Power Analysis – Oliver Half





The above shows my performance statistics from Oliver Half in 2011 and 2012. 2012 is green because it is the faster of the two rides, and red is the slower of the two rides. The average power in 2012 was lower, so to fairly compare the pacing strategies I am displaying a graded power (mean matched dataset) instead of the raw values. I had computer trouble in 2011 for the first kilometer and am consequently only displaying a subset of the full ride of 93 kms (starting from a bit past the first mile marker onwards). Discussion of the contributing factors to faster speed on less watts are detailed in my 2012 Race Report. In summary, a lighter bike (almost 700g down) and a collection of improved aerodynamic factors made that possible. This post details the strategy, which is as we will see, a major contributor.

The faster sections of the course are the parts where there was a tailwind in 2012 where there were negligible wind conditions in 2011. (km 13.5-24.5 & 52.5-63.5 were faster due to tailwind) There are basically no slower sections with the exception of an early portion where I was suffering the effects of poor swim-training. There are also many situations where my several-second power peaks in 2011 were higher than in 2012 with no net result of improved 30 second power (the smoothed line doesn’t indicate a net power expenditure increase by spiking the power up). The interpretation is that when I briefly push hard I need to briefly rest, but I can get more power out by staying steady. These occur throughout the files, a couple examples are: km 20-21, 27-29, 33-34, 57-58, 69-70, 72-73, 88-89. Every time this happens it is probably worth a second or two advantage, and my files are littered with them. That’s not to say there were no situations where the reverse happened (worse pacing in 2012) see km 58-59, 61-62, 81-82. These all occurred towards the end of the race where I was starting to push the pace a little bit. The conservative riding early on was strategically superior to the racing mentality that occurred later in the race. The opposite occurred in 2011 when I was in the midst of other closely paced riders early on and was riding solo off the front in the second half. By swimming slower I began the ride just blowing past other riders and caught similarly paced athletes in the closing stages, the pacing outcome reflects this.

So, to try and investigate with some summarized statistics, was my power more distributed or less distributed in 2012 than 2011?

Photo from gallery: Oliver Half Iron 2011 Photo from gallery: Oliver Half Iron 2012
Photo from gallery: Oliver Half Iron 2012

These plots compare my speed (x axis) with my power output (y axis). Top left is 2011, and is compared with 2012 on the right and on the bottom. I displayed the 2012 image twice to help draw correlations both vertically and horizontally.

Stats for the rides are as follows:

2011 2012
Time: 2h20m14s 2h17m41s
Rank: 5th 2nd
Avg Power: 315 298
Norm Power: 298 286
Variability: 5.7% 4.2%

The answer to the question “was my power more distributed or less distributed?” is that my power is less distributed. I was more careful with where I spent my watts in 2012 and didn’t deviate widely from my average power… on average. This shows in the variability of the ride. The variability index is down by a one and a half percent. That’s a lot if you ask me compared against the kind of range I see across all the rides I would do in a season (Rides vary from around 3 percent to 15-20 percent). If I hadn’t been sick I wouldn’t have had the cautious attitude, I think that helped me out in this regard. The cautious attitude is one that stops the body from hammering and ramping up huge power spikes.

If we look closely at the comparison of the two density plots you can see that with this visualization my power actually appears to be more distributed. The density cloud in 2012 is narrower and more stretched out than in 2011. This means that with respect to my speed, I made a more conscious effort to work hard when moving slowly and to back off slightly when moving quickly. I have very few data points in 2012 where I was soft-pedaling when I wasn’t going quickly, nor do I have many datapoints where I was drilling it when already at high speeds. In this regard my power is very distributed according to what was going on during the race, it is strategically distributed. The impressive thing is that I was able to strategically distribute power more effectively in 2012 but still reign in my overall power distribution (variability %). This to me shows that I am developing a strong maturity in pacing, that I am capable of executing the ride with a strategic advantage over my previous self. This is encouraging to say the least!

Moving forward I believe that I can still improve my power variability overall. Being sick and cautious really helped me out during this race, but I wouldn’t want to race sick all the time. I should be able to calm myself and focus into the same mental space when racing. If I am confident that the patient and conservative race strategy is superior then I have good reason to execute it. This is very difficult to do in practice, it’s difficult to actually race with a body full of testosterone, adrenaline and other stress hormones, and restrain yourself from feeding off of them and punching the power way up. At basically any point in time during that ride my body is capable of being at four times the power output of where I’m currently riding within just 5-10 seconds. I have evidence of this capability from sprint training where I routinely hit 1200+ watts a dozen times over the course of a ride. When I want to go fast it requires a lot of restraint to not start cranking huge power right now!

Allow me to do some inaccurate math here, consider these numbers as largely qualitative. Keeping the power variability within 4% on a ride that averages 300 watts is really asking my body to keep the power variability within 1% of my demonstrated 1200 watt capacity. Improving on that (to, say 3.5%) is asking myself for an improvement that’s only a small fraction of one percent, a fractional improvement of only a couple thousandths over where I’m at right now! I shouldn’t be surprised, that’s what it’s like at the top, the differences are minute: I missed the fastest bike split by only 14 seconds this year!

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