New 255 Triathlon event with 5km swim, 200km bike and 50km to take place at the UK’s famous Goodwood motor racing circuit on 8 August 2021.

Billed as the world’s longest single-day triathlon event, the 255 Triathlon is designed to be a step up in the physical and mental challenge of Ironman competition with added distance in each leg. There’s an extra 1.2km in the swim, 20km on the bike and 7.8km on the run totalling 5km/200km/50km for the event’s titular distance.

255 Triathlon Course Map
The 255 Triathlon makes the most of the historic Goodwood circuit, promising traffic-free roads. (Image: TriBourne Multisport Events)

Hosted at the historic Goodwood Motor Racing Circuit in West Sussex, UK, the inaugural race will be limited to just 300 intrepid history-makers and athletes will have 18 hours to complete the full 255km event.

The 5km swim will take place at the nearby Westhampnett Lake before heading to the motor circuit for 52 traffic-free laps on the track’s beautiful surface. Finally, 10 laps of the circuit’s perimeter path will take athletes to the finish line.

“We feel the time is right to introduce the next step for endurance triathletes”

Matthew Dowle, 255 Triathlon race director

Organisers TriBourne Multisport Events are also making use of Goodwood’s pits line, which will provide the focal point of the event with spectators able to support athletes continuously throughout the day. In this race hub, there will be music, commentary, live lap timing and leaderboards, promising a unique race experience.

255 Triathlon race director, Matthew Dowle, said: “Ironman has always been widely regarded as the ultimate single-day endurance event. We feel the time is right to introduce the next step for endurance triathletes.

“255 Triathlon will not only push competitors to a new level of physical and mental endurance but will also provide an unparalleled level of engagement for spectators throughout the whole event. We’re very excited to share our vision with the triathlon world.”

Registration is now open for the first event, but with a limited field for the first edition, places are filling fast. Visit to secure your entry.


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