Tour de France 2023 - Stage 9: Saint-Leonard-de-Noblat - Puy de Dome | 182.4 kilometres
The 9th stage ends on a volcano. The Puy de Dome has not been part of the Tour de France for 35 years, but has now been reactivated. The prelude to the fiery spectacle is formed by 150 undulating kilometres that add up to 2600 metres in altitude. Theoretically, this is good terrain for an escape group, but the classification riders will be alert after what happened in this Tour and will be studying who is riding at the front.
The predictable spectacle is definitely the climbing battle of the superstars in the overall standings, which will probably take place on the last 4.3 kilometres of the volcanic cone, as the mountain is particularly steep there, with over 11.5 per cent throughout.
Various scenarios conceivable at the Puy de Dome
We ran through various scenarios for the finale of stage 9 of the 2023 Tour de France to test the nature of the climb. If there was an attack from the start, the climb to the summit would take around 35 minutes. The lightest possible bike would be the best basis for a top time in this scenario.
However, it is far more likely that the GC riders will let their aides ride hard in the first part of the climb and save energy in their slipstream. How much wind resistance can you expect on a 7.5 per cent gradient? At 23 km/h, there is still around 42 watts of wind resistance, but if there is a downdraft, it can be more. In the slipstream behind individual riders, you can save up to 40 per cent, and even more in a small field.
If one of the helpers really picks up the pace, for example to prepare for an attack, 60 watts of air resistance and more are possible on the climb. So having someone who can provide a slipstream is also a factor on the mountain. This is another reason why the top teams have strong climbers at the start who support the captains in the mountains, such as Emanuel Buchmann at Bora-Hansgrohe or Adam Yates at UAE Team Emirates.
Aerodynamics also important uphill at the Tour de France
Accordingly, aerodynamic material is also advantageous uphill. Wide-open, flapping jerseys? Not in modern cycling. Riders also wear aerodynamic clothing on mountain stages. In the middle section, the ascent of the Puy de Dome flattens out so much that a 40 km/h pace is possible. The attack will probably only be mounted afterwards.
The graphic shows what the speed profile could look like for the entire ascent:
Number of the day: 13:28 minutes
The hot phase of the race at the end of stage 9 of the Tour de France 2023 lasts 13:28 minutes in our scenario. Over this time, the top riders can ride over 7 W/kg. We calculate 480 W at 66 kg (7.28 W/kg).
Surprise: the material effects are not very pronounced in this final, it can be seen that the fastest wheels are the lightest wheels in this case. The usual suspects with good aero characteristics, which were ahead in the last simulations, do not have an advantage, the steeper gradient makes a difference.
The (almost) entire field at a glance
*) 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.
