There are no distance-related "targets" for biking to school that can be applied to all schools. However, generally speaking, it seems that people are willing to travel up to about 30 minutes to get somewhere. A 2008 article by McDonald, titled "Children's mode choice for the school trip: The role of distance and school location in walking to school" indicates that a typical walking rate for school-aged children is about 2.7 miles per hour (or 1.35 miles per 30 minute-period). Therefore, most children will probably not walk farther than 1.35 to/from school. Unfortunately, similar estimates do not exist for bicycling rates among school-aged children. Most estimates assume a bicycle travel time of 12mph, but this figure is more appropriate for adult bicyclists.
To estimate reasonable distances for children to bike to school, we must make assumptions. First, let's first assume that children (and in many cases, their parents) are willing to bike up to about 30 minutes to get to school. Next, let's assume that the typical child bikes at a speed of 8 miles per hour (mph). Using these assumptions, we arrive at a one-way trip length for biking of about 4 miles. However, other things besides trip time and distance must be taken into consideration when establishing distance targets. These include, but are not limited to:
(1) The distance along travel routes that people use and interruptions along the route between home and school. Though the "as the crow flies distance" between a student's home and her school may be short (say within 1/2 mile), her route to school may not be direct, which will increase the distance between her home and school. And as distance increases, so does travel time. Also, interruptions along a child's route to school can increase his travel time. For instance, a route with a lot of intersections which make a child stop often will increase the amount of time it takes him to get to school.
(2) The amount of effort involved in biking. Having to bike up steep hills to get to school will take longer than gliding along flat terrain. Therefore, an area's topography should be included into travel time estimates.
(3) The number of other distractions along the way to school. Scary dogs, having to carry heavy school bags, adverse weather, and many other things can impact the amount of time it takes children to get to school.
In conclusion, travel time can be used to estimate distance targets. To do this, try to estimate the distance a typical 3rd or 4th grade student could bike in 30 minutes. Make sure to take into account the number of stops a child would encounter on the way to school and the topography of your school's area in making this travel time estimate.
For example, let's assume that a 4th grade student encounters 3 stop lights on her way to school. The stop lights have her waiting an average of 1 minute each. Also, toward the end of her trip, she must also bike up a medium sized hill. On flat land, she travels at about 8mph; but on this hilly section (which is about a mile long), her speed drops to about 4mph.
Using this example, we can calculate the following in terms of travel time:
Stop light interruptions time = 3 minutes
Last hilly mile = 15 minutes (assuming a speed of 4mph)
Remaining time to equal a total of 30 minutes = 12 minutes
Number of miles the student can travel in 12 minutes assuming a speed of 8mph = 1.6 miles
Total distance in 30 minutes = 2.6 miles
Assuming that this child's route is similar to other students' routes to school, this school could decide that 2.5 miles is its "distance target" for bicycling.