Updated July 6, 2026 03:12AM
So you thought darker jerseys were hotter jerseys?
You were wrong (sort of).
Visma-Lease a Bike defended its use of dark kits during a Tour de France heatwave by claiming that fabric trumps color when it comes to cooling.
“It’s not at all strange that people think a dark jersey absorbs more heat than a light one,” Visma head of performance Mathieu Heijboer said in a team note. “Studies in the past have shown that darker clothing can be warmer than lighter colors.
“However, the textile industry in elite sport has developed to such an extent that it’s been discovered that much bigger differences can be achieved with specific fabrics,” he said.
“The choice of fabric has a far greater impact on heat retention than the color.”
It’s an explanation that could make you reconsider your clothing choices this summer.
The question about wearing dark or light bubbles up every time the mercury goes north.
Darker colors are proven to absorb more sunlight than lighter ones. On the flipside, lighter tones reflect it.
And when thermoregulation is proven to be a key limiting factor at all ends of performance, that matters.
Velo tech chief Josh Ross was so concerned about the topic last summer that he even turned his backyard into a science lab to research it.
A black swap-out in a Tour de France heatwave
Dark jerseys didn’t slow down Visma-Lease a Bike when it won the stage 1 TTT of the Tour de France. (Photo: Anne-Christine POUJOULAT / AFP)
But hold it right there.
Why is Visma-Lease a Bike giving us the thermoregulation science lesson?
Surely Jonas Vingegaard and Co. have got bigger things to worry about. They look like Tadej Pogačar and Isaac Del Toro.
Visma issued its explanation on the eve of this Tour de France after commentators reminded the Killer Bees that “dark kit is hot kit.”
And the team is riding in a very black kit this summer.
The dark “architect” swap-out kit the team is wearing was favored over a creamy yellow alternative in a public vote.
It’s a fan favorite that could be a heat trap that hammers performance.
And with temperatures forecast to reach 40°C in southern France next week, that sounds like a very big problem.
Raging wildfires are already impacting how the race is being run.
Fabric trumps color for keeping cool
The Tour de France is being cooked by a European heatwave. (Photo: Dario Belingheri/Getty Images)
Heijboer’s not worried about his team getting hot at this Tour de France.
He said that the UV resistance and weight of apparel are at the top of the hierarchy in terms of an athlete’s overall cooling.
“Ultimately, you want to make sure the body doesn’t heat up too quickly in the sun,” he said. “It’s also about how quickly moisture is dissipated. Does the moisture stay in the jersey, or does it evaporate quickly enough?
“The fibers used in our jerseys are treated to be UV-resistant. That UV protection is an important factor, as it ensures that some of the light is reflected rather than absorbed.”
Visma-Lease a Bike claims it proved its color vs. fabric theory by testing prototypes of its Nimbl kits in climate chambers.
The results showed that jersey color causes only “insignificant differences” in body temperature.
“All results show that the choice of fabric plays a much greater role than the color,” Heijboer said.
Visma-Lease a Bike is not the only team using a swap-out kit for this Tour de France.
Pinarello-Q36.5 was one of many teams to roll out a special-edition uniform.
How the team described the “fresh summer look” of its Q36.5 jersey is intriguing.
There was no suggestion that the pale blue colorway was inherently cooler than its year-long navy blue. A press release instead cited ultralight mesh panels and thermoregulating yarns as the central cooling components of its Dottore Pro kits.
Why does this matter to us?
The mostly white jerseys worn by UAE Emirates-XRG will only be cooler than the black of Visma if the fabrics are suitably optimized. (Photo: Getty Images)
Vimsa-Lease a Bike’s research should make cyclists reconsider how they approach their wardrobe deliberations.
During our temperature testing last summer, tech chief Josh found that a dark jersey was 20°F warmer than a paler alternative after one hour in the sun.
His experiment also found black helmets and water bottles to be significantly warmer after being left to bake in some Portland sun, FYI.
But here’s the thing.
Velo‘s testing did not compare like-for-like jerseys. We don’t have endless kit, after all. A white Gobik Infinity short sleeve was lined up against a black Castelli Aero Race 8.
So what’s the takeaway from all of this?
Yes, dark jerseys are hot jerseys. Josh proved that.
But like Visma’s performance guru Heijboer said, fabric is king.
A dark but lightweight jersey – ideally with UV resistance – will feel cooler than a pale but heavyweight alternative.
Many high-end jerseys nowadays boast ultralight and UV-resistant materials. Examples include the Velocio Luxe Ultralight SE, the Castelli UPF short sleeve, and the Rapha Pro Team range.
One wrinkle in Visma’s jersey defense?
The discarded creamy switchout jersey will be cooler than the black alternative worn at the Tour de France. They’re made of the same materials.
The team is clearly confident that fabric is cool enough not to get in a sweat about it.