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Iroman Hawaii - Power data analysis
Bike Power vs. Running Speed
It is now the fourth consecutive year that we are fortunate to gather race data from the best contenders in Kona. This, in combination with what we have learned over the years from other events as well as what we learn each day from the data we gather from many of you, allows us to give something back. Recently we have been wondering if it’s better to hold back a bit on the bike or go full throttle right from the start… read on.
One way to answer is by calculating the necessary amount of energy to cover the total distance in a fixed time. We have computed the numbers based upon the power data and race time of Torbjørn.
The experimental question: What is the ideal ratio between bike and running speed in order to minimise the necessary energy for the whole distance? The following graph has the answer:
The graph shows the correlation between bike and running energy for a given total bike & running time as a function of running speed. Sounds too complex? The easy message is this: The faster you run, the less energy you need overall.
The reason is that running energy increases less with speed than cycling energy due to the lower impact from air resistance at low speeds. Going super fast on the bike is a waste of energy unless the superior speed is the result of superb aerodynamics.
What we learn:
=> running speed is the number one limiter for overall performance
=> saving energy on the bike is a good strategy
=> aerodynamics are crucial!
=> refuelling (easiest on the bike) is very important
So, what is my ideal pace on the bike? The speed which allows me to fulfil my maximum running potential.
Here you see Torbjørn`s running output compared to his bike output (vertical mark). His running output was higher, despite the bike being his strongest leg.
The same graph as above, but with he data from age grouper Andreas Bodenmann (50). In relation to his body weight (69 vs. 80 Kg from Torbjørn) his energy expense was exactly the same as Torbjørn`s. Admittedly, Andreas needed more time to consume the same energy, as of course he was no able to produce the same output per time as a pro. His comparison of bike vs. running output is shifted even more towards running output as for Torbjørn (vertical mark). His total time was 10:40:42 with a 5:46:21 bike and an excellent 3:16:42 marathon; the swim was his weakest discipline due to an injured shoulder).
Torbjorn Sindballe, 3rd place overall Kona 2007 (8:21:30)
Under hot, but almost windless conditions and without being challenged by the other two strong riders Normann Stadler and Faris Al-Sultan who suffered from an upset digestion, danish Torbjørn "Thunderball" Sindballe rode away the fastest bikespilt of the day. The bike split started fast regardless. Torbjørn began to reel in the unleashed US-American Chris Lieto on the climb to Hawii and caught him an hour later. By then he had already put 11 minutes on the chase group from which he rode away before. His data reveals his impressive receipt for the lead: Torbjørn did not slacken by the end of the ride. Overall his ist the highest and most consistent average power output so far measured and published at the IM on the Big Island: 309 watts in average over the whole bike leg. Impressive! (Average value cadence: 82, heart rate: 139 – both with a slight falling trend over the distance). Until the turnaround point in Hawii, Torbjørn averaged a power output of 313 W and was able to hold an excellent average of 305 W on the way back. In this way his power profile differs radically from most other pro data 2PEAK has been able to analyze so far, which mostly show a sharp falling trend which begins after the turnaround point.
With his closing marathon in 2:57:25 Torbjørn proved that he did not even ride at his limit and was able to secure himself a well deserved podium spot, so far his best result in Kona.
It is also interesting to note that Torbjørn needed a weaker power output in 2005 to establish a new bike course record (286,6 W),(which Normann Stadler broke again in 2006). 2005 his power output was also less consistent. The numbers prove a dramatic improvement in his riding strength.
Rutger Beke, rank 898 in Kona 2007 (11:13:58)
Rutger Beke wanted to race for the crown and several top 5 placing suggest that his goal was realistic. Unfortunately he got tit badly in the head during the swim which affected his day. On the bike he put in an effort to finish just a minute down to he group with Chris McCormack despite having lost time already during the swim. Stunning to see that he managed to do the bike leg in 4:36 with a surprisingly low average power output of 232 W. His aerodynamics looks like being one of he very best. Rutgers power profile shows the typical falling trend. During he run his legs failed him, but he nevertheless fought his way to the finish!
Wolfgang Teuchner, rank 211 in Kona 2007 (9:49:22)
Wolfgang is the training partner of Faris Al-Sultan. The speciality of the 81 kg (179 lb) heavy giant is the bike. Apparently he also does misplay his energy like barely someone else, as you can see in his power graph: until the turning point Wolfgang was able to keep the pace of the best pros and averaged 336 watts. After the downhill from Hawi he lost his pedal stroke as his average falls to 212 watts (average overall: 272 W) and his resulting bike leg time of 5:01 is therefore disappointing for a cyclist of his caliber. With a more even power output he most probably could have finished faster.
