About.com relates that if 34 calories are expended per mile ridden on a bike, a 175-pound person should be able to shed 1 pound for approximately every 100 miles ridden. Riding five miles a day, seven days a week, would therefore generate a loss of 1 pound every three weeks.
Losing weight involves burning off more calories through exercise than are taken in as food. According to About.com, in order to lose a single pound, it is necessary to burn around 3,500 calories through exercise. However, how many calories are burned by an activity, such as bike riding, is a function of the intensity of the activity relative to the weight of the person doing it.
HowStuffWorks gives the example of a hypothetical 175-pound person. Since riding a bicycle at a steady 15 mph burns 0.049 calories per pound per minute, this person would burn 515 calories an hour, or around 34 calories per mile ridden.
In riding a bike for weight loss, the key is in the intensity of the workout, rather than the distance covered. About.com recommends measuring the distance that can be ridden in 30 minutes and setting the goal of covering that distance in progressively less time.