PezCycling News - What's Cool In Pro Cycling : Power Play: Analyzing Gearing Strategies

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Power Play: Analyzing Gearing Strategies
Toolbox readers will know that one of our recurring themes has been about pedaling dynamics and figuring out just what cadence is optimal for particular applications. Never one to leave well enough alone, we take a first-hand look at different gearing and cadences for a short interval effort and what the power data teaches us…

The Simplest Thing is the Hardest
Just like a sport as technical as swimming, cycling is ultimately a slave to efficiency. Aerodynamic efficiency is one thing, but just as important is the metabolic efficiency in turning those cranks. The less energy required to turn the pedals each revolution, the more energy you conserve and have left over.

This is a secret known by the top pros. Ironman legend Dave Scott spends his bike time during training and races specifically focusing mentally on proper pedaling technique. Scientific studies on Lance’s physiological changes from 1993 – 1999 conclude that one of the keys to his progression has been a huge increase in pedaling efficiency. Another Spanish study also concludes that, rather than VO2max, the main distinguishing characteristics of top pros were their pedaling efficiency.

The Cadence Question
Thanks to Lance’s well-documented switch to a high cadence pedaling style, the most popular pathway to an improved efficiency has been attempting to ride in lower gears and higher cadences in most terrain and situations. The general theory is that a higher cadence shifts the stress to the cardiovascular system and away from the muscular system. For triathletes, this shift also leaves their legs fresher for the run. Finally, a higher cadence generally makes it easier to accelerate, a critical component of almost all racing!

The general theory is sound, but very few scientific studies have been able to support this notion of improved efficiency. We’ve taken a thorough look at three recent studies, along with the limitations inherent in these studies, so we won’t rehash them again here.

One Simple Case Study
Newly armed with a swanky set of PowerTap SL’s built onto a set of Zipp 303 clincher wheels (keep tuned for reviews and an in-depth series of articles on training with power over the coming months), I set out this past week to try out some of these cadence theories in a setting and manner that was appropriate to ME. I wasn’t trying for lab-based levels of control, but I also wanted to get away from the rigid requirement to ride at particular cadences with large 20 rpm gaps in between.

The basic parameters:
• A 3 km out and back course that was essentially flat. There were a few little bumps, but certainly nothing that demanded standing up or shifting more than one gear down in order to stay seated. I wanted something fairly short and hopefully free of motivation errors (e.g., it’s hard to stay focused for multiple long efforts), while also being long enough to be primarily aerobic in metabolic demand.

• I didn’t plan it this way, but there was a screaming 30 km/h headwind on the outward leg. This actually worked out for the better, as forced distinct gearing choices for the outward and homeward legs. Wind remained pretty much constant throughout my test.

• I did 30+ min of gradual warmup beforehand, including one 4 min hard effort to get myself primed. My legs felt great and there were no physical issues. My intervals between Trial A and B were very similar in data from Trial A.

• Rather than confine myself to set cadences, I used my “preferred” gear and cadence for Trial A, then went with one gear lower on Trial B. I felt this was a pretty realistic choice that people need to make. As we’ll see below, this resulted in about 7 rpm greater average cadence in Trial B, as opposed to the huge 20 rpm set intervals in the lab studies.

• PowerTap was set to 1-s recording intervals and calibrated according to manufacturer instructions.

Trial A: Preferred Cadence


Yellow = power, blue = speedx10, grey = torque(left vertical axis); red = heart rate, green = cadence (right vertical axis). Image from PowerTap software.

Basic Stats: Average (Max)
269 W (537), average 4.20 W/kg
37.1 km/h (48.8)
91 rpm (103)
150 bpm (157)
2.85 km (74 kJ) in 4:36
Generally, I went out in a 53×19/17, and back in a 53×15/14.

One Gear Lower


Yellow = power, blue = speedx10, grey = torque(left vertical axis); red = heart rate, green = cadence (right vertical axis). Image from PowerTap software.

Basic Data for the trial where I tried to stay deliberately one gear lower than preferred:
252 W (466), average 3.94 W/kg
35.2 km/h (46.2)
98 rpm (111)
150 bpm (156)
2.97 km (77 kJ) in 5:04
Generally, I went out in a 53×21/19, and back in a 53×15.

