How a triathlon works

Major races require athletes to register and attend a race briefing the day before the actual race. This race briefing details the course, the rules, and any problems to look out for (road conditions, closures, traffic lights, aid stations). At registration the racers are provided a race number, colored swim cap, and, if the event is being electronically timed, a timing band. Often racers are also given competitor wrist bands that allow them in and out of the transition area or other athlete-only areas. At a major event, such as an Ironman or a Long Course Championship, triathletes are required to set up their bike in the transition area the day before and leave it overnight under guard.
For shorter distances the racers arrive at the venue about an hour (or more) before the race is to begin. They register and receive their swim cap and number, then proceed to set up their spot in the transition area. For most races, competitors have their race number marked on their arms and legs, along with having their age group marked on their calf.
In the transition areas, athletes will generally be provided with a rack to hold their bicycle and a small section of ground space for shoes, clothing, etc. Generally, transition spots are allocated to racers by their competition number, though in some events, athletes choose their spot in the transition area on a first-come, first-served basis. In some races, the bicycle stage does not finish in the same place it begins, so athletes set up two transition areas: one for the swim-to-bike transition, and one for the bike-to-run transition.
Racers are generally categorized into separate professional and amateur categories. Amateurs, who make up the large majority of triathletes, are often referred to as "age groupers" since they are typically further classified by sex and age. One feature that has helped to boost the popularity of such a complex, time-intensive sport is the opportunity to compete against others of one's own gender and age group. The age groups are defined in five or ten year intervals.
In some triathlons, amateur athletes may have the option to compete against others in heavier-weight divisions. "Clydesdale" athletes are generally those men over 200 pounds, while "Athena" athletes are generally women over 150 pounds. These weight based divisions are not officially sanctioned in any of the professional or Olympic events.[citation needed]
As in most marathons and other competitive endurance sport events, there is typically a lower age limit, though many races have been organized to allow children and teens to compete in their own categories.
After setting up their transition areas, athletes don their swim gear and head to the swim area (usually a lake, river, or ocean) for the race start. Depending on the water temperature, swimmers may be permitted to wear a wetsuit - triathlon specific wetsuits are now common. Depending on the type and size of the race, there may be any of the following methods implemented to start the race. Mass starts, traditional in full distance events, see all the athletes enter the water at a single start signal. In wave start events, smaller groups of athletes begin the race every few minutes. An athlete's wave is usually determined either by age group or by predicted swim time. Wave starts are more common in shorter races where a large number of amateur athletes are competing. Another option is individual time trial starts, where athletes enter the water one at a time, usually 3 to 5 seconds apart.
The swim leg usually proceeds around a series of marked buoys and exits the water near the transition area. Racers run out of the water, enter the transition area, and attempt to change from their swim gear into their cycling gear as rapidly as possible. In some races, tents were provided for changing clothes. However, competition and pressure for time has led to the development of specialized triathlon clothing that is adequate for both swimming and cycling, meaning many racers' transitions consist of little more than removing wetsuit and goggles and pulling on a helmet and cycling shoes. In some cases, racers leave shoes attached to their bicycle pedals and slip their feet into them while riding. Some triathletes don't wear socks, decreasing their time in transition even more.
The cycling stage proceeds around a marked course, nearly always on public roads. In many cases, especially smaller triathlons, the roads are not closed to automobiles, though marshals are often present to help control traffic. Typically, the cycling stage finishes back at the same transition area. Racers enter the transition area, rack their bicycles, and quickly change into running shoes before heading out for the final stage. The running stage, also typically held on public roads, usually ends at a separate finish line near the transition area.
In most races, "aid stations" located on the bike and run courses provide water and energy drinks to the athletes as they pass by. Aid stations at longer events will often provide various types of food as well, including such items as energy bars, gels, fruit, cookies, and ice.
Once the triathletes have completed the event, there is typically another aid station for them to get water, fruit, cookies, and other post-race goodies. At the end of most larger or longer events, the provisions and post-race celebrations may be more elaborate - ranging from ice cream and professional massage tents to cookouts and barbecues.