BAGNÈRES-DE-BIGORRE, France—If Julian Alaphilippe was going to become the first Frenchman in half a decade to wear the Tour de France’s yellow jersey, he knew he had to do something a little bit crazy—at least by cycling standards. By non-professional cyclist standards, it was a lot crazy.
Alone on a downhill, he crunched his 130-pound frame into the smallest position he could manage. He slid his backside forward off the saddle and onto the top tube. He moved his hands from the ends of the handlebars onto the tops, nowhere near his brakes. And he lowered his chin over the stem—he was now attacking the descent goatee-first.
It was not how bikes are meant to be ridden. But at this Tour de France, it’s how they’re being raced. The supertuck, as the position is known, is at once considered the most efficient way to speed down a mountain and the most controversial. Bike racers take plenty of risks as it is. Now, much of the peloton is adding another to the list.
“Super dangerous,” Team Ineos director Nicolas Portal said. “You really have to be confident.”
The idea behind the supertuck is to maximize aerodynamic gains while going downhill. Elite riders have experimented with versions of it for years. Marco Pantani, the Italian champion, toyed with a tuck that involved shifting his rear end behind the saddle and stretching for the handlebars as long ago as the 1990s. But racers and team directors at this summer’s Tour de France agreed: they have never seen quite so many people break out the supertuck quite as often.
Any time the road pitches downward enough to roll a marble, riders are shifting into the most aggressive position they know to gain every possible advantage. What used to be a move reserved for solo descents with victory on the line has even found its way into the main bunch, where riders are close enough to rub shoulders.
Part of it is down to a widespread obsession in the peloton for anything vaguely aerodynamic. This is, after all, a sport that pays minute attention to where it puts the seams on jerseys to reduce drag. “Aero is the Wi-Fi code of bike racing,” said Team EF Education First director Charley Wegelius. “It’s all anyone wants all the time.”
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But wearing tighter skinsuits and sleeker helmets in the name of aerodynamics is one thing—those are only risky if you’re worried about looking funny in Lycra. The supertuck is another. Riders sacrifice control and reaction time while hurtling downhill at speeds that can exceed 60 miles per hour. A pothole snagging a wheel barely one inch wide can be a career-ender.
“If you’re doing it, you obviously know what you’re doing,” said Team Mitchelton-Scott rider Adam Yates, who was prepared to make that trade off. “We’re all professionals here.”
Except it’s making other professionals nervous too. Especially, as Team Ineos rider Michal Kwiatkowski point out, when they see people give up on the handlebars entirely and clutch the bike’s stem instead.
Lance Armstrong, a difficult man to shock when it comes to the Tour de France, raged about the safety risk on his podcast earlier in the race. And veteran rider Dan Martin was so incensed about the prevalence of the supertuck last year—not to mention the example it was setting for amateurs who don’t have preternatural bike-handling chops—that he called on the sport’s world governing body to outlaw it.
“Dear [UCI], How about we think about banning this new descending technique of sitting on the top tube,” Martin tweeted during the 2018 Tour. “Pro riders may have the skills but how many kids at home will endanger themselves attempting to imitate what they see on TV.”
Especially when they start doing more than just tucking. Once Alaphilippe launched his downhill attack on Stage 3, he felt comfortable enough in his crouch to resume pedaling and even crane his neck around to check for chasers behind him. Four-time Tour de France champion Chris Froome had broken out the same move in a dive-bombing run off the Col de Peyresourde to grab the yellow jersey in 2016.
“Please don’t try this at home,” he tweeted at the time.
The UCI isn’t any closer to meeting Martin’s request. There is, however, one important detail that could yet turn the supertuck from essential technique into passing fancy. As it turns out, the science behind it is far from settled. “For some guys, if they tuck properly while sitting on the saddle, they can go just as quickly as someone riding on the frame,” Portal said.
American bicycle manufacturer Specialized tried to figure it out with a wind-tunnel test in 2014. Here is the unsurprising part: the supertuck position was around 10% faster than leaning forward from the saddle with hands by the brakes, according to the company’s leader of innovation and engineering, Chris Yu.
What might stun the likes of Alaphilippe is Yu’s finding that pedaling from the supertuck didn’t do much for you on a steep downhill. If anything, he said, it adds more drag because the rider’s knees come out to the side and add “effective frontal area,” canceling out any extra power in the pedals.
But if this Tour de France is any indication, the supertuck isn’t going anywhere soon. Most of the time, riders will look at the road tilt away from them, weigh up the risks, and decide that they are worth it.
“You have to look kilometer by kilometer,” Kwiatkowski said. “What’s the danger? But what gains you can make?”
Write to Joshua Robinson at joshua.robinson@wsj.com
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