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Have we reached peak aero?

In-depth
15 Jul 2020
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Everything is getting more aero, but how much more speed can we squeeze from our kit – and is it worth it anyway?

Words Joseph Delves Photography Tapestry

Like supermodels in the 1990s, bikes are getting taller and thinner. Even mid-market racers now seem to come with aerofoil tube profiles, integrated cockpits and deep-section wheels.

Where once aerodynamics were the preserve of a peculiar breed of time-triallist, resplendent in their pointy helmets and go-faster socks, the science has since found its way into the mainstream. But do we really need it?

Absolutely, according to Nathan Barry, an engineer responsible for making Cannondale’s bikes as slippery as possible. He believes the move to a practical approach to aerodynamics is possibly the biggest step-change in bike design we’ll ever see, ‘yet because it’s invisible, it’s hard to get riders to pick up on it’.

As an example, Barry cites Vincenzo Nibali’s win at the 2018 Milan-San Remo. Escaping on the short final climb of the Poggio 6km from the finish, the Italian arrived at the summit with a 12-second advantage over the bunch.

Once over the far side he gave away almost all of those seconds to the charging pack in the flat 3km final dash to the finish, but just managed to hang on long enough to raise his arms for the win.

Nibali’s remarkable victory was achieved aboard Merida’s Reacto aero bike, rather than the brand’s conventionally shaped Scultura that he had ridden on previous attempts.

‘I don’t have data on the differences between the two bikes, but I bet there’s a lot there,’ says Barry. ‘Given the numbers I crunch all day at Cannondale, if I compare, say, the SystemSix to the less aero SuperSix, at racing speeds it saves about three seconds per kilometre. So differences in kit can absolutely be the difference between winning and getting swamped on the line.’

Rules and regulations

Air is a total drag. Its force on a rider increases exponentially as you get faster, such that by the time you hit 45kmh it accounts for 90% of the resistance you have to work against. You don’t have to be Vincenzo Nibali to see the advantage of being more aerodynamic.

 ‘In the 1930s people started experimenting with fairings, and suddenly you saw this crazy increase in speed records,’ says Barry. ‘That’s how we existed until things like Y-frame bikes or the Lotus bike appeared in the late 1980s, at which point the UCI stepped in and decided it wanted bikes to look how people already imagined them.’

A whole handbook of rules now dictates the exact form of the bikes and kit racers can compete with. ‘We treat it as just another set of constraints we have to work with,’ says Barry.

‘If you want to run a Shimano drivetrain you have to accept the components will need to be located in certain positions. In both cases, you try to get the most out of what you’re given.’

Advances in carbon composite materials and computational fluid dynamics mean that bike manufacturers can now make machines that are much more slippery in the wind, even within the restrictions placed on them by the sport’s governing body, and that translates to faster bikes. But aero bikes still tend to be harder to sell to the wider cycling public than more conventionally shaped frames. So why is that?

‘People want performance, but there’s always something that they’re not willing to give up in return,’ says Barry. In most cases, he believes, that thing is weight.

‘For most riders, investing in an aero bike and kit will leave them much faster than focussing on weight will. But we don’t see it happening.’

It probably doesn’t help that weight is easy for the layman to judge, while aerodynamics has to be taken largely on trust. Yet even in the increasingly science-driven world of pro cycling, aerodynamics is often still overlooked.

‘Cycling is pretty conservative. We’ve had 100 years of weight and only a decade of real interest in aerodynamics,’ says Barry. ‘There’s also a split when you talk to pro cyclists. If you ask them about time-trialling, they are obsessed with aerodynamics. But suggest that the same thinking might help them on the road and they’re not interested.’

Under the radar

So what do you do when aerodynamic bikes have proven advantages, yet you still can’t seem to convince everyday riders – and in many cases even pros – of the benefits?

In the case of many top brands, the answer has been to slip aerodynamics in as an additional perk rather than the headline act of new bike launches. Cannondale recently overhauled its flagship race bike, the SuperSix Evo, replacing its traditional frame shape and round tubes with a racier silhouette complete with dropped seatstays and truncated aerofoil tubes. Yet the focus remains on the bike’s lightness and ride quality rather than the aerodynamic gains.

The same has happened with other popular lightweight race lines, such as the Specialized Tarmac, Scott Addict and BMC Teammachine. Each retains a reputation as a nimble climber and comfortable ride companion, but now with added aerodynamic efficiency as a bonus. Part of this deliberate lack of attention to all things aero could also be that, for a period, the drive to improve aerodynamics simply got out of hand.

‘Aerodynamic design got to a point where the people buying these bikes were finding them pretty useless,’ claims Gerard Vroomen, co-founder of Cervélo and owner of 3T and Open Cycle.

‘They’re perfect for pros racing on smooth, closed courses, but for normal people riding around potholes and other traffic, those bikes are useless. Look at the geometry. In the catalogue everything is beautifully integrated, but add a couple of spacers so you can reach the handlebars and they suddenly look like a jigsaw puzzle gone wrong.’

