The sport is based on riders attempting to maintain an exact schedule, regardless of the difficult terrain and conditions they may encounter. Checkpoints, where crews will mark the time of each rider arrival, are located along the course. After the race, the score of each rider is calculated. The riders with the lowest number of penalty points are awarded trophies in their respective classes.
Key Time -
The scheduled starting time and scheduled time of arrival at each checkpoint for a rider on row OO. (Row Zero)
Timed checkpoints, including Known Controls, cannot be located closer than 3 ground miles apart. Therefore 3 ground miles before, or 3 ground miles after a timed checkpoint can be considered "Free Zones". Similar Free Zones may apply to Gas Stops, usually with timed checks no closer than 2 miles before, or 3 miles after the Gas stop. A "Free Zone" is a distance on the race course where no checkpoints are possible.
A point along the course where the posted Mileage is advanced to some greater number. This gives a rider on schedule a rest period of the period of time it would have taken the rider to ride the mileage advanced.
A point along the course where the Mileage remains fixed while the time is allowed to run. A rider on schedule would wait until the Free Time has run out, then he would proceed down the course. It has an effect very similar to a Reset.
The actual Mileage traveled by a rider, which is the posted Mileage minus any Resets.
Checkpoints are located along the course where crews will mark the minute, and seconds if an Emergency check, that a rider enters the check. The Key Time and the Mileage for that check should be posted near the flags. The Mileage accuracy for the check location must be within 1 tenth of a mile, while the clocks used at the check must be within 10 seconds of the master Key Clock. The colors of the flags used to mark each check are shown in parenthesis.
Secret (Red & White) An unknown, timed checkpoint.
Emergency (Green & White) Same as a Secret check, except the minutes and seconds are recorded.
Known Control (Yellow) A timed checkpoint whose location is known to all participants.
Observation (White) An unknown, un-timed checkpoint where no time penalty is recorded.
After the race, penalty points are computed based on the riders variance from a perfect schedule.
All checks -
EARLY: More than 15 minutes disqualified from that point.
LATE: More than 60 minutes and 59 seconds disqualified from that point.
EARLY: 2 points for the first minute, plus 5 points for each additional minute
LATE: 1 point for each minute.
The major points are computed like a Secret check, with Tie-breakers points placed after the major points.
Tie-breaker points are the total number of seconds from the 30 second point of the riders due minute.
EARLY: Zero points for early up to 15 minutes, 2 points for each minute for an early departure.
LATE: 1 point for each minute.
To ease course layout and scoring, timed checks can only be located where a whole tenth of a mile falls on a whole minute. Below is the time and distance between possible checkpoints at each speed average from 1 to 99 MPH.