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Cervélo S5 2019 review

30 Oct 2019

Takes outlandish aero design to a new level and is incredibly fast and fun to ride, but not as nippy or well mannered as a true road bike

Cyclist Rating: 
Supremely fast • Head turning appearance • Wide tyre clearance • Did we say supremely fast?
A touch skittish in corners • Suffers in crosswinds • Divisive looks

For years aerodynamics just meant riding in the drops. Then it meant cutting off your ponytail and wearing pointy hats.

Then it meant deep section wheels and soon-to-be-banned riding positions.

The common theme was taking things in isolation, optimising parts of a bike or rider without much consideration for the way all these elements interacted.

Then Cervélo came along, and by 2007 it had a life-sized, poseable model of its Team CSC-sponsored rider, Dave Zabriskie.

As the company’s co-founder Phil White told us, ‘We took Dave to this place in LA and had him 3D-scanned. Now we have foam Dave and virtual Dave.’

With foam Dave on wind-tunnel duties, positioned atop whatever rig Cervélo was testing, and virtual Dave doing the same in the theoretical world of CFD, Cervélo was a pioneer of the rider-bike system concept, where aerodynamics is treated as a holistic whole.

With such methods comes this third generation of the S5, a direct descendant of what most consider to be the first aero road bike, the aluminium Soloist of 2002.

And Cervélo has created a marvel, albeit a highly divisive and, in my opinion, brilliantly compromised one.

The S5 smacks you between the eyes like an angry Eubank. The first person I showed it to described it as ‘fugly’.

But, like Chris Eubank, this bike’s eccentricities are its main sell.

For nearly ten grand you want your superbike to look super and, love it or hate it, the S5 looks like the kind of bike that should only be ridden with flames coming out of your shoes.

Each piece segues seamlessly from the last, the frame wrapping around the wheels and rearing up into that stem.

Called to the bar

Instead of the standard-issue single tube, the S5’s stem comes up to meet the bars in a V-shape, with a large triangular gap in between (about which a second friend remarked, ‘Is that where it feeds on plankton?’).

The handlebar sits on top of the V’s prongs and is bolted in position from below.

Cables and hoses run through each prong (in a way Cervélo says improves shifting for mechanical groupsets thanks to the relaxed bends, and makes assembly and maintenance easier), and a shim between the stem-bar intersect means the bar angle can be adjusted between 0°, 2.5° or 5° from the horizontal.

However, says Cervélo, ‘We recommend leaving the bar at 0° to achieve maximum aero advantage’.

Cervélo says that advantage is tantamount to a 42g saving in drag, meaning a real-world saving of 5.5W to the rider.

That’s hardly staggering given that generation two of the S5 saved 28W over the first, which is indicative of how far bikes have come and how hard it is now for engineers to squeeze out further gains.

And to put the V Stem’s contribution further into perspective, an S5 with Cervélo’s last generation of aero bar with exposed cables adds 30g of drag. How so?

Well, in simple terms, it’s because air can flow through the V stem (not around as per regular set-ups) and through the rider’s legs.

Does it actually work? The proof is in the blisteringly fast pudding.

Easy speed

There are a number of things that make this bike quick besides the V bars: the main tube shapes, now larger in dimension with the relaxation of the UCI’s 3:1 ratio rule; the wheel cutouts; the external steerer; the narrow profile – and they all add up to a bike that is the personification of aero-rapidity.

I found myself cruising past riders who were clearly putting in considerable effort, and regularly bagged Strava medals on rides that weren’t exactly performed with intention.

Everything from the first crank stroke through to easily maintaining 41kmh on the flats felt effortlessly quick (usually I’d be happy with 38kmh).

The S5 also made light of headwinds, where I could almost feel – or at least imagine – the bike slicing the air with blade-like finesse.

However, the S5 does not enjoy blustery conditions, and nor does it thrive on technical roads.

To its credit the bike is relatively comfortable all told, and could be more so, as it will fit up to 30mm rubber, but it is found wanting in the cornering and handling departments.

Buy now from Sigma Sports here.

Compared to a more rounded race bike its handling sits in the early stages of languid, and although stable at speed (Cervélo has lowered the bottom bracket a touch to encourage stability) the S5 doesn’t duck and dive as I’d like or track the road anything more than ‘quite well’.

I think both of these things are unavoidable upshots of what Cervélo has set out to do, namely to provide greater stability by lengthening the trail (as a general rule, longer trail means more sedate handling) and to increase head tube and BB stiffness by 13% and 25% respectively.

That’s great for sprinters and those who live by smooth roads, but less great for tackling fast, bumpy corners.

For the rider I am and where I ride, I feel the S5 could do with a touch more frame flex to promote grip at the tyres, and shorter trail (the trail is 57mm incidentally, and I would call 53mm short).

That said, more assured cornering could be had on 28mm or 30mm tyres run at lower pressure than my chosen 85psi for these 25mm tyres.

So perhaps that’s a moot point. But what’s impossible to ignore is how the S5 handles in windy conditions.

Flicking the V

If the wind is relatively consistent then the S5 is great, but when the going gets gusty, the S5 gets pretty wavy.

It’s not an insurmountable problem – vigilance to conditions, such as looking out for gaps between buildings or hedgerows, pays dividends – and crosswind instability is a problem that befalls all aero bikes to some degree. It’s just in the S5’s case it is that much more pronounced.

However, in a strange way all this only makes me like the bike more, because there’s only one thing the S5 cares about: speed.

And it doesn’t mind who it upsets to get there. V Stem? More like a V-sign to anyone doubting how much fun a fast bike can be.

Buy now from Sigma Sports here.

Rating - 4/5


Frame Cervélo S5 eTap Disc
Groupset Sram Red eTap HRD
Brakes Sram Red eTap HRD
Chainset Sram Red eTap HRD
Cassette Sram Red eTap HRD
Bars Cervélo AB08 
Stem Cervélo CS28 V 
Seatpost Cervélo SP20 
Saddle Dimension TiRox
Wheels DT Swiss ARC 1450 DiCut 48mm, Continental GP4000S II 25mm tyres
Weight 7.77kg (56cm)

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