Immersion in a day of wind tunnel testing

In modern professional cycling, the quest for performance is no longer limited to physical training or nutrition. Every detail counts, and aerodynamics play a decisive role. When a rider at over 50 km/h, around 90% of their power is used to combat air resistance. Gaining a few watts can translate into several seconds off a time trial... or a victory snatched at the finish line.

With this in mind, we travelled to Friedrichshafen, Germany, in the company of our partner Swiss Side. An invaluable partner with long experience in Formula 1, with whom we share the same demand for precision and performance.

No coincidence in the choice of location: this is one of the most advanced and rigorous wind tunnels in Europe.

There, the aim is not simply to validate existing choices, but to push the thinking further. Observe, compare, understand and, often, discover. The wind tunnel is both a validation tool and an exploration laboratory, where intuitions rub shoulders with physical reality.

The term "wind tunnel" can be misleading, since in fact the opposite occurs: air is not blown toward the rider, but sucked in behind them. This principle generates a turbulence-free airflow. As a result, the data collected is extremely stable, and the variations measured are truly due to changes made to the rider their equipment.

On the ground, a precision scale records the forces exerted on the rider, allowing their aerodynamic drag coefficient (CdA) to be calculated. This figure alone sums up rider ability rider "cut through the air." The lower it is, the more efficient the rider . From there, the CdA is converted into aerodynamic watts, i.e., the power a rider exert solely to overcome air resistance at a given speed, simulated here at 55 km/h.

Swiss Side engineer Bjorn adds: "Aero power is the power you need to develop just to overcome aerodynamic drag, but not rolling resistance, transmission friction or other losses. It's a pure, isolated figure that allows us to compare."

The tests are also conducted at different angles of incidence to simulate crosswinds, such as those riders in real-world conditions. "If we only tested with a perfectly head-on wind, the data would only be valid in a velodrome," adds Paul Barratt, our Director of Innovation.

Finally, to complement the force measurements, Swiss Side uses a sophisticated tool: a system of dynamic pressure sensors that pass behind the rider testing. The aim is to understand where turbulence forms.

"The scale tells us if there is a difference, but not where it is. The pressure sensor creates a map of the air pressure drops right behind the rider. This shows us precisely which areas of the body or equipment generate the most drag. And that's very valuable when working on helmets, textiles, or changes in rider position rider explains Jean-Paul Ballard, founder of Swiss Side.

The day begins with Léo Bisiaux. This is his first session in the wind tunnel, and an opportunity to validate his position on the time trial bike. This had already been worked on by the performance team, and immediately proved effective, with a CdA measured at 0.179. We use this as a basis for making a series of targeted adjustments: increasing the angle of the aerobars by five degrees, bringing the arms 15 millimeters closer together, and refining the position of the head and torso. After these adjustments, the CdA dropped to 0.170. This corresponds to a gain of 4 watts, without compromising the rider stability or comfort.

But the most memorable moment came when we tried out the new Van Rysel time trial helmet, fresh from the design office. Léo was one of the first to test it. The result is striking: an extra 11.7 watts are saved. "I thought I was going to gain a little more with the settings, but my position was already good," explains Léo. "On the other hand, the difference the helmet makes... almost 12 watts on its own, that's crazy."

Mathias Ribeiro Da Cruz, the team's innovation engineer (and last year's French amateur time trial champion), points out that these results are highly personal: "What works for Léo won't necessarily work for another rider. The goal is to build a high-performance, sustainable position that is unique to each individual."

In the afternoon, it's the tour Felix Gall, one of our leaders, to take to the stage. The challenge is strategic: optimizing his equipment for the Tour France time trial in Peyragudes. The unique feature of this time trial is 3 km of false flat followed by an 8 km climb. The dilemma is classic but complex: should he prioritize the aerodynamics of a time trial bike or the lightness of a road bike equipped with aerobars?

We test both configurations in a wind tunnel at different speeds, recording the CdA, positions, and sensations. All this data is then integrated into simulation software developed by Swiss Side, which can accurately model the course of a race, taking into account the profile, weather, weight, and equipment used. This software simulates hundreds of combinations and identifies the fastest setup for the rider profile rider the race. It is even possible to simulate the benefits of changing bikes mid-race, a bold strategy that can sometimes pay off.

Felix also tests the new Van Rysel helmet, with a 10-watt gain. This helmet was developed from the dummy of Bruno Armirail, double French time trial champion. Bruno wasn't using it at the time of his last title, but had already benefited from extensive optimization work. He won by three seconds. Not much, but enough. And that's exactly what the wind tunnel allows: to transform a performance hypothesis into measurable reality.

Behind every wind tunnel session, there is a real synergy between people and technology. Modern cycling is a team sport at every level. On the wind tunnel platform, surrounding the rider in a time trial position, there are dozens of eyes and tools observing, analyzing, measuring, and adjusting.

Fluidity between roles is essential: Paul Barratt, Director of Innovation, discusses strategy with Swiss Side engineers and supervises the modifications made during the day; Mathias Ribeiro Da Cruz, Innovation Engineer, analyzes results in real time to adjust protocols; Gilles Martinet, mechanic, makes precise modifications to the bikes; Alexandre Pacot, coach and positioning specialist, checks that the adjustments also respect the rider physical abilities. All this is done under the watchful eye of Van Rysel engineers Louis and Alban, and our head coach Stephen Barrett, who is responsible for training and race performance and knows Felix and his abilities particularly well.

Paul is right to explain how marginal gains work: "Everyone talks about marginal gains, as if they systematically add up to a massive advantage. In reality, we test a lot of things. Most of them bring little or nothing. But sometimes, an idea has a huge impact. And that's exactly what we're looking for. The process is one of guided discovery. We start with a hypothesis, experiment, adjust. It's a testing ground."

The wind tunnel isn't just a place for measuring: it's a space for dialogue, intuition and experimentation, where each team member brings a complementary viewpoint to bear on the best possible solution.

The day's results speak for themselves. Léo gained over 15 watts between the position adjustments and the new helmet. Felix, around 10 watts. These figures, translated into seconds on a time trial, can be enough to change the standings.

But these gains are only valuable if they are understood and embraced by those who need to apply them: the riders . That's why we always express these results in watts, a unit of measurement that speaks to them immediately. " riders exactly what it means to push 20 or 30 more watts. When you tell them that a helmet saves them 10 watts, it's not abstract: they realize the difference," explains Paul Barratt.

Beyond the numbers, the wind tunnel allows us to make technical decisions, confirm certain approaches, and rule out others. It is a decision-making tool. And for us, it is a key element in preparing for major events such as the Tour France.

Each rider the team undergoes aerodynamic testing at least once a year. The leaders return as soon as a key element (helmet, clothing, equipment, etc.) is ready to be tested. This is an essential step in our approach to performance.

The wind tunnel is not a technological showcase. It's a practical, demanding and sometimes thankless tool in the field, but it's extremely effective when used properly. It allows us to test, fail, learn and then succeed. It helps us transform ideas into measurable realities. And above all, it reminds us that in this sport, every watt counts, because every second counts.

But as valuable as these figures are, they cannot replace the essential: the rider commitment, their ability to push themselves, to suffer, to fight for that fraction of a second when their legs are burning and everything seems frozen.

We do everything in our power to ensure that our athletes have the best possible conditions, the most accurate data, the fastest equipment. But at the end of the day, it's they who turn these efforts into performance. Because no simulation, no test, can model mental strength, the will to win.

And this is undoubtedly the best part of cycling.