In my first visit to Matteson lo those many years ago, I had a devil of a time insinuating myself into the pack. So not wanting to be stuck at the back, I would race to the front, quickly tire myself and then sit up. This very nearly caused a crash every time because the rider behind me wasn’t expecting me to slow down, and a teammate rightly scolded me: “Don’t do that!”
But that’s why you do Matteson, to learn things like that.
What I learned is that you shouldn’t just sit up, and you should always signal when you’re about to pull out of a line. The best way to do this is a simple wag of the elbow. Use the elbow of the side on which you want people to pass you. If you want to pull over to the left and have the pack pass on your right, wag your right elbow. If you want to pull to the right, wag the left elbow.
This goes for races as well as group rides. Whether your paceline is a Sunday training ride or a winning breakaway, good communication will keep things smooth and efficient. And just as important, it will keep people from yelling at you.