From Inside Peloton: SLO Motion

Rotor, Kinesiology and Cal Poly San Luis Obispo

How does a small Spanish company famed for its funny-shaped chain rings end up with a lab at one of California’s most prestigious engineering schools? It’s a story that starts a few years ago with a grad student in kinesiology, a passion for cycling and the curiosity and skills to definitively answer one of cycling’s hottest questions: Do oval chain rings really work?

Words & images: Ben Edwards

Christie O’Hara (shown below) was a James Madison graduate looking for an opportunity to publish sports-related research. Not wanting to add to the deluge of published sport’s nutrition research, she found Bob Clark in the Cal Poly San Luis Obispo’s kinesiology department. Clark is a cyclist, and in a field focused on obesity issues he is one of the few kinesiologists interested in cycling-related research; he suggested a study on oval chain rings. With a look at Cal Poly’s resources and the friendly faculty, O’Hara knew she had found a home and a subject to get her masters degree and her work published. It didn’t hurt that year-round riding weather and incredible terrain were right outside her door on the West Coast.

Interestingly, for a woman who now works for Rotor, O’Hara actually set out to debunk the company’s claims of a 4-percent increase in power and 9-percent in lactate production. Those numbers came from a 2006 Spanish study completed in partnership with Rotor that was never published. During O’Hara’s study, she purchased the rings and spoke to Rotor only to ensure they were set up correctly. Rotor had no idea what her research focused on. Using eight elite-level athletes from the university’s triathlon and road cycling teams, O’Hara began a long study due to Rotor’s claims of a six-week adaptation process.

The results of her study, published in 2011, were definitive—with some of Rotor’s claims verified while others were debunked. A 9-percent decrease in lactate was not confirmed (essentially, no difference was found), but the power numbers were more than verified. At maximum efforts over one kilometer, Rotor rings delivered a whopping 6.2-percent average increase in power. Even at sub-max riding, Rotor rings lowered heart rate by one to two beats. While this seems small, over a long day or three-week grand tour it is massive. O’Hara’s study also found that the adaptation process is much faster, essentially immediate, although getting comfortable with the feel can take a bit longer.

The most important thing to remember about this study is that it was not commissioned by Rotor. It was peer-reviewed, published in the International Journal of Sports Science and Engineering, and presented at the American College of Sports Medicine conference. This is real science, not wind-tunnel voo-doo or magazine-based, stiffness-to-weight ratios. It’s this simple: If you have legs, and those legs pedal a bike, oval chain rings are better. Period. Through this study, O’Hara’s following studies and her work with hundreds of pro and amateur riders, she has never seen a rider with a pedal stroke that would be better off on round rings.

As she puts it: “The biggest take away from this is there is no disadvantage to using them [Rotor oval rings]. The benefit will be different for everyone, but there will be some advantage, from 1 percent to 6 percent. It will be a benefit.”

So O’Hara proved they work, but how? Oval rings work because a rider does not produce power evenly through a pedal stroke; they maximize the part of the stroke where power is produced and minimize resistance where it isn’t. Convincing pro riders of this is now a big part of O’Hara’s job.

After earning her masters and finishing her study, she began to look for work. A firm believer in Rotor’s technology, O’Hara contacted the Spanish company and found that it was looking for someone to work with its athletes, continue research and start a sports science division. A month later she was flying to the Garmin-Sharp pro team’s training camp. Thanks to Spain’s immigration laws and the expense of starting a research facility, O’Hara found herself back in San Luis Obispo with the offer of a lab from the university and plenty of student help. She agreed to keep publishing and the match was made—Rotor and Cal Poly San Luis Obispo, with Christie O’Hara in the middle.

The Rotor lab is all business, with the Spartan look of higher education, but the resources are profound: metabolic cart, Computrainer, Velotron, lactate analyzer, EMG system, motion analysis system and, of course, bikes and plenty of Rotor gear, from power meters to chain rings. The lab has already completed two more studies, including a blind analysis of Rotor QXL rings and a study of pedal smoothness and torque effectiveness. While the data is still being analyzed, the latter study will hopefully tell us what to do with all the new metrics power meters are providing.

The other half of O’Hara’s job is working with Rotor’s extensive line-up of pro athletes. While Rotor would never attempt to force a rider to use its rings, O’Hara simply presents her research, telling the riders the benefits are real peer-reviewed, published science. Half of the Garmin riders are now on the oval rings, and those that aren’t should be. In a traditional sport like cycling many riders will tell O’Hara they ride better on round rings, despite never having tried oval ones; or their coaches are resistant. The Australians on the team, however, have been early, enthusiastic adopters.

O’Hara’s goal is always to get the riders to just try them and then help them quickly find the right position of the adjustable rings for their riding style. While typical riders will find position three right, some climbers who slide back on the saddle will be more comfortable in position two, while some sprinters may prefer position four, with the power phase as late as possible in the stroke. Interestingly, even if a rider isn’t in the optimum position and their stroke doesn’t feel quite right, they will still be better off than riding a round ring. The benefits are that deep.

In a sport so focused on technology, so determined to find even marginal gains, data is thrown around all the time: Wind-tunnel numbers, frame-torsion tests and metabolic analysis are conducted by brands and teams constantly. They aren’t neutral, and they aren’t typically conducted under the scientific method—and the results should be, and are, taken with a grain of salt. O’Hara’s work is different. Peer reviewed, published science from a top American university should not be taken lightly, certainly when it proves something so profound.

The basic way we transmit our power to the road is wrong. Round rings do not optimize the way humans produce power. It’s as simple as that. Anyone interested in going faster on their bike needs to switch to oval rings. As O’Hara’s study percolates through the pro peloton and the entire cycling community, 10 years from now, when only vintage bikes have round rings, we will look back on her study as the turning point.

From Issue 33.