If I'm approaching someone from behind, I will pick up the pace. I can't control it. Do I go out of my way for a little action? No. I did so a couple of times and then had the sense to ask myself why? Like was mentioned, if I'm the only one racing, is it a race? Or, is it a desire to prove myself better and faster than that unsuspecting fellow cyclist? I race to prove/disprove that I'm fast. A one-person race is just an interval and I can do those whenever I want. I try to avoid humiliating other people for my own benefit. Nobody wins in that case.