GOING FOR GOLD
He’s the Commonwealth Games champ and Olympic medallist, and yet has never been in a wind tunnel. So what would Henri Schoeman learn from his Silverstone tunnel debut and how can you apply it to your racing? We find out
For an Olympic medallist, Commonwealth Games champion and World Triathlon Series Grand Final winner, it’s surprising that Henri Schoeman has never visited a wind tunnel before. If the South African’s potential performance gains are realised, it might also prove alarming for his ITU World Series rivals. As one of the world’s best triathletes, the 28-year-old has flown into the TotalSim HQ at the Silverstone Sports Engineering Hub to hone his riding position and test out new tri kit ahead of the World Triathlon Series and another assault on the Olympic podium [Henri’s visit and interview took place before news of the year-long delay broke].
“I’m really excited to see how we can improve going forward,” Henri exclaimed. “Aerodynamics will play a big part.” It can be argued that Henri has more reason than most to optimise his aero gains. As a renowned swimmer, regularly rivalling another Huub-sponsored athlete, Slovakian Richard Varga, to emerge first from the water, Henri is often in a solo or mini breakaway on the bike, increasing the time he’s exposed to cutting through the wind at the head of race.
Furthermore, much discussion over the big race in Japan centres on how to mitigate the fierce heat and humidity, and, while it’s conceded that being in the slipstream typically saves energy, spending more time facing a cooling headwind might not be such a disadvantage. “It’s changed the way we think about race tactics,” Henri says. “I might rather be cycling into the headwind, cooling down, than in the pack. We’re here to play around with my bike position and see what fabrics work best. I’m fortunate that Dean [Jackson, Huub founder] has been able to bring me over from South Africa for this opportunity because there’s always room for improvement. There was a different athlete on every World Series podium last year; it’s become so competitive. So, if we can find a 20-watt saving just on bike aerodynamics, over an hour’s cycling, that saves a lot of energy for the sprint at the end of the run.”
After placing ninth in the Tokyo test event last year, Henri is optimistic about his 2021 Olympic chances. “I’ve grown up in Durban accustomed to tropical, hot and humid weather,” he says. “And having a smaller frame [170cm and under 60kg] is an advantage. Hopefully I’ll cope better than other athletes, but don’t get me wrong, it’s still super tough, it’s also going to be mentally hard. I’m confident that if I’m in shape, it could be my day.”
Henri is testing Huub’s proposed tri-suit for the 2020 season against the South African team’s 2016 version – one that he wore to secure his country’s only Olympic triathlon medal to date. At first glance they look similar: the cut; tailoring; familiar green hue with multicoloured trims of the Rainbow nation’s flag. Yet the variables are almost endless in the focus to triangulate hydrodynamic, aerodynamic, cooling and comfort properties to deliver the optimal performance trisuit.
“Keeping the fabric close-knit retains its hydrophobic and aerodynamically efficiency,” Dean explains. “But we also need to be looking at the cooling effects. Henri is slighter than other athletes, so this shouldn’t be as important, but for races where the water and air temperature will be high, it’s still something to consider.”
There is the option of spraying on a hydrophobic coating during production. Hydrophobic essentially means to repel water, with studies showing a performance gain of 1.5% less drag compared to traditional tri-suit materials and an increase in speed of around 1.2%. That’d represent a time saving of 12secs over 1,500m for Henri, potentially critical as the race splits around T1. There is a pay-off, though. “It can block sweat leaving the body,” Dean says, meaning core temperature rises. “That’s something we’ll need to figure out.”
FIT IS KING
It might seem obvious, but the tri-suit also has to fit. Many an age-grouper will be familiar with trying to squeeze into a suit that has seemingly shrunk over the winter months, but comfort and range of motion are not the only considerations. If the fabric is stretched too far, its surface becomes rougher, disrupting the airflow rushing over the material, and compromising its aerodynamics. Dean also discusses bonding the seam rather than stitching it because of a potential hydrodynamic benefit of “about 1%”. But Huub also needs to learn the aero benefits from the wind tunnel, as seams – or ‘trips’ – can add as much as 30-watts resistance if placed incorrectly.
