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Performance: Paris-Roubaix by numbers

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Paris-Roubaix is often likened to a lottery, but on the 253.5km route from Compiègne to Roubaix John Degenkolb (Giant-Alpecin) demonstrated that you can make your own luck if you have the requisite mix of strength, savvy and a solid team.
To underline the importance of supporting riders, Xavier Disley PhD has analysed the team results of Paris-Roubaix winners since 2005. The only rider to win the event with fewer than two team-mates in the first forty positions was Fabian Cancellara, in 2013. Last year, Degenkolb finished 2nd, but only had one team-mate anywhere near (Bart De Backer, who finished six seconds back in eleventh place). Yesterday, Degenkolb had three team-mates in top-40 positions – De Backer again (12th), Ramon Sinkeldam (27th) and Koen De Kort (31st) – and won in a bunch sprint.
Soon after he exited the venerable Roubaix Velodrome showers, Giant-Alpecin’s Koen De Kort, re-entered the 21st Century and uploaded the day’s ride to Strava. De Kort provided the following descriptive title for the file: “Paris-Roubaix, another Monument win. Hard day, great legs and the best teamwork yet. Proud of John and the entire team.”
The statistics from his ride provide an insight into the demands of Paris-Roubaix, as well as the tactics and team-work which underpin victory in a Monument Classic.
The first 100 kilometres of the parcours are little more than an amuse-bouche. Beginning in Troisvilles, the peloton gobbled 27 teeth-chattering cobbled sectors before the race arrives in Roubaix.
The road captains need to keep team-mates close to offer a spare wheel in case of a puncture, pilot their leaders to the front of the peloton and allow them more space to select a favourable line through the stones.
We find evidence for this multifaceted role in De Kort’s Strava file. After 80km of racing, he begins to pick up the pace, accruing a number of KOM’s and podiums in short succession. Koen De Kort continues his aggressive ride securing high-placings on the majority of the cobbled secteurs.
Analysis of De Kort’s power output over the race reveals the stochastic surges of power required to hold position on the cobble-stones. Former Paris-Roubaix winner Magnus Backstedt likened riding the segments of pavé to stringing together a series of track-pursuit efforts: repeated intervals of four to five minutes at a power output equivalent to between and five watts per kilo.
This is consistent with De Kort’s efforts. Weighing 70kg, the Dutch rider produced 375 watts (5.4w.kg) for 3min50sec on the Trouée d’Arenberg. However, unlike the track, the cobbles are a brutal and inconsistent surface, leading to spikes, surges in power and even periods without pedalling, likely caused by the swerves and bunny-hops required to make progress and avoid the worst sections. Again, we can see the evidence of this in De Kort’s power file. Early in the Arenberg forest there are two periods where his pedalling stopped completely. While his average power for the segment was 375 watts, De Kort was forced to make bursts up to 859 watts.
After covering a total distance of 256km, De Kort reached the velodrome in Roubaix with an average power of 286 watts. However, it is the ‘weighted average power’ which provides the most telling insight. The ‘weighted average’ is a way of describing average power which accounts for the changes in power output over the course of a ride. Effectively, it describes how hard you would have had to ride to generate the same workload if you held a consistent power output for the duration. De Kort’s 2015 Paris-Roubaix ride was equivalent to him riding at 321 watts (4.6 watts per kilo) for over six hours – an effort many amateurs would struggle to maintain for 20 minutes.
As with all Classic races, the distance, repeated high-power efforts and large field combine to create a race in which only the strongest team survived, and from this team, the champion emerged. For the likes of Cancellara, Roubaix can be conquered single-handed. For all others, even for a rider as strong as Degenkolb, it is a team event.

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