Pacing with Power: the Real-World Application of Using a Cycling Power Meter in Triathlon

Pacing with Power: the Real-World Application of Using a Cycling Power Meter in Triathlon

By Matt Dixon, coach and founder of purplepatch Fitness

There is little doubt that adding a cycling power meter to your arsenal of riding tools is of high value for most athletes. The measurement of objective output throughout training can supply you with immediate feedback within a training session and can also provide valuable perspective following the session and over time. A bike power meter can also be useful in racing, but successful utilization requires some real-world understanding of what happens with your output in varying conditions and terrain.

It is not difficult to find many articles and resources that can outline calculations and algorithms for you to find your "race power" relative to your training or tested potential. Many coaches will tell you to get onto the bike portion of the race and simply plug into race power. No matter what happens, if you hit your power then you will be ready to maximize your race potential. By way of reference, the most common race efforts are roughly promoted as:

IRONMAN Bike Racing: 70 to 80% of Functional Threshold (lower the longer the bike ride will take you).

IRONMAN 70.3 Bike Racing: 80 to 95% of Functional Threshold (lower the longer the ride will take you).

Easy right? You "know" your power; we can remove all human element and simply plug and play. All elements of intuition, internal pacing and management of terrain are simplified to sticking to a narrow band or range of power.

While there is nothing wrong with creating a framework of a range of power that we understand the athlete can safely sustain, it doesn’t tell the whole story of triathlon bike riding, and I fail to see how we can throw away for intuitive elements of self-management throughout any given course.

Cyclist on bike using power meter

Let me give you a specific example that would unhinge this approach.

If you had a stretch of road that was 3-4% consistently uphill for 5 km, then was consistently 3-4 % downhill for 5 km, your fastest route to navigate would not be to maintain the same power up as you would down. The grade on the uphill makes the production of power easier to generate for most riders, and the speed return is great for the little extra work.

In comparison, forcing yourself to hold onto the same power downhill is causing metabolic stress with very limited speed return for the effort. The faster you go, the greater the work needed to add incremental speed. By way of a tangent, a similar message could be delivered for your cadence (RPM), in which you wouldn’t want to ride the same cadence up a grade like this as you would down.

These concepts are what are tough to coach, especially remotely, so most coaches and writers simply return to overall output, making it simple and accessible for athletes. The concept of retaining power output up and down a grade is called flattening the course. Using our World Championships as an example, if you flatten the course at the Hawaii IRONMAN you will unfortunately either leave a lot of unused speed on the course, or you will likely blow yourself to bits with high effort going downhill.

Cyclist on bike using power meter

Let’s consider a few real-world influences of power output on the bike, which are ignored if you simply decide to rigidly stick to a narrow range of power no matter the conditions (aka: flattening the course).

Different Grades

Athletes will always have their own favorite grade that allows them to generate their optimal power for a given metabolic stress. If you ask any rider to perform a best effort trial on flat terrain, then repeat on a smooth grade, the flat terrain will always produce less power. This has a real-world consideration in the power you expect to see when riding a race course as effectively as you can.

Riding the same power on the flats as on a grade isn’t the fastest race to navigate terrain.

Head and Tail Winds

If you are sitting on a stretch of road with a strong tail wind, you will typically find it more challenging to maintain the designated power relative to riding in the opposite direction. Interestingly, the reward of retaining the high-power output with a tail wind typically results in minimal reward of speed, with each 0.5 mph speed gain requiring more and more power to create.

If you stubbornly "hold your power," you have a high risk of under-riding sections that present a head wind, while over-working the tail wind sections with minimal speed reward. At the end of the day, it isn’t who holds most power, it is who goes fastest, then runs well off the bike.

Rolling Terrain

Terrain management is a key component to maximizing speed relative to your output. By loyally holding to a set, narrow power range you will undoubtedly fail to utilize the variance of terrain in your favor for fastest navigation.

Imagine a piece of rolling road which has a grade up, a crest, a small descent, and finally a valley at the bottom leading into the next "roller". Holding a tight power range throughout this piece of road is not the fastest way to navigate this all too familiar stretch of pavement.

