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. 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.
If the fitness and talent had been the only thing improving Kona performances, we should actually expect to see cycling improve at a slower rate than running, as the nature of aerodynamic resistance limits how much time is saved by a more powerful athlete. But we actually see that cycling is improving about 1% faster than running at Kona over the time period. 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.