Urban bicyclists don't fear moving cars that much. There might be the occasional lunatic tearing unexpectedly across an intersection, but mostly they are pretty predictable. Despite their poor reputation, I've found Boston-area drivers to be fairly courteous and flexible (except for the occasional pickup truck, for reasons that still mystify me).

No, what we fear is what I encountered today: the swinging open car door. That can take you out instantly, and if it pushes you out into traffic, can kill you. It's hard to predict, and maneuvering around it can be almost as dangerous as hitting it.

I was on my way to work. I know the pattern of lights on the hill down toward the Charles and the Science Museum on Cambridge Street in Cambridge, so I had timed my approach down the hill for the extremely short green at First Avenue.  I saw the seconds counting down on the pedestrian signal. As it hit zero, I pushed forward along the line of cars that was about to start, keeping half an eye out for anyone who might go suddenly right, across my path. But I was going pretty fast, about the fastest of the entire ride.

A passenger, opening her door and jumping out just as the cars started, hit me like a baseball bat across the forehead.  I smashed into the end of the door and went down instantly, face planting on the pavement. Once I realized I could move, and wasn't lying in a pool of my own blood, I jumped up, and may have uttered a few oaths.

The woman who had taken me out was apologetic. What could I do? My cheek was cut, my prescription sunglasses scraped up and pushed into my face. I got her contact information, but was not sympathetic to her apologies. We've all opened our door without looking, but...Jesus, she could have killed me. I was in a bike lane, I had the green light: rarely am I so virtuously in the right.

Seven stitches and a tetanus shot later, I was in my office.  I should have been home in bed, because the shock had me quite shaky. But I have a week's vacation coming up, and a lot to make sure gets done before I go.

It certainly could have been worse. I'm an aging bag of bones, and don't bounce like I used to.  I'll see how black and blue I am tomorrow, but I think I escaped more serious consequences than a potential GI Joe scar on my right cheek.

It's those passenger doors that are the most dangerous. I regularly scan parked cars for heads.  But I just don't have the bandwidth to keep my eye on passenger-side doors too. Cars in the street naturally have heads in them, so it's impossible to filter. So, please, car passengers who get out in the middle of the freaking street. Give a mind to who you can kill, particularly in a busy biking city like Cambrige, and give a quick look before you swing.