I pitted the Colnago Y1Rs against the Cervélo S5 – and the winner shows why the devil is in the detail

The Colnago Y1Rs and Cervélo S5 might seem like obvious choices as finalists for our 2025 Race Bike of the Year category, and with good reason.

Beyond the fact that these bikes were ridden to first and second on GC at the 2025 Tour de France, both espouse some of the latest thinking on aero bike design.

You could even argue that these latest aero bikes are the bikes that might herald the death of the lightweight climbing bike, such is the influence of aerodynamics in racing. 

They’ve impressed me enough in testing to warrant their inclusion for the final shootout, alongside their success on the WorldTour stage, putting many strong contenders, such as the Scott Addict RC, Van Rysel RCR Pro and Trek Madone SLR in the shade.

There can only be one winner.

Introducing the Colnago Y1Rs

Unveiled in December 2024, the Colnago Y1Rs is the bike on which Tadej Pogačar earned his fourth Tour de France title in 2025. 

Arguably, though, it had a troubled start to life. For the first few months of the year, despite the Y1Rs being used to win atop Jebel Hafeet at the UAE Tour in February, more often than not it was the V4Rs that Pogačar opted to use.

Speculation was rife that the Y1Rs was little more than a concept bike – a piece of statement design wheeled out for the PR opportunity. While I felt the new V5Rs was a conservative bike compared to the Y1Rs, I also thought it would still be the bike Pogačar would most often choose to race.

How wrong I was.

At launch, Colnago suggested the Y1Rs was the fastest bike in the pro peloton, beating its nearest competitor (at the time) by 1 watt at 50kph.

Despite that, it was its looks that drew most observers' attention. The offset seat tube design, especially, was touted to contribute to the bike’s aerodynamics, while improving compliance. At the same time, it nodded strongly to Pogačar’s noticeably pitched-forward ride position compared to the bottom bracket area. 

Many described it as an ugly duckling, but in a sport where aerodynamics are so important, the old adage has begun to ring true: what’s proven to be fast is never ugly. 

• Read more: Colnago Y1Rs review

Introducing the Cervélo S5

One could easily argue the Cervélo S5 is the bike that made the Y1Rs a reality. 

When Jonas Vingegaard and his Jumbo-Visma team emerged as the dominant GC force at the Tour de France in 2022 and 2023, the S5 was the main weapon of choice. 

It was aerodynamics versus Pogačar’s Colnago V4Rs lightweight-oriented all-rounder, and aero had won two three-week-long wars. The writing was on the wall.

Of course, success is never down solely to the bike, but the latest S5 sought to double down on the previous bike’s strengths given they’d served Vingegaard and his teammates so well. 

Refinements to the head tube and fork leg chord lengths, while slimming the head tube, seat tube and seatpost, plus a new Reserve wheelset, contribute to a claimed 6.3-watt saving at 50kph compared to the old bike.

The refinements also brought about a claimed net frameset weight saving of 124g, albeit the fork gained 57g due to the deeper leg profiles. The majority of the saving (around 100g) is seen at the cockpit, which has dropped the bolt-together design of the previous model.

Arguably, Cervélo saw Colnago and Pogačar’s continued competitiveness on the V4Rs and sought to deal with the S5’s relative weak point (weight). Meanwhile, while Colnago was also working on refining the V4Rs into the V5Rs, it developed the Y1Rs to plug the aero-bike hole in its arsenal that Cervélo and Vingegaard had exposed.

• Read more: Cervélo S5 review

Allegedly, kings of the aero hill

However, neither Cervélo nor Colnago is willing to positively identify the other when it comes to the relative performance of its aero bikes. Cervélo won’t confirm whether it tested the Y1Rs in full UAE Emirates-XRG team build, stating that, at launch, the Pinarello Dogma F was the new S5’s closest competitor. 

Meanwhile, given the Y1Rs arrived first, Colnago’s claim that it was 1 watt faster than the nearest competitor clearly didn’t factor in the latest S5, which it obviously wouldn’t have had access to at the time. 

