At Boise, due to expected extreme cold and windy conditions on race day, organizers revised the course from a 56 mile bike ride to a distance of 13.69 miles, while keeping the usual half ironman distances -- 1.2 mile swim and 13.1 mile run -- in place. The revised mix resulted in the rare situation where more than half the race took place on the run.
After a remarkable 24% DNS rate, and a 1% DNF rate, roughly 1250 athletes covered the revised course in an average time of 3 hours, 32 minutes. Our analysis of the 2012 results are presented below, with average times and splits by age group.
The course revision in 2012 presents the opportunity to tackle three bike and run questions compared to 2011 performance.
1. Bike: How much faster, in average miles per hour, would 2012's 13.69 mile ride be compared to 2011's full 56 mile distance? Answer: only about 10% faster, or about 1 mile per hour, on average. I would have expected faster speeds, even if riders faced extremely cold conditions.
2. Run: Having prepared to ride 56 miles, but instead riding far less, with presumably fresher legs, how much faster would average 13.1 mile run splits by in 2012? Answer: about 10 minutes on average. Much faster than I would have expected; especially the top 2 pros running sub-5:30/mile pace.
3. Bike/Run Split Correlation: For many races, we correlate all finishers' bike and run splits to gauge how many triathletes rode too hard on the bike course, and ultimately paid for it with a painfully slow run, for example. At Boise, with a significantly shorter bike course with an average split of 42 minutes, would many athletes suffer on the run? Answer: not too many. Most raced steadily or even had energy to spare after conservative bike splits.
Finally, putting all the pieces together, here are the average swim, bike, run and transition splits for each age group. If you finished Ironman Boise 2012 in tough conditions, you have plenty to be proud of. If you beat these average splits, even more.