The fastest skinsuits you can’t buy
The technology behind the world’s fastest onesies
You could be forgiven for thinking that skinsuits are one of the simplest aspects of the complex aero package that helps the world’s best time trialists get the maximum speed for their effort. After all, once it’s skintight, what else can you do?
“The difference between a club rider’s skinsuit – the best you can buy – and what the pros have is huge,” says aero bike fit specialist Stephen Roche (no, not that one) who works from the University of Southampton’s wind tunnel. “It’s around 20W for each step, that’s two seconds per kilometre. We once had a national team skinsuit here – I can’t say which one – and it even blew away the pro kit.”
Historically, skinsuit development has been driven by track events at the Olympics. Assos claim to have made the first ever skinsuit in the 70s after testing ski race suits in a wind tunnel. For the 2012 Games, Assos developed the Fenomeno suit for Fabian Cancellara at a cost of $250,000, even though they don’t sponsor a pro team to benefit from it later and they knew it wouldn’t be possible to put a version of the suit into production. “The skinsuit exemplifies the essence of Assos being made to win,” says Assos experience manager Désirée Bergman-Maier, “and the most prestigious race our product can win is an Olympic medal.”
Perhaps unsurprisingly given their TT focus, Garmin-Sharp have been developing skinsuits for longer than most. Robby Ketchell is an aero consultant for the team and previously worked for them directly. “Skinsuits were the first thing that Garmin had me working on from 2008,” he tells us. “Clothing in general gives the biggest gain of any equipment, as 80-90 per cent of total drag comes from the rider. Castelli are great to work with, they are so open-minded. When we have an idea we immediately prototype it and explore the gains. The first new Castelli skinsuit for Garmin in 2011 saved 30W over the previous skinsuit. Then we made another huge step, 17W, for Ryder Hesjedal at the 2012 Giro. We gave it to him on the morning of the final TT.” Over the fast 28km TT course, that 17W improvement will have been worth at least 20 seconds. Hesjedal won that Giro by 16…
A fast suit requires close attention to the fabrics used, the placement of each type of fabric, the location of the seams and the specific amount of stretch on the fabric… but it always begins with the fit. Obviously it has to be tight but the big gains in recent years came from getting the fabric to sit flat. Look at the photo of Lance Armstrong from 2009 (left) – never one to be left behind in the aero arms race, his suit is still all wrinkled. The latest suits are all pre-shaped for the TT position.
Getting the best fit also means teaching riders how to put skinsuits on properly, taking the time to position the seams correctly. For instance, in the arm, the seam should always be at the back.
Certain fabrics that have tested well in the wind tunnel have been problematic to use because their performance hinges on the amount of stretch, forcing every suit to be tailored to the millimetre. Chris Boardman, who worked with British Cycling on the Team GB skinsuits for the 2008 Beijing Olympics, told us that, “Custom fit is essential for optimum performance because you want the fabric to be skintight but under the lowest possible tension so that the weave of the fabric isn’t opened up as that would increase the drag.”
Steve Smith, brand manager at Sportful and Castelli, says that’s an issue they’ve now overcome. “Our latest fabrics have more stretch without losing their aero properties so it’s getting easier to fit riders using standard sizes. Only four of the Tinkoff-Saxo team needed custom suits. That also means it will be easier to put these suits into production one day but that will only happen once we’ve developed something faster for the team. They want to keep the advantage and we want to keep our tech secret. There’s less advantage in selling the fastest skinsuit to privateers than there is to supplying the best kit to a successful pro team. Plus, it’s a small market, even in the UK.”
With the basics nailed down, the development process has become very advanced. The extra
“performance is the overwhelming factor. If we couldn’t prove world class aero on our kit, Movistar
wouldn’t have considered us”
investment is justified by the gains that teams and manufacturers know are there to be had. Ketchell, now freelance, has built himself the world’s only carbon fibre wind tunnel, a small scale system at his home in New Hampshire. What’s more he has the computing power to model the rider’s body and study fabric properties. What his system can calculate in 30 minutes would take the most powerful gaming PC around 36 hours.
“We’re working with boundary layer control, the top 3mm of air flowing over the garment,” says Smith. “By keeping airflow laminar (attached) and only detaching it when we want to, we’ve found very significant gains. We’re also using CFD to look for the inflection point at which the air separates from an oscillating body, in this case the rider’s leg. The aero consultant we’re working with actually wrote the CFD program for oscillating bodies. An off-the-shelf program can’t do that because cars and airplanes move straight through the air but cyclists wobble. The changeover point is around 90rpm – above or below that you’d choose a different structure for the leg of the suit. It’s all about maintaining laminar flow for as long as possible and then achieving a clean detachment.”
One team pushing harder than most to be in the vanguard of cycling technology is Movistar. At the start of this season they began a project with new clothing supplier Endura and renowned cycling aerodynamicist Simon Smart of Drag 2 Zero, who has previously designed his own skinsuits and also contributed to the design of the team’s new TT bikes. Smart explains the benefit of the joined-up approach: “Skinsuits are part of the positioning process. By looking at position, skinsuit and equipment together, we can really fine tune a product so it’s specific to the scenario and rider.”
The partnership with Endura plays to each party’s strengths. “It’s so hard to develop clothing and the expectation of the cost of the final product is so out of kilter with the R&D cost,” says Smart. “Endura have a great manufacturing capability and
they’re based in the UK so it’s ideal. We can each do what we’re best at.”
With lofty targets, this project would stretch any clothing supplier. So were Endura, new to the WorldTour, confident that they could deliver?
“We weren’t freaked out by the challenge,” says Endura’s managing director Jim McFarlane, “but nor were we complacent. Movistar want to retain their #1 UCI team ranking in 2014 so performance is the overwhelming factor. If we couldn’t prove world class aero on our kit – as well as temperature control and pad technology – then Movistar wouldn’t have considered us.”
Now that all the top skinsuits have adopted special fabrics, carefully positioned seams and anti-wrinkle patterns, the question is once again, where do skinsuits go from here?
Smith says skinsuit design has yet to reach its peak. “We’ve gained around 25W since the start of our project and there’s maybe the same again still to come but we’re now looking for refinements – the low-hanging fruit has been picked. We’ll be looking more at thermo-regulation, too.”
Ketchell expects future designs to be even more focused, especially for GC riders and TT specialists: “Fitting will have to be more customised; whenever we focus development on one person we find something really fast. There’s also scope for a suit just for team time trials, one that creates a bigger slipstream for the rider behind. The TTT is unique because the recovery is so key. You have to treat the team of nine as a unit and adding a little drag to create a bigger tow will make that unit faster.”
That leaves us with two things to look forward to: faster kit for us amateurs, eventually; and the world’s first 60kph TTT before long.