Nevertheless, relying on brand claims is a moot point – test protocols are almost always different from one another, with those tests carried out in different wind tunnels (yielding slight correlation differences). 

It’s a fair assumption that they’re ‘competitive’ with the most aerodynamic bikes out there, but it’s certain that neither bike would be raced if the teams weren’t confident they were the fastest bikes available to them for a given race. 

There are design similarities here, especially towards the front. Both have bayonet-style forks, yielding a ‘floating’ head tube front section, which enables the total head tube structure to be lengthened without moving the effective position of the steerer. 

This is said to preserve the kind of handling you’ll find on all-rounders and climbing bikes, while increasing the level of air management in this key area.

The distinctive handlebars are also similar – both are designed to fit flush with their framesets, are one-piece and exhibit a two-prong stem section with a significant rise. Naturally, both are proprietary, meaning you can’t swap to a standard layout, but both can be swapped for free at point of purchase.

The Colnago uses a particularly small 19mm (0.748in) upper and 1-1/8in lower headset bearing, employing CeramicSpeed Solid Lubrication Technology; the Cervélo is a little more standard at 1-1/8in and 1-3/8in.

Towards the back, things are very different. The Y1Rs’ most distinctive feature is undoubtedly the offset seat tube, which is claimed to increase the effective chord length (air continues to flow smoothly down the structure), but also allow for a level of comfort through the saddle.

Importantly, this also makes the effective seat tube angle steeper (73.7 degrees), arguably playing to its star rider’s natural riding position, while helping to open up the rider’s hip angle.

The S5, though, is notable for its curved seat tube, which hugs the rear wheel. Both designs limit how far the seatpost can sit inside the frame – on both my test bikes, I had to have them cut to size. 

Given seatpost real estate is at a premium, a Shimano Di2 battery is stored in a port on the underside of the bottom bracket on the S5, while the Y1Rs has it tucked away in a port under the down tube bottle cage.

It’s important to note that the Cervélo’s Reserve 57/64 wheelset, complete with widened spoke angling, has also been designed hand-in-hand with the S5’s asymmetrical layout – a clear sign that the entire riding system has been considered, rather than only the frameset.

Only the best will do…

Colnago will only spec top-tier 2x road groupsets for the Y1Rs (Campagnolo Super Record 13 is also available, on top of Shimano Dura-Ace Di2 R9200 and SRAM Red AXS), but offers a selection of wheelsets ranging from mid-level Vision SC45s up to ENVE SES 4.5s. 

Cervélo also sells the S5 in a Jonas Vingegaard and Wout van Aert-mirroring Red AXS 1x configuration, and second-tier Ultegra Di2 R8100 and Force AXS groupsets, with DT Swiss 240 hubs laced to the Reserve wheels, instead of the top-spec 180s tested here. 

All this means the entry point for an S5 is a little more accessible, even before the test bike specs are compared. You can have one from £9,200 with the Ultegra Di2 R8100 or Force AXS drivetrain.

As tested, each bike costs £12,000, and fundamentally, this buys you more on the Cervélo.

The Reserve 57/64 Turbulent Aero wheelset is notably wider (25.4mm / 24.4mm inner, 34.3mm / 32.5mm outer) and deeper, featuring different rim profiles front to rear to balance aero efficiency with stability and weight. 

Despite this, it weighs a claimed 1,554g, compared to the SC45 at 1,590g (this is 21mm wide internally, and 31mm wide externally). This also features SINC ceramic bearings, compared to standard steel bearings on the Vision wheels.

Of course, Y1Rs customers could opt for ENVE’s SES 4.5 wheels instead, which aren’t dissimilar in terms of nominal specification and aftermarket price, but you’ll need to pay extra for the privilege.

Colnago also doesn’t spec the Y1Rs with a power meter, which is a significant omission given its key use case as a race bike. You get a dual-sided 4iiii power meter with the S5, making it a more complete spec package. 

That said, Cervélo hasn’t scored a complete home run here – while you can swap the cockpit size for one that will fit you best, you can’t change the default seatpost for the inline or setback version. 

