There is this biker that scares the crap out of me when I see him on my morning commute. I will periodically look behind me on the street I am on and discover that he's back there (generally he bikes faster than me). He's passed me on the left while I was signaling a left turn and crossed in front of traffic. I had caught up with him and yelled passing on your left when he swerved across traffic and decided to take the sidewalk for awhile. I didn't think I was near him any longer until he came flying on to the street from the sidewalk and blew a stop sign right in front of me. He wears no helmet. And he scares the crap out of me. Never has he taken the same path when I run into him. I'm sure I look really weird frantically looking for where he has gone some days.