How does a triathlon work?
B · Beginner · The race and the swim · 1 of 5A swim, a bike ride and a run, done one after another without a break. The clock starts at the swim start and stops at the finish line, so the time spent changing between them, in the transition area, counts. The first athlete whose torso crosses the finish line wins.
How it works
- Three segments: swim, then bike, then run.
- Two transitions: from swim to bike and from bike to run, both in the transition area.
- One clock: in a relay the rules say it plainly: "Time is continuous and the timing does not stop between athletes." The same holds between segments.
- The swim: "Athletes may use any stroke to propel themselves through the water."
- The bike: athletes may not make forward progress "without being in possession of the bike".
- The run: athletes "run or walk". They may not crawl.
- The finish: "the moment any part of the torso crosses a vertical line extending from the leading edge of the finish line".
- The course: athletes must follow the prescribed course, and staying on it is their own responsibility.
- Unassisted: no pacing by anyone who is not competing, on or beside the course.
- Penalties: a warning, a time penalty or disqualification from the technical officials.
- Two kinds of race: draft-legal, where riding close behind another cyclist is allowed, and draft-illegal, where it is not.
The glossary has triathlon, the segment, the transition, the overall time, the finish chute, the technical official and the draft legal racing entry.
Tricky cases
An athlete has a slow change from swim to bike. Is that time taken off?
No. The clock keeps running through both transitions.
An athlete's bike breaks and they run with it to the finish of the bike course. Is that allowed?
Yes, as far as the general rule goes: forward progress must be made in possession of the bike, and nothing read says it must be ridden.
Two athletes sprint for the line and one throws an arm forward. Who wins?
The one whose torso crosses first. Arms, legs and head do not count.
Can an athlete walk the run?
Yes. The rule says run or walk. Crawling is not permitted.
Why the rule exists
Counting the transitions is what makes triathlon one race and not three. Changing fast is a skill, sometimes called the fourth discipline. The order is practical: the swim comes first while athletes are fresh and can be watched in the water, and the run last, where tired legs are the least dangerous.
Where it differs
| Where | What changes | Source |
|---|---|---|
| Triathlon | Swim, bike, run | WT 4; 5; 6 |
| Duathlon | Run, bike, run | WT distance table |
| Aquathlon | Run, swim, run | WT distance table |
| Para triathlon | Its own section and classes | WT 17, not in this set |
From the rule book
World Triathlon, Competition Rules (2026 edition, amended 29 April 2026), sections 3, 4.1, 5.1, 6.1, 6.2 and 16.2. Checked 14 October 2026. Official document: World Triathlon Competition Rules (PDF).