Tech Briefing on the Tour de France Femmes: Every gram counts on Mont Ventoux

Showdown on Mont Ventoux. The stage runs from La Voulte-sur-Rhône to Mont Ventoux, covering 146.8 kilometres. The climb up the windswept Mont Ventoux overshadows all the other climbs in the Tour. Higher, longer, tougher. The expectation is that the general classification will be decided here. Whether this proves to be the case depends on the riders and the conditions. If a strong wind is blowing, even on this barren mountain, drafting becomes a real factor and shaking off a rival is correspondingly much more difficult. The course of the Tour so far has shown that, with an aggressive riding style, even much smaller obstacles can result in significant time gaps.

One thing is certain: the breakaway riders will attack early and set off with reckless abandon in pursuit of the stage victory. They’ll be given free rein if they’re far enough down the general classification. Towards the end, the GC riders will step up the pace and the exhausted breakaway riders will be caught. Usually, the GC riders come out on top in the end. But there are races that don’t stick to the script.

​From a personnel perspective, what needs to be done to create opportunities for victory?

That depends on the rider’s role. For the protected team captain, it’s simple: above all, the bike should be as light as possible. So it should weigh exactly 6.8 kilos, plus a few extra grams to avoid falling foul of the UCI scales’ measurement inaccuracy.

For female breakaway riders, things are a bit different. To break away from the peloton and build up a lead, aerodynamics are the key factor. The ideal breakaway bikes are therefore aero bikes. To perform at the highest level, these should, of course, be as light as possible.

Equation of the day: 900 grams = 36 seconds

Today’s simulation centres on the final climb. Which bike is the fastest when the action really kicks off right at the start of Mont Ventoux?

We’ve recalculated the shortest ride time for the Cervélo S5, followed by the other bikes that weigh 6.8 kilos. An extra 900 grams means, for a 56-kilo rider, 36 seconds A gap at the finish line – that’s what the figures for the Ridley Noah Fast show; it’s top-class aerodynamically but not exactly lightweight.

So 25 grams makes a difference of one second. Armed with this knowledge, the mechanics will trim down whatever they can to push the car to its limits.

The aero performance of the bike really counts on climbs, particularly when a rider is able to break away in windy conditions. Simply prioritising lightweight construction whilst neglecting all other aspects is therefore not a good strategy.

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

​The calculated ride times for a 56-kilo female cyclist on Mont Ventoux. Lightweight bikes top the rankings. Weight is the most important factor, but aerodynamics also play a part. The expected climbing speeds range from 15 to 26 km/h depending on the section (average 18.3 km/h).

* 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.