When I bike to work, I bike 1.5, 3, or 4.5 miles (the whole trip is 4.5, but I have the option of putting my bike on a bus for part of the trip). But sometimes I go farther. One instigation is that I sold my car (I wasn't using it enough to justify keeping it) and sometimes biking is more convenient (and more fun!) than taking the bus to wherever it is I'm going.