Aerodynamic and lightweight: Tour Tech briefing on Stage 5 of the Tour de France Femmes

​Macon > Belleville-en-Beaujolais | 140 kilometres. On paper, the fifth stage is the perfect terrain for breakaway riders. However, a battle for the general classification could just as easily develop early on, as the race is difficult to control due to the many steep climbs; it heads uphill right from the start. If a favourite is caught off guard, she risks significant time losses. It’s a day on which a GC rider could lose the Tour, but not win it.

The race is likely to be decided by a breakaway group. It’s quite possible that GC contenders will be among them.

​From a technical point of view, this stage presents a number of challenges: in the sections where attacks are likely, the short climbs are really steep. This means that the bike should not exceed the minimum weight in order to provide the best possible support.

To sustain the attack and carry it through to the finish – this applies particularly to a solo rider – the bike’s aerodynamics must also be top-notch.

The number of the day: 1 minute 23 seconds

Let’s imagine an attack on the penultimate climb, 31 kilometres from the finish. Which bike would give a female rider the best chance of making it through?

One thing is clear: on steep sections, weight matters; bikes with the lowest possible weight are the best choice here. But what about the rest of the route?

We calculated the shortest ride time for the Cervélo S5; it finished 1 minute and 23 seconds ahead of its slightly lighter sister model, the Cervélo R5, at the finish line. Once again, aerodynamics are the deciding factor – and by a surprisingly wide margin – despite the sharp peaks and troughs in the route profile.

Would you have thought that when you saw the double-digit gradient?

What will the female riders actually be riding?

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

​The table shows the remaining riding time for an attack 31 kilometres from the finish. Despite the steep sections of terrain, aerodynamics are the key factor in maintaining a lead all the way to the finish. Ideally, the bike should still be as light as possible, just like the S5.

A look back at the third stage – Aero-Performance wins the race

The third stage went something like this, as in our simulation as shown earlier, with a long and successful solo breakaway covering 88 kilometres.

Norwegian champion Sigrid Haugset demonstrated outstanding time-trial skills, beating the peloton, which had allowed her a lead of up to five minutes. Even Lotte Kopecky, who was chasing solo and has won almost everything, failed to catch up with the little-known Norwegian. Although she closed the gap to ten seconds by pedalling harder on the climbs, she then ran out of steam on the flat finish against Haugset, who maintained a steady pace.

What were the ingredients behind this outstanding success? A pinch of daring, excellent time-trial skills and a large dose of mental strength. Sigrid Haugset spent two hours in a perfect aero position on her Ridley Noah Fast, a bike tailor-made for this scenario; aerodynamically, the bike is among the best in the field. But it was Haugset herself who made the decisive difference. She appeared more efficient at all times than Kopecky, who was chasing her and who can certainly pedal harder. Haugset gripped the narrow handlebars tightly, her forearms parallel to the ground, brought her head forward of her torso and didn’t waste a single metre fidgeting. You could literally see how efficiently she sliced through the wind. Riding like that for a short while is one thing. But maintaining such discipline for a good two hours is testament to a great deal of training in that position.

And so the race went to a clever breakaway rider who turned a small opportunity into a big victory. Her victory also illustrates that our statistical analysis has a basis in reality. Pedalling isn’t everything. It’s the whole package that counts.

* 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 rider weights, 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.