Olympics guide: Triathlon

Unless escaping some impending super evil, to run, ride a bike and swim all in the same day is madness as far as we're concerned. But these lot seem to be really into it. No one's even chasing them.

Athletes: 110

Golds up for grabs: 2

Olympic presence: Since 2000.

Olympic Format: 1500m swim followed by 40km bicycle race, then 10km run.

Contenders: Australia, New Zealand, Canada and Germany occupy the first four places in the all-time Olympic medals table, followed by Switzerland and Austria. Although it evidently helps to come from a mountainous country, the UK’s Alistair Brownlee is the favourite for the men’s triathlon in London.

Past Champions: Australia, New Zealand, Canada, Germany, Switzerland and Austria: 1 medal each.

Watch it: 4 & 7 Aug 2012, Hyde Park. Catch the BBC’s coverage of the Olympic Games across 24 dedicated channels on freesat

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THE BASICS

Swimming

Olympic triathlon races begin with the competitors diving en masse off a pontoon or on-shore launching platform. During the swimming section, athletes may use any stroke they like but it will be headline news if anyone opts for other than front crawl. They can take a breather by treading water, floating or holding on to a marker buoy but it’s a bad sign if they do. Swimming caps must be worn at all times. If the water temperature exceeds 20°C the wearing of wetsuits is forbidden; if it is below 14°C they are mandatory.

Cycling

After emerging from the water, athletes enter the first transition zone, where they remove their wetsuits and put on their cycling shoes, which may be placed on their bicycles in advance. Before removing their bikes from the racks, they must put on cycling helmets and fasten them properly. Failure to do so leads to disqualification, as does removing a helmet at any point before racking the bike in the second transition zone, unless stationary and doing something desperate like repairing a puncture.

Running

Athletes must dismount when they reach a line just ahead of the second transition zone. Here they will find their running shoes placed as close to their personal racks as possible. Having racked their bikes, removed their helmets and changed their footwear (in that order), they can set off.

(Image: Rex Features)