Updated Oct. 2, 2014 9:42 a.m. ET

Not long ago, I shaved my legs. Not for a column. For victory.

In the world of riding bikes, shaving legs has long been a ritual without a universal explanation.

I shave because it makes bandages easier to apply and remove when I crash and get road rash on my legs, some riders will say.

I shave because it's easier on my legs when I get a postrace massage.

I shave because it makes my legs look cool.

I shave because…look, a red-tailed hawk! (Rides away.)

The closest thing to the truth is that cyclists shave because it's a rite of passage. It's The Big Move That Proves You're Taking This (Perhaps a Little Too) Seriously. You're joining the club. The pros do it, after all. For the price of a cheap razor, you can do it, too. I did it years ago, in my brief career as the slowest bike racer in the history of New York City.

And when somebody asked me why I did it, I bumbled for an answer like everyone else.

But what if the shaving explanation wasn't just a mixture of rationalizations. What if shaving your legs actually made you faster?

For some time the cycling and triathlon worlds have been buzzing with the news that leg shaving might have a significant, previously undocumented performance benefit.

The notion gained momentum after a random experiment in January at a wind tunnel owned and operated by Specialized, the Morgan Hill, Calif.-based bike company. Professional triathlete Jesse Thomas had arrived for a session of testing on the aerodynamic benefit of various equipment.

It was also the off-season, and Thomas had let his leg hair grow as lush as Zach Galifianakis's jawline.

Just for fun, Thomas and Specialized road brand marketing manager and aerodynamicist Mark Cote decided to test Thomas's wind-tunnel performance with the hairy legs. Then Thomas shaved his legs. And he was tested again.

They were staggered by what the results found. So they did it again. And again. And again.

The testing repeatedly showed that a shaved-legged Thomas had gained a significant speed advantage over his hairier version. The benefit was equivalent to an improvement of 15 watts of power at race pace, which roughly translated to 79 seconds over a 40-kilometer time trial.

"In sporting terms, a complete eternity," said Specialized's lead aerodynamic engineer, Chris Yu.

The news was both amusing and unexpected. Even at an amateur level, cyclists and triathletes will use aerodynamic skin suits and helmets and make numerous adjustments to their riding position in order to save time. Here a major bike company was saying shaved legs offered a benefit comparable to switching from a standard rounded-tube bike to a top aerodynamic frame.

"We were all just shocked," Thomas said. "For me, a half Ironman is a four-hour race, and the winning margin can often be less than a minute, even 30 seconds. If you can find something that shaved 15 seconds or 30 seconds—or maybe a minute or two—is huge."

The study wasn't fully scientific, of course. Yu said that the operating theory is that hairier legs are like fuzzy tennis balls—the more fuzz, the more resistance. Specialized tested other cyclists with hairy legs—it created an index of hairiness it called "The Chewbacca Scale"—and the improvement stayed consistent after shaving. Specialized made a YouTube video which now has more than 150,000 views. Thomas, a regular columnist for Triathlete magazine, wrote a story which he said became "by far the most popular article I've ever written," and the experiment was chronicled in numerous cycling and multisport outlets.

The attention wasn't a surprise. Biking is a world that can be comically obsessed with the minor—and often expensive—tech alteration. But Jesse Thomas's legs also gave a legit-sounding cover story to cyclists who'd struggled to explain own their leg-shaving ritual.

"For all the stories that we tell," said journalist Alex Hutchinson, who wrote about Thomas's experiment for the Globe and Mail in Canada and covers sports science for Runner's World magazine, "no one ever really believed it was aerodynamic."

Yes: Perspective is essential here. Most elite-level cyclists were already shaving their legs to begin with. And leg shaving is not going to convert a weekend warrior to pro material. "If you want to get faster," Hutchinson said, "all these things—leg shaving, making a bike an ounce lighter, a helmet slightly more aerodynamic—are just noise on top of noise compared with training more."

This was very true. If I really wanted to get faster, I would need to train harder. Right now when I ride my bike, I look like Kermit the Frog shopping for flowers. And I probably need to knock off the frozen margaritas and nachos.

Still, I'd heard enough. After years of letting the leg hair run freely, I got out the razor. First I shaved one leg, and kept the other one hairy, just to see if I could feel the difference. I looked like a lunatic. After a couple of days, I shaved both.

I am not fast. I'm in the back of the pack. I am never going to win anything.

But I've returned to the club. With a better-sounding explanation.