It's my third bike winter and people are still astonished to see I've cycled in to work. "Don't you get cold?" they ask.

"Never," I say. "When used properly, after all, the body is a remarkable furnace."

It's the "when used properly" that gives it the right touch of smugness. I use my body more properly than you do, neener neener.

But it's true. As I believe Bob has pointed out, biking may be the warmest way to get around Chicago. By the time I get to Montrose, less than 10 minutes into my ride, I am usually shedding layers. (I've gotten good at riding with no hands and taking off my glasses and helmet in order to yank off my balaclava.) Walking into work I will have unzipped my sweater, leaving just a T-shirt between me and the elements, but I'll share an elevator with women wearing fur coats the size of phone booths.

A person waiting for the El is lucky to wait in the cold less than 10 minutes, and after 10 minutes, has a car warmed up?

People at bus stops often shoot me looks that say: "It's 15 degrees out. Look at that dummy on the bike." I'm more than happy to shoot back a look that says: "It's 15 degrees out. Look at those dummies who've waited 20 minutes for a bus."