Digital simulation, the Jumbo-Visma’s secret weapon

Each moment has its own emotion. Since the yellow coronation of Jonas Vingegaard, the green coronation of Wout Van Aert or the tricolor deliverance of Christophe Laporte, the Jumbo-Visma has been entitled to all moods. First consternation, as was the case at the heart of the climb to Cap Blanc Nez. Then admiration, when Jonas Vingegaard took the yellow jersey at the top of the Col du Granon. Then the congratulations, renewed on each podium of the Champs-Elysées, or almost (only the white jersey escaped the Jumbo-Visma). And finally, unfortunately, doubt. At the press conference, the questions flared up. Jonas Vingegaard, as usual, remained calm.  » I can guarantee you 100% that we are clean the Dane simply blurted out. Questioned in his turn, Wout Van Aert lost his temper.  » Shit question he snapped at the instigator.

Wout Van Aert went to inspect his dummy himself on his new Cervélo prototype at the Eindhoven University of Technology / Credits: Anton Vos/Cor Vos – Ansys

Then everyone immediately highlighted the considerable work done behind the scenes, upstream. “We do courses at altitude and we go very far during these courses. We do our best in terms of equipment, food… That’s why you have to trust us. » said the yellow jersey in person. Thus has come the time for the explanation. In collaboration with Bert Blocken, professor at the Technical University of Eindhoven (Tu/e) and Ansys, a software publishing company, Team Jumbo-Visma has become one of the pioneering teams in digital simulation. Focus on the « marginal gain » of the year, with Thierry Marchal, Healthcare and Sport Solutions Director, at Ansys, leader in the field.

Digital simulation, an industrial technology at the service of cycling

In short, numerical simulation allows “ optimize performance through aerodynamics “, as summarized by Frédéric Grappe, director of the Performance division within the Groupama-FDJ formation. In fact, it consists of the resolution of huge systems of equations, with tens of millions of unknowns, at the heart of which is Newton’s fundamental equation, establishing that the resultant force F exerted on a material point, of given mass m, is equal to the product of the mass of the point and its acceleration a.

Simulation of a team time trial / Credits: Ansys

In other words, the higher the speed, the greater the resistance that the air opposes to the advance of the runner. It is even estimated that when riding on flat ground in calm weather at more than 40 km/h, more than 90% of the resistance that the cyclist must overcome to move forward comes from the resistance of the air “, as Thierry Marchal tells us. Therefore, it is not surprising that the automotive and aeronautical industries have adopted numerical simulation for many years!

Thus, by multiplying the experiments at the speed of a processor, this method leads to the design of a predominant model, varying according to the conditions (weather, slope, speed, etc.). Finally, this study allows the runner to refine his position of penetration in the air in order to increase his speed by developing the same power. The explanation for the Jumbo-Visma double at the end of the Rocamadour time trial then takes shape.

The differences in air resistance coefficients in a platoon illustrates the need to optimize this point / Credits: Ansys

Significant progress and convincing results

Is digital simulation the determining factor in this victory against Tadej Pogacar (UAE Emirates), Geraint Thomas, Filippo Ganna (INEOS Grenadiers) and others? It would obviously be wrong to make this the only explanation for this feat. As Thierry Marchal humorously points out, “ even by exploiting this technology to the maximum, I could not win the Tour de France myself: what these athletes are doing is just phenomenal.” But if the digital simulation does not make the feat, it contributes notoriously.

Indeed, air resistance is extremely sensitive to variations in aerodynamic drag, similar to that of a boat on a river. However, as our speaker explains, the purpose of the numerical simulation is to identify and locate the origin of each of its components « . Once known, these can therefore be targeted by modifying the position of the athlete on his machine. “Faults and gray areas” are then discovered and brought to light, as explained by Frédéric Grappe.

Wind tunnel tests accompany the digital simulation / Credits: Ansys

And the results are not long in being observed.  » Even a reduction of a few percent could translate to a saving of 1 or 2 seconds or more per kilometer says Thierry Marchal. On the scale of the 40 kilometers of the final time trial of the Tour de France, this gain could therefore exceed one minute. Unfortunately, the exact benefit of the digital simulation on the performance of the riders of Team Jumbo-Visma has not been communicated to us for reasons of confidentiality.

Digital simulation, a symbol of Jumbo-Visma’s investment

In fact, the triumph of the Jumbo-Visma in the Tour de France is the result of a multitude of sources of progression put together. As Jonas Vingegaard explained in the introduction to this article, the Dutch team is looking for performance gains on all possible fronts, whether it’s power supply, altitude familiarization or penetration in the air. . And their work on this last point is particularly representative of this last point, completing the metamorphosis of cycling from a purely physical discipline to a scientific field in its own right.

Primoz Roglic was entitled to his real size mannequin! / Credits: Bart van Overbeeke – Ansys

Indeed, Thierry Marchal reveals in this regard that Team Jumbo-Visma has gone so far as to reproduce in the experiments the exact morphology of its main riders, in order to take into account the smallest geometric detail of each person’s body. He even adds that for Wout van Aert and Primoz Roglic, a real life-size mannequin was created from this scan to validate the numerical simulation with experimental studies in the wind tunnel. « . Finally, the Dutch team did not fail to check the progress made on the road, being particularly attentive to the feedback provided by its riders. As summarized by Thierry Marchal,  » the last word always comes back to the cyclist « . And one could add that the successes thus systematically fall into the arms of the Jumbo-Visma.

Nevertheless, digital simulation is already being emulated. Frédéric Grappe’s intervention in this article thus illustrates Groupama-FDJ’s commitment to Ansys, as another high-profile client of this technology. However, with its 4^e place in the final general classification, David Gaudu is also the author of a remarkable performance on the Tour de France. Is this not further proof of the effectiveness of digital simulation?