Austin Tri-Cyclist Blog

Tuesday, October 14, 2014

Kona Ironman Bike Stats

by Jack Mott

A common topic of debate is how much faster modern triathletes are today thanks to fancier bike equipment. Some claim that legends like Mark Allen and Dave Scott rode their round tube frames just as fast as today's pros ride their high-tech carbon, aero equipment. Comparing bike performance is a tricky business, as a host of factors make bike times very "noisy." The winds at Kona vary greatly, which can affect bike times by as much as 15 minutes or more. Tactics also affect times, as some years the contenders will all be together on the bike course with nobody pushing the pace. To try to answer the question and make sense of it all we have put together some interactive charts.

The slowtwitch kona archive provides a handy source of data on the top 10 finishers each year since the start of Kona. We chose to look at the time period from 1988 to 2014, as this represents a period when the depth of talent was solid and the course was relatively constant. It also represents a time after the introduction of the aerobar, when professionals were already adopting bike positions similar to modern athletes. Some small course changes have occurred over these years, but the bulk of the bike course has remained the same. Before 1998, bike times used to include transition times. They generally add up to about 4 minutes, so we have subtracted 4 minutes from all bike times prior to 1998. First up, we take a look at the average bike splits among the top 10 overall finishers. Hover over a year for more info, pictures, and links when available.
You can see that there is a clear downward trend in bike times. The linear trend shown in light blue suggests that bike times have improved by about 8.3 minutes over the time period. However, that isn't necessarily all a result of improved bike gear. Records have been dropping in all sports, even those like running, in which equipment plays almost no role. Since running isn't impacted much by technical advancement, it gives us a great point of comparison. We can compare the trends in the Kona run and bike and see if one has been improving at a faster rate than the other.

We find that running times have improved by about 3.7% since 1988. If athletes were making 3.7% more power on the bike course, we would only expect about 4 minutes faster bike times, not 8. This suggests that bike gear could be responsible for about 4 minutes of time savings, which is in line with what we might expect given the drag improvements in gear since then. Another interesting thing to note is that there has not been any improvement in the top 10 average bike splits since 2006. This is not entirely surprising as the degree to which bike gear has improved since that time is not huge, and not every athlete has access to the very best gear.

Another way to slice the data is to look at the fastest bike split each year. In this case we took the fastest bike split each year among the top 10 finishers. Anyone setting a fast time and then blowing up on the run is thus excluded. Hover over a point below to see who set the fast time that year.
Again we see a clear downward trend in bike times, almost the same trend as in the top 10 analysis in fact. One interesting property of both the top bike splits and the average bike splits is the consistently slow times between 1997 and 2005. Wind, tactics, drugs, and talent are possible explanations that come to mind, but we really don't know. If you have any ideas, drop us a comment and let us know. Also interesting is that unlike the top 10 bike splits, the best bike split is still trending down since 2006, perhaps reflecting that the top cyclists in the sport are taking more care to get the best performing sponsors and setting up their bikes as slick as possible.

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