Cycling performance is often evaluated based on two varying metrics: absolute and relative power output. These metrics provide valuable insights into a cyclist’s fitness and performance capabilities, but understanding when to prioritize one over the other can be crucial for achieving success on the bike.
Relative Power Output vs. Absolute Power Output: What’s the Difference
Let’s start by clarifying the difference between relative and absolute power output.
Absolute Power Output measures the total amount of power a cyclist can produce, measured in watts. As an example, your Functional Threshold Power (FTP) is usually presented as an absolute power output.
Presenting your raw power output for a given time reflects your raw strength and muscular capabilities, regardless of body weight. Absolute power output is often emphasized in disciplines such as time trials and flat terrain racing, where sustained high power outputs are required to maintain speed and overcome aerodynamic drag.
Relative Power Output is the amount of power a cyclist can produce per unit of body weight (measured in watts per kilogram, or W/kg). For example, an athlete that weighs 70 kg and has an FTP of 250 W would have a relative threshold power of 3.57 Watts per kg.
As the name suggests, relative power output accounts for variations in body size and weight between athletes, which allows cyclists to compare their power outputs on an equal footing. Relative power output is most important for climbing, where minimizing body weight while maximizing power output is crucial for success.
The Impact of Terrain
The type of terrain encountered during a ride has a significant influence on whether absolute or relative power output is more important:
Hilly Terrain: In hilly or mountainous terrain, where climbs are frequent and steep, relative power output becomes paramount. Climbing efficiency is directly related to a cyclist’s power-to-weight ratio, as lighter riders can ascend faster with less power compared to heavier riders. Therefore, cyclists who frequent hilly terrain should seek to prioritize improving their relative power output.
Flat Terrain: On flat or rolling terrain, where sustained efforts at high speeds are common, absolute power output takes precedence. Time trials, criteriums, and flat road races demand sustained high power outputs to maintain speed and fend off competitors. Cyclists who aim to excel in these disciplines should focus on increasing their absolute power output through targeted interval training, strength development, and aerodynamic optimizations like equipment & body positioning.
Choosing the Right Metric
If you’re looking to improve your riding performance, the decision to prioritize absolute or relative power output depends largely on the type of riding that you do and your specific goals. I’ve listed a few general guidelines to help you determine which metric to focus on:
Prioritize Relative Power Output If:
- You frequently ride in hilly or mountainous terrain.
- Climbing efficiency is essential for your riding goals.
- You’re aiming to excel in climbing-centric events such as hill climbs or mountain bike races.
Absolute Power Output If:
- You primarily ride on flat or rolling terrain.
- Sustained high-speed efforts are common in your riding discipline.
- You’re targeting time trials, criteriums, or flat road races where maintaining speed is critical.
A Developing Field – Compound Score
There is still ongoing debate among researchers as to which metric is more advantageous when trying to analyze athletic performance. Therefore, Peter Leo & colleagues opted to combine both absolute & relative power to create a ‘Compound Score’, which they showed to correlate very well with professional cycling performance (Leo, et al., 2022).
This new “Compound Score” can be calculated by simply combining your absolute & relative power output. To calculate it, you will need to know your 5 minute power:
Compound Score [W2/kg] = absolute power output [W] × relative power output [W/kg ]
For example, an athlete that weighs 70 kgs and has a 5 min power of 325 W would score a compound score of ~1508 W2/kg. Initially, this value might not mean much, but I did find the ranking charts below on the Compound Score website (https://compoundscore.com/), which you might find very helpful.
Men’s Categorization based on Compound Score:
Women’s Categorization based on Compound Score:
Conclusion
Relative and absolute power output are both important metrics for assessing cycling performance, but their relative importance varies depending on the terrain and riding discipline. By understanding the impact of terrain on the significance of these metrics, cyclists can make informed decisions about where to focus their training efforts and achieve their riding goals more effectively. Whether climbing mountains or chasing speed on the flats, choosing the right metric can help cyclists maximize their potential and enjoy greater success on the bike. That’s all for this month – stay safe, ride fast, and I’ll see you next month!
References
Leo, P., Spragg, J., Wakefield, J., & Swart, J. (2022). The Compound Score in elite road cycling. Journal of Science & Cycling, [Conference Paper]