If you instead push just above any power range or level heading up the grade, accelerate the bike over the crest of the hill with a small ramp of power and/or cadence, carry the speed down the back side of the roller, then hold the speed through the bottom of the valley, you will gain maximal speed over the stretch of road. Review your power graph following and you will see well-utilized small surges of power which create accelerations

Cyclist on bike using power meter

A cycling power meter is super tool, but it is just that: a tool. It isn’t something that should shackle or govern you and your riding, and successful utilization requires a real balance and understanding of how different conditions and terrain will naturally effect your power and output that you ride. All the above features and scenarios require the athlete to train themselves to successfully develop the tools and skills to navigate terrain and conditions well, but successful application of terrain management is key to best performance.

Lessons From An IRONMAN Bike Leg

Let’s finish with a real-world example, and draw on another myth of the importance of reviewing power over the course of a race course. Average power review can be mildly interesting, but doesn’t provide true insight into the effectiveness of an IRONMAN bike ride.

Instead of jumping to average power as your first barometer of riding success, you should review the sections of the course that you rode well, relative to conditions. A great example occurred at a past IRONMAN event with a couple of professional athletes.

Race Scenario

A race course with general loss of altitude going out, with a tail wind, and a general climbing effect heading back on each loop with a head wind. So:

Going Out: Generally loss of elevation with a strong tail wind.
Coming Home: Generally gain of elevation while battling a head wind.

In this two-loop course, we got to review the power files of two riders. Both female athletes are very strong riders, and of very similar weight and set-up on the bike. Bike power meters were identical and fully calibrated and aligned (note: this is a simple user example of something we see time and time again, so not too much number crunching needed!).

Rider A: Averaged ~235W for the ride.
Rider B: Averaged ~ 215W for the ride.

Same weight, same set-up, surely rider A goes faster, yes?Unfortunately, that wasn’t the case. Rider B completed the course about 7 minutes faster than Rider A. How?

Cyclists on the road

Going Out

Rider A was determined to "hold power" and charged along with a tail wind holding as close to 240W as she could. A tough ask in a strong tail wind. The neurological cost was quite high, and the speed reward was minimal.

Rider B ramps to speed and floated along with fluid pedaling and high speed, but at a much lower wattage. She was completing the out section at close to the same speed, but at much lower output. Her penalty of speed was minimal, but the energy savings were great.

Coming Home

Rider A remained at her power goal and maintained cadence. She pushed, but by the second loop was fighting to hold that average.

Rider B returned both times with great energy, and shifting to a bigger gear, and lower cadence, and could maintain an output above the average. Pushing consistently higher than race average power was a greater general cost than her algorithm would suggest, but the wind and grade, coupled with specific training, allowed it. The speed reward was massive.

The net result was a faster overall ride, a touch of variance of load (which the body loves), and a readiness to run well.

By no means do I suggest you freewheel down all hills, spin in tailwinds, then charge and attack every hill. There is a strong balance, but simplifying down to "hold XX power" is ultimately limiting. This approach needs to be supported by training, both physiological and technique. As the athlete evolves the tools required, application and return on investment on race day will improve.

The power meter is not just a way of tracking overall output, it’s also useful for learning how to maximize current physical resource for speed on course.

Matt Dixon

Matt Dixon is one of the leading endurance coaches in the world. He brings a unique background of professional coaching experience, elite athletics and education to lead the purplepatch team. He is a highly sought-after resource in the endurance community, writing and contributing to multiple publications such as Triathlete Magazine, Lava Magazine, Outside Magazine and Triathlete Europe.

His Master's degree in clinical and exercise physiology, as well as his experience as an elite swimmer and professional triathlete, form the backbone of his coaching philosophy, but it is his incredible ability to lead, educate and develop all levels of athletes to their potential with his excellent communication style that makes him such a sought after resource. You can follow him on the purplepatch blog, Facebook or Twitter @purplepatch.

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