Power File Post-Mortem: Church Creek Time Trial

[ed: This is so cool. Once in a while you'll see a pro's power file online with some analysis of the 32-minute 425 watt climb, followed by a 2-hour on a 2-up break at 350 watts before throwing down 1200 watts to win the stage. Good for him (and his sponsors), but what does it have to do with you? BJ is bringing it home, with Power File Analyses of us - actual local racers competing in actual local races. So even if it's not your power file, you can compare yours on the same course and see how you measure up. And because they're from local races, you'll get some additional insight into these events as well.

Like I said, so cool. And if you want BJ to analyze a file of yours in the same way (for publication here or not) by all means contact him.]

Power File Post-Mortem: Church Creek Time Trial
by BJ Basham
USA Cycling Level II Certified Coach

Almost every coach will agree that we learn more from mistakes and failures than we do from success and winning. One event that this is the most true is the individual time trial and the best way to really look at a time trial effort is to study and dissect the power file. Many riders will not look at their power meter displays when racing, but will ride with that little extra weight for no other reason that to look back at what happened and hopefully learn from their mistakes.

Today I want to look at the power file for a rider from the most recent Church Creek TT. According to the rider it was not a good day. The initial numbers showed that his average power was 20 watts lower than last year and his time was exactly 3 minutes slower. Some of you may be thinking, ”so what? Lower power slower speed the rider is just weaker than last year.” This may be a pretty logical interpretation, but there is much more to be learned by looking at the power file. In fact the riders tests leading up to the event showed that he had the same watts/kg at threshold as last year.  Everything else being equal, the rider should have been able to at least match his average power from last years race.

Of course the differences could be just chalked up to a bad day, or poor race day preparation, or lack of motivation. There are lots of variables that can be addressed, but for now, lets look at the power files.

First lets look at last years file.

I have decided to break the race up into 3 distinct parts.
1.    The first part from the start around to the first turn
2.    The second part is the middle section along the back road on the all the way to the final turn.
3.    The third part is when you come back out onto the main road for the last 10k to the finish line.

In the first file, the first thing that you might notice is that the overall trend for the effort was fairly steady with the rider holding power pretty good across the distance.

Looking at the individual parts you can see that in part 1, the ride made a pretty casual start of the race with no big sprint off the line. He did a good job of abiding by the second most important rule of time trialing after not missing his start time. He did not start too hard, keeping the power right around his threshold with just a bit of a spike which was likely from going over the first bridge. Part 1 was the key to the next section of the race.

Part 2 has always been a challenge section with slightly rough roads and very little shelter from the wind. This is where most rider’s will end up having to give up a little speed due to the wind and roads. Since the speeds are lower, every mile per hour that you lose is amplified compared to the faster section. In this case, our rider kept his power steady throughout the middle section with just a couple of spikes for bridges or curves in the road.

Part 3, back on smooth main road and heading for the finish. You can see that the rider speed climbs back up on the smooth pavement, but he does not lose his head and sticks to what he knows he can do. You can see the small spike just before 50 minutes where our rider catches and passes another rider and then has to back off a bit because he went a little too hard trying to make a big pass. After the short recovery, we were back to threshold or there about until the finish line finally came into view and the rider sprinted to the line.

An overall good race with an average power slightly below the riders estimated FTP. After the race the rider’s impression was that he could have gone a bit faster and had a bit left in the tank.

One other thing to notice in this graph is the steady to upward trend of the rider’s heart rate (red line). He did a great job of taking at least 5 minutes to get his HR up to his threshold.  After the final turn into the last 10k, our rider was even able to lift his effort to squeeze even more speed out of his system as can be seen by the slight upward trend of his HR in the last 15 minutes.

Now lets look at the race from this year.

Again we will look at the three sections of the race.

But first, you will notice that the overall trend for this effort was definitely declining with a greater amount of variability in the riders power output and speed.

