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Cervelo S5 Ultegra Di2 Disc



Superfast, cutting-edge aero road bike that's a more comfortable ride than you might expect

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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  • Bad
  • Appalling

The revamped Cervelo S5 is, in my opinion, one of the most exciting bikes in the peloton right now and a mighty impressive piece of engineering. The new V-shaped stem solves the issue of having no adjustability on integrated front ends, even though it looks as clean as any one-piece bar and stem system out there. You do pay a little more for the S5 than some notable high-end aero options from other big brands, but I can't see anyone who simply wants to go faster being disappointed with this bike if they can afford it.

  • Pros: Very fast, adjustable, superbly stiff and stable
  • Cons: Expensive, 35mm-deep wheels don't get the best out of the frame

The third iteration of Cervelo's S5, its flagship aero road racing bike, was eventually launched in late September 2018 after a four-year wait. A couple of months before that, its most high-profile sponsored team Dimension Data had switched allegiances to BMC, but I reckon Dimension Data may be wishing they'd remained faithful to their old sponsor (now sponsoring Team Sunweb), because the S5 might just be the cream of the crop when it comes down to pure speed and clever integration.

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Cervelo admits it was forced to go back to the drawing board and be better in order to satisfy the demands of the fastest riders in the world, and the S5 project started by aiming to create a whole aerodynamic 'system' rather than trying to improve individual components. Cervelo set itself a goal of creating a bike that would have fully integrated cable routing, would be built around flat-mount disc brakes (sorry, rim brake fans) with tyre clearance up to 30mm, have easy positional adjustment and an increase in stiffness. It would also have to be considerably faster of course, and Cervelo says through using computational fluid dynamics and extensive wind tunnel testing, it achieved this to the tune of 5.5 watts (42g of drag) compared to the 2014 S5 riding at 40km/h.

Cervelo S5 Ultegra Di2 Disc - riding 2

The frame is also 100g lighter than the old version, with my test bike coming in at 7.8kg. While that's not featherlight, the wind tunnel would suggest lighter doesn't necessarily mean faster, so Cervelo wouldn't have been too concerned with challenging the UCI's weight limit – its initial target was the same weight or lower than the Gen II S5. Cervelo has named the specific tube shapes chosen to improve aerodynamic flow 'TrueAero', with examples being the oversized bottom bracket area, seat tube and down tube and a larger sized asymmetric left chainstay.

Cervelo S5 UItegra Di2 - UCI sticker.jpg

Despite its wildly different looks, the (aggressive) geometry of the new S5 is largely unchanged. On my 54cm test bike you get a short head tube at 13.4cm, 54.2cm of stack, 38.4cm of reach and a short 97.5cm wheelbase. The seat angle and head angle are both 73°. Compared to other cutting edge aero bikes this is pretty much no more or no less aggressive – the Specialized Venge has a slightly lower head tube at 13.3cm and slightly longer reach at 38.7cm compared with the S5's 38.4cm on a 54cm frame, but the numbers and angles are largely the same elsewhere.

Cervelo S5 UItegra Di2.jpg

What about Cervelo's aero but less aggressive cousin, the S3? On a 54cm frame, the seat and head angles are the same, but the reach is slightly shorter at 37.8cm with a taller head tube (14.8cm) and stack (55.5cm) – so the S5 is definitely designed to get you lower.

Cervelo S5 Ultegra Di2 Disc - riding 3

Cervelo also claims the new S5 is more comfortable and stable than before, even though the stiffness is claimed to have been improved to the tune of 13% in the head tube and 25% in the huge bottom bracket area.

Cervelo S5 UItegra Di2 - head tube.jpg

Cervelo's definition of comfort doesn't necessarily mean comfortable in the traditional sense, with Cervelo instead choosing to focus on the 'rider experience'; essentially the bike is supposed to be ridden fast and the cyclists in the market for an S5 will expect a bike that rides as such, which means characteristics such as a low front end and high levels of stiffness. Cervelo has aimed to make the bike as comfortable as possible within these parameters.

The S5 is very much built with aerodynamics in mind first, with Cervelo then working out how to build vertical compliance and comfort in afterwards. On its bikes built more for day-long riding, such as the R5, Cervelo starts with tube shapes that prioritise vertical compliance and lightness with a shorter, more upright geometry, and forgo the use of ultra-high modulus carbon to create a more damped ride feel.

