Tour de France 2023: TOUR Tech briefing for Stage 21

Robert Kühnen

· 23.07.2023

Tour de France 2023: TOUR Tech briefing for Stage 21

Photo: Getty Velo

From July 1 to 23, the world's best cyclists will compete in the Tour de France. Victory and defeat on the roads of France will be decided not only by the legs, but also by the material. The TOUR Tech briefing for the 21st stage.

Tour de France 2023 - Stage 21: Saint-Quentin-en-Yvelines - Paris | 115.1 Kilometres

Photo: A.S.O.

The grand finale in Paris is just around the corner. After an opening stretch, the riders will complete eight laps of 6.8 kilometres each on the boulevard of Paris. The course is fast, easy to follow and free of major difficulties. The riders are fresh, as far as one can be after these three weeks. In any case, the stage itself is the easiest of the entire Tour. A bit of exhibition riding plus an hour of hard bike racing. The main difficulty is the muck riders: the final sprint is particularly prestigious and thus fiercely contested.

Tour de France 2023 - stage 21: Sprint on cobblestones

What to do to be well equipped in the sprint from the technical side, we have presented in several issues of this newsletter. First and foremost: be aerodynamic. Things are no different on the Champs Elysees. The last corner 700 metres before the finish line has to be negotiated, a sprinter has to be in position there, and then the race goes straight ahead towards the finish line. The sprint is on relatively smooth cobblestones. With 28 mm tyres and adjusted air pressure, as they are driven by most riders anyway, the surface is well manageable. However, ultra-firm tyres without puncture protection, as is the case with many time trial tyres, are not recommended on the inner-city course. Experience shows that the risk of punctures is higher there.

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As the number of the day we do not deal with the sprint but look back to Tuesday's time trial - stage 16 of the Tour de France 2023. In our briefing we had predicted a winning time of 32:56, which was beaten by Jonas Vingegaard by 20 seconds. We had advised against a bike change. Most of the riders did not change their bikes. But co-favourite Tadej Pogacar changed the bike, which took about 14 seconds. According to our calculations, this did not give him an advantage, on the contrary. He lost 34 seconds to Vingegaard on the core climb, and in the further course, when the hill flattened out, Vingegaard's aero and power advantage came through. Here the Dane made up massive ground (-43 seconds). Pogacar certainly didn't have his best day, but neither did he have the best strategy to reach for yellow.

Vingegaard said after the race that he held back on the flat part of the course and pedalled 380 watts. Based on this information and with the track data, we calculated his cwA value.

Number of the day: 0.18 square metres

That Jonas Vingegaard sat fast on the tt-bike, everyone saw. The head was completely in front of the torso. Based on the split times, our model of the course and Vingegaard's statement, we calculate his cwA value to be 0.18 square metres.

This is an absolute world-class value. We know of only one lower published value. The American Colby Pearce, former American hour record holder, was measured with 0.1656 - but in his special discipline on the track, not comparable to a road race in the Tour de France. The cwA value is the product of the frontal area and the cw value; it describes how aerodynamic an object is. The lowest possible values should be aimed for. Normal cwA values for very good time trialists are around 0.195 square metres.

But this absolute top aerodynamics was only one component in Vingegaard's winning ride. He also took high risks in the downhill, had the right pacing and material strategy and kicked exceptional power. All of this combined to produce the fabulous time.
That brings this year's tech briefing to its conclusion. I hope it was entertaining and yielded an insight or two into the technology behind the stars' great performances.

See you next year!

Our Expert

Photo: Robert Kühnen

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.

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