Tour de France 2025 - Stage 5: Caen - Caen | 33 kilometres (individual time trial) | 200 vertical metres
The fifth stage is a time trial. The route is a roller course, seemingly made for the heavier time trial specialists in the field. Heavier riders often have a more favourable power to drag ratio (cwA) than lighter riders, which enables them to ride a little faster on the flat.
But no rule is without exception: Remco Evenepoel, reigning time trial world champion, is also very fast on the flat, despite being neither tall nor heavy. His outstanding time trial performance has a lot to do with how he sits on the bike. The side view clearly shows how the large helmet fills the gap between his arms and torso, transforming his body into a streamlined body. Jonas Vingegaard also sits incredibly well on the bike, especially for a racer of his petite stature. His Giro time trial helmet elongates his body perfectly. The helmet, which is wide at the back, connects to the shoulders and the protruding nose channels the airflow around the helmet. The helmet acts like a fairing and stretches the regulations, which prohibit fairings, to its limits.
How aerodynamic the riders are on the road can be estimated based on riding data. Using data from last year's Tour de France, we determined a cwA value of 0.175 for Remco Evenepoel. Converted, 205 watts is enough for a speed of 45 km/h. By comparison, an average amateur cyclist has to invest around 350 watts for this speed!
However, the classification riders will by no means leave the field to the specialists. Because although the route is short, it is important for the overall classification. Remco Evenepoel won the time trial at the most recent Tour of the Dauphiné, gaining 49 seconds on Tadej Pogačar and 21 seconds on Jonas Vingegaard in just 17.4 kilometres. Pure climbers are a few minutes behind on a stage like today.
Number of the day: 20 seconds
In flat time trials, 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 track simulation to show the influence of aerodynamics on riding time.
A three per cent improvement in the cwA value saves around 20 seconds driving time, whereas one kilo of ballast does not even add 1.5 seconds, even for a 60-kilogram driver.
The strategy is therefore clear: aero is everything. What the bike weighs is secondary, it's all about having the airflow under control.
The most important factor here is the positioning of the rider, as they generate the majority of the drag with their body. Customised, slightly angled trailers, aero helmets and aerodynamically effective textiles with the right amount of roughness in the right place are the tricks used to gain seconds in the wind tunnel. The bike is also optimised, but individual adaptation to the rider is crucial.
Simulation of various time trial set-ups for the 33-kilometre route
The table shows the journey times for different configurations, with variations in weight and aero performance. As you can easily see, the weight is largely irrelevant. It's all about the aerodynamics, which can be used to effectively turn the clock.
For Jonas Vingegaard, we expect cwA values at the lower end of the table. The fastest driving time in the table corresponds to an average of 54.6 km/h!
For comparison: the Tour de France road book calculates a journey time of 37 minutes.
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.
