simple rules that will make you accepted or banished. If you're a newbie, start at the back and ask to stay there until you've gained some experience. Ask if you can join in. Some groups don't want outsiders but I've found no rejections by being polite and asking. Don't be afraid to say your new to the game as others more experienced will happily give advice. If you stay quiet, others assume you know what you are doing. Take note of others hand signals, slowing, turning, stopping, elbows to indicate your turn to take a pull at the front, and the calls for holes, clear(intersection), car up and car back.
These guidelines from the web.
Paceline and Group Ride Etiquette: The Untold Story
By Gregg Stepan
Certified USA Cycling Elite Coach
Most cyclists have ridden in some type of group ride or paceline formation. Usually, each person in a paceline takes a turn riding in front, breaking the wind. Many cyclists, however, overlook the most important principles of riding in a paceline, simply because those principles remain untold. Many of those principles also apply to a less formal group ride situation. So, this article is designed to tell the "untold story" of paceline and group ride etiquette.
The principles of paceline etiquette are designed to keep the group's speed consistently high and to avoid accidents. The essential purpose of the paceline is efficiency. In other words, the group is trying to keep its speed consistently higher than any single member of the group could maintain on his or her own. This efficiency is possible because it is as much as 30% easier to ride behind someone, where the wind resistance is considerable lower. A secondary but important goal is to avoid the accidents that can arise when cyclists ride within inches of each other.
Many cyclists, however, seem to forget that the essential the purpose of their formation is efficiency. To illustrate some common mistakes, consider whether the following scenario sounds familiar.
Imagine that you are riding along in a single paceline, and you are the third rider in the line. The rear wheel of the rider in front of you is about 12 inches from your front wheel, and you are enjoying the draft. Suddenly, you notice that the rider in front of you, who has just taken the front position in the wind, is now 5 feet ahead of you. This front rider's sudden increase in speed has caused a gap, and when you notice the gap, you put forth a hard effort to close the gap, and so does each rider behind you, like an accordion. Then, this same front rider moves very gradually to the side. You wonder whether it is your turn to pull or whether the front rider is just wandering a bit. After a long pause and a bit of a slow down, you decide you are supposed to pull. When your turn pulling on the front is done, you want to move to the side so that the rider behind you can assume the front position, but the rider who was previously in front of you in the line is still right there on your side; he has not yet moved to the back of the line. You now begin to tire of pulling and gradually slow down. Finally, it is safe for you to move to the side. The rider behind you accelerates rapidly (because of the previous slow downs), and the entire scenario starts over again with closing gaps . . .
Here are three principles of paceline etiquette that often remain “untold”:
1. KEEP YOUR SPEED STEADY WHEN YOU ASSUME THE FRONT POSITION. In the scenario above, the riders in the paceline were constantly closing gaps. Their paceline looked like an accordion. Eventually, this gap closing effort wears down the riders in the paceline. To avoid this problem, the front rider must watch the speed on his computer just before his turn at the front, and then maintain that speed within one-half mph or one kmh. If the speed of the paceline needs to be increased, wait until you have been pulling on front for several strokes, and then SLOWLY increase the speed. A gradual increase in speed will avoid gaps and help keep you (and everyone behind you) fresh.
2. WHEN YOU ARE FINISHED PULLING ON THE FRONT, MOVE OFF TO THE SIDE WITH A CRISP AND SAFE MOVEMENT. In the scenario above, the front rider very slowly wandered to the side, making it unclear whether he was finished on the front. A more deliberate movement to the side (after checking your path to be sure it is safe) will keep the paceline flowing smoothly.
3. AFTER YOU HAVE PULLED OFF OF THE FRONT, SLOW DOWN IMMEDIATELY. This principle may seem intuitive, but it is amazing how often this principle is ignored. After moving to the side, you must immediately slow down (soft pedal) so that the next rider can move off of the front without bumping into you and/or without waiting for you to get out of the way. Of course, you also must make sure that your decrease in speed does not cause you to “back” into a rider behind you who has not yet rejoined the line.
There are a few other principles of paceline etiquette, but the three principles discussed above will give you an excellent start.