Helen Wyman’s power file from the 2016 World Cyclocross Championship Course
This year’s world championship takes place at the well-known Zolder motor racing circuit, at 3.2km long it is one of the longest courses on the world cup circuit. The course is famous for its sandy terrain, and its 3 climbs and 3 man-made flyovers.
Below is the power trace taking from the world cup race which acted as the test event for the World Championship course.
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.
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.
Now, let’s have a look at a few different elements of the course…
Section 1 – Formula 1 and the Woods
The first section of the course involves a few key of elements. It starts with a long section of road through the start finish straight and past the grand stand. In the power file you can see that Helen holds power for a prolonged period—around 30s. This 30-second effort in zone 5 might not sound a lot but in cyclocross terms it is a long effort.
The big spike in the middle of this section is where Helen has to go over the first flyover. 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.
The race then enters a technical section through the woods; tight U-turns and small rises punctuate this section this leads to repeated short accelerations. You can see that out of each of these corners Helen has to produce a lot of watts, three of her five highest wattages come in this section of the course.
Section 2 - Climbing
The second section of the course incorporates the first two climbs of the lap. The first—the famous Sacramentsberg—comes as you exit the woods. You will see in the power file that the power output on the climb actually takes the shape of an M. This is because in the middle of a climb there is a small patch of concrete sticking out this means Helen has to unweight her wheels as she goes over it to ensure she doesn’t puncture. This is one of those nuances that every cyclocrosser knows about, but probably not something that you’d pick up watching the race on TV. For the racer this concrete means that the climb is actually two hard efforts – 321w for 10s followed by 362w for 8s with a peak of 524w and with a 1s break in the middle.
These nuances are what makes a cross circuit much harder to ride around than it would seem on the TV.
After the descent of the Sacramentsberg comes a section where Helen has to complete 3 hard sprints in the space of 35s. These efforts take her up and over the second bridge on the course—another example of how hard those bridges really make the race.
From here the course climbs, only slightly at first (fig 6), but then steepens. It is a section of the course where the wind can play a big role. This head wind section can offer the smart racer a respite if they are on a wheel and in the draft.
The middle of the next climb is one of the most spectacular parts of the course, and the following off-camber section is one of the most technical sections of the entire race. All together, the section consists of an uphill U-turn into a section of off camber. This section is often wet, slippy, and requires a lot of power to get through quickly. It also has 2 lines, the upper line and the lower. The upper line (which Helen prefers a is faster but the lower line requires less power. 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 has her peak power here of 742w and holds over 650w for 3s. This in fact is her highest power output of the entire lap.
The pain doesn’t end here, however, immediately after the off camber section comes another climb, this time on tarmac and takes the riders to the highest point of the course. You will see that throughout this whole section Helen’s heart rate has been rising slightly. This means she has been riding at an unsustainable pace since exiting that first wooded section.
Section 3 – Technical Descending and Recovery
From the highest point on the course riders now dive back down to the racetrack. This descent starts with a rooted wooded section before dropping into the traditional sandy and rutted descent that characterizes Zolder (fig 8). This descent is dangerous enough that the organizers employ inflatable barriers at the bottom for rider’s safety should they loose control.
While this descent is challenging at the best of times, imagine negotiating it when you are approaching it at 190bpm. One of the true skills of a cross rider is being able to control their bikes expertly when they’re in the red. Most riders would be about ready to fall off their bikes at this point.
The amazing thing about this section of the course is that Helen actually uses it as recovery. In this section her heart rate actually drops roughly 10bpm, from 195-186bpm (fig 7). In fact, this is one of the only sections of the course where she is able to recover. This section takes Helen 1min 12s. In that time she’s still averages 115w.
Section 4 – Running and (more) climbing
You may have noticed in the power file that in the last section of the course Helen’s heart rate hits it’s highest peak however she doesn’t seem to be producing any power. This is because the final section of the course starts with a brutal run up that is so steep in places riders have been known to use their free arm to brace themselves while running up the banking.
Immediately after the run up the riders have a very small space to re-mount. At that point they turn right onto a new feature in the course—a very steep 100m climb. Dependant on the weather this section may be run or ridden (fig 10). From the top its all downhill 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. 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.
And there we have it, a lap of the World Cyclocross Championship course.
Fig 1,Outline of the World Championship Course in Heusden-Zolder
Fig 2, Helen's power and heart rate trace for lap 2 of the test event - the graph has been split in 4 sections which will be looked at indivudall
Fig 3, Power and Heart Rate Trace for Section 1 Fig 4, Helen in training in section 1 of the course (photo CX magazine)
Fig 5, Power and Heart Rate Trace for Section 1 Fig 6, Helen at the start of the climb (photo Anne-Marije Rook)
Fig 7, Power and Heart Rate Trace for Section 3 Fig 8, Helen descending the infamous Zolder drop (photo Kona)
Fig 9, Power and HR trace for Section 4 Fig 10, Helen running up the steepest section of the course (photo Lasala)