“There’s a lot of sensitivity around seam placement,” says Jon Paton, group leader of TotalSim, an expert in computational fluid dynamics and a member of Huub’s Fellowship of Speed, along with other world-leading experts in physiology, design, aerodynamics, hydrodynamics, thermoregulation and athlete performance. Jon knows about skinsuits because his insight is also integral to the work of TotalSim brand Vorteq that makes elite level cycling equipment. “It’s also athlete sensitive,” he adds. “There’s an optimum design for every athlete for every event for every speed. One size does not fit all – trying to understand what makes you faster is the hard bit.”
The lanyard for the tri-suit zip is noticeably absent. It serves little purpose given the quickrelease mechanism at the neck and would simply sap watts flapping in the wind. Even sponsor logos are a consideration. If they can be sublimated into the fabric (a sealing technique using an extremely high heat) as opposed to vinyl printing, it should provide a further aerodynamic advantage.
The first task is to capture Henri in his regular cycling position using scanning hardware
reminiscent of a handheld airport security scanner. While this could be used to make a mannequin of the South African for wind-tunnel testing different fabrics in the future, it equally allows for a virtual prototype tri-suit to be created. “We take the right dimensions and remove all the wrinkles on the computer,” Jon concludes.
THE DEVIL IN THE DETAIL
Henri adopts a fixed body position, aided by an outline of his silhouette projected on to the floor in front to assist in holding form. It’s not as easy as he makes it look, but has the desired effect of isolating the performance of the different tri-suits. Three different speeds, 40, 50 and 60km/h, are also tested and to become more specific still, Jon suggests looking at the speeds that will be generated on the ITU World Series circuit.
“It normally makes sense to target our efforts towards the higher speeds,” he explains. “Because drag is proportional to velocity squared, the faster you’re going, the more energy you’re putting in to fight air. Finding a 1% aero gain going uphill isn’t going to give you the same performance improvement as 1% downhill.”
The results are impressive. The 2020 version, the Anemoi+, shows a 15-watt saving at 60km/h, akin to descending at speed, compared to its 2016 counterpart. This promises a sizeable improvement for Henri. Where savings can be lost in an instant, though, Dean insists, is if the tri-suit zip is released at the start of the bike leg. “Everyone just undoes their suit during the race,” he laments, and the testing proves Dean correct. The data suggests a loss of 3-5 watts for an unzipped suit and sharpens the focus on other innovative Huub kit where substantial aero savings can also be made.
For example, Henri’s cycling shoes have a Boa closure system to help provide a secure fit, but the protruding tightening-and-release dial juts into the wind. Prototype Huub aero-overshoes are tested that cover the dial and instantly produce an eyewatering 6.7 watt saving at 50km/h and a 7.3 watt saving at 70km/h. “That has to be worth a 4sec extra faff in transition,” Dean exclaims, but decides a better option still would be to tailor three-quarter
overshoes that already cover a clipped-in cycle shoe and won’t restrict Henri slipping his feet in quickly on a flying mount exiting T1. The devil, as always, lies in the detail.
THE HOLISTIC APPROACH
“In a race, all I’m thinking about is trying to get into as tucked a position as possible,” Henri says. “The nice thing about this wind tunnel is that I can see my body position on the camera and, by getting a feel for it, I can practise that position.”
Today, the 15-time ITU race winner is in the safe hands of TotalSim’s Paton, also part of Huub’s Fellowship of Speed collective. “We’ve been lucky to work on the past three Olympic campaigns and the focus has slightly shifted from the technology to working in combination with the cyclist,” Jon explains. “Bang for buck, it’s becoming easier to find the gains with the athlete than it is purely in equipment.
