Why the aero road bike is making a comeback

You might well have seen Tadej Pogacar winning this year’s UAE Tour on the new Colnago Y1Rs – a bike that was introduced a couple of months ago as “the most aerodynamic in the WorldTour” - but hang on! Haven’t many of the big bike brands been telling us over the past few years that the era of the dedicated aero bike is over? So what’s the truth, and what does this mean for you? 

A bit of history...

First of all, we need a little context. Over the past couple of decades, many of the major bike brands have taken a two-pronged approach at the top of their road range, offering a lightweight model and a more aero – but slightly heavier – model (plus an endurance bike, but let’s leave those out of this discussion).

2006 Cervelo Soloist (credit: peanutian CC BY-SA 2.0 via Wikimedia Commons)

Bikes don’t always fit into neat categories but the Cervélo Soloist is usually regarded as the first aero road bike, introduced for the 2002 product year – long before road.cc even existed – and originally made from aluminium alloy. It's a 2006 Cervélo Soloist pictured above.

The Soloist was radical for its time in using tube profiles derived from NACA (National Advisory Committee for Aeronautics) airfoils. Rather than using tubes from existing brands, Cervélo went off and made its own. It also used smooth welds and largely internal cable routing that was designed to improve aero efficiency further.

With a short head tube and a reversible seatpost, the Soloist had a lot in common with a time trial bike. Although not especially light by today’s standards, it got lighter with the introduction of the Soloist Carbon in 2005, and subsequent versions.

Specialized Venge Pro 2019 (credit: Specialized)

Of course, Cervélo didn’t have the aero road bike space to itself for long. Most other brands soon piled in. Eventually, Specialized had the Tarmac and the Venge (it's the 2019 Venge Pro pictured above), Trek had the Emonda and the Madone, Giant had (and still has) the TCR and the Propel… The list goes on. Not every brand took this line of action – Pinarello, for example, always had the Dogma in its various incarnations to cover all eventualities – but this two-bike strategy was the norm for years. 

2021 Mark Cavendish TdF Specialised Tarmac SL7 (credit: Alex Broadway/SWpix.com)

Then, in 2020, Specialized announced its Tarmac SL7 as “one bike to rule them all”, saying the new design was sub-6.8kg (the minimum permissible weight for UCI-sanctioned racing) with as little drag as its Venge aero road bike (that's Mark Cavendish pictured above on a 2021 Tamac SL7). The Venge was seen as surplus to requirements and put out to pasture.

“This is one bike to rule them all, putting an end to the idea of a climbing bike and an aero bike," said Cam Piper, the product manager for the Specialized Tarmac SL7.

2025 Soudal Quick-Step Specialized Tarmac SL8 (credit: Soudal Quick-Step)

Specialized is sticking to this approach, at least for the time being. It launched the Tarmac SL8 in August 2023, claiming that the new bike was 15% lighter than the Tarmac SL7 and 16.6 seconds faster over 40km (25 miles).

> Check out our review of the Specialized S-Works Tarmac SL8 - SRAM Red eTap AXS

Specialized also said that while the SL7 didn't test as fast as the discontinued Venge at numerous angles in the brand's own ‘Win Tunnel’, the SL8 was faster than the 2019 Venge and also the lightest bike in the WorldTour peloton.

Would the brand be tempted to launch an ultra-aero road bike that’s a little heavier than the Tarmac SL8? A new version of the Venge, essentially? There have been various rumours, but nothing more. Right now, Specialized seems very happy with its single-platform approach (it also offers the superlight Aethos which, although it's UCI-approved, isn't primarily designed as a race bike). 

> Read our review of the Specialized Aethos Pro Ultegra Di2

2024 Factor Ostro VAM (credit: Factor Bikes)

Several other brands have followed Specialized's lead. Last year, for example, Factor described its new Ostro VAM as “the benchmark aerodynamic, lightweight race bike", and then Trek effectively merged its aero Madone and lightweight Emonda lineups. The new Madone was said to be as aero as the previous model and 320g lighter.

> One bike to rule them all — are lightweight aero bikes the ultimate race weapons for the pros?

There has certainly been a trend to amalgamate aero bikes and lightweight bikes into a single platform, then, but the traffic hasn’t all been in one direction. Plenty of brands continue to develop specifically aero road bikes alongside their lighter-weight road bikes, saying that in many circumstances it's worth incurring a small weight penalty in pursuit of reduced drag. It looks like there's still plenty of life in the aero road bike genre.

One of the reasons why many bike designers still believe in the idea of aero road bikes is that the UCI (Union Cycliste Internationale, the governing body of cycle sport) has altered its equipment rules in recent years. 

For a long time, the UCI had a 3:1 rule that controlled bike design. The rule limited the ratio of a bike tube’s height (or depth, depending on how you look at it) to its width at a maximum of 3:1. 

