Tell me what eats you up regarding other cyclists, here's two of my faves:
1. Cyclists who zoom past me without any verbal or nonverbal ("ding!") warning and usually within inches of my bike. I ask, would you like a car to do the same to you, stupid cyclist?!
2. Cyclists who ride scary Blvds in town without wearing a helmet or bright colors. Hawthorne Blvd (SE Portland) is the area where I see this action the most. Please stop this, ride quiet streets, not war zones without protection or visibility!!!