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Here’s the rule most pro riders are breaking … but not really

The UCI's rule on sock height is one of many vague regulations that seem silly. Why even bother with rules like this one?

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The UCI’s equipment regulations read a lot like a late-night high school essay: If something can be said vaguely, it will be said vaguely. That allows the governing body to interpret those rules as it sees fit. That’s problematic, however, when it comes to equipment regulations.

Sock length is a prime example of this. Take a look at the socks Tom Dumoulin used during the stage 16 time trial at the 2018 Giro d’Italia. They extend pretty far up his leg, above the bottom of his calf. Is this legal?

To get the handle on what riders can and cannot wear, we’re back to our old friend, UCI Article 1.3.033, particularly the part that states:

“The socks and shoe covers used in competition must not extend above the middle of the leg.”

Okay, after reading that statement, let’s all perform a quick experiment. Stand up from your chair, nice and straight. Bend down and place a finger on the middle of your leg. Where did that finger land? Chances are we all have our finger somewhere different because the UCI rule does not specify the ends of the leg. Are we measuring from the bottom of the foot to the top of the hip? From the knee to the ankle?

Common sense dictates the midpoint of the leg would be somewhere around the knee, so racers should be able to wear a sock that extends all the way up the calf.

Well, not so fast.

To “clarify” its rules, the UCI includes this photo and caption:

Photo: UCI

Okay, got it now?

Yeah, me neither. And that’s the point: Teams will give riders whatever equipment affords the most significant advantages without clearly violating the rules. Since the UCI’s rule is so vague, it’s nearly impossible to break it. Teams insist these high socks are well within the confines of the UCI rules, and frankly, they’re right. This rule is essentially unenforceable, at least with any consistency.

This isn’t a reflection on the teams. It’s a reflection on the UCI and its practice of writing rules that aren’t clearly enforceable. (VeloNews reached out to the UCI for this story, but representatives declined to comment.) To be fair, so much of cycling is a subjective matter. Did Peter Sagan throw an elbow and knock Mark Cavendish off his bike? Equipment is no different; what constitutes a fairing? Is an aerodynamic gel spread onto the legs of a rider illegal under UCI rules? There are plenty of gray areas to choose from.

So the UCI might simply find itself in an impossible position, and offering specifics on sock length would only muddle the issue. For example, it seems logical to just put a specific length as the limit for socks. But that length — for the sake of argument, let’s say six-inch cuffs — would certainly have more of an impact on a short rider like Esteban Chaves, and less of an impact on a tall rider like Chris Froome.

Dumoulin’s not the only one wearing marginally legal socks. Geraint Thomas, Chris Froome, Simon Yates, and basically any other top contender you can think of probably pushes the boundaries of this rule. Which begs the question: Are high socks even advantageous to begin with?

“If done right high socks can be more aerodynamic than a bare leg,” says Chris Yu, director of integrated technologies at Specialized. “This is the golf-ball dimple effect — rough textures can re-energize the boundary layer around the leg and delay flow separation since the leg size and speed are generally in the right range for this to work. This results in a smaller wake behind the leg and lower drag.”

So it stands to reason that the higher the sock extends up the leg, the more aerodynamic advantage the rider is getting. A rider can still get an aerodynamic advantage with a shorter sock, but clearly, a taller sock offers even more advantage.

We’re talking minuscule gains here, and those gains aren’t guaranteed. “The ‘if’ is a big one,” says Yu. “There are a lot of high socks and shoe covers that are slower since the texture effect is pretty sensitive to having the right amount of roughness or disturbance, in the right place, which varies somewhat with leg size and speed.” So despite the potential advantages, riders still take on the risk of actually slowing themselves down with such socks.

All this brings up another important question: As cycling fans, do we really want the UCI stringently regulating sock length? Imagine Peter Sagan rolling up to the starting line, only to be met by a UCI official with a jig that measures the specific length of his sock cuff. And Chris Froome next to him. And Mark Cavendish. And on and on down the line. Sound like boring minutiae? Perhaps we’re seeing the UCI’s side of the tale. With so many other important issues facing the regulatory body, who really cares about sock length?

That’s the fine balance between using the best, fastest, and most aero equipment, and sticking to what makes a bike a bike — the latter of which has been the UCI’s goal all along. In order to keep the competition between competitors and not between teams of engineers in a wind tunnel, the UCI regulates. But the governing body doesn’t want to over-regulate to eliminate the technological aspect from competition entirely. Hence the vagueness of the rules. If that seems like an impossible balance, that’s because it is. That’s why we’ll continue to see socks creeping ever higher until someone at the UCI decides it’s gone on long enough.

Then riders will just use aero gel. (Or will they?)