That rule has been scrapped. The UCI still has stringent equipment rules, of course – which you can read to your heart’s content if you have a few hours to spare (hint: don't do it) – but the 3:1 thing has gone.

2025 UCI compensation triangles and boxes - 1 (credit: UCI)

These days, bike designers can go with an 8:1 profile. We’ll spare you the finer details but UCI rules say that the various elements of a frameset (top tube, seat tube, and so on) must be able to fit into a series of rectangular boxes on a template, those boxes being 80mm wide (it gets a bit more complicated at the head tube ‘reinforcement zone’ where 160mm is permitted, but let’s put that to one side here).

While the maximum dimension of any tube is 80mm, the minimum thickness is 10mm. If a frame designer goes right up to these limits, they’ll have a tube with an 8:1 ratio; that’s what the rule means.

One other fairly recent change is that whereas the seatpost used to have to extend from the seat tube, now it can be attached to the frame anywhere on the seat tube or top tube. 

Why do we mention these changes? Because they’re important to understanding what’s going on in road bike design at the moment.

For example, when Colnago started the development of its Y1Rs aero road bike in 2021, the UCI had just communicated the upcoming revisions to its regulations. 

Colnago Y1Rs WC livery (credit: Colnago)

Filippo Galli, lead engineer on Colnago’s Y1Rs says, “Those two changes in the UCI Technical Regulation are the ones driving the design of Y1Rs.
 
“The 8:1 ratio rule just states that the lateral view of each tube must be covered by the 80mm rectangular boxes, and the minimum tube width is 10mm (from here the 8:1 ratio). 

“None of the tubes of Y1Rs is 80mm long and 10mm wide since using such extreme profiles would mean increasing the final weight to guarantee the proper lateral stiffness, but almost all of them exceed the former 3:1 rule. 

2024 Colnago Y1Rs (credit: Colnago)

“In particular, it wouldn’t have been possible to realise such a thin frontal area, which significantly affects the aerodynamics of the whole bike, without penalising the stiffness of whole front end (which is crucial in sprinting). Most of the brands are exploiting this rule nowadays for aero/TT bikes.”

The position of the seatpost on the Y1Rs is unusual, too. It is fixed in place at the point where the top tube and extended seatstays meet. 

2024 Colnago Y1Rs (credit: Colnago)

“In Y1Rs, the tube starting from the bottom bracket and following the shape of the rear wheel can be considered as the seat tube and, as long all the other tubes can fit into the two main triangles built with the rectangular boxes [described in the UCI’s equipment regulations], the seatpost can be positioned on the top tube and slackened without constraints,” says Filippo Galli.

“Of course, we looked for the best position and angle (combined with the tube dimension and shape in that area) in order to allow all riders to find the optimal height and seat back, and allow better deformation and shock absorption of the area – to give more compliance and comfort, especially in an aero position. We also moved the seatpost forward, cleaning the airflow behind the rider’s legs.

“Such a design wouldn’t have been possible before since the seatpost had to be aligned with the seat tube, or at least a straight line should have been drawn along these two elements.”

Colnago Y1Rs UAE Tour 2025 (credit: Colnago)

Not surprisingly, Colnago says that the whole Y1Rs design process was data-driven with the key goal of reducing drag and, according to the White Paper it released to support the launch, “In a real racing setup, you need 20 watts less on a Y1Rs to go 50km/h [31.1mph] than if you were riding a V4Rs”.

Weight? Colnago was prepared to take a small hit there. The V4Rs frame – which has been around for a few years – has an official weight of 798g (unpainted) and a fork weight of 375g. The new Y1Rs has a claimed weight of 972g (unpainted) and a fork weight of 450g. In other words, the combined frame and fork weight of the new bike is 249g heavier. Okay, 249g isn’t massive in the overall scheme of things, but we’re talking about a frame and fork weight deficit of more than 20%. 

2025 Movistar Canyon Aeroad CFR (credit: Movistar)

Over at Canyon, we saw the release of the updated Aeroad last July, the aero road bike that sits at the top of the range alongside the lightweight Ultimate. Again, there’s no doubt that the Aeroad is itself a lightweight bike – the Aeroad CFR AXS that we reviewed hit the scales at just 7.07kg, for example, and the frame comes in at just 960g.

> Check out our review of the Canyon Aeroad CFR AXS 

No one is saying that’s heavy – not by any means – but it’s a touch heavier than the previous-generation Aeroad frame, albeit by just 45g, and aerodynamics is at the top of its list of priorities. A deep head tube, narrow down tube, a seat tube that’s cut away around the leading edge of the rear wheel, an integrated cockpit… you get the idea.  