“We’re looking at super top-end, elite level performance,” he continues. “Cycling-wise it’s head position, posture, working with an athlete to see how their form changes as they tire. The purpose-built cycling wind tunnel at Silverstone allows them to complete a turbo set that, if they repeat 20mins later, may see an increase in drag of 2-3% just as a result of deteriorating form through fatigue.
“Our job is to inform the athlete that this stuff could be as important as the latest shiny suit. Change the angle of the elbow. Work on the head position. Practise yoga to strengthen the core. Then it all starts to knit together – the marginal gains approach.”
Henri is first invited to undertake a freeform session to investigate potential drag from subtle changes in body geometry. He tilts his head, flexes the elbows and switches hands from hoods to drops. “Ninety-nine percent of the freeform session we look at the drag coefficient, not at what affects his power input or comfort on the bike,” Jon explains. “CdA (drag coefficient x area) is a convenient measure because it is non-dimensionalised to allow comparisons between different speeds and athletes. We can also see it in real-time, as can the athlete on the screen in front.”
ONE STEP AHEAD
Jon cites the Huub-Wattbike track test team as some of the most aero cyclists to have visited the wind tunnel. The successful quartet, led by another Huub associate, cyclist and aerodynamicist Dan Bigham,
“Henri’s new bent elbow position demands more core stabilisation – ‘I shot myself in the foot a little with the position,’ he notes wryly”
have made lowering CdA an artform. The riders are able to dip below 0.2 CdA, meaning they can put in around 30% less power to go the same speed as your ‘average’ rider. However, a 4km track team time trial is markedly different from a 40km ITU cycle leg, where squeezed hip flexors need to remain responsive for a 30min 10km run.
“It comes with work and perseverance,” Jon says of lowering CdA. “This is Henri’s first time in the tunnel and when we show him these numbers and explain how he can put in 20% less effort to go the same speed, I think he’ll be pretty surprised.”
And so it proves. When Henri sits up with hands on the hoods, it takes 327 watts to pedal at 45km/h. Around 20 watts can be saved by switching to the drops, but there’s a further 10 watts advantage by keeping his hands on the hoods and simply bending the elbows. The advantage of adopting a more aero position on the hoods versus straight arms on the drops equates to a time saving of around 35secs over a 40km ITU bike leg. His overall body position is higher, but his riding position more aerodynamic, and it mirrors a trend currently seen more frequently in track cycling, with the handlebars set slightly higher and riders flexing their elbows.
“Currently, the fastest on the track, sprint-wise, are the Dutch,” Jon explains. “But their hand position isn’t as low as they can go. It also allows them to generate more power because it opens the hip position and brings in the glutes more.”
Henri’s new bent elbow position does demand more core stabilisation, though, as he confirms during a brief break in testing. “I shot myself in the foot a little with the position,” he notes wryly, but appreciates its potential in the chop-and-change world of criterium-style ITU racing. “It’ll be more tiring, but worth it to get another 20-watts benefit,” he notes. “If I adopt it to take a 20sec ‘pull’ on the front, I only have to hold the uncomfortable position for a short period.”
It’s a familiar epiphany to Jon. “Everyone whinges [when adapting to a new position] and then everyone says: ‘Well, for 40 watts, I’ll work a bit harder’,” he says. “Henri is never going to be able to find 40 watts in training between now and the Olympics [even in 2021], but he might through aero adjustments. He needs to rotate the pelvis to roll the hips forward and consistently drop the elbows, but trying to get there in one step is a tall order. It’s similar to going for a bike fit and getting slammed into a 50mm lower stem. It’s too uncomfortable initially, but you can move there over time.”
Henri’s already one step ahead when it comes to conditioning. “It’s incorporated into the programme,” he says, speaking fondly of his training base at the Prime Human Performance Institute in Durban. “Making sure the hip flexors are always flexible is essential for cycling and running. I know a lot of people coming from a running background are inflexible, but I find I have good flexibility coming from a swimming background. And if there are any tight areas, I make sure they’re worked on by a physio, just to minimise injury risk.”