This year's historic race has two athletes, Daniela Ryf and Jan Frodeno going for their third World Championship victory in a row. While Ryf is the clear cut favorite in the women's race, the men's side is shaping up to be extremely competitive with several hopefuls eyeing the top spot. We will obviously focus heavily on the bike portion of the race, but at Kona every discipline is humbling and will challenge even the most seasoned endurance athletes. While not overly technical, the bike course at Kona is in a word, "brutal". With roughly 5000 ft of climbing, high heat and humidity, plus gnarly wind, athletes face a bike course much more difficult than many standard Ironman courses.

Bike Split Predictions

We will again be estimating power and bike splits for a few select pro athletes. These are based on past performances, weather conditions and publicly available data coupled with our advanced power modeling algorithms. As always the data will be adjusted as weather forecasts change right up to race morning.

Athlete TSS Watts/kg Avg. Watts Avg. Speed Bike Split  
Lionel Sanders 256 4.25 308.50 watts 25.91 mph 04:20:15 View Plan
Ben Hoffman 239 3.81 276.22 watts 25.85 mph 04:20:51 View Plan
Sebastian Kienle 246 3.87 282.28 watts 25.56 mph 04:23:48 View Plan
Jan Frodeno 264 3.65 272.93 watts 25.36 mph 04:25:56 View Plan
Timothy O'Donnell 285 3.78 281.27 watts 25.14 mph 04:28:14 View Plan
Daniela Ryf 257 3.75 221.29 watts 23.21 mph 04:50:37 View Plan
Heather Jackson 293 3.87 219.20 watts 22.69 mph 04:57:12 View Plan
Sarah Piampiano 302 3.82 207.73 watts 22.05 mph 05:05:50 View Plan

Weather Forecast

Athletes who go into the course without accounting for the conditions can easily see their day turn into a lot of walking throughout the marathon. Missing the lead swim group can leave a really hard gap to close, and pushing too hard early to gain a small amount of time can lead to huge losses later in the course when the wind tends to pick up. With temperatures hovering around 80 degrees and humidity often close to 80%, non acclimated athletes will need to vary their effort levels similar to racing at altitude. Pros often push 10% less power at Kona than they would at a typical Ironman race.

The wind at Kona can vary quite a bit, but if it follows the prevailing pattern, early morning winds tend to originate from the east interior of the island and as the athletes travel up the coast the wind starts to shift going from a more sheltered low headwind to a stronger more exposed northern headwind up to the turnaround at Hawi. Once athletes make the turn to head back into town the wind is coming off the coast from the west and is much stronger (the famous cross winds). For the final section of the course the winds shift more to the south and often increases so athletes face additional headwind back into transition. This shift tends to increase in intensity throughout the day so age groupers often face harsher conditions than the pros. Essentially athletes face a head or cross wind for the vast majority of the course.

For the most realistic results with the model we suggest looking at the past three years weather data and running the model against those as the forecast data we use does not typically pick up these shifts until they correct the data after the fact. Checking out the weather on course a few days ahead of time can help narrow down the type of weather to use in the model based on those previous year's conditions.

Race Analysis

If weather conditions follow similar patterns as previous years the power profile for Kona should be fairly consistent. While the first 60 miles is net positive gradient with the climb to Hawi the trip back features rolling terrain with the possibility of stronger cross and head wind so maintaining a steady power level and a low VI below 1.05 is still the best strategy. Poor pacing and going out too hard on the early sections of the course could cause big time losses to add up in the headwind sections heading back into town. Athletes that typically only race based on power may also want a secondary HR target limiter to prevent going into the red in the harsh conditions.

As aerodynamics and tactical racing have become the focus of the last couple of years at Kona the times separating the front pack athletes on the bike has narrowed significantly. This trend could continue, but some new elements and evolving tactics like those shown by Ben Kanute at 70.3 World Champs could shake up the field. On the women's side barring some disaster Rfy is poised to take home her third Ironman World Champion and like 2015 complete the double with her 70.3 World Championship win in Chattanooga. The rest of the women will most likely be battling for 2nd and third with Heather Jackson eying a move up the podium this year.

On the Men's side it is still the defending two time champion Jan Frodeno's race to lose, but several athletes who have had outstanding performances this year have their eye on the top spot including Ben Hoffman, Patrick Lange, Sebastian Kienle, Tim Don, Tim O'Donnell, and of course Lionel "The Colonel" Sanders. We expect fireworks right from the gun with Kona rookie Josh Amberger doing what he does best in the swim and daring anyone to try to go with him on the bike. With the incredible field and a few new dynamics we expect times to be a bit faster this year on the bike, but as always things at Kona can change fast so stay tuned for updated predictions and insight right up to race day!


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