Tour de France 2025 - Stage 3: Valenciennes - Dunkerque | 178,3 Kilometers
The end of the third stage is perfect for a bunch sprint: flat, almost straight except for a slight right-hand bend 200 meters before the finish line, six meters wide. However, it is unlikely to be a real bunch sprint, as the Côte de Cassel (2.3 km, 3.8 %) stands in the way of the sprinters 32 kilometers before the finish line. It is quite possible that the field will split into groups here and that there will be a sprint with a reduced field. The wind could also play a role in the approach to the finish, as the route heads towards the sea.
If the wind is strong, a motivated team can initiate an echolon race. The riders spread out across the width of the road to enjoy the maximum slipstream. However, the key to success with echolons is the willingness to ride at full throttle collectively. The man at the front must go all out, pedaling at 600 watts or more in the short lead to reach speeds of 50 km/h or more in the wind.
The pursuers only have a chance if they also organize themselves into an echolon – and push just as hard. In a mixed group, however, the motivation is usually not as high as in a team that acts as a unit. And the space for an echolon is limited. A large group therefore usually breaks up into several echolons.
Equipment for the wind
What does this mean for the choice of equipment today? Aero bikes and wheels are a given, as are aero accessories. The riders wear one-piece racing suits, aero helmets, and some even wear time trial helmets. Aero socks, no longer than mid-calf length as required by the regulations, tight gloves, maybe even aero overshoes. Each of these details on its own does not make a huge difference. But the sum of the details does. The fact that the pace is so high today is also because riders are much more aerodynamic than in the days of fluttering jerseys and wide handlebars.
Those who take echelon riding into account can do even more in terms of detail. The front wheels in particular play an important role, as they are the sails of the road bike. In extreme cases, they can even generate propulsion in crosswinds, and they are also crucial for handling. How much wind pressure is felt in the steering and how predictable the forces are depends on the shape of the rim and the interaction between the rim and the tire.
If the pairing works well, the handling is less twitchy. The Conti Aero 111 tire has a special tread pattern that ensures that the airflow stays on the tire longer and fewer pressure fluctuations are felt. TOUR tested the tire with different wheels and was able to confirm what the manufacturer promises: wind resistance is reduced, and handling is improved. With the aero tire, the bike rides more stably in gusty winds.
A team that consciously plans the wind edge therefore has levers on the material side to get the most out of the situation.
Today's simulation focuses on the question of how much time the aero bikes gain over conventional bikes on flat, fast sections. We have chosen the ten-kilometer flat segment on the approach to today's finish line.
Number of the day: 23 seconds
A lightweight bike without any special aerodynamic attributes loses 23 seconds over ten kilometers in the final. Anyone who has something planned for today and doesn't have the motor reserves of Tadej Pogačar will therefore, from a rational point of view, do everything they can to be as aerodynamic as possible at the start of the stage.
An overview of (almost) the entire field*
The simulation of ten flat kilometers offers no surprises: On flat terrain, aero bikes have the tire in front. The slowest bike loses 23 seconds over ten kilometers.
*) The calculations are based on the bikes tested by TOUR in the laboratory and wind tunnel. The machines used in the Tour de France may differ in detail. Of course, we were not yet able to examine last-minute prototypes. Background information on the simulation.
Our expert
Robert Kühnen studied mechanical engineering, writes for TOUR about technology and training topics and develops testing methods. Robert has been refining the simulation calculations for years, they are also used by professional teams.
