Tour de France Femmes 2025 - Stage 4: Saumur - Poitiers | 130.7 kilometres | 780 vertical metres
The fourth stage is another sprint stage. There are only 780 metres of elevation gain in total, so the route is as flat as a cake base and the few small hills in the profile are ironed out by the peloton.
The finish in Poitiers is also flat and extremely clear. The last kilometre is dead straight along the Avenue John Kennedy, with only six metres of elevation gain between the devil's lobes and the finish line.
The tactical scenario is therefore clear: the sprinters' teams will control the race. Only the wind could throw a spanner in the works. Riding in the wind always harbours the risk of the field breaking up into several groups.
What does that mean from a technical point of view? The riders will be using aero material. Without exception, everyone can benefit from this - whether at the front of the field during the chase, at the start of the sprint or the sprint itself, the aero set screw is the one with the greatest effect.
If crosswinds are expected, there are tricks to get a little more out of them. Special aero front tyres, such as the Conti Aero 111, improve aerodynamics, especially when the wind blows from the side. Two effects can be observed: The front wheel wriggles less in gusty winds when these tyres are fitted, which benefits the handling and the riding resistance is also lower. Win-win!
In the wind tunnel, we were able to test the tyre's behaviour at different speeds and in combination with different rims. Surprisingly, the tyre always worked. The special profile, which consists of cuboidal indentations, stimulates a so-called turbulent boundary layer, which means that the air flow can follow the contour of the rim profile for longer. This reduces the pressure resistance on the profile and the steering feels an increasing but continuous torque: the front wheel then behaves like a sail and can even generate propulsion from the flow. If, on the other hand, the flow stalls, the steering torque fluctuates greatly.
In our simulation of the day, we run a slightly shorter sprint than the day before from a higher starting speed. Does that make a difference to the result?
The number of the day: five thousandths of a second
The technological lead is narrowing, but it's still there. The Cervélo S5 beats the Canyon Aeroad by five thousandths in the high-speed sprint. From a technical point of view, Marianne Vos once again has the best cards for the final sprint.
The (almost) complete field at a glance
The table shows the ranking after 180 metres of virtual sprinting. The bikes at the top are united by their excellent aero performance.
Our expert
Robert Kühnen studied mechanical engineering, writes about technical and training topics for TOUR and develops test methods. Robert has been refining the simulation calculations for years and they are also used by professional teams.
