Tour de France 2023 - Stage 9: Saint-Leonard-de-Noblat - Puy de Dome | 182,4 Kilometres
The ninth stage of the 2023 Tour de France ends on a volcano. The Puy de Dome was not part of the Tour for 35 years, but has now been reactivated. The prelude to the fiery spectacle is 150 undulating kilometres that add up to 2,600 meters of altitude. In theory, that’s good terrain for an escape group, but the classification riders will be alert after what happened in this Tour de France and will study well who’s riding up front.
Different scenarios for the Puy de Dome
The predictable spectacle is definitely the climbing battle of the superstars in the general classification, 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% throughout.
We ran different scenarios to test the character of the climb. If we attack from the start, the climb to the top would take around 35 minutes.
In this scenario, a bike that is as light as possible would be the best basis for a top time.
But it is far more likely that the GC riders will let their aides ride hard in the first part of the climb and save grains in their slipstream. How much wind resistance can you expect on a 7.5% incline? At 23 km/h there is still about 42 watts of drag, if a downdraft is blowing, it can be more. In the slipstream behind single riders up to 40% can be saved, in a small field even more.
Tour de France 2023: Helpers play an important role on stage 9
If one of the helpers pulls the pace really high, for example to prepare an attack, also 60 watts of drag and more are possible on the mountain. So having someone who can provide slipstream is also a factor on the climb. That’s another reason why the top teams have climbing-strong noble helpers at the start to support the captains in the mountains, like Emanuel Buchmann at Bora-Hansgrohe or Adam Yates at UAE Team Emirates.
Accordingly, aerodynamic material is also advantageous uphill. Wide-brimmed, flapping jerseys? Not so much in modern cycling. Riders wear aerodynamic textiles even on mountain stages. In the middle section, the climb of the Puy de Dome even flattens out to such an extent that a 40-km/h pace is possible. The attack will probably be set after that.
The graphic shows what the speed profile might look like for the entire climb:
Number of the day: 13:28 minutes
13:28 minutes lasts the hot phase of the race at the end of the ninth stage of the 2023 Tour de France according to our simulation. Over this time, the top riders can go 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 bikes are the lightest bikes in this case. The usual suspects with good aero properties, who were ahead in the last simulations, have no advantage today, 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 details. Of course, we have not yet been able to examine last-minute prototypes either.
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.
