PRO BIKE
Lighter, stiffer, faster and disc- braked – can the new Cervélo S3 Disc live up to its makers’ bold claims of ‘savage speed’? Procycling’s Jamie Wilkins "inds out
Cervélo S3 Disc U12 on test
Perception versus reality – which is most important? Until it comes down to cold, hard facts and results, it’s perception all the way. What people think of you, or your brand, or your new bike, is more important than the truth of it. Our job as journalists is to try to align the two things, to give you the chance to base your understanding, your perception, on facts, on reality, whether of Chris Froome in a feature interview or his bike on these pages.
One of the most satisfying experiences as a journalist – whether it’s testing bikes or talking to riders – is when something surprises you. To have preconceptions is human and years of experience mean you’re often right but you must always be open minded to the reality that presents itself.
Sometimes that’s more of a challenge. By the time I first swung a leg over the new Cervélo S3 Disc, preconceptions were legion. I recalled a conversation with former professional David Millar in which he shuddered at the memory of Cervélo geometry. “They always seemed to be made for doctors, not racers,” he’d said. “Lazy geometry, tall headtubes.” And disc brakes got an even stronger reaction. Millar has been a strong voice of dissent against their introduction, simply arguing that they aren’t necessary.
You can imagine, then, that Millar would likely be none too taken with this new S3 Disc. As well as those new-fangled brakes, that infamous Cervélo headtube is present, along with one of my own pet hates on an aero bike, an ill-matched and gappy 11-28 cassette. There have been more auspicious starts. And yet a look through Cervélo’s marketing material for the S3 suggests there is actually plenty to get excited about. Cervélo claim that it’s lighter and stiffer than before (by 40g and 9%), and that the disc brake conversion yields a 2W aero gain as well as improved braking performance. Perhaps the S3 has the power to surprise us after all.
Cervélo have been relatively slow to adopt disc brakes but when you look at how much work has gone into the conversion, and their other recently launched all-new models requiring attention ahead of the S3, it’s unsurprising that it has taken some time. The fork, for instance, has been completely reshaped in order to optimise the integration with the caliper and take advantage of the opportunity to reprofile the crown, allowing more air to pass over the tyre to fill what had been an area of low pressure with a rim caliper in place. These changes are solely responsible for the claimed drag reduction of 2W, worth around 1s every 5km. Well you’d rather have it than not.
The frame itself features a rear triangle that draws heavily on that of the R3 Disc, Cervélo’s superlight option and the first in their range to get disc brakes. The downtube is also new. It’s still ‘dropped’ – Cervélo’s idea of angling it down as much as possible to reduce its frontal area, elongate its airfoil profile and reduce its drag – but Cervélo say it’s now stiffer and that its flattened trailing edge better integrates bottles. At first glance it may appear as if bidons still stick out like a sore thumb but on closer inspection you can see the downtube broaden in time to deflect air around the bottles.
The cobra-head seatpost does nothing to save your backside and the bike seems to amplify road surface wrongdoings
This S3 also gets 12mm quick-release through-axles for increased stiffness and disc alignment, plus ‘Future-Proof’ cable routing which doesn’t only enable mechanical or electronic cables, but also hydraulic braking and shifting, the latter for Rotor’s imminent groupset.
Only two builds of S3 Disc are available; this is the top one with a Shimano Ultegra Di2 groupset, FSA SLK crankset, Cervélo’s own AB04 aero handlebar and Enve 3.4 disc-specific aero rims built onto Formula hubs. The rims alone, unbuilt, would cost you £2,000 in the aftermarket so even for £6,200, the S3 looks like a formidable package.
With big miles planned, I swapped the Fizik saddle for my preferred Specialized Power and the cassette for an 11-25, then slammed the stem, measured it, and found the bar to be still 25mm higher than I like. At 185cm I’m usually able to ride either a 56 or 58 comfortably, though I prefer the former with a long stem. However, I have a short torso. If you prefer a racier position then look to size down from your normal size as Cervélos generally come up taller.
I resolved to just bend my elbows more and make the most of the relatively deep drops on Cervélo’s clever aero bar, which has an air-piercing section ahead of the clamp area to give most of the benefit of the one-piece designs now prevalent among aero bikes without the loss of practicality. It’s a good shape, too, with lots of wrist clearance and stiffness for sprinting, and it comes with a Garmin mount.
After a shakedown ride, I joined friends Dave and Ben for a brisk 200km ride on Christmas Eve, a downpayment on the Festive 500 challenge and the following day’s calorie excess. While we clipped it off in just under six hours, the S3 didn’t feel especially fast. Moreover, it proved to be very firm, tiresomely so over such distance. Other riders even commented that it looked jarring – I’ve never experienced that before. The cobra-head seatpost does nothing to save your backside and, if anything, the whole bike seems to amplify road surface wrongdoings.
The hydraulic braking is both controllable and strong but the discs frequently howl (often followed by howls of laughter from friends at this ‘progress’), the hoods are less ergonomically shaped owing to the hydraulics inside and, most troubling, the fork can be overwhelmed by the forces involved, sometimes breaking into a flutter of flex and rebound. The steering is at least decently accurate, if rather pedestrian in its responses.
Over subsequent rides I went looking for the promised speed, doing big efforts, practically laying on the handlebar to make up for the headtube’s excesses, but all in vain. I suspected that the
Continental GranSport Race 23c tyres – a rather modest selection on a bike of this price – might be to blame. While they inflate to the right size to match the shape of the Enve 3.4s, they are far from supple, sacrifice comfort and don’t roll like their legendary GP-series siblings. I swapped them for the new Michelin Power 4 Competition clinchers, tyres we know from our own testing in collaboration with sister site BikeRadar.com to be extremely fast. The S3 immediately felt keener and the worst of the frame’s harshness was muted but it still wasn’t all you’d hope, neither race fast nor sportive compliant. Back to back, my alloy Cannondale CAAD12 felt smoother, faster and more fun.
It certainly isn’t all bad, though. The Ultegra Di2 drivetrain remains excellent, subservient to Dura-Ace only in weight, wanting for little but clearer button feel. The pedalling stiffness is high, too. The real highlight, though, is the Enve wheelset, to the extent that the rest of the bike doesn’t always feel deserving. Like singer Adele in a local choir, the 3.4s are always there raising the bike’s level, and then you get out of the saddle up a steep grade for the first time, they get their solo, and the pedal simply falls away beneath your foot. The S3 Disc is not a light bike yet when standing, with the low inertia of the 3.4s more tangible, it does a good impression of one. They’re stiff and stable, too, though Enve have just launched a new version - see p118.
You could argue that this really isn’t a bike for racers. That would mitigate the tall geometry, low gearing and slight heft. But the bendy fork remains an issue and the lack of compliance only becomes a bigger problem. And if you’re not racing, why do you need an aero bike, especially a harsh one? In total I rode over 900km on the S3 in search of a surprise but all I found was disappointment. Check out our test rides on Strava, powered by Etixx nutrition: https://tinyurl.com/cervelos3