This piece has been made in association with Cervélo.
Get a group of engineers together and you’ll find an assembly of minds charged with thinking outside of the box. Get a group of bike engineers together and they’ll be thinking very much inside the box – the ones within which the UCI constraints have limited frame design. Happily, those boxes recently expanded, so at least engineers got a bit more space to play with, or at least a bigger box to think inside.
The Cervélo S5 explores that space with a subtlety that’s easy to miss, yet offers much consequence in our sport of millimetres and grammes of drag. The S5 is, in fact, three to four per cent faster than its predecessor, all while looking nearly identical.
Those similar looks belie a mass of big improvements. The process of reimagining what the S5 was capable of required goals to shoot for. Simplify, refine, and enhance: those were the directives guiding the redesign, and while you’re likely to miss them with a casual glance, the improvements are vast to the careful eye that lingers.
To simplify, Cervélo engineers designed a new, more user-friendly cockpit. The spaceship shape remains, but no more will riders need to order a dealer fit kit. The bike ships with spacers, and a new fork design means there’s just one bolt length for all sizes and stacks. That’s great if you need to adjust your position. And if you don’t, you still benefit from a weight savings of 53 grammes.
Refining the S5 started at the front of the bike. Cervélo reshaped the handlebar to improve adjustability and comfort. The bars tilt from 0 to +5 degrees using a two-bolt interface – no finicky shims to contend with. The shape of the bar also streamlines the interface with your shifters, providing a flat transition and a more comfortable location for your hands.
With that same user-first design process in mind, Cervélo expanded the S5’s tyre clearance. Riders can now fit up to a 34mm tire with 4mm of clearance on every side of the tyre. The S5 comes stock with 28mm tyres, for which the new Reserve wheels are optimised. But if you’re after big rubber, the S5 is up to the challenge.
While the general eye-catching silhouette of the S5 remains largely unchanged, a closer examination reveals tweaks and tabulations that make the bike vastly more slippery in the wind. Part of that aerodynamic improvement lives in changes to frame tube shapes. But even more comes from the Reserve 52/63 wheels.
Cervélo managed to chop 50 grammes of drag through the wheels as compared to the Reserve 50/65 wheels. As the name implies, the front wheel is 52mm deep, while the rear wheel is 63mm deep. And the front wheel features a slightly wider 25.4mm inner rim width than the rear wheel, which sports a 24.4mm inner rim width. Different dimensions benefit different wheels based on the position on the bike, so that’s exactly what Cervélo did with the 52/63 wheels. They’re optimised to work in conjunction with the frame to reduce drag in the over-all system.
The front wheel profile is slightly smaller, not to mention wider and rounder, to counteract the effects of crosswinds on the wheel. You get more stability balanced with as much drag reduction as possible. The rear wheel is taller and asymmetrical, since it’s partially shielded by the frame and the rider. The taller rim profile also lessens the effects of crosswinds, since winds hit the rear wheel at narrower yaw angles.
Boxed in, boxed out
But what about the frame? And what’s the story with these UCI boxes? Cycling’s governing body, the Union Cycliste Internationale, has written rules that constrain frame design. Until recently, designers had to ensure each tube shape did not exceed a 3:1 ratio – that is, the length of a tube shape could not be more than three times its width. The result? Less aerodynamic frames.
The 3:1 rule went away a few years ago, and since then the UCI has further opened up more possibilities in frame design by refining its regulations to include thinner tube sections. Notably, frame designers can now add compensation triangles.
Without getting too deep into the weeds, you can see a compensation triangle on the S5 at the bottom bracket junction. A taller, flatter bottom bracket helps increase aerodynamic performance, and it even works in conjunction with water bottle placement to improve airflow.
Both the head tube and the bottom bracket have gotten deeper. And the head tube extends forward in an ‘aerodynamic nose’ that further decreases drag over this leading edge of the frame.
Less noticeable are the new aero shapes on the down tube and other tubes. Frame engineers can tweak tube shapes to improve airflow in key sections of the frame. Another example is the sharper, more modern corners you’ll see throughout the frame. This helps discourage ‘dirty air’ from forming behind tubes, thereby creating drag.
Overall, the S5 is lighter than its predecessor, yet its surface area has increased by 1.5 per cent. Lighter and more aero? Not a bad combo.
(Not so) secret testing
Pro riders have been aboard the new S5 for quite some time now – perhaps even before many of us even noticed. Given the consistency of the bike’s silhouette, only keen eyes would have noticed anything.
Yet there it was, the S5 crossing the finish line first underneath Jumbo-Visma riders at Paris-Nice, Omloop Het Nieuwsblad, and E3. And again on the podium at Gent-Wevelgem men’s and women’s races, Dwars door Vlaanderen, and Liège.
Oh, and perhaps you watched the Tour de France this year? The S5 had more than a few shining moments. If you didn’t notice, well, that’s good enough reason to go watch some replays, right?
All told, Cervélo’s holistic approach to the S5 redesign has netted riders a faster bike that’s lighter and even more user-friendly. It’s race-proven but more ready than ever for everyday riding too, with added tyre clearance, comfort, and adjustability.