On Tuesday I blogged about GasFreeCommute.com, which got the attention of the Trek Bicycles guys in Waterloo. It seems Trek is offering something similar with its "Go By Bike Challenge."

The challenge is a national pledge campaign sponsored by 1 World 2 Wheels -- Trek's cycling advocacy initiative -- to encourage people to bike rather than drive.

But whereas GasFreeCommute.com tracks the miles you've already biked, walked or skated, 1 World 2 Wheels helps you calculate your potential mileage, calories burned, money saved and carbon offsets accumulated if you biked rather than drove to work, for example, for a week. (You'll understand better once you see the site.)

At my easy four-mile commute to work, I'm potentially riding 173 miles a month, burning an extra 8,131 calories, reducing my carbon output by 168 pounds and saving $38.06 in gas (though probably more for me, since my engine is diesel, which costs more than gas.)

And those numbers are just for my work commute. Once again, it's physically seeing the stats in front of you that is the real motivator here. Once you're done calculating, you can pledge your miles and one pledger will win a Trek 7.2 FX fitness hybrid bike. The challenge runs through Aug. 31.