New 1x Cervélo S5 is a rocket ship that might be even faster - but not for the reason you think

The new Cervélo S5 landed this summer, rather overshadowed by Factor’s new prototype aero bike, which remains unreleased at the time of going to press. The Factor, with its wider set fork legs and bare black carbon, strolled into the light in Lille, with an air of mystery, stealing the gaze of the media and fans alike. It must have been galling for the engineers at Cervélo to be upstaged by a bike which, by definition, wasn’t even finished yet.

Dressed in more mainstream aero attire, the subtle updates to the new S5 were just an evolution of the previous version, already one of the best aero road bikes, and if you were to squint, you’d struggle to see the differences. It was, we dare say, conservative in comparison.

Construction

However, there are differences, 6.3 watts of them in fact, making it faster than the already excellent old model, according to the press material. It’s also a not insignificant 124g lighter. Up close and personal with the revised S5, you start to appreciate the changes.

The fork now features a bow-like intake scoop in place of the closed older design, encouraging air in and over the tyre and not around the crown as before. The bars, though similar looking to the last version, have been updated for further watt savings whilst also being lower in weight.

Even the seat post has been subtly updated. It’s narrower now, with a modification at the top of the leading edge of the post, presumably shielding the air over and around the hardware. The rear end is, at first glance, still in the Vroomen-White design school, where the seat post closely tracks the circumference of the wheel before darting upwards and almost forward.

The rear end itself is now fascinatingly asymmetrical, hiding more of the tyre. A lower BB drop of 72mm allows the expanded but familiar, edged aero sections of the bottom bracket cluster to dip lower into the wind, yet somehow perform better.

So it’s fast on paper, but what about the specs?

Well, it’s a very expensive bike, at an otherworldly £12,000, so you’d expect the very best kit, and Cervelo relies on its excellent Reserve wheelset here, in 57mm and 64mm depth, shod in Vittoria Corsa Pro TLR tyres in 29mm. The wheels use DT Swiss’s 180 hub, which is lighter than the 240 and uses ceramic bearings. They’re laced with 24 Sapim CX Ray spokes - a sensible number - and tip the scales at just over 1.5kg (1554g). Measuring 25mm wide up front, and 24mm wide at the rear, they are also hooked. The wheel rim profile has been redesigned to work with the S5 and you can fit 34mm tyres in the frame.

The groupset on this bike is unusual in that it’s Sram Red 1x XPLR, usually more suitable for gravel. But here, where dispensing with rings and a front mech gives an aero advantage, I can see why it’s available. For me, this kind of set-up lacks the immediacy and closeness of a shift made in the middle of a regular block, to make minor adjustments to my cadence. I prefer a close ratio gear set-up for this reason.

The ride

In practice, I could not find fault with the shifting, and it will make sense to many. My colleague, Jamie Williams, recently ran the numbers using this very same system, and by the time you remove duplicates in a 2x system, the feeling of having fewer closer gears is more prominent than the reality. It was fair to say that I did fairly quickly get used to it and really enjoyed the flappy-paddle, one-for-up, one-for-down feeling that I do love from Sram set ups anyway. Braking on the new generation of Sram groupsets is obscenely good and was faultless on test.

One issue that needs further investigation and feels like a Sram problem, rather than something specific to Cervélo or the S5, is the drag apparent in the system in the lowest gears. In the largest two sprockets out back there is discernible resistance at the pedal. The rear end of this bike is short at 405mm, and the SRAM red chain is laterally very stiff, with a rear mech very close to the cassette and solidly fixed in what used to be a soft or damped position in older systems. Any one of these issues could be causing the problem. We’ll look into it and report back in more detail in another article. For now, we can’t ignore it as part of the review.

One area where you can’t argue with Cervélo’s choices, is in the engineering department for this frame. Not only is it objectively the slipperiest frame I’ve ridden all year, it is also now, discernibly less portly than the old bike, by 124g. This build is just over 7.5kg.

How? By tweaking almost everything. It’s lost some bolts in the handlebars, losing some adjustability in the process, and everything front to back is narrower from the head tube to the seat post. On the subject of bars, the widest they offer is 40cm centre to centre, so bear that in mind if you’re broad, but it's appropriate for the type of bike this is. Stems go out to 120mm, but you’ll need to pay to change the spec if you do need a different stem bar combo so do check the fit for the size of frame you need.

The bars themselves whilst lighter, feel just right in use, with a subtle flare on the drops, making it an easy place to hang out, and the manta-ray-esque mouth gives a nice variety to the hand positions without ever feeling in the way.

