Breakaway riders, descents, aerodynamic advantage: The TOUR Tech Briefing for Stage 6

The sixth stage is another low-mountain stage, which, like a surprise bag, allows for all manner of race scenarios. It covers 153.4 kilometres from Montbrison to Tournon-sur-Rhône. Mont Ventoux, which is to be climbed on the seventh day, is already casting its shadow and may deter GC contenders from giving it their all, knowing full well that the seventh stage is likely to be decisive. This is precisely what others could capitalise on. Breakaway riders are the favourites, but changes in the general classification are also possible at any time. This is because a rider who is already behind must go on the offensive to retain any chance in the GC. This bodes well for an entertaining race.

​The number of the day: 2 minutes 24 seconds

We are simulating an attack 53 kilometres from the finish, on the climb to the Col de Lalouvesc, a second-category mountain pass.

We’re already familiar with the resulting bike rankings from the previous day. Once again, Team Visma is in an excellent position with the Cervélo S5. Aerodynamics have the greatest impact on the average speed right up to the finish. Anyone looking to break away after an attack must maintain their pace down the descents and through the valleys. This is best achieved with an aero bike. However, it should also be as light as possible on the climbs.

By the time they reach the finish line, the S5 has a massive lead of 2 minutes and 24 seconds over the slowest bike in the field. There’s really no question as to which bike will come out on top. It’s actually rather surprising that the bikes aren’t tuned for speed even more aggressively. In the wind tunnel, we’ve already tested prototypes that significantly outperform even the fastest bikes in the field. The 190 W threshold is slowly coming into view.

An overview of the (almost) full line-up*:

​A look back at the fourth stage – a shaky time trial by Ferrand-Prévot

The time trial went as expected. Time trial world champion Marlen Reusser was He lived up to his role as favourite and won with a time we had predicted in our pre-race simulation. Lieke Nooijen’s second place came as a surprise, as she came within four seconds of Reusser. The Dutch rider was particularly fast in the second half of the race. Co-favourite Demi Vollering also put in a very fast second half in particular, making up seconds on the blistering downhill section to finish third, 17 seconds behind. Vollering, who had given it her all, pounded her chest at the finish line and was clearly very pleased with her performance.

Kasia Niewiadoma, the 2023 Tour winner, kept her deficit to a minimum; she finished 1 minute and 8 seconds behind, which is an acceptable result for a climber. The Polish rider, who is a strong climber, had clearly been working on her time trial performance.

Pauline Ferrand-Prévot fared less well; she was already 1 minute 21 seconds behind Reusser at the first timing point, i.e. after the climb. She lost almost another minute on the descent. At the finish, the Frenchwoman was 2 minutes and 13 seconds behind Reusser – which is a considerable gap for such a short course and could spell the end of her hopes of defending her title.

Nevertheless, Ferrand-Prévot said afterwards that she was satisfied with her performance in this unfamiliar discipline, which she hadn’t competed in for years. But she never looked in complete control on the course. Given how brilliantly the Frenchwoman had mastered her MTB on difficult courses and during technical descents, it was almost painful to watch how much she struggled on the time trial bike.

With every pedal stroke, she steered in the opposite direction, causing her to ride in a constant zigzag. As a result, she ended up covering a longer distance than some of her competitors.

Team Visma, which is usually at the cutting edge in technical terms, could have made things easier for its captain. With In our experience, the K.I.S. steering stabiliser would be Ferrand Prevot performed significantly better when riding in a straight line. However, the system devised by the Bavarian inventor Jo Klieber remains largely unknown in the road cycling world and is only used sporadically in mountain biking. It’s a shame, because this time trial demonstrated very clearly that even in elite sport there is still plenty of potential to improve the bikes’ ride characteristics and to make their handling – particularly when it comes to high-speed descents – better and safer.

* Simulation calculations

Based on our own wind tunnel tests, we carry out simulation calculations for the Tour de France tech briefing. How TOUR tests: Aero road bike test in the wind tunnel.

We are investigating which wheels can offer a technical advantage in which situations. The variables we can control in the simulation include wheel weight, rider weight, the inertia of the wheels, the drag coefficient, the rolling resistance coefficient and the efficiency of the drivetrain.

To model ride times, we use realistic power outputs and weights for the riders, combine these with our wind tunnel data, and have the riders race virtually along selected sections of the route, which we extract from the official route data; the derived elevation profiles are key to this. The modelling also includes bends, which we can brake for realistically, and adjustable power profiles for different types of riders. This allows us to distinguish between hill climbs and proper final sprints. Taken together, this makes the simulation very realistic. What we cannot replicate are dynamic handling effects such as the individual behaviour of the wheels on different surfaces.

The journey times calculated for the sections of the route that are decisive for the race highlight the influence of the wheels – provided that the riders always behave in the same way in a given scenario.