Tour de France 2025 - 9th stage: Chinon - Châteauroux | 174.1 kilometres | 1400 vertical metres
The ninth stage is the last opportunity for sprinters to make their mark for the time being. Accordingly, a bunch sprint is the likely scenario. The finishing straight in Châteauroux is 1.4 kilometres long, dead straight and perfectly flat. Perfect for the fastest sprint train to set the stage for the chief sprinter.
But just when things seem so clear, it might be up to a puncheur to launch a daring attack. There is a sharp left-hand bend 2200 metres before the finish where a lone rider could try to break away and pull away. We are simulating this scenario today.
The hero of the simulation starts from an initial speed of 57 km/h, carries full speed through the bend and stays on the accelerator. Is there the slightest chance of getting away with it?
The number of the day: 0.27 seconds
The probability of getting away with it is low, but not zero either. A rider who can push exceptionally hard for 2:20 minutes has a small chance of getting away from the field if it gets tight in the bend or the field misses a kick or two for other reasons.
Our simulation shows which bike would be the best for this: with a lead of just under three tenths of a second, the Van Rysel RCR-F Pro is mathematically the fastest bike in this insane race and has a lead of 4.5 metres over the second bike.
The perfect visibility on the dead straight finish line also speaks against the manoeuvre succeeding. But everyone knows that. All the greater the element of surprise when a rider nevertheless starts early. It wouldn't be the first time that a brave rider has managed to pull it off against all odds. The necessary ingredients are powerful leg power, mental toughness and an outstanding aerodynamic position.
Ben Healy recently proved that one rider can be stronger than the pack on stage six, which he won with a long solo ride after attacking from a high-calibre breakaway group. However, his opponents were exhausted breakaway riders and not fresh sprint riders.
However, Healy demonstrated to perfection what is important: the Irishman contested the final like a time trial. Always in the optimum position and with pressure on the pedals every second. No easing off, no catching his breath. He even made up time continuously against the combined efforts of his pursuers.
The (almost) complete 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.
The table shows: If you want to escape just before the finish line, you need courage and enormous stamina as well as top aerodynamics. The bike plays the smallest role in this, but can tip the scales. An aerodynamically weak bike loses over four seconds at 2300 metres. A difference of two watts in the wind tunnel measurement is reflected here as a difference of 0.27 seconds - the equivalent of four and a half metres!
What tricks can you use to gain speed?
Cyclists struggle with many obstacles. But above all with the air. Air resistance is by far the most dominant factor when you're not cycling uphill. Every detail counts when it comes to minimising air resistance: position on the bike, the quality of the racing suit - the roughness of which can even be adjusted to the target speed - aero socks, shoe covers.
For the finale outlined above, the fabric would have to be designed for almost 60 km/h - in other words, it would have to be more of a time trial suit than a one-piece suit for long escapes (40-50 km/h).
The aero helmet is of course also included. In addition, a position that allows maximum speed. However, the rules of the UCI are problematic in this respect. This is because the fastest position for the soloist is the brake grip position with the elbows pulled inwards. If you ride like this, you tend to automatically rest your forearms on the upper handlebars - and that is precisely what the regulations prohibit.
After all, it helps if the material is optimised. Here and now, that means a flat frame and wheels/tyres that are tuned for 60 km/h, all cables under plaster, flat handlebars. The fastest tyres for such a final are time trial tyres. You can still make a few watts on these tyres. Even the best lubricant on the chain - wax according to our measurements - adds a few watts. In the end, the sum of many small details makes a substantial difference for the outlined finale, which has to be ridden with around 600 W for a victory to be conceivable.
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.