For the Colnago, you can swap both through its dealer programme, plus make tweaks to the groupset specification. There are limits, but you can select your chainring size, crank length and cassette at point of purchase, which is certainly a nice-to-have.

A case in point is the S5’s 54/40-tooth chainrings – a great choice for racers on a flat day, but for most customers (those who aren’t racing professionally), it could prove just a bit too big. 

The scores on the scale doors? 7.53kg for the S5 in this size-58cm frameset and 7.66kg for this size-large Y1Rs. 

Excitement abounds

It won’t surprise you to learn both bikes feel really fast, but it’s how easily they handle that surprised me most. 

Aero bikes, of course, have a reputation for being harder to ride – slab-sided tube profiles tend to make a bike feel more susceptible to crosswinds, while the aggressive layouts often mean they aren’t as agile as all-rounders or lightweight bikes.

Neither bike suffers from these drawbacks, though; they’re among the most stable and easy to ride race bikes I’ve tested, very close to all-rounders such as the ENVE Melee (2023’s Performance Bike of the Year winner) and lightweight bikes such as the Orbea Orca.

I’d argue the S5 feels slightly more sure-footed of the two in windier conditions, but I suspect that’s down to the more progressive rims. Overall, though, it’s easy to see why the so-called death of lightweight bikes – in men’s racing, at least – is upon us. 

When it comes to technical descents, both feel predictable and confidence-inspiring – you get that business-like feeling at the front end, but thankfully neither is too aggressive or twitchy-feeling. 

For me, the Y1Rs is just a touch more agile-feeling – the steering takes a little less input to effect a similar turn – but in testing I found it was simply a matter of adapting to the characteristics of each bike. This didn’t take long, given they’re fundamentally very similar.

But it’s when you ride these bikes at speed, pedalling hard, that they make the most sense. The S5’s huge bottom bracket area offers a really tangible sense of stiffness when you’re giving it the beans. The Y1Rs is plenty stiff enough, of course, but arguably not quite as unyielding.

You’ll never get great compliance from bikes such as these, but neither feels distinctly harsh. The S5 again has the edge here, though – the 29mm Vittoria Corsa Pro tyres dovetail well with the wide Reserve rims, measuring 30.4 and 30.2mm front to rear at 75psi / 5.2 Bar. They offer a little extra volume compared to the 28mm Pirelli P Zero tyres on the narrower Vision rims (these measured 28.5mm wide) 

You can really feel the difference on chip-seal style roads; the sensation through the bars and saddle feels smoother.

Of course, this can largely be offset by running, for example, a wider ENVE SES 4.5 wheelset with 29 or 30mm tyres on the Y1Rs – but you’re not getting that for the same money here. 

It’s also worth noting that the upper limit is higher on the S5, at 34mm, versus 32mm on the Y1Rs. If nothing else, let’s say you never intend to run tyres as wide as that, at least the S5 gives a little more breathing room at the 30 or 32mm mark.

Colnago Y1Rs vs Cervélo S5 bottom line

The Cervélo S5 is the deserving winner of the Race Bike of the Year category for 2025. 

When it comes to specs, the bottom line is you get more for your money. A power meter is an essential piece of equipment for any racer – a serious omission on the Y1Rs – while the top-level wheelset and tyres help to pull it ahead too.

This results in a slightly lighter, more premium ride experience versus the Y1Rs, although there’s plenty to like there, too.

Of course, the Colnago is currently basking in the Pogačar glow, but it offers a fuller programme of customisation. 

Yes, you have to pay to upgrade the wheels to Reserve-rivalling models, but you can choose your gearing and crank length, as well as between an inline and setback seatpost for free – something brands should increasingly look to offer.

There’s no doubt that both bikes are playing right at the cutting edge of race bike design, and the sense of performance is tangible. The fact that both can be just as enjoyable on a hilly ride as they are on the flat speaks to the level aero bikes are reaching.

However, with these bikes delivering performance worthy of the best professional bike riders in the world, the devil is in the detail – the Cervélo is the better value package, even if £12,000 is an eye-watering sum of money.