I work with a guy that got right hooked by a pickup truck a few weeks ago. He ended up with a broken wrist.

He told me about how he glanced over his shoulder and when he turned around the truck's bumper was right there.

I told him how he really needed to get a helmet mounted mirror. He just smiled and said, nah, he didn't need one.

He rides in boston traffic. How the hell anyone would ride in that mess without a mirror is beyond me.