Faris Al-Sultan, 3rd place overall, Kona 2006
Faris averages the same power he achieved when he won in 2005: 283 Watts. His cadence was a bit lower this year averaging 81,7 RPM. The race separates again in two pieces. High power on the way to Hawi, averaging 301 W in the first half and a drop to 267 W in the 2nd half. It is visible from Faris’ data that 7 meters distance between the athletes isn’t enough to avoid drafting effects. Luke Bell, who was riding in a group in Faris’ wake, especially in the 2nd half of the race, needed remarkably less power for the same speed. Comparison of the average power output proves that as much as comparing the mechanical work expressed in energy: Faris burned 4592kJ (mechanically) vs. Luke who spent 164 kJ less despite being taller and (2kg) heavier. Our spotter who followed the leading men, confirmed what we measured. The true shootout on the bike took place between Normann at the front and Faris behind him.
Luke Bell, 7th place overall, Kona 2006
Luke had a good start and went with Faris right from the beginning. His power profile is very similar to Faris’ one. In the 2nd half drafting effects are visible. This results in a slightly lower overall average of 273 Watt at 82,9 RPM.
Mike Montgomery, Rank 281 overall, Kona 2006
Mike Montgomery (Age Grouper) delivers a solid and remarkably stable performance. In contrast to the Pros, who did a tactical race, he starts the bike leg rather slow and paces himself very well so that he doesn’t slow down in the 2nd half of the race. His power outputs almost remains the same after the turn in Hawi. The resulting bike split is very good: 4:53:45 – Rank 124.
Faris Al-Sultan, Ironman World Champion 2005
Data from the champion: the graph shows power (green), speed (pink) and cadence (blue) from the bavarian pro Faris Al Sultan. The power output over the bike leg averaged 283 watts, the average speed: 40,45 km/h, the average cadence was around 85 rpm.
Faris, who had the third best swim split, got himself ahead and leading the field after just 14 minutes and produced an average of 324 watts until the first split taken. Herewith he started much more conservately then last year when he averaged 343 watts for the same split. His bike race can be seen in two halfs at least what his power output is concerned and they are marked by the turnaround point in Hawi. During the first 90 km he kept his power always very close to the average of 309 watts, in the second half however he had a few weaknesses but the rest of the field must have had a very similar problem as he was able to defend his advantage. Just by the end of the bike leg he got passed by Torbjörn Sindballe which data can be seen below as well.
Torbjorn Sindballe, sets new bike leg record in Kona
New record: 4:21:57 hours with hot but pretty calm wind conditions.
Torbjorn Sindballe breaks the record which Thomas Hellriegel established in the distant 1996 and was set at 4:24:50. The graph shows how Torbjorn has paced himself very well. His average power output of 300 watts in the first half of the bike leg is only slightly higher then in the second half when the danish express produced an average of 273 watts. With his consistent and strong effort, he managed to pass Faris with 10k to go after having spent most of the race just 3:00 behind. It is pretty obvious that he sits with an excellent aerodynamic. Despite his 10k in surplus of Faris that he needs to houl up Hawi, he managed to spend in average only 3 more watts then the champion to hold the same speed. And we can assume the difference lays in his chase to pass Faris. (286 watts).
2004 World Championship data
Data from Faris Al Sultan, 3rd place overall
The graph shows the power (green), speed (pink) and rpm (blue) of German Pro Faris al Sultan. Faris averaged 286,9 W and 37,0 km/h on the windy and difficult course. The interval marks (vertical lines) show average data for the first and second half of the race. Average power dropped from 309 to 268,5 in the second half. Faris started out very fast, hammering way above 300 Watt for the first 1,5 hours. After this fearless wild phase he remains pretty constant at a slightly lower level. Ups and downs in the speed graph indicate all the climbs and descents. Speed is generally higher in the second half. Look how Faris keeps his power output even in the descents by using a huge gear. Beside the descents, where he reaches 100 rpm, he is pedalling at a steady 80 rpm.
Smoothed signal: The average power output is better visible in this graph. The sharp drop in the last 20 minutes is mainly due to the smoothing.
Distribution of the data: This graph shows how much time Faris spend at which power/speed/rpm. Most frequent speed (highest peak in the pink curve) is 30 km/h - the total range reaches from 20 to 60. His power band is broad reaching from 180 to 400 W. Most frequent power is around 300 W.
Data from Fernanda Keller, 9th place
Fernanda`s speed signal is similar to Faris` but on a lower level due to the lower power. Fernanda averages 161 Watts and 30,6 km/h. Taking her light weight into account she has a power/weight ratio of 3,22 W/kg - approx. 20% less than the top men.
Smoothed graph: look how constant she is pedaling! After 3:11 hours something happend: Power dropped to a lower level.
Power distribution: compared to the men the power curve is shifted to the left and it is less broad because of the more controlled and constant style of riding.
Data from Thomas Hellriegel (DNF)
Not a good day for the champion: Although Thomas started controlled he couldn`t maintain the desired power level of 300W. In the end he averaged 268 Watt. (no speed signal)
Power distribution
Data from Markus Forster, place 27
Too fast in the beginning: Markus started with 400W, averaged 312,5 in the first 1,5 hours (first split only 2 minutes down to the winner) but had to pay for his effort later. In the last 2 hours he averaged 243 Watts.
Fluent style: Markus pedals between 80 and 90 RPMS. His Powerband is broad reaching from 140 to 400 W.
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