Tour de France 2024 - Stage 7: Nuits-Saint-Georges - Gevrey-Chambertain | 25.3 Kilometers
The seventh stage is a time trial. The route is not very spectacular. There are 300 meters of elevation gain over 25.3 kilometers. Essentially, there is a gentle climb with a gradient of just under five percent and a descent - a rolling course that should also suit heavier time trialists.
Number of the day: 30 seconds
In this relatively flat time trial, aerodynamics are the key to top speed. As we don’t have any concrete data on time trial bikes, we ran a bunch of fictitious bikes through our course simulation to show the impact of aerodynamics on riding time.
A five percent improvement in the cdA value saves around 30 seconds of riding time on the track. At a speed of 52 km/h, a five percent improvement corresponds to a power saving of around 18 watts (converted to 45 km/h around 12 W). That’s a lot. In the wind tunnel, a rider who already starts in a very good position will achieve smaller gains. But in the sum of several details, such improvements are definitely possible. Because the aero details are numerous:
- Optimal racing suit for the targeted speed
- Tailor-made aero handlebars
- The best helmet for the rider and their body shape
- Aero details: shoes, socks, gloves
- Wheel/tire combination
- Frame and other add-on parts
Other ingredients for carefree racing are time trial tires with optimized rolling resistance and optimized chain lubrication. The time trial bike should also be as light as possible. On the seventh stage, however, the weight effects are small, as our simulation shows. A kilogram saving brings 2-3 seconds. If in doubt, it is therefore better to optimize the aerodynamics and compromise on weight.
Simulation of different time trial set-ups for the 25.3-kilometer route*)
The table shows the ride times for different configurations, with variations in weight and aero performance. The marked lines with TT9 and TT15 correspond to the five percent improvement discussed above.
For Jonas Vingegaard, who put in a sensational time trial in 2023, we expect cwA values at the lower end of the table.
We’re excited to see what tricks the riders will pull out of the team trucks today. Keep your eyes open! It’s all about the details.
Update on the fourth stage: 1x12 aero set-up in the high mountains
Jonas Vingegaard started the fourth stage over the Galibier on a weight-optimized Cervelo S5 aero bike. He has thus changed his strategy compared to last year, when he often rode the aerodynamically much worse Cervelo R5.
The Cervelo S5 he used on the Galibier was special in several ways: Vingegaard rode a 1x12 setup and tubular tires. After photo analysis, we identified a gear ratio of 52 to 10-36. We have never seen such a set-up in the high mountains.
But since the Galibier is not super steep, this gear was no problem. The longest gear downhill was even bigger than usual and certainly not an obstacle. The uphill was so fast that the smallest gear 52 x 36 was probably not used at all.
The reason for the 1x12 set-up: to save weight and improve aerodynamics. The S5 will probably have come close to the 6.8 kg mark, but unfortunately we weren’t allowed to weigh it.
Aero chainring and the omission of the front derailleur saved a few watts of drag. This made the already very fast S5 even faster. In the wind tunnel, despite the not very deep Reserve wheels, which Vingegaard probably chose for weight reasons, just like the tubular tires, we would presumably measure aero values below 200 watts (the benchmark for super aero bikes in the TOUR wind tunnel test with dummy legs). Aerodynamically, Vingegaard was better equipped for the descent than Pogacar. Even with the fast Enve wheels, his Colnago is a long way from the aero performance of the S5. One thing is clear: Tadej Pogacar’s legs made the difference in the descent from the Galibier.
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.
