2025 Changes to Ironman Race Rules Announced – Triathlete

2025 changes to Ironman race rules include reduced drafting penalties, water bottle restrictions, aerobar extension limits, and guidelines around neoprene swim caps. Photo: Brad Kaminski/Triathlete

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Now we know exactly how far aerodynamically-fixated triathletes can push the envelope on bike-mounted hydration volume. Ironman announced revised guidelines yesterday limiting the amount of water you can carry between your arms and behind your saddle to 2 liters in each location. This update follows rule changes issued by World Triathlon in January and responds to concerns we covered last week in our story about the trend toward larger and larger hydration rigs.

The latest change to Ironman’s race rules also focuses on reducing drafting penalties from five minutes to three minutes (Ironman-distance events) and two minutes (70.3-distance events) for “Blue Card” penalties, while leaving lesser “Yellow Card” penalties at 60 seconds and 30 seconds, respectively.

In a conversation with Triathlete for this recent story on between-the-arms hydration, Ironman head referee Jimmy Riccitello cited several reasons why he favored adopting the water bottle changes. One was purely practical: For referees and athletes alike, there’s less confusion and risk of controversy when the two organizations’ rulebooks are aligned. He also spoke about safety concerns that could arise from amateur athletes overloading the front end of their bikes. Limiting the volume they can mount on the cockpit, he said, could prevent accidents that arose from unwieldy steering.

As happens with many regulations, however, there’s a loophole. The 4-liter limit only applies to front-end and behind-the-saddle bottle placements; it does not restrict how much water you can carry inside your frame’s triangle or within the frame itself. In theory, athletes could still carry 10 liters of water on a bike. (We can’t imagine why you’d do this, but send us a picture so we can shame you on social media.)

This issue came to head as race officials were seeing increasingly outlandish hydration configurations that raised concerns like those Riccitello cites. “The Great Hydration Battle” all began back in 2022 when Norwegian pro Gustav Iden stuffed a water bottle down the front of his race kit en route to setting an overall course record at the Ironman World Championship in Kona. Overnight, copycats proliferated, with pros and amateurs alike sporting various bottles and even bladders inside their suits. Studies emerged with eye-opening claims about the potential benefits of Iden’s innovation, but Ironman (and World Triathlon) cracked down last year, specifically outlawing the practice as an unfair use of chest fairings.

Undaunted, athletes and brands shifted to experiments with bottle platforms and cages that allowed them to mount two and even three bottles in the space between their arms (BTA), elbows, chest, and hips. Their goal – a very legitimate one – was to use those bottles to divert air around their torsos that would otherwise eddy into the space behind their elbows and push against their hips. Many reported instant results, with reductions in drag that could save three or five or even 10 minutes over 112 miles.

Not everyone was sold, though. Some experts voiced concerns about the rush to join what pro Matthew Marquardt called “an aerodynamics arms race.” Marc Graveline, an aero guru to Lionel Sanders, Chelsea Sodaro, and numerous World Tour cyclists, said that he never saw anyone get more than four watts of savings from stacking multiple BTA bottles. He also warned that the average amateur’s drag characteristics are too variable to assume that multiple bottles will make them faster.

“When you measure it, you find that it’s extremely, extremely individual,” Graveline told Triathlete. “There are simply too many variables affecting the average amateur’s drag characteristics to assume that multiple bottles will make you faster.”

Not quite. As noted in last week’s water bottle deep dive, there’s also a safety component at play, as moving an athlete’s center of gravity far forward – via additional fluid over the wheel and cockpit – can have unintended consequences for age groupers with less-than-expert handling skills. “Bikes just won’t steer the way the manufacturer intended when you put heavy fluids [high up] on the front,” Riccitello noted in our initial interview.

Ultimately, Ironman and World Triathlon appear to have staked out a sensible middle ground that allows athletes to reap the aerodynamic gains of multiple bottle placements while protecting against overkill. The only question now is how aggressively will referees police the new Ironman bike rules. Will they be counting bottles on course? Estimating volume to ensure that you’re not carrying 2.5 liters behind your saddle? Yes and no.

“Importantly, the maximum volume capacity limits are dependent on the capacity of the water bottles or water containers placed between the bar hydration systems, and not on the amount of actual liquid in the bottles,” Riccitello told Triathlete for this story.

Other rule changes in this most recent update include following World Triathlon guidance on limiting aerobar extension length to “not extend beyond the leading edge of the front wheel,” and only allowing neoprene swim caps in wetsuit-legal swims.

The new regulations go into effect on March 17, 2025, and Ironman confirmed to Triathlete that the first Ironman-branded event with enforcement will be Ironman 70.3 Geelong on March 23.