Interpreting the Data
Some of the things that I’ve learned from doing this simple test.
• The beauty of the PowerTap is that pretty much all vagaries are removed from either indoor or field testing. Even if the wind changed a little in direction or velocity over the course of the test, the power data should remain fairly robust, and gives you infinitely more detailed information than simply the time required to ride the interval.

• Power monitors also strip away all vagaries of subjective perception. I’ve been in the sport for 20 years now, and figured I had a pretty good handle on subjectively monitoring my efforts from racing and numerous tests in the lab.

Was I ever wrong subjectively! After Trial B, I raved to my riding buddy how awesome I felt during that interval. I thought I was flying – completely pegged on the rivet – but I finished that interval feeling incredibly strong and convinced that I had the best time of all of the intervals that day.

• Yet by every important measure of speed, power output, and time to completion, Trial B was quite significantly worse than when I went with my preferred gearing and cadence. A drop in average power of 17 W for such a short distance and duration is enormous, supported by the ~20 s difference in time to completion.

• Power and cadence (along with gearing except on the track) is NEVER constant out in the real world, even if you spend the interval staring at the power monitor! This can created difficulties translating lab-based, controlled studies to actual riding and racing situations.

Summary
So for me as things stand right now, the power data is completely clear that I am far more powerful and faster when I go with my a relatively low (90 rpm) cadence for intervals that primarily stress the aerobic system. Keep in mind that, as we’ve written previously, everybody has different physiological and biomechanical strengths, so this is certainly not guaranteed to apply to you! Also, this is the case for a relatively flat effort, and my results may differ for climbing efforts.

The point is that careful analysis of your own riding characteristics is the key, and you should optimize your riding to your own individual traits rather than blindly accepting general rules of thumb. As we’ve seen in this article, a power monitor is an awesome tool in this analysis.

It’s been noted, by Brian Walton (Cadence Cycling’s Director of Performance) amongst others, that I tend to ride with a relatively low cadence. While this may be true, the ability to generate higher power outputs often holds the trump card in many riding and racing situations.

Final note of the day goes to PowerCranks’ founder Frank Day: “Just because lots of people write in with rationalizations as to why they want to keep riding at higher cadences than “optimum” doesn’t mean that optimum cadence can be increased by riding at higher cadence.”. In other words, it’s more important to be efficient at your “normal” or “optimal” cadence than having a higher cadence just for the sake of a higher cadence.

So keep on optimizing your cadence, whatever it may be, by always continuing to work on your pedaling efficiency!

Acknowledgements
Thanks go to Saris Cycling Group and Zipp USA for providing a PowerTap SL power monitor built up into a Zipp 303 clincher wheelset.

Related Stories
Pedaling Cadence and Efficiency: we examine 2005 and 2006 studies on optimal cadence.

Josh Horowitz’s Season 3 intro to PowerCranks, with links to all our other PowerCrank articles

We examine Lance’s improvements in pedaling efficiency from 1993 through his first Tour victory

We analyze another Spanish study that finds pedaling efficiency much more important than what your VO2max is

An article by Bruce Hendler on pedaling efficiency and training drills

References
1. Coyle EF. Improved muscular efficiency displayed as Tour de France champion matures. J Appl Physiol 98: 2191-2196, 2005.
2. Foss O and Hallen J. Cadence and performance in elite cyclists. Eur J Appl Physiol 93: 453-462, 2005.
3. Foss O and Hallen J. The most economical cadence increases with increasing workload. Eur J Appl Physiol 92: 443-451, 2004.
4. Lucia A, Hoyos J, and Chicharro JL. Preferred pedalling cadence in professional cycling. Med Sci Sports Exerc 33: 1361-1366., 2001.
5. Lucia A, Hoyos J, Perez M, Santalla A, and Chicharro JL. Inverse relationship between VO2max and economy/efficiency in world-class cyclists. Med Sci Sports Exerc 34: 2079-2084, 2002.
6. Lucia A, San Juan AF, Montilla M, CaNete S, Santalla A, Earnest C, and Perez M. In professional road cyclists, low pedaling cadences are less efficient. Med Sci Sports Exerc 36: 1048-1054, 2004.




About Stephen:
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University, with a research specialization in the effects of thermal stress on human physiology and performance. He can be reached for comments at stephen@pezcyclingnews.com.

 

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