Cervélo S5 (Dura-Ace Di2) review: the 2025 S5 is blisteringly fast and easy to ride, but is it overgeared for you?

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The Cervélo S5 is one of the best aero bikes on the market right now.

It offers a well-balanced ride quality and excellent handling, underpinned by a devilish turn of speed. It’s also stable in changing wind conditions, and perhaps its biggest asset is how easy it is to ride quickly.

That said, you can’t change the seatpost for free at point of purchase, and it’s overgeared for most amateur riders on this particular model.

However, these niggles aside, Cervélo’s new S5 is an incredibly well-rounded aero road bike, with a build you’re unlikely to ever need to upgrade.

Cervélo S5 (Dura-Ace Di2) frameset

The latest Cervélo S5 builds on the reputation of its predecessor, with refined aerodynamics and lighter weight without sacrificing stiffness.

The S5 is nominally a pure aero bike, but it’s also the bike most often used by the likes of Jonas Vingegaard, Wout van Aert and Matteo Jorgenson in races.

Before its launch, Vingegaard used the S5 exclusively during his general classification bid at the Criterium du Dauphiné.

It’s only when the race hits the high mountains that the team switches to the R5 (a new model of which was seen at the 2025 Tour de France, weighing only 7.03kg in a size 58cm with pedals, bike computer and empty bottles). This indicates that the S5 is considered something of an all-rounder compared to the R5’s climbing specialism.

From the side, the most noticeable changes are to the head tube and fork legs, which are now deeper than before, making more of the UCI’s latest 8:1 tube ratio regulations.

This helps to manage airflow more effectively at this key frontal area, assisted by the bayonet fork design retained from the old S5. This enables the steerer tube to be recessed further back relative to the leading edge of the head tube, increasing the effective chord length without compromising handling (more on geometry to come).

Also retained is the frame’s curvature around the front and rear tyres, providing a familiar overall silhouette despite the changes.

Front-on, a slimmer structure to the head tube, seat tube and seatpost is suddenly obvious, while the new cockpit’s reprofiled top bar widens the aperture relative to the old one, which is said to create less drag-inducing turbulence behind it.

Also important is the new Reserve 57/64 wheelset, which is designed to complement the S5’s asymmetric design with widened spoke angles and a new rim profile.

All these factors add up to a 6.3-watt saving at 50kph compared to the old S5 with its Reserve 52/63 wheels, according to Cervélo.

It also says that a refinement of its carbon layup and curing processes (where it uses an inflatable bag, rather than traditional foam mandrels) led to less waste material in the frameset to the tune of around 30g.

The new HB19 cockpit is also one-piece, thanks to the removal of the bolts and hardware for the old cockpit's topbar attachment.

This saves around 100g, but comes at the cost of the 5-degree angle adjustability the previous bolt-together layout had, and means you’ll need to swap the whole thing out if you want a different handlebar width or stem length.

Cervélo has also limited the deeper fork’s weight gain to a claimed 57g, with downsized hardware at the dropout and brake caliper mount points.

Unlike the as-yet unreleased R5, it still requires the use of the caliper’s flat mount bracket, but you’re locked into using a 160mm rotor.

Overall, the frame is claimed to weigh 1,006g, and the fork 465g in a size 56cm.

Further weight savings are seen at the seatpost. This is thinner than before, but the saddle mount features a new carbon plate and alloy clamping bars, which are said to improve adjustment range (a weakness my colleague, Simon von Bromley, noted in his review of the previous version) while shedding 27g compared to the old design.

The seatpost is fastened in place by a simplified wedge clamp which is covered by a simple push-on top cap.

Cervélo has even gone to the trouble of designing its own direct-mount hangers for the bike, known as éUDH.

Probably inconsequential in the grand scheme of things, this saves a single gram over SRAM’s UDH, and 5.8g versus its old Shimano hanger. The frame is also compatible with direct-mount derailleurs.

The bike uses a BBRight pressfit bottom bracket, and retains the old model’s 34mm tyre clearances.

Cervélo S5 (Dura-Ace Di2) geometry

Cervélo says a key request from Visma-Lease a Bike pro riders (who it sponsors) was to retain the old bike’s handling.

The new S5’s geometry is therefore almost unchanged, with steep 73.5-degree head tube angle and 73-degree seat tube angles on my size-58cm test bike.

Only the trail has increased, by 0.8mm. In isolation, this should steady the steering slightly, without transforming it.

However, it’s worth noting the new model is optimised around 29mm tyres, rather than 28mm ones as on the previous model, so this may simply be to account for that change (because tyre size affects trail).

Compared to the popular Specialized Tarmac SL8, the new S5 is 1mm shorter and 3mm lower (in terms of reach and stack) in the same size, yet 0.5 degrees slacker in the seat tube angle (effectively positioning the rider slightly further back at the saddle, all else being equal).

The head tube angle is identical, though.

My test S5 features a top-spec Shimano Dura-Ace Di2 R9200 build, for £12,000 / $14,100 / €13,999, complete with the latest RT-CL900 rotors (by no means a guarantee) and a 4iiii Precision 3+ Pro dual-sided power meter.

It’s worth noting that the SRAM Red AXS build, complete with its own Quarq power meter, is £500 / $150 more expensive in the UK and US (the 1x version with Red XPLR AXS is slightly cheaper).

