Know your enemy part 4:
A power pacing calculator.

Alan Couzens, M.S. (Sports Science)

June 16th, 2016

“If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.”-Sun Tzu

In the last article in my series of getting to “know your enemy”, I outlined the importance of developing a power pacing plan that is specific to the race course at hand. While fitness and developing your absolute race specific power is important, applying that power tactically to the specific requirements of the race course that you're working with is equally so. Not all distributions of a given power output will yield the same speed & in this way, the intelligent athlete can gain a distinct advantage over an athlete who paces the event in a more ad-hoc manner.

I modelled some different outputs on different hypothetical courses to illustrate how the optimal strategy changes and suggested that the best way to play things, to get the most speed 'bang' per power 'buck', is to alter output in accordance with speed, i.e., in the words of Robbie Ventura, "go fast when the race is slow". I expressed an example of this via the 10/20/30/40/50 'rule of thumb' for the hypothetical athlete in the post. But, of course, every athlete is an individual - with different sizes and different speed goals and best 'rule of thumb' for you will likely be different to the hypothetical example I gave. In this post, I want to dial things in a bit more for you.

It is also handy to have a little bit of a 'heads up' on just how much time we'll be going slow vs going fast, or more pertinent to the training planning, how much time we'll be spending in each power zone, i.e. to identify just how much of each given course is 'fast' 'medium' or 'slow' & where these segments lie. While do-able in Excel, this process was a sufficient pain in the rump that I decided to code up a little script that will automatically pull these grade segments from a tcx file so that getting a visual representation of the optimal pacing plan for any given course, specific to the target power output of the individual athlete is much easier. I’ve provided that below…

To use, plug in your target power output (Normalized Power), and select your race course from the drop down (I will keep adding courses over time so keep checking back or let me know if there is a specific course you want to see!) and the segment smoothing that you want to use and the model will go to work to provide a visualization of the optimal pacing strategy for your event.

Goal wattage:
Height (m):
Weight (kg):
Smoothing:5 km
Show optimal power file

You'll also see a breakdown of estimated speeds (given the power you provided and the grade) for each segment of the course. Having these numbers in mind offers some handy, personalized guidance of how to apply the 'go hard when the race is slow' strategy in real time, i.e. when you see a speed range in the 'black', providing you're not in a hurricane :-), you're likely on one of those black segments of the course and it's time to lift effort. Contrary-wise, when speeds are in 'the blue' it's time to save those watts for when your air speed is lower. You can make these speed v power guidelines more accurate by entering your own height and weight in the fields. Keep in mind, these speeds are just a guideline & they assume light winds & a good aerodynamic position. If it's blowing a gale or your position is a little less Kienle & a little more 'urban cruiser', you may want to adjust the 'height' field a little to something that is a better fit (based on your own data from previous races or simulation workouts).

For the segment smoothing, the more ‘fine’ the smoothing, the better the model will be, i.e. the more speed ‘bang’ you will get for a given power ‘buck’. However, the more complicated it can make the pacing plan as well. In general, I would recommend starting with a 5K segment smooth and then dialing it back to identify any key features that demand a more fine tuned approach, e.g. you may find a key 2K climb of sufficient grade that a threshold effort is appropriate. However, holding this effort for the whole 5K segment may not be quite so appropriate :-). In other words, smooth enough to keep things simple while still identifying key features of the course.

If you check the 'show power file' box you'll be able to get a nice visualization of how an 'ideal' power file should look so that you can compare with what actually happens in the event (at the same level of smoothing).

Finally, if you hover over the speed table, you will also see the gearing range for each section. This can be useful in determining the most important 'weapons' to bring to your enemy. By looking at the chart, you can get a clear sense of which gears you'll be using the most and plan accordingly. The ranges represent a cadence of 80-90rpm for each of the speeds given. Most of the time you'll probably be somewhere in the middle of that range (though obviously, physiology & cadence preference come into play) so if you see a lot of the course falls between 53/21 and 53/17 & your sweetspot is ~85rpm, a 53/19 will be an important gear to have! If you find that the black range is outside of your gearing, either be prepared for some low cadence 'grinding' or make a switch. If the rear number is prohibitive, you may want to consider switching to a compact or triple up front

Hopefully you find the tool useful in coming up with optimal pacing plans (& consequent training plans) for this year’s key events.

Race smart,



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