Tour de France 2024 - 18th stage: Gap - Barcelonnette | 179.5 kilometres
The unorthodox route continues: the planners have also realised an atypical route profile on the 18th stage. Five 3rd category mountain classifications and a total of 3100 metres in altitude have to be overcome. However, the finale is almost flat, the course climbs gently over the last 25 kilometres. The last kilometre in Barcelonnette also has a slight incline, with a bridge forming a chicane 250 metres before the finish. The planners are obviously not expecting a sprint from a larger field.
On paper, this is a stage for breakaways. The start ramp for the breakaway is the Col du Festre, 32.2 kilometres after the start. The undulating profile that follows is perfect for a breakaway. As always, however, it depends on the riding style of individual teams whether the opportunity for a breakaway actually arises. The battle for the green jersey could influence the stage.
The material for the route is clear. Whether sprinter, breakaway or controller: the aero set-up is set. As usual, the riders will wear skintight one-piece suits, put high wheels on their bikes, make themselves long and flat and compromise on weight by a few hundred grams. Aerodynamics are the key to the high speeds that the pros ride at. For this stage, we have broken down how the riding resistance is distributed on this undulating stage:
- Aerodynamic resistance: 44%
- Mountain resistance: 42%
- Rolling resistance: 14%
In this overview, we have not included the low mechanical losses in the drivetrain (around 3 per cent for the chain and bearings) and the acceleration work after slow bends. On this mountainous stage, aerodynamic resistance and uphill resistance are similarly distributed. If the stage is flat (1000 metres of climbing over 180 km), the distribution changes to 66/17/17% aero/mountain/rolling resistance. If the rider rides solo, the proportion of aerodynamic drag increases a little more.
The calculation is based on the assumption that six breakaway riders will slipstream each other on stage 18, which reduces the proportion of work against the wind accordingly. The longer a rider rides alone at the front, the more the weighting shifts in favour of aerodynamic resistance - and the less likely it is that one rider will be able to get through alone.
Number of the day: 6:17 minutes
The simulation for the 18th stage shows that the best possible bike aerodynamics give you a 6:17 minute advantage over a light bike - even though more power is invested uphill than on the flat or downhill.
The (almost) entire field at a glance*
*) The calculations are based on the bikes tested by TOUR in the laboratory and wind tunnel. The bikes at the Tour de France may differ in some details. Of course, we have not yet been able to analyse last-minute prototypes. Background to the simulation.
Table: The ranking of the escape machines on the 18th stage. Aerodynamics trumps lightweight construction - despite the 3100 metres of altitude.
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.
