Four days a week, I ride my bicycle to my evening art history class. Four days a week, as I arrive on campus and lock up my bike, I see many other bicyclists arriving and departing. I am one of the few who doesn't have iPod earbuds jammed into my ears.

Don't get me wrong, I dig my iPod. I listen to it quite a lot. I'm listening to it right now, in fact. I listen to it while I'm studying, I listen to it while I'm doing the dishes, I listen to it while I'm watering the garden, I listen to it while I'm drawing...I do not, however, listen to it while I'm riding my bicycle. Why?

Well, an Ford F-150 weighs somewhere between 2.5 and 3 tons (depending on options) and is made mostly of steel. I weigh around 200 pounds (depending on what I had for lunch) and am made mostly of meat. In truck-bicyclist collision, I lose. Being hit by a truck hurts. A lot. I know this because I have, in fact, been hit by a truck and it hurt. A lot.

Further, as a bicyclist, I am legally obligated to ride on the street. Riding my bicycle on the sidewalk is illegal.

Additionally, I do not possess eyes in the back of my head. I therefore find it useful to employ the sense of hearing - which, unlike vision, operates in 360° without any additional effort on my part - to help me determine if a three-ton Ford F-150, or for that matter a one-and-a-quarter ton Mini Cooper, is behind me.

Ergo, I think it best not to engage my ears in another activity whilst bicycling. Though it might be fun to listen to Freddie Mercury singing "Bicycle Race" while I ride my bike, it strikes me as unwise. Though it might be nice, as I ride through Denver, to listen to Warren Zevon's "Things to do in Denver when You're Dead," I fear that it might cause me to need the song's advice in a more literal sense. Lest you think I exaggerate: Patricia McMillan.

And yet everybody seems to do it. Is it simple carelessness? Probably. The thing is, bicycling - especially urban bicycling - is not an inherently safe activity. It's not terribly dangerous, either, but that's only true if the bicyclist is actively making it so. The sad truth is that most motorists are entirely self-absorbed and can barely be bothered to pay attention to what other cars are doing. They're not watching out for bicyclists. It never even crosses their minds. As a cyclist, you have to make up for their lack by paying constant attention to what they're doing and being prepared for just about anything. This means watching and listening, not keeping a finger on the handlebars while you're switching playlists.

Cars aside, it's not safe in terms of other cyclists. How are you going to hear it when a faster cyclist comes up behind you and calls out, "On your left!"? You aren't, of course, and then perhaps you swerve to the left just as the other cyclist is passing. Probably not as bad as a collision with a car...but still not a whole lot of fun.

More than anything, it baffles me. Part of the joy of cycling to me is that I'm not in a car, isolating myself from the rest of the world. When I ride through the city, I feel connected, like I'm a part of it. I don't understand the desire to cut oneself off in a new way.

Of course, the real mind-blower is that the iPod listeners are almost always among the probably half of the people I see biking on-campus who aren't wearing helmets. Personal experience has reminded me time and again of the importance of the ol' brain-bucket. I can't fathom the people who climb on a bicycle without strapping on a helmet. And then they compound that by listening to Fallout Boy instead of the world around them while they ride. Ultimately, it's their Darwin Award to win as they choose. All I can do is shake my head and wonder when they'll win it.