Ironman World Championship champion’s “chunky” shoes spark controversy

Last week at the Ironman World Championship in Kona, Hawaii, Norway’s Gustav Iden ran a 2:36 marathon after a 180-kilometre bike and 3.8 km swim, earning his first world championship title. Iden ran a new marathon record on the Kona course in a unique pair of On’s carbon-plated running shoes, the Cloudboom Echo 3, which have a reported stack height of 50 mm, which is outside of World Athletics legal stack height rule of 40 mm for road-running events.

Iden is allowed to wear these shoes in competition, since professional triathletes do not have to comply with any rules over their choice of running shoes, World Triathlon has confirmed.

Despite regulations in athletics governing shoe technology–such as limiting the sole thickness–World Triathlon stated they will not follow World Athletics standards and no checks are being made on any of the footwear being worn.

Some fans of the sport are calling for World Triathlon to follow suit in controlling stack height for competition. The second-and third-place finishers, Sam Laidlow of France and 2020 Olympic champion Kristan Blummenfelt, both wore the WA-legal shoes Nike Alphafly Next% and Asics Metaspeed Sky 2.

Iden said this in a post-race interview with his sponsor On:

“In the last 10 kilometres, I felt like I had an advantage heading back towards Kona…Not only with the Cloudboom Echo 3 shoes but also envisioning the win the whole time. These shoes were a motivation for me because you really feel the power, you feel the sense of speed straight away.”

World Athletics rules state the sole must be no thicker than 40 mm and that the shoes must not contain more than one rigid or embedded plate that runs the full length of the shoes. The Cloudboom Echo 3 has a single carbon plate that runs the full length of the shoe.

Canada’s Ben Flanagan also wore the Cloudboom Echo 3 during his win at the 2022 Falmouth Road Race. Since the seven-mile road race is not sanctioned by World Athletics, elites are allowed to wear shoes which are normally not allowed at national championship road races.

Iden won in the Ironman World Championships in his Kona debut with a time of 7:40:24, taking 11 minutes off the previous course record time from 2019. On, who signed Iden in the week leading into the race, was given a green light from Ironman for the Norwegian to wear the shoe.