An Enduro is a competitive event, where the rider races against the clock more so than against other riders. They ride motorcycles along marked trail through trees, fields, and even roads while attempting to maintain a predetermined speed average.
Riders draw numbers before the race to determine what minute they will start on. In Iowa there are normally 4 riders that start on each minute. These riders leave the start area at the top of the minute for which they drew.
There are secret and known check points (checks) that the rider must ride through along the trail and be scored. Points are added to your score for being either early or late to each check. Reach the check within your minute to avoid penalty. One penalty point is assessed for the first minute you arrive late and one point for each minute after. Two penalty points are assessed for the first minute you arrive early and five points for each extra minute if you arrive two or more minutes early. If you are 60 minutes late to a check you "hour out" (60points), meaning you are not scored for the remainder of the checks. Also if you are 15 minutes early to a check you "hour out"(60 points).
After long woods sections or tight terrain there are usually "resets". These are added to races (usually after passing through a check.) to let the riders catch back up to their minute if they are unable to maintain the speed average. This keeps people from trying to race while riding down the roads. Eventually the racers return to the area where they started so they can refuel. Most enduros in Iowa consist of two loops.
At the end of the race penalty points are added up and the rider with the lowest point total is the winner.
Most enduro riders use enduro computers to help them stay on time (this is very helpful, but not a must). Before the start of the race each rider gets a route chart, a piece of paper that shows any intersections on the course that may be hard to mark with arrows. This also includes the odometer reading you should have at each intersection. They use the chart to program their computer. As they race they make sure their odometer matches what their computer and route chart show that it should (this is easier than it sounds). If everything matches at each check they should "zero" the check. Meaning they lose no points.