The first leg in the Olympic triathlon competition consists of a 1500m open-water swim.
As the first leg of the triathlon competition, the swim sets the stage for the entire race and can often make or break a competitor's shot at a medal. How an athlete approaches the swim leg depends on the competitor's individual strengths and weaknesses. If the swim is a triathlete's strongest event, it is important that he or she pull ahead of the pack and leave the water as far ahead of the other competitors as possible. Building up a lead going into the bike leg gives the swimmer a buffer zone that the other competitors, who may be stronger cyclists, must overcome. Positioning is key for the athletes whose strongest event is not the swim. This triathlete needs to stay close to the lead pack and not fall so far behind as to make catching up on dry land impossible. Weaker swimmers often hang back and draft off the lead swimmers, allowing them to conserve energy for the next leg, the bike.
After the opening swim, the second leg of an Olympic triathlon requires competitors to ride a bike over a road course that is 40,000m (24.9 miles) in length.
As in the swim leg, a competitor's strengths and weaknesses determine how he or she will attack the bike course. The strong bikers will often break away from the pack in order to build up a lead over the other athletes who might excel at the run, while the stronger runners will stay in the pack and draft off the lead riders (a legal tactic in Olympic triathlon competition). In an Olympic triathlon, every second counts, so an efficient transition from swim to bike is crucial. A clean swim-to-bike transition typically takes between 20 and 30 seconds.
The final leg in the Olympic triathlon competition consists of a 10,000m run over a road course. This distance corresponds to the longest Olympic running event contested on the track.
All the strategy and positioning of the first two legs bring the triathletes to the final segment of the competition. In the run, the primary tactic for triathletes is simply to cover the 10,000 meters as fast as they can. The athlete whose strongest event was either the swim or the bike hopes to have built up enough of a lead that he or she can hold off strong runners challenging from behind. The racer whose best event is the run hopes that, over the course of the first two legs, he or she has been able to stay within striking distance of the leaders and has enough reserved energy to make a final push at the end. The transition from bike to run tends to be a bit quicker than the swim-to-bike exchange. Competitors must discard their cycling gear and put on their running shoes as efficiently as possible.