Great Britain's Joe Skipper had his best Kona performance ever this year. A look at his bike data on the record-setting day.
October 26, 2018 | TRAINING|
The perfect conditions on race day at the Ironman World Championship this year ensured that the bike splits were faster than ever before in Kona. Five professional men rode faster than Cameron Wurf's previous bike course record (4:12:54 hours), while the Australian pro set a new standard of 4:09:06. There were a number of pro men who finished the bike between 4:15 and 4:20, keeping them in contention for a top finish. One of those was Great Britain's Joe Skipper, who rode a 4:15:41 bike split. After that, the 30-year-old ran the marathon in 2:54:15 to finish seventh in a total time of 8:05:54 - his best Kona result by far. After the race, Skipper made his cycling performance data public. We took a closer look at the numbers.
42.3 km/h, 3.78 watt per kilogramm
Joe Skipper started his bike computer a little late, which is why his original record showed only 179.06 kilometers covered and a time of 4:13:43. His official bike split was 4:15:41. The Brit rode at an average speed of 42.3 km/h and had a maximum speed of 74.5 km/h, which he hit on the downhill from Hawi shortly after the turnround. His cadence averaged 83 revolutions per minute. Perhaps the most interesting info gleaned from his date are the wattages he maintained: Skipper achieved an average power (AP) of 288 watts and a weighted power (NP) of 295 watts. Skipper's body weight is 78 kilograms, which means he scored 3.69 watts per kilogram of body weight (AP) and 3.78 watts/kg NP. Also interesting is the specified energy conversion. This is estimated in Skipper's records to be 4,883 kilocalories. The average heart rate data appears to be an error - it came out at 45 beats per minute, which seems to represent a measurement error.
Variability index of 1.024
The difference in power output of seven watts between AP and NP is reflected in the variability index (VI). This value is obtained by dividing NP by AP. The VI provides info on how consistent the rider was on the road and gives information on whether the race was well paced. Skipper's number comes up to 1.024. A value below 1.1 is considered excellent. This result suggests that the mains chase group, that Skipper was part of, rode very consistently and there were very few attacks.
Comparison with Lionel Sanders' performance data from 2017
It is interesting to compare Skipper's performance data with that of Lionel Sanders from the previous year, which we analyzed in detail after the 2017 Ironman World Championship. It makes it very clear how much better and faster the conditions must have been this year. Sanders completed the course in 4:14:19 in 2017, a tick faster than Skipper. In addition, he spent most of the ride in a small group that included Cameron Wurf and Sebastian Kienle, and eventually found himself alone on the road. The performance differences are much larger than the similar time might suggest: Sanders completed the 2017 course averaging 305 watts AP and 313 watts NP. That means a performance of 4.13 watts/kg for the Canadian uber-biker. This comparison once again underlines the tremendous influence of wind and temperature on Kona times.