This year’s Tour de France Femmes has been rocked by allegations that some riders are artificially exaggerating their bust size to gain an aerodynamic advantage.
Several women’s World Tour teams have raised concerns that cyclists on rival teams are padding their sports bras to give them a boost in time trials, according to leading Dutch cycling news site, WielerFlits.
Every second counts
The practice of “chest fairing” – also known as “bra boosting” or “bra doping” – involves increasing the surface area of the chest to change the airflow around the torso. Other forms of chest fairing include placing a water bottle or radio receiver under your cycling jersey. This can reduce drag, potentially saving valuable seconds in a time trial, where aerodynamics are crucial.
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An optimised chest fairing can reduce drag by as much as 3.6%, which could gain a time-trial cyclist at least 0.78 seconds every kilometre, according to research published in the Journal of Wind Engineering and Industrial Aerodynamics in 2024. “You won’t gain tens of seconds,” said study lead Bert Blocken, an aerodynamics expert at Heriot-Watt University in Scotland. But over a 20- to 30-km time trial, “it could save enough seconds to make the difference”.
“We’ve done some testing with a push-up bra versus a sports bra” and “we’ve definitely found some differences there”, Koen de Kort, head of technical and innovation at professional cycling team Lidl-Trek, told The Athletic. We haven’t used enhanced bras in competition, as we “don’t think it’s in the spirit of the sport” but I’m sure other teams “have found the same results and have experimented with it”.
It’s a controversy that has echoes of the row at the Winter Olympics earlier this year, when male ski jumpers were accused of artificially boosting their penis size in order to be fitted into ski suits with larger, more aerodynamic dimensions in the crotch area.
Grey area
Using any item to “artificially modify the morphology” of a rider to gain an advantage is banned by the UCI, cycling’s governing body. Riders found violating these rules can be disqualified and fined. Yet, at present, they are “virtually unenforced”, said WielerFlits.
For male riders, the policing of chest fairing “is relatively easy”, said Cycling News, but it becomes “complicated for women, who all have different sized breasts and use all different kinds of sports bras during races”.
On Monday, the UCI took the unusual step of issuing a warning that the Tour de France Femmes race jury overseeing final checks for yesterday’s stage 4 time trial will play “particular attention” to clothing and accessories which “could modify riders’ morphology”.
But “confusion remains as to what exactly” the jury was tasked with looking for, said Cycling Weekly. I don’t see how they are going to police this in future, de Kort told The Athletic, describing sports bras as a “grey area”. How can you define how much padding “a woman needs”?