Cervelo S5 UItegra Di2 - seat tube shape 2.jpg

In terms of usability and allowing for adjustments, the party piece is the new V-Shaped stem. Even though it's technically not integrated and can be bought separately in various sizes, it cleverly bolts straight into the underside of the new AB08 handlebar, creating a look as clean as any integrated bar and stem system out there – with rubber caps covering the bolts to complete the tidy aesthetics. The bar/stem combo also allows for electronic and mechanical gears to be routed straight through, which means the cables are completely concealed on any spec of S5 you choose.

Cervelo S5 UItegra Di2 - stem 2.jpg

The stack range goes up to 30mm in 5mm increments, and you can make handlebar pitch adjustments in steps of 2.5° or 5°. If that's still not adjustable enough for you, a standard bar and stem can be fitted instead.

Cervelo S5 UItegra Di2 - stem 3.jpg

There's no complicated trickery going on with the seatpost, you just need to loosen one bolt to move it up or down.

Cervelo S5 UItegra Di2 - seat post clamp.jpg

The shaping of the seat tube around the tyre means there wasn't anywhere for my excess seatpost to go, so I had to get it cut down to size to account for my annoyingly short legs.

Cervelo S5 UItegra Di2 - rear.jpg

I could go on all day picking apart Cervelo's S5 white paper, but select other differences in the new version include a cutout in the down tube around the front wheel as well as the sizeable cutout in the seat tube, a twisted shape in the handlebar that creates an aerofoil to reduce drag, and an increase in steering stiffness to improve handling.

Cervelo S5 UItegra Di2 - bars 2.jpg

There are also two mounting options for a bottle cage on the down tube; although slightly more difficult to access, the lower position will provide more shielding from the wind because the down tube gets thicker towards the bottom bracket area.

Cervelo S5 UItegra Di2 - down tube.jpg

The ride

Setting off on my first ride, I definitely noticed how long and low the S5 felt compared with a more relaxed bike I'd been used to riding, but I quickly became accustomed to it and the raw acceleration is very addictive indeed. Average speeds noticeably increased, and while I don't have any hard proof I can quite confidently say the S5 is a different beast to any road bike I've ridden extensively before – it's almost like cheating, that's how much difference I think we're talking compared with a more traditional-looking lightweight endurance bike.

Cervelo S5 Ultegra Di2 Disc - riding 4

My esteemed colleague David Arthur made similar comments in his recent review of Trek's new Madone, saying 'it's impossible to go out for a gentle jaunt', and after a month of barely being capable of averaging under 20mph on the S5, it was the same for me. Although I only tried out our Madone test bike very briefly and haven't ridden any of the other aero road bikes launched in 2018, I do think the bike industry raised their game last year in terms of how much speed advantage an aero bike can give you. I'd put the Madone and the Specialized Venge in this category based on David's testimony, and also the BMC RoadMachine and Cannondale SystemSix.

> Lightweight vs aero: which is best?

I was sceptical about Cervelo's claims about comfort, but I see its point – the S5 is a damn fast bike and forces you to ride it as such, with the aggressive geometry actually helping you get the most out of the tube shapes. The larger tubes shouldn't equate to a comfortable ride as such, but because of the way you ride it, the huge stiffness adds to the comfort and it swallows up road vibrations well. If I tried to ride a long and tall sportive bike in the same fashion I'd possibly be left more tired and achy because that's not really what it's built for, if you catch my drift. I did find on an 80-mile ride that my back needed a bit of a stretch in the final hour, but that was to be expected.

Cervelo S5 UItegra Di2 - seat tube shape.jpg

Although it's almost a kilo heavier than the best lightweight race bikes, I didn't really feel the S5 held me back on climbs, and it felt as snappy and responsive as I could ask for out of corners.

Build and adjustments

My test bike was the Shimano Ultegra Di2 version that retails at a cool £6,999, with 35mm-deep DT Swiss PRC 1450 carbon wheels, Continental GP 4000 S II tyres and a 52/36, 11-30t gearing combination.

