I am rudderless — unless I have a goal. Stick a carrot in front of me and I can usually get it done.

Case in point: earlier this year I vowed to start using my bike more for utilitarian purposes. To date, I believe I’ve gone for coffee on it twice. Appalling as that is, it became even more so when I pulled up a map of everything within a two-mile radius of my Cary house and discovered my bank, Starbucks, REI, Performance, Harris Teeter, Home Depot, the Galaxy Cinema, two malls and a Taco Bell. My basic needs, all within two miles.

That’s why I just signed up for the Clif Bar 2 Mile Challenge, the challenge being this: ride your bike on as many errands under 2 miles from home as possible. According to the Challenge Web site, 40 percent of all trips by folks in the U.S. are under 2 miles, and 90 percent of those are taken by car. Clif gives some good reasons to take the Challenge, most of them environmental and involving the amount of carbon dioxide your internal combustion engine pumps into the atmosphere. Check out the Web site for details; In short, if you truly are concerned about global warming, the 2 Mile Challenge is something you can do about it.

I was more motivated by another stat: It costs $5.17 per gallon to operate a car; it costs $120 a year to maintain a bike (that’s slightly more than 23 gallons of gas, btw). I’m cheap, I signed up.

I like the accountability aspect of the 2 Mile Challenge. Every time I need to run a 2-mile errand, if I take my bike I can log in and earn points for it. If I take the car, I’ll just feel guilty. And I like logs; for reasons I probably don’t want to explore, they validate whatever it was I did that I desperately seek validation for. With my Clif Bar 2 Mile Challenge Web log I can confidently claim I did four errands this week on my bike! I try simply telling someone that and I’ll get that cocked-eyebrow-”Sure” response. Enough about my issues.

More importantly, my logged rides earn points for a good cause. In the 2 Mile Challenge, you can sign up to ride for one of three teams: The Blue Team rides for 350.org, which advocates cycling for environmental reasons; the Gold Team rides for the Alliance for Biking & Walking, a coalition of 160 grassroots bike and pedestrian groups advocating for more bike-and-foot-friendly communities; or the Red Team, which rides for Safe Routes to School, which is working to restore the lost art of walking or riding your bike to school without getting run over. Good causes all; I opted for the Red Team because of everything I kvetch about in this blog, the lack of opportunities kids have for getting exercise is near the top of the list. Clif Bar will divvy up $100,000 to the three, based on who gets the most points.

Speaking of safe routes, that may preclude me from making certain trips. The bank, the grocery store, Starbucks, the book store, the movie theater — I have safe ways to reach them all. But to reach REI and Home Depot, for instance, requires riding down five-lane Walnut Street in Cary. I like living in Cary, in part, because it largely deserves its Bike Friendly status. But Walnut is not Bike Friendly, it is Bike Nasty; not even Volcano Nachos justify tangling with it. (What I will do, though, is reduce the number of trips I take in that direction by piggybacking visits. I reduce emissions and, more importantly, guilt.)

If you like the idea of the challenge but don’t have a bike, the Clif Bar 2 Mile Challenge Web site has a feature that helps you figure out what kind of ride best suits you. If you do have a bike but are baffled by how you can pull off errands on it, the site can help with that, too.

That’s another think I like about the Challenge: It gave me permission to go out and buy a set of new grocery-toting, environment-saving panniers.

Panniers I’ll be obliged to go and get on my bike.