Tour de France Femmes 2025 - Stage 8: Chambéry - Saint François Longchamp (Col de la Madeleine) | 111.9 kilometres | 3520 vertical metres
Short, steep, decisive; the eighth stage promises to shape the overall standings. Last year's winner Kasia Niewiadoma is expecting a gap of minutes rather than seconds.
The climbing starts right after the start with the Col de Plainpalais (13.2 km, 6.3 %). The peloton will already split up here. The riders will warm up extensively on the rollers before the stage.
The toughest climb of the tour, the Col de la Madeleine (18.6 km, 8.1%), awaits from kilometre 91.6. At the end of this climb, the overall classification could look very different to the start of the stage.
The last few briefings have been all about aerodynamics and downhill performance. Will the eighth stage finally be the time for the mountain bikes?
To answer this question, we simulate the ride up the Col de la Madeleine.
The decisive climb of the tour: 8.1 per cent average gradient and over 1500 metres of altitude difference will shake up the classification.
The number of the day: 1:06 minutes
On the climb up the Col de Madeleine, the Cervélo S5 once again comes out on top. Under the premise that the S5 is close to the minimum weight of 6.8 kilos, it is even faster uphill than the R5, which safely adheres to the 6.8 kilos.
The lead over the slowest bike on the mountain is 1:06 minutes. One kilo overweight means around 47 seconds behind on the Madeleine. The lighter the rider, the greater the leverage of the material.
As everyone will be aware of the importance of weight on this stage, we can assume that the mechanics will be busy swapping and weighing parts until the bikes actually weigh 6.8 kilos. The wheels and tyres in particular are likely to put the bikes on a diet. Visma could once again realise the trick with the 1x12 drivetrain to make the S5 as light as possible.
Such an aero light bike also has the advantage over pure climbing machines that it offers advantages in the approach to the final climb. As the stage is short, the pace will certainly be high between the mountains. A fast bike can be particularly important for an isolated captain if she falls behind before the finale due to a defect.
The (almost) complete field at a glance*
The table shows the riding times for the final climb. As expected, light bikes are ahead. However, if the differences are small, aerodynamics are again the deciding factor, as aerodynamically relevant speeds are reached in the flatter sections of the climb.
*) The calculations are based on the bikes tested by TOUR in the laboratory and wind tunnel. The bikes at the Tour de France may differ in some details. Of course, we have not yet been able to analyse last-minute prototypes. Background to the simulation.
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.