The seat post features a simpler clamp, and has a little rubber cap, and all worked well for the duration of the test. The seat post does come in a lay back version (-15mm), but I’m told you have to buy that. A bike at this price point really should have some options in the fit department at point of sale. The frame uses a version of UDH, in Cervélo’s own design. It saves a gram, and looks cool, but it’s all essentially just a nice looking UDH set-up.

Cervélo has done an exceptional job in finding much higher levels of sophistication in S5’s ride quality. For me, the old bike was not comfortable at all, especially at the rear end. When you have chunky seat posts in any bike, and then do away with a fork steerer, add a bar set up like this, and with all that carbon in the fork, it shouldn’t be comfortable at all. But it is, and that’s a triumph. Ok, it’s not as comfortable as a bike with rounder tube profiles and more minimal forks and stays, but it isn’t harsh.

The position isn’t that extreme either., It’s unchanged except the lower bottom bracket which is always welcome, and it’s not far off a Specialized Tarmac SL8, which considering that bike is an all rounder, is pretty good. It’s still aggressive of course, but it’s not as low as the Van Rysel RCR-Pro for example.

The S5 tracks, turns in, rides, climbs and shifts along just as you’d expect it to; if anything it feels quite neutral in terms of the handling geometry. It feels incredibly stiff in out of the saddle efforts, as you’d expect, but it also manages to feel pretty refined too, with no jarring.

I was riding the Specialized S-Works Mirror saddle for most of the test. The actual bike comes with a Selle Italia Novus Boost Evo SuperFlow Carbon, which certainly isn’t less comfortable in the main, both rank amongst the best saddles available, but the switch might have been responsible for some of the improvement in rear-end comfort, especially since there’s only so far you can get in comfort terms with a seat post shaped like the one on the S5. Regardless, the front end is discernibly more comfortable, even over potholes; I’ve been hitting these on my non aero bikes recently whilst on test and have been left feeling like I’d snapped my wrists at times, such was the impact felt through the bars. I didn’t have anywhere near the same levels, or any level really, of discomfort on this revised S5. Combine that improvement with the weight, and the aero improvements, and this is a spectacular exercise in improving the old bike.

The big question isn’t whether it is better than the last effort however, rather it is more important to assess whether this is a good bike when compared to its competitors. And the answer is emphatically, yes. It’s an incredible aero bike for sure. Our colleagues at Cycling news just tested the world's best aero road bikes in the windtunnel, and they say it was faster than anything else on test with a rider on board, with its ‘system tested’ Reserve wheel set up.

More subjectively speaking, it is plainly very fast in use, effortless in fact, and as with a lot of modern aero bikes these days, sidewinds don’t bother it in the way they used to either. Its ability to build and hold speed comes with almost no downside for it being an aero bike, with all of the substantial upsides.

No wonder the R5 stayed in the truck for the entirety of the Visma-Lease a Bike’s Grand Tour season. The climbing bike is (perhaps) dead, long live the S5.

Conclusion

The S5 is a rocket ship, and a brilliant package. Cycling News have done some actual science and proved it is indeed the S5 is the fastest out there, backing up Cervélo’s confidence in sticking with the ‘old’ design, and Jonas Vingegaard just won the Vuelta on it, which gives you some confidence its half decent.

As if you needed more convincing, I’ve now ridden it, and with my old overweight legs measuring it less scientifically, I can confirm – for what that view is worth – that it is an absolute weapon against the wind, and importantly you can genuinely feel this thing helping you along, even at my slightly less than Vuelta winning pace. Perhaps more interesting for geeks like me, is that it is also a triumph of engineering that its made a previously terrible ride plush in the same overall template, and Cervélo deserves full credit for it.

The drivetrain choice on this particular bike did charm me in the end and I can’t wait to ride a road bike with it again, but there is sufficient resistance in the lower two gears to give some concerns about where those watt savings in the air might be being lost to the drivetrain. It comes with conventional 2x SRAM drivetrains (or Shimano Ultegra Di2 and Dura Ace Di2) if that bothers you. We will test this further to see if there’s some kind of set-up issue peculiar to this bike, or if it is due to something more fundamental.

I’m marking the S5 down a tad only because they want you to pay for a seatpost if you want more set back. At this price a good fit is essential, and doable. I understand how the bar stem combo could be problematic at a dealer level, although others like Factor are doing it and going further, so that’s got to be deliverable too, surely?