THE "HOW-TOS" TO TRIATHLONS
In a typical triathlon, racers arrive at the venue about an hour (or more) before the race is to begin, to set up their spot in the "transition area". Here they will generally have a rack to hold their bicycle and a small area of ground space for shoes, clothing, etc. In some races, the bicycle stage does not finish in the same place it begins, and athletes will 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 groups; amateurs are often referred to as "age groupers" who form the great majority of triathletes. 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 typically set at between five and ten year intervals.
In some triathlons, amateur athletes may have the option to compete against others in heavier-weight divisions. "Clydesdale" athletes are those men generally over 200 pounds, while "Athena" athletes are women generally over 150 pounds. This is not officially sanctioned in any of the professional or Olympic events.
There is usually (as in most marathons) a lower age limit (typically 18) for the longer triathlons (all of the 5 events listed above) but many shorter races have been organized to allow children and teens to compete in triathlon.
After transitions are set up, the athletes don their swim gear and head to the swim area - usually a lake, river, or the ocean - for the race start. Depending on the type and size of the race, either all the athletes will enter the water at a single signal ("mass start", traditional in Iron-distance races), in waves spaced every few minutes, usually by age group (wave starts are more common in shorter races where a large number of amateur athletes are competing), or individual "time trial" starts where the athletes enter the water one at a time, usually 3-5 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 and attempt to change from their swim gear into cycling gear as rapidly as possible. In some of the earliest races, tents were provided for changing clothes. In the modern day, 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 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. Professionals often don't even wear socks.)
The cycling stage proceeds around a marked course and finishes back at the transition area, where racers rack their bicycles and change quickly into running shoes before heading out for the final stage. The run finishes at a finish line usually near the start and transition areas.
In most races, "aid stations" located on the bike and run courses provide water and energy drinks to the athletes as they pass through. Aid stations at longer events will often provide various types of food as well, including such items as energy bars and gels, fruit, cookies, and ice.