Tour de France 2025 - Stage 9: Chinon - Châteauroux | 174,1Kilometers
The ninth stage is the last chance for sprinters to make their mark for the time being. Accordingly, a mass sprint is the likely scenario. The home stretch in Châteauroux is 1.4 kilometers long, dead straight, and completely flat. It's perfect for the fastest sprint train to set the stage for the lead sprinter.
But just when things seem so clear, it may be up to a puncheur to launch a daring attack. There is a sharp left-hand bend 2,200 meters before the finish line, where a lone rider could try to break away and pull through. We are simulating this scenario today.
The hero of the simulation starts at an initial speed of 57 km/h, carries the full speed through the bend, and stays on the gas. 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. A rider who can push exceptionally hard for 2:20 minutes has a small chance of breaking away from the field if things get tight in the curve or the field misses a kick or two for other reasons.
Our simulation shows which bike would be 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 for this crazy maneuver and has a 4.5-meter lead over the second bike.
The perfect view on the dead straight home straight also argues against the maneuver succeeding. But everyone knows that. All the greater the surprise when a rider nevertheless makes an early move. It wouldn't be the first time that a brave rider has succeeded 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 the sixth stage, which he won with a long solo ride after attacking from a high-caliber breakaway group. However, his opponents were exhausted breakaway riders and not fresh sprinters.
Healy, however, demonstrated perfectly what it takes: the Irishman rode the final stage like a time trial. Always in the optimal position and pushing hard on the pedals every second. No letting up, no taking a breather. In this way, he even continuously made-up time against the combined efforts of his pursuers.
An overview of the (almost) complete field*
*) The calculations are based on the bikes tested by TOUR in the laboratory and wind tunnel. The machines used in the Tour de France may differ in detail. Of course, we were not yet able to examine last-minute prototypes. Background information on the simulation.
The table shows that anyone who wants to break away shortly before the finish line needs not only courage and enormous stamina, but above all top aerodynamics. The bike plays the smallest role in this, but it can tip the scales. A bike with poor aerodynamics loses over four seconds over 2,300 meters. A two-watt difference in wind tunnel measurements translates into a difference of 0.27 seconds—which is equivalent to four and a half meters!
What tricks can be used to gain speed?
Cyclists battle many forms of resistance, but above all, they battle the air. Air resistance is by far the most dominant factor when not riding uphill. To minimize air resistance, every detail counts: position on the bike, the texture of the racing suit – whose roughness can even be adjusted to the target speed – aero socks, shoe covers.
For the final stage outlined above, the fabric would have to be designed for speeds of just under 60 km/h – in other words, it would have to be more like a time trial suit than a one-piece suit for long breaks (40-50 km/h).
The aero helmet is also a must, of course. In addition, a position that allows maximum speed. However, the rules of the UCI are problematic in this regard. This is because the fastest position for a solo rider is the brake lever position with the elbows pulled inwards. When riding in this position, riders tend to automatically rest their forearms on the upper handlebars – and that is precisely what is prohibited by the rules.
Finally, it helps if the equipment is optimized. Today, that means: a flat frame and wheels/tires that are designed for speeds of 60 km/h, all cables hidden under the frame, and flat handlebars. The fastest tires for such a final are time trial tires. These can also help to squeeze out a few more watts. Even the best lubricant on the chain – according to our measurements, wax – adds a few more watts. The sum of many small details ultimately makes a substantial difference to the final outlined above, which must be ridden at around 600 W for victory to be conceivable.
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.
