Kona will be won in record time this year

It’s Ironman World Championships week again and this year the men and women are back in the same place, racing on the same day – just like the good old days. Last year was the final rendition of the split competition, with the men’s race in Nice and the women in Kona but this year we are all back in Hawaii – hooray!

The race has moved around the calendar a bit in the past and the weather can change a lot depending on when it is, which is what makes this course so interesting for myWindsock users. Its usual slot of the 2nd weekend in October was ditched in 2024 – part of the reason for the fast time though the trend of the past decade in race times is clear.

The famous bike-course wind comes from the Kohala coast near Hawi, where the trade winds and the island’s terrain produce strong gusts (the “mumuku” winds).

The wind on the big island of Kona has already seen off one victim, with defending champion Casper Stornes being taken out by a big gust.

The trend in results dictate that the men’s course record almost certainly is going to have to be broken by the winner. Lucy Charles-Barclay’s over-performance of 2023 means that the women’s race could be won without necessarily breaking the record, though it’s a fast day as we’re about to see so it’ll probably go down too.

This graph shows the trend in overall finish times in the Ironman World Championships for the past 10 years. Each year improvements in aerodynamics and nutrition are causing the race to get faster and faster. Kienle’s winning time from 2014 would have only just cracked the top 30 in 2024.

The Course

You can check out the forecast yourself here.

The Ironman Hawaii course is really boring. It has achieved legendary status as it is pretty hot and humid which has caused some blowups and meltdowns over the years – though this is mostly down to the way people race it and not because the course itself is inherently crazy. Huge advancements in pacing, nutrition and aerodynamics have neutralised a lot of the challenges too.

The course is essentially an out and back along a coastal highway. The trade winds come from the land side and there’s a volcano which kind of shelters the riders from it. The wind can be strong, though on race day the forecast is for extremely low wind.
The only time the athletes have to really do anything other than look at their power meter is through town. They do a mini loop to get onto the main highway and a mini loop when they get back. What little wind there is forecast to be this year is sheltered from the buildings as you can see with this surface friction layer on the myWindsock map.
The elevation profile is equally simple. There’s one hill – the road up to Hawi. It’s not even steep. It’s a huge motorway drag strip. It is a point on the course where it’s possible to make a difference and split groups though so expect moves to go during this section of the course.

How to break the course record – Women

The women’s bike course record is a time of 4:26:07 set in 2018 by Daniella Ryf. This was another fast day with low air density and pretty low peak wind speeds. We will see what it would take in order to ride a 4:25 for a woman with a system mass of 70kg (including bike and kit) and a cda of 0.2 with Saturday’s conditions. The candidate most likely to break the course record is Taylor Knibb, who recently finished in the top 15 of the World TT champs and has a reported FTP of around 300W.

Conditions suggest a rider of around Knibb’s size with an average cda of about 0.2 (with some variation on the climbs and descent) will be able to ride 4:25:29 with an average power of 242W – roughly 80% of Knibb’s reported threshold. That is around the upper limit of the power professional athletes ride in Kona relative to their Critical Power but it suggests a course record is not unlikely.

How to break the course record – Men

The men’s course record was broken more recently, with Sam Laidlow riding a 3:57:22 in 2024. Laidlow is around 75kg so we will assume a system mass of 85kg (bike plus kit plus rider plus water). The question is, do Saturday’s forecasted conditions make a 3:57 or lower bike split impossible to obtain with human watts?

A 3:57 this year, as the forecast stands, will require a power of 330W. This is on the high side but not unheard of for Ironman athletes at World Championships. The men, being at the absolute front of the race, will also have more motorbikes in front of the front group – making a fast split easier to achieve with less watts than this.

If I was a betting man, I’d say every single course record will go down this year apart from the men’s swim course record. This is due to a unique combination of conditions, field strength and likely race dynamics. 2026 will probably be the fastest Kona ever!