it is great exercise (very light cardio, if your on level ground)
me and the wife were discussing the boys weight and i mentioned to her i used to be chunky until i hit highschool
we didnt have school busses and i had to pedal 6 miles one way, 5 times a day
that knocked the pounds right off
(by the time im met the missus, i was 6 even and 175 pounds)
so i figured, no reason to wait for him to get there, might as well get started now