Ahead of the UCI World Cyclo-cross Championships this weekend, Helen Wyman has shared her power data from the Heusden-Zolder course in Belgium, which was also used for Round five of the UCI Cyclo-cross World Cup. The data has been overlayed onto on-bike footage of a lap of the course in order to give an idea of the demands of the 3.2km circuit.
Wyman’s numbers are taken from her second lap in the World Cup race on Boxing Day, where she finished 12th. Sanne Cant took the win in the women's race while Mathieu Van der Poel triumphed in the men's event.
The head-cam footage is provided by Yu Takenouki, who rode the course during an open practice session. Stages, the power meter manufacturer used by Wyman, have produced two videos, the first pairing Wyman's data with key parts of the course, and the second (at the bottom of this article) showing a lap in its entirety, with no overlay.
The course, situated at the Zolder motor racing circuit, is long at 3.2km and features three climbs and three man-made flyovers, as well as several patches of sandy terrain and one particularly steep section where riders should be forced to dismount and run.
Crunching the data
James Spragg, professional coach who works as a consultant to Wyman, has broken down the numbers to provide an in-depth analysis of the effort it takes to race a lap of the course.
Helen Wyman's power data from Round 5 of the UCI Cyclo-cross World Cup (HelenWyman.com)
“The first thing to notice is the amazing number of power spikes per lap. The dotted line represents Helen’s FTP power, her power rises above this on 28 separate occasions within the 8mins 43s it took her to complete this lap. That’s on average a sprint every 18s,” explains Spragg.
“The women’s race was, in total, 5 laps – and in doing the math, you will see that makes for a total of 140 sprints in 45mins! Try doing that at home on the turbo.
“All of this sprinting makes for an extremely variable effort – the VI rating (the difference between average and normalized power) for this lap is 1.2. For comparison the VI for time trial would be 1.05.”
The race starts out on the motor racing circuit before entering the woods and becoming increasingly technical, with Wyman having to produce high power through the corners.
The Sacramentsberg is the first proper climb on the menu and Spragg explains that Wyman’s data takes the shape of an ‘M’ due to the small concrete section in the middle that forces riders to unweight and turns the climb into two separate hard efforts.
The next climb produces Wyman's highest power output of the lap as riders tackle an uphill U-turn into a section of off-camber where there are two possible lines to take, as shown in the second video below at 6 minutes when Takenouki takes the high road and Astana's Lars Boom goes low.
“The upper line is faster but the lower line requires less power," says Spragg. "To get up to the upper line Helen has to put out a huge amount of power to stay high enough in the U-turn and get into the upper rut – she posts her peak power here of 742w and holds over 650w on her Stages Power meter for 3s."
The Heusden-Zolder cause for the 2016 UCI World Cyclo-cross Championships (HelenWyman.com)
From the highest part of the course, the riders are then able to descend and though it's steep, technical and sandy, it is "one of the only sections of the course where she [Wyman] is able to recover" and "her heart rate actually drops roughly 10bpm, from 195-186bpm".
There is one section of the course which is so steep that riders are forced to shoulder their bikes and run on foot, and immediately after remounting they have to tackle a steep 100-metre climb before descending to the finish.
“Savvy fans will watch this point in the circuit come race day – this is most likely where the medals will be won and lost," says Spragg. "To get to the top of this feature, Helen produces 415w for 20s – her peak 20s power for the entire race. This is undoubtedly the hardest part of the course – even thought it’s not her max wattage, Helen hits 197bpm at the top of this climb.”
There are three flyover sections spread evenly through the course, and Spragg warns against underestimating their importance to the outcome of the race since they caused some of Wyman's biggest power spikes.
"For spectators the bridges in Zolder may just seem like a way of the course getting over fences that protect the racecourse from the fans, however, Helen’s power file shows how they can have an impact on the race. Getting over each bridge is one of her biggest efforts each lap."