A triathlon is a multi sport competition involving three stages: 1) swimming, 2) biking, and 3) running. Also part of the race are two transitions: one after the swim, before the bike and the other after the bike and before the run. The distances can be varied depending on the type of race you are competing in. If you've never done a tri before, it's not difficult to learn how to get ready for a race and here's how you do it: