by Colin Gibson
American Bobby Lea won the omnium 4k Individual Pursuit yesterday at the Track World Cup event in Guadalajara, Mexico with a time of 4:16.7, just shy of Taylor Phinney’s US national record effort of 4:15.1 set at the World Championships in 2009. Lea’s World Cup effort was pretty burly, so I tracked down the lap splits to see how the race played out.
In the chart below, the 20 competitors are ranked by finishing time. The lap times of each athlete are color coded based on speed: green is faster, red is slower. As would be expected, riders toward the top of the rankings have more green than riders toward the bottom:
The first thing to notice are the times from Lap 1. There is much less correlation between a rider’s Lap 1 time and his final time. In fact, Lea had the 4th slowest opening lap, riding it 0.4 seconds behind the group average, while last-place Frantisek Sisr of Czechoslovakia was 4th fastest, 0.4 seconds quicker than average.
The color-coding based on absolute speed is nice, but what if we color code each rider’s laps relative only to himself? This will give us an idea of how each rider paced his effort regardless of his strength. In the following chart, green is faster and red is slower, but only compared against that same rider’s other lap times. So Lea’s Lap 2 is red, but only because it was his slowest lap (aside from lap 1):
Now we can start to pick out some pacing trends. Lea negative splits his race, meaning that he increases his pace as the race goes on. After getting up to speed, laps 2, 4, and 5 are his slowest of the race. Meanwhile, laps 13, 14, 15, and 16 are his four fastest. Lap 16 even included changing his line as he overtook 4th place Juan Arango!
Comparing the top-three finishers to everyone else, there is a clear inversion of pacing: for the podium finishers, laps 1-8 are almost all slower than the rider’s average, while laps 9-16 are almost all faster. For everyone else, especially 6th place and below, there are some pretty fast opening 2k splits, followed by slower (by up to 2mph) second halves. Highlighting each rider’s four fastest (green) and four slowest laps (red) shows this pacing trend:
So what happens around lap 8? In short, 8 laps are completed in around two minutes, and it takes about two minutes for a rider to run out of anaerobic energy. All of a rider’s power from that point forward must be produced aerobically. So are all of the fast starters missing out on free speed just by changing their pacing? Not necessarily. Remember: these are world-class athletes who have ridden this event many times and have had the chance to experiment with pacing. Because some riders have higher anaerobic capacities while others have higher aerobic capacities, different pacing strategies may benefit different riders. Riders with stronger anaerobic fitness will go out harder to use their strength while they can, while riders with stronger aerobic fitness will go out more conservatively to preserve their steady-state power. However, the former will often be outperformed by the latter because of the energy demands of the individual pursuit:
More than 80% of energy demanded during a pursuit may be aerobically derived, and so trading aerobic fitness for anaerobic fitness is often a negative marginal change.
The takeaway is that by learning our relative aerobic and anaerobic strengths, working on our weaknesses, consolidating our advantages, and choosing events that suit us, we can set ourselves up for success, regardless of what kind of riding or racing we do.