Originally Posted by
Fiery
This would be a pretty inaccurate calibration method since there is no way to be sure the ride has followed the one-mile course line exactly. The proper way to calibrate a cyclocomputer is to roll the bike down a marked straight line for exactly one wheel revolution (mark the tyre with chalk or something similar if necessary), and then measure the distance. For additional accuracy, repeat the process three or four times and take the average result.
Taking only one wheel revolution is dodgy since you are then extrapolating the slight error you made and multiplying it by thousands.
The best way is to take a measured course.
The second best option is to use google maps and find a straight road with cycle path next to it ... then ride from and to a specific point that is easily pinpointed on the map and take a long enough ride of 10 miles or something like that ... the margin of error will be very small then.