Cervelo S5 UItegra Di2 - rim.jpg

In terms of the fit adjustments promised, it's pretty much as easy to work on the front end as a regular stem and handlebar. It's just a couple of hex bolts to loosen the stem to reveal an FSA IS2 headset, and the S5-specific spacers can be added or removed to lessen or increase your stack height.

Cervelo S5 UItegra Di2 - stem.jpg

Although Cervelo does say it gave consideration to how easy it is to 'live' with the bike day-to-day when designing it, I did run into a bit of a problem when my Shimano Di2 battery mysteriously went flat. This isn't Cervelo's fault, of course, and Di2 is very reliable 99% of the time, but the integration on the S5 means the battery is located in the bottom bracket area (see the manual if you want to geek out on the assembly guide for yourself).

Cervelo S5 UItegra Di2 - bottom bracket.jpg

To access and replace it, this required the use of a specific bottom bracket tool for Cervelo's BBright Connect 24x90 BB, something most of us aren't likely to have kicking around in the shed. This meant a trip to a Cervelo dealer to get the issue fixed quickly, and when it was I had no further problems.

For charging the Di2, Cervelo has specced the handlebar mount Junction A Charging Point to Port, so you just plug the charger into the end of the right handlebar to add juice.

Groupset and finishing kit

There's not much I can say about the performance of Shimano Ultegra Di2 that hasn't already been said on – it's befitting of a bike like this, and if I'm honest I can't really tell the difference between the shifting performance of Ultegra and top-of-the-range Dura-Ace nowadays. Pairing 52/36 chainrings with an 11-30 cassette will get competitive cyclists up anything at the bottom end, with the fastest maybe just missing out on the ideal chain line at the top for races where the average speeds are furious.

Cervelo S5 UItegra Di2 - drivetrain.jpg

Cervelo's new S5-specific handlebar is really ergonomic and comfortable, pleasant in your hands on the tops or drops and eating up road buzz.

Cervelo S5 UItegra Di2 - bars.jpg

I can be a little fussy about saddles, but being partial to a cutout I was happy with the Prologo Dimension T4.0 – it did it for me and there was no need to swap it out.

Cervelo S5 UItegra Di2 - saddle.jpg

The 35mm-deep DT Swiss PRC 1450 carbon wheels are stiff, stable in the worst of crosswinds, and faster than alloy training wheels, but if I was to buy the bike off the peg I would want to swap for something deeper; 35mm is neither here nor there in my opinion – if you want an S5 you'll likely have another year-round/winter bike and be using this for best training days and racing, so you want to eke out every bit of speed from the frame you can get.

Cervelo S5 UItegra Di2 - tyre.jpg

There's one retailer I can find online claiming to sell the S5 with the 48mm-deep DT Swiss RC wheelset, and those would be more appropriate in my opinion. Continental's new GP5000 tyres wouldn't go amiss either.


There's no getting away from the fact that the S5 is pricey, even compared with other cutting-edge aero road bikes. For £6,500 you can get a Specialized Venge with Ultegra Di2 and 50mm Roval carbon wheels, and for £5,899 Giant will sort you out with a Propel Advanced SL1 Disc complete with Ultegra Di2, deep rims and even a power meter included. You can pay more though: the Bianchi Oltre XR4 Disc comes in at £7,700 with an Ultegra Di2 groupset, while Trek's Madone SLR 7 Disc is £7,550.

> Buyer's Guide: 18 of the best and fastest aero road bikes

It's worth bearing in mind that the S5 isn't a bike to be ridden year-round in all situations. As I said earlier, I'd recommend it as a bike for racing and best days; for a fast do-it-all, Cervelo's S3 will be more appropriate. That said, if I could sell my three bikes and someone topped the total up considerably I'd definitely be interested in just having an S5 and an adventure bike, which would cover all types of riding I do apart from time trials.


All things considered, I really had a very good time on the S5 and missed it when switching back to my own considerably less punchy 'normal' road bike when the test period was up. It's one of a new wave of aero race bikes that will truly make a difference to your average speeds, and getting up to those speeds feels easier thanks to the S5's ability to accelerate so quickly off the mark and hold it there.

It's a shame that most of us are priced out at the moment, and might always be, considering how much R+D Cervelo put in to producing such a weapon, but if going fast is your priority for the majority of your riding and you're willing to fork out for that advantage, I would highly recommend this bike.