This year, in part 1, the rider seemed to believe that he was much stronger than he knew he was. In fact for the first 5 minutes of the race, our rider was exceeding his expected threshold by 35 watts. This may not seem like a big deal, but you can see from that point onward, our hero’s power and speed started to drop. The hard start had a profound affect on his ability to produce power even at his threshold due to essentially over using his muscle glycogen with an effort that had far too big of a contribution from his anaerobic energy system. He started fast, but paid the price in the second section.

In part 2, where keeping your speed up and steady is a key to a fast time, this rider could not push hard when he needed to in order to battle the head winds and rougher roads. The loss of momentum can be seen in the blue speed line as the rider tried over and over to get that speed back up, but could not maintain the effort unless he was well below threshold and running purely on aerobic steam.

Part 3 got a little better and the rider was able to pick up some speed again, but as with part 2, he was unable to maintain any effort that was at or even above his threshold. The spikes in power are his desperate attempts to punch his way to more speed. Basically attempting to even use his creatine phosphate energy system to get that speed. His short burst, to get the speed up, were unfortunately matched by big drops in power as he had to back off in order to recover between bursts.

Again looking at the rider heart rate line on the graph, this time, he got up to his threshold HR in about 2 minutes and then by 5 minutes in he was already well beyond threshold. At least for the first 10 minutes. 

Ideally, if this rider could have had a bit more confidence in what he knew about his abilities and limitations, he would have started much slower and worked to maintain a solid pace through the whole 40k race. On a flat course like Church Creek, a steady effort right at or below threshold for most of the race is the key to a faster time.  You can try to go a bit harder in the final miles but be careful, blowing up with a mile to go will still have a big affect on your time.

Training and then racing with a power meter is a great way to help yourself to remember and practice the keys to fast time trialing. Learning from your mistakes will hopefully help you to avoid them the next time around and looking at your power files and doing a post mortem will let you find the areas where you might need extra attention. My discussion with this rider the next time he does a time trial at Church Creek will be almost entirely about that first section of the race and sticking to what he knows.

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BJ Basham is a USA Cycling Level II Certified Coach with Peaks Coaching Group. He lives in Fairfax, VA and competes in most of the same races you do. To learn more about his coaching practice and philosophy, visit his website at PowerTrainingCoach.com.

Comments

[Ken]

Excellent analysis. Now, what happens if we change the scenario to include a headwind on the first stretch of road (leading to the first turn)? How would that change the ideal pacing strategy?

[Jordan]

Ideally, if this rider could have had a bit more confidence in what he knew about his abilities and limitations, he would have started much slower and worked to maintain a solid pace through the whole 40k race. On a flat course like Church Creek, a steady effort right at or below threshold for most of the race is the key to a faster time. You can try to go a bit harder in the final miles but be careful, blowing up with a mile to go will still have a big affect on your time.

[BJ]

Ken

Good question, but in this case the issue would likely still be an issue since the rider went out way too hard in the first section and even found it hard to keep the power on in the easier section of the course.
In this case I would have had the rider go a bit over threshold in the head wind after an initial start below threshold.
The head wind scenario would compound the issue since if, as he did in this case, our rider when too hard for the first 10 minutes and was still in the head wind after blowing up, he would still have to fight the rest of the head wind section.

Pacing for wind and hills get interesting, but the one constant is that if you cannot do 35% over your threshold for 10 minutes without having to take a nap, it is a bad idea to try it in the first miles of a 40K TT.
How hard to go into the head with or up the long climb (like at Boonesboro) is the question that can be answered by looking back at your power in training.

Great question.

[BJ]

Number like 35% and 10 minutes are just for arguments sake. This rider was only 10% over threshold and it hurt him pretty bad.
A big part of this kind of analysis is knowing information other than just looking at what is in the power file. Knowing the temps, wind conditions, course profile and even who the rider was chasing and who was chasing the rider should all be taken into consideration.
This riders 30 second man last year started hard and was out of sight for the first 30k, but came into view in the last 10k and our rider used him as a carrot to chase. It is likely that his time last year would have been a bit slower if he did not have the motivation of someone to chase.