The second race to analyse this weekend was Ironman Chattanooga 2019. A mid-sized US race with the standard 40 age group Kona slots on offer for the 2020 Ironman World Championship. Chattanooga isn’t the fastest course and has seen some variations over the years. Most notably the swim was cancelled in 2018 so I’ve excluded those results from this analysis.
Hot and humid conditions made this year a particularly tough day of racing. Tough enough to place it third in the table of highest Ironman DNF rates I’ve recorded (see below).
Every one of this year’s split distributions trends slower than the amalgamated results from past races. I would note that the historic swim distribution is actually quite fast for Ironman so while this year’s chart is slower, it doesn’t look unusual for an Ironman race. It’s really on the bike and run where times become significantly skewed and we see the impact of conditions. Similar conditions impacted the 2016 race, but this is masked by the results from other years, position data further down shows this better.
We can see the raised rates of DNF in both bike and run caused by heat and humidity. The only year we can compare this with is 2016 which was also hot and humid and saw slightly higher drop out rates on the run.
If I rank the ten highest Ironman DNF rates I’ve recorded in my database Chattanooga 2019 comes third in the table. With 2016 experiencing very similar conditions, Chattanooga holds two of the three highest DNF rates and unlike Frankfurt doesn’t have a 15 hour cut off. You can read more about Ironman DNF rates here.
Age group medians repeat the trends shown in the split distributions across all age groups. The impact of conditions is such that swim, bike and run are consistently slower.
Only a handful of athletes come from outside North America to race Chattanooga. While not fully proportionate, the majority of slots do remain with US athletes.
Tracking the times for specific age group positions shows how variable this race has been. From a comparatively fast debut in 2014 through to the significantly slowed years of 2016 and 2019. As ever the impact of conditions is biggest further back in the race, amplified by a smaller starting field at this year’s race. Such variance makes it harder to anticipate potential qualification performances.
Based on the start list I’ve calculated the slot allocation and automatic qualification times for each age group. As two age groups had no finishers their slots will roll into others, but roll down is not factored into these calculations. You can compare this with other races on my Kona qualification page.
Unsurprisingly, the age group top twenties mainly trend slower than the course averages. That said when we look at the very front and Kona qualification we see times close in on the average. As often noted for Kona qualifying positions, performances tend to be less impacted by the heat and humidity.
You can access a spreadsheet of the full results from Ironman Chattanooga 2019 on my Google Drive.