The only major concern is Cervélo’s decision to spec a 54/40-tooth crankset on this specific build, versus a more typically found 52/36T combination.

On the one hand, this makes sense – the S5 is all about unadulterated speed, and this is how pro riders will want to run it (big chainrings have become de rigueur on pro bikes in recent years).

However, it’s likely to be too big for most riders parting with their own money for an S5, even with a wide, 11-34t cassette out back.

It’s certainly too big for me as a ‘normal, pretty fit’ bike rider who generally tackles rolling terrain alongside flat roads.

Cervélo won’t swap this out for you at point of purchase, either, albeit some leeway is left for dealers to change this for you at their own cost.

Fundamentally, it’s a shame that the cost of entry to an S5 with a Dura-Ace would appear to be incredibly strong legs in addition to a large budget.

The SRAM Red AXS build has 50/37T chainrings, but (of course) a 10-33t cassette – not a night and day difference, but a slightly bigger spread with a slightly easier smaller gear is worth noting.

That said, the HB19 cockpit size can be changed. The 400mm / 110mm size was a good fit for me on my 58cm bike, but having a guaranteed choice is great when you’re spending this much money on a bike.

I’m pleased to see that 400mm (measured centre-to-centre at the brake hoods) is as wide as Cervélo goes now, though, given the aero focus of the bike.

The drops are flared slightly to improve handling during sprints and on descents.

Cervélo won’t provide your choice of seatpost for free, though. Two are offered – 15mm and zero setback, dropping the 25mm-setback option from the previous S5.

You’ll get the zero-setback model for the four smallest sizes, with the 15mm-setback seatpost fitted to size-58 and 61cm frames.

Elsewhere, the build would be hard to upgrade, given the Reserve 57/64 wheelset is designed to perform best with the S5 frameset.

DT Swiss supplies its flagship 180 hubs at this spec level, which carry ceramic bearings and a reputation for top performance, and less weight versus the 240 hubs.

The rims are progressive – 25.4mm wide internally for the front wheel and 24.4mm wide at the rear, with a hooked design.

The rims are fitted with Vittoria’s wide-rim optimised (and top-level) Corsa Pro TLR 29c tyres. These inflate to just over 30.3mm at the front and 29.4mm at the rear.

A CeramicSpeed SL bottom bracket is fitted, with a carbon-railed Selle Italia Novus Boost Evo SuperFlow saddle finishing off the spec.

Cervélo S5 (Dura-Ace Di2) ride impressions

I’ve ridden the new S5 on a pre-launch press event in the Netherlands, and back at home in the UK, where the roads are far lumpier in surface and topography.

While the S5 is best suited to flatter terrain, undoubtedly, it doesn’t feel so specialist as to be leaden and slow on climbs.

On steep rises, while not quite as whip-crack sharp-feeling as a true all-rounder or lightweight bike, it’s more than reactive enough.

At 7.53kg (without pedals), it feels competitively light and incredibly stiff, meaning it accelerates keenly and then feels efficient when punching through the air at speed.

Vingegaard’s decision to stick with it through the Dauphiné and the Tour de France – even on mountain stages – could also be viewed as corroboration of the S5’s all-round prowess.

In any case, the new S5 feels incredibly quick and notably efficient at higher speeds, just as you'd hope, ably backed up by an almost-unimpeachable build. Chainrings (and personal saddle preference) aside, I wouldn't change a thing.

The handling is well balanced, too – unsurprisingly, practically identical to the old S5 – agile, but predictable, and well considered for changes in terrain.

In my experience, bikes designed primarily for racing can feel overly aggressive (the Ridley Falcn RS and BMC Teammachine R spring to mind) for even keen enthusiasts such as me, but there’s a modicum of sensibility here.

Appealingly, it feels stable at speed and when cornering – the odd pushing sensation when engaging a gusty crosswind aside, it’s easy to ride in a relaxed manner than more twitchy alternatives.

I'm especially impressed with the HB19 cockpit shape, which offers a comfortably-raised position at the tops to rest on when not tucking down, and easy access to the drops (which are 4cm wider than the hoods).

Cervélo has also shortened the distance from the tops to the drops by just over 3mm – a marginal difference, but one that makes moving between the two slightly easier than it would otherwise be.

Cervélo S5 (Dura-Ace Di2) bottom line

The latest Cervélo S5 is a very well-rounded aero bike, exhibiting the kind of handling that will appeal to racers and non-racers alike. The highly rated formula of the previous bike hasn’t been unduly tampered with, which is to its benefit.

It feels as fast as any aero road bike I’ve tested.

Of course, it’s expensive, but greater value could be had if Cervélo offered the choice of seatpost setback at point of purchase. When you’re parting with £12,000 / $14,100 / €13,999 for any bike, it’s not unreasonable to expect it to meet your fit or performance needs without compromise.

I also understand why Cervélo has specced such large chainrings, but it remains unlikely that most riders will be best served by this gearing. The SRAM Red AXS-equipped bike comes with smaller chainrings that are arguably better suited to non-pros, so why not here too?

That aside, the specification is top-notch and the new Cervélo S5 stands out as an aero bike that can rival lighter all-rounders on the scales, yet keep pace with the fastest bikes on the flat.

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