After my second ride I return to ride the cal course 4 times. I compare pre and post cal numbers and adjust the course length if the numbers are larger post cal. The reason for pre and post cal rides is that tire pressure can vary, affecting course length. A bike with a Jones counter is much more accurate than a measuring wheel because wheels bounce and it's harder to walk a straight line. The bike is much faster also.
Uncertified courses are invariably short.
This makes it tougher to determine PR's. In 1982, prize money was first given out at the East Lansing State Bank 10km.