Superfast, cutting-edge aero road bike that's a more comfortable ride than you might expect test report

Make and model: Cervelo S5 Ultegra Di2 Disc

Size tested: 54cm

About the bike

List the components used to build up the bike.

Cervelo lists:

FRAME: Cervelo S5 Disc

FORK: Cervélo All-Carbon, Tapered S5 Fork For Disc

BOTTOM BRACKET: Cervelo BBright Connect 24x90

STEM: Cervélo, CS28 V-Stem

HANDLEBAR: Cervélo, AB08

HEADSET: FSA IS2 1 x 1-3/8

FRONT BRAKE: Shimano Ultegra 8070 hydraulic disc, Shimano SM-RT800,160mm

REAR BRAKE: Shimano Ultegra 8070 hydraulic disc, Shimano SM-RT800,160mm

FRONT DERAILLEUR: Shimano Ultegra Di2 8050, 11-speed

REAR DERAILLEUR: Shimano Ultegra Di2 8050, 11-speed

SHIFT LEVERS: Shimano Ultegra Di2 8070, 11-speed

CHAIN: Shimano CN-HG701, 11-speed

CASSETTE: Shimano Ultegra CS-R8000, 11-30

CRANKSET: Shimano Ultegra 8000

CHAINRINGS: Shimano 52/36

FRONT WHEEL: DT Swiss PRC 1450 Spline 35 Disc

REAR WHEEL: DT Swiss PRC 1450 Spline 35 Disc

FRONT TYRE: Continental GP4000 SII 25mm

REAR TYRE: Continental GP4000 SII 25mm

SADDLE: Prologo Dimension T4.0

SEATPOST: Cervelo SP20

Tell us what the bike is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?

Cervelo says: "The S5 is an aerodynamic road bike built for the fastest sprinters in the world. It is stiffer and more aerodynamic than ever before, while offering excellent comfort and ride quality. If you live for the exhilaration of going fast, the S5 will give you every possible advantage."

After testing, I'd be inclined to agree with Cervelo for the most part.

Where does this model sit in the range? Tell us briefly about the cheaper options and the more expensive options

This is the 'cheapest' version with electric gears. Below it is the mechanical Ultegra version at £4,299 and the top-end model with Shimano Dura-Ace Di2 and Enve carbon wheels is £9,699.

Frame and fork

Overall rating for frame and fork

Tell us about the build quality and finish of the frame and fork?

It looks mean, with everything optimised to cut through the wind. You can tell Cervelo has put its homework in, with details such as the cutout in the front of the down tube where it meets the front wheel showing what lengths it's gone to in aero-optimising the bike.

Tell us about the materials used in the frame and fork?

All-carbon frame and fork.

Tell us about the geometry of the frame and fork?

Aggressive: on my 54cm test bike the head tube is 13.4cm, the reach is 38.4cm and the wheelbase is short at 97.5cm. The seat angle and head angle are both 73 degrees.

How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?

The reach is long to help you lean over the bike and sprint, and height-wise the bike is low. The Specialized Venge has a very slightly lower head tube at 13.3cm, and slightly longer reach at 38.7cm compared to the S5's 38.4cm on a 54cm frame.

Riding the bike

Was the bike comfortable to ride? Tell us how you felt about the ride quality.

It's a very aggressive bike with a short head tube and long reach, so over one particularly long test ride I did need to stretch my back out a little. Anything up to two hours I found it surprisingly comfortable, despite the stiffness.

Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?

Stiffness was spot on in all areas, no flex and no effort is wasted.

How did the bike transfer power? Did it feel efficient?

Incredibly so, one of the fastest bikes I've tested.

Was there any toe-clip overlap with the front wheel? If so was it a problem?


How would you describe the steering? Was it lively neutral or unresponsive? On the lively side of course, it's razor-sharp through corners.

Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?

It's a really well handling bike, not overly twitchy and it feels predictable even though it's very aggressive. All in all, it's a really good balanced ride feel. I felt particularly confident taking tight corners on the S5.

Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?

It's not really built to be super-comfortable, but if you want more comfort and a more relaxed position you can add more spacers to the front end.

Which components had the most effect (good or bad) on the bike's stiffness? would you recommend any changes?