Vroomen believes that by not putting enough value on comfort, the industry has been off track for the past 20 years. ‘I was partly guilty myself during my time at Cervélo,’ he says.

‘My P4 time-trial bike is a favourite design, but user-friendly is not how anyone would describe it. It had a rear brake that did a poor job of its primary function but was aerodynamically well hidden. It had a nicely integrated bottle that made the bike faster but was so low it was hard to reach and was such a cumbersome triangular shape it was awkward to drink from. It’s definitely engineering gone a little too far.’

Vroomen reckons the trend for companies to tailor their aerodynamic bikes more to the needs of their normal customers will continue well into the future.

‘Aerodynamics will make you faster, but not if you give up all these other things. Instead, I’d rather design something aerodynamic around a setup that actually works. For some brands, a first step was aero bikes that accepted bigger tyres. Except when you fit these to most of them, it messes up the airflow.

‘I’ll take the tyres as the starting point and design around them. In doing that I’m focusing on the paying customer. That’s a difficult thing to do when you’re making bikes for professional racers who don’t want to use 30mm tyres, and then trying to sell the same product to your customers.’

Vroomen now believes many riders would be better served by the versatility and comfort of the average gravel bike as opposed to apeing the pros by choosing an aggressive racer. The 3T Exploro he recently designed remains the world’s only full-aero gravel bike.

‘“Gravel bike” is a bit of a stupid name,’ he says. ‘For most people, it’s a bike to ride everywhere, including on asphalt. On asphalt the same rules apply as on a road bike, so why wouldn’t you improve it aerodynamically?

‘Then off-road you might not be riding as fast, but what if that’s because you’re facing a 50kmh headwind? Your ground speed might be 10kmh, but relative to the wind that’s 60kmh, so your frame, wheels and apparel all still matter.’

The price of speed

If, as Vroomen suggests, aerodynamics should simply be built into all bikes and kit, why aren’t we seeing it across the board at every price point? The reason is that, historically, it has always been very expensive to make something aero – wind-tunnels don’t come cheap.

‘There are a handful of companies that take it seriously,’ says Vroomen. ‘For the rest it’s a marketing gimmick, no different from a paintjob or the odd swoopy tube shape.’

One company looking to change the way aerodynamics is perceived – and priced – is Sussex-based wheelmaker Hunt. In 2017 it hired Italian wheel engineer Luisa Grappone, who used to design aeroplane components before moving onto bicycle wheels with stints at 3T and Campagnolo. 

In her view, the key to making aerodynamics more affordable lies in the ability to build virtual environments in which to experiment. ‘These days software is absolutely fundamental,’ she says. ‘Without it, you can’t do anything.’

Typically created for the aerospace or automotive industries, the programs necessary to create and test aero components used to be prohibitive, but now they can be bought on subscription, and with cloud-based computing are more affordable.

‘Plus you no longer need your own servers or an incredibly powerful computer to run them,’ says Grappone.

No one is making software just for the cycling industry, so a large part of her job is adapting what she has. ‘It means we can start playing with our ideas without needing to go to a wind-tunnel itself. Now the goal is to refine it further. The model for each wheel can easily contain up to nine million cells or data points.’

In other words, it still takes a fair amount of time to refine wheel shapes in virtual reality, and a fair amount of money to test those designs in the real world in a wind-tunnel.

However, that will likely change as the virtual process continues to become more refined, with less time required in wind-tunnels, which should make aerodynamically efficient wheels and components cheaper.

According to Grappone, this is a sign of just how advanced the bike industry is becoming. ‘Before, no aerospace engineer would want to work in it,’ she says. ‘Now it’s seen as no less worthwhile than the automotive industry.’ 

Where next?

Vroomen believes that unless the UCI relaxes its rules on what a road bike can look like, we could be nearing peak aero in terms of frame design.

‘I don’t think the bike itself can get much faster,’ he says. ‘You can make greater improvements in the rider – through legal or illegal means. Right now it’s more about the power going in rather than what’s being consumed by drag. We’ve reached peak aero, and designers are now finally looking at how to make their bikes comfier and more fun.’

Barry believes the integration of components and accessories across all types of bikes is likely to be the next step. ‘We’re integrating a lot more things now, but away from racing we’re only scratching the surface. When you consider storage and lights, there’s far more we can do.’

With aero bikes becoming lighter and more usable, and climbing bikes becoming more aero, Barry sees the circles in many manufacturers’ Venn diagrams increasingly converging – the result being bike brands producing one single do-it-all aero-optimised racer.

Whatever happens, taking aerodynamics seriously is now a prerequisite for brands looking to make the best bikes they can. And while many big goals have now been met, there’s still plenty of interest across a diverse range of fields to pursue those that remain. That will lead to bikes and components that are faster, comfier and more user-friendly than ever.

However, with uptake among racers and everyday riders still surprisingly tentative, there’s plenty of advantage to be had for those accepting of the science to make gains over their rivals. It looks like we’ll be chasing peak aero for a few years yet.