The huge bottom bracket area and large tube profiles make the bike extra stiff.

Which components had the most effect (good or bad) on the bike's efficiency? would you recommend any changes?

Deeper rims to save watts, that's about it.

Rate the bike for efficiency of power transfer:

No effort is wasted, it's a rocket ship.

Rate the bike for acceleration:

Very quick off the mark, more so than any other bike I've tested.

Rate the bike for sprinting:

Other worldly.

Rate the bike for high speed stability:

Very stiff and predictable even at very high speeds.

Rate the bike for cruising speed stability:
Rate the bike for low speed stability:
Rate the bike for flat cornering:

Sharp and predictable, I was impressed with the cornering.

Rate the bike for cornering on descents:

Same as above.

Rate the bike for climbing:

It's quite light for an aero bike so climbed quite impressively.

The drivetrain

Rate the drivetrain for performance:
Rate the drivetrain for durability:
Rate the drivetrain for weight:
Rate the drivetrain for value:

Tell us some more about the drivetrain. Anything you particularly did or didn't like? Any components which didn't work well together?

Shimano Ultegra Di2 is a fine groupset, no complaints here.

Wheels and tyres

Rate the wheels for performance:
Rate the wheels for durability:
Rate the wheels for weight:
Rate the wheels for comfort:
Rate the wheels for value:

Tell us some more about the wheels.Did they work well in the conditions you encountered? Would you change the wheels? If so what for?

I'd want deeper wheels to make the most out of the frame – it's an expensive bit of kit and built for racing, so 50mm-deep rims would be preferable. I don't really see the point in 35mm carbon wheels, they're neither training wheels nor full-on racers.

Rate the tyres for performance:
Rate the tyres for durability:
Rate the tyres for weight:
Rate the tyres for comfort:
Rate the tyres for value:

Tell us some more about the tyres. Did they work well in the conditions you encountered? Would you change the tyres? If so what for?

An upgrade to the new Continental GP5000s wouldn't go amiss, but the 4000s are fast and reliable enough.


Rate the controls for performance:
Rate the controls for durability:
Rate the controls for weight:
Rate the controls for comfort:
Rate the controls for value:

Your summary

Did you enjoy riding the bike? Yes

Would you consider buying the bike? Yes (if I had the money).

Would you recommend the bike to a friend? Yes (if they had the money).

How does the price compare to that of similar bikes in the market, including ones recently tested on

For £6,500 you can get a Specialized Venge with Ultegra Di2 and 50mm Roval carbon wheels. For £5,899 Giant will sort you out with a Propel Advanced SL1 Disc complete with Ultegra Di2, deep rims and even a power meter included.

You can spend more, though: the Bianchi Oltre XR4 Disc comes in at £7,700 with an Ultegra Di2 groupset, while Trek's Madone SLR 7 Disc is £7,550.

Rate the bike overall for performance:
Rate the bike overall for value:

Use this box to explain your overall score

I was hugely impressed with the S5 over a long test period, it's certainly the most exciting road bike I've ever ridden and accelerates like a rocket. The only marks down are for the price premium compared to some brands, and the in-between wheels supplied with this build that don't make the most of the frame's speed.

Overall rating: 9/10

About the tester

Age: 27  Height: 179cm  Weight: 75kg

I usually ride: Road bike (currently Specialized Tarmac)  My best bike is: Ridley Chronus TT bike

I've been riding for: Under 5 years  I ride: Every day  I would class myself as: Experienced

I regularly do the following types of riding: road racing, time trialling, commuting, club rides, sportives, general fitness riding, triathlon races

Arriving at in 2017 via 220 Triathlon Magazine, Jack dipped his toe in most jobs on the site and over at eBikeTips before being named the new editor of in 2020, much to his surprise. His cycling life began during his students days, when he cobbled together a few hundred quid off the back of a hard winter selling hats (long story) and bought his first road bike - a Trek 1.1 that was quickly relegated to winter steed, before it was sadly pinched a few years later. Creatively replacing it with a Trek 1.2, Jack mostly rides this bike around local cycle paths nowadays, but when he wants to get the racer out and be competitive his preferred events are time trials, sportives, triathlons and pogo sticking - the latter being another long story.  

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PeterJB | 4 years ago

Anybody buying this bike needs to see this video

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