2024 Canyon Aeroad CFR AXS - seat tube junction.jpg (credit: road.cc)

For comparison, the Ultimate CFR frame is just 762g (size medium, including paint and hardware), so you get to choose between a lighter model and a bike that’s more aerodynamically efficient. Has Canyon considered merging the Ultimate and the Aeroad platforms?

Lukas Birr, lead engineer for the Aeroad, says, “When it comes to road racing our focus is on racing to win and delivering maximum value to our customers. As long as we can maintain a competitive edge through distinct and specialist product families that serve these two principles, then we'll stay true to this strategy. And looking ahead, this remains our plan.”

Okay, so has the UCI’s ditching of the 3:1 rule given the aero bike a new lease of life over the past few years?

“We see more potential for gains in 3D shaping, transition details, accessory optimisation and the general inclusion of more realistic real-world setups in simulation/wind tunnel testing than simply elongating already existing frame aero-shaped profiles,” says Lukas Birr.
 
Would the current Aeroad have been possible if the 3:1 rule was still in place? Lukas Birr says, “Yes. The goal of the Aeroad is to be the ultimate race bike, and its design guarantees top-tier performance in both weight and aerodynamics.”

2024 Canyon Aeroad CFR AXS - riding 4.jpg (credit: road.cc)

Although a touch heavier (it's all relative), Canyon says that the Aeroad offers an advantage of around 15W versus an Ultimate with the same spec (Canyon got its figures in the GST Wind Tunnel at a speed of 45 km/h/28mph, using its Ferdie leg dummy automaton with DT Swiss ARC1100 50 mm wheels and Schwalbe Pro One TLE 25F/28R tyres).

“The Ultimate is advantageous in races with long, steep climbs, such as alpine stages in the Tour de France, where its lower weight improves climbing efficiency and acceleration,” says Lukas Birr.

“In contrast, the Aeroad is superior on flat and rolling terrain, like in one-day classics or sprint stages, where aerodynamics provide greater speed savings at high velocities. In hilly races with frequent accelerations, such as the Ardennes classics [Liège–Bastogne–Liège, La Flèche Wallonne, Amstel Gold Race], the Ultimate’s lower inertia can offer a more responsive feel, whereas the Aeroad excels in breakaways and high-speed sections.”

A two-pronged offering from Canyon remains on the cards for the foreseeable future, then, and many other brands are sticking with aero-specific road bikes. Ridley, for example, recently launched the updated Noah Fast with the claim that it offers 8.5 watts of speed savings over the previous version at 50km/h (31.1mph) by “pushing the limits of UCI regulations”. It went so far as to say, “In 2025, aerodynamics is everything.”

2025 Ridley Noah Fast aero road bike Uno-X (credit: Ridley)

> "Pushing the limits of UCI regulations": Ridley officially unveils new Noah Fast aero road bike claiming 8.5 watts of speed savings

The most striking feature is an ultra-deep head tube that looks like it has been borrowed from a time trial bike. The fork and seatstays are extremely narrow yet deep – now possible thanks to the UCI's changes to equipment regulations mentioned above – and the oversized down tube is designed to channel airflow around water bottles, a feature increasingly common on modern aero bikes.

2025 Ridley Noah Fast headset (credit: Ridley)

Again, weight takes a back seat here. Ridley says that a Noah Fast 2025 frame weighs 1,053g (medium size, unpainted) with the fork 509g (+/-10%). Ridley does attempt to cover all bases by also offering the Falcn bikes, which are designed to provide a balance between aero efficiency and light weight, the superlight Helium bike (plus the Grifn and Fenix endurance models).

2025 Van Rysel RCR-F (credit: Van Rysel)

Over at Van Rysel, designers have been working with aero wheel outfit Swiss Side on the RCR-F which, it claims, will be “setting a new standard for aero bikes”. Details on this one are scarce because the bike has yet to be officially released, but just check out the depth of those tubes, particularly the mighty head tube. 

Van Rysel says that the new bike “achieves aerodynamic savings of over 13 watts compared to the RCR-R”, although it hasn’t yet said in what conditions that applies.

2025 Van Rysel RCR-F (credit: Van Rysel)

Van Rysel still describes the RCR-R as being “the favourite choice for hilly and mountain stages” for riders of the Decathlon AG2R La Mondiale team, so we can reason that the RCR-F is a little heavier.

Meanwhile, Quintana Roo describes the new Service Course as its “fastest-ever UCI-legal aero road bike”. A narrow head tube is designed to reduce frontal area and features a “chine” that’s intended “to redirect air sent upward by the fork legs, sending it rearward and reducing drag”.

> Triathlon specialist Quintana Roo unveils new "all speed" aero road bike — and it's actually quite reasonably priced 

2025 Quintana Roo Service Course aero road bike - blue (credit: Quintana Roo)

A deep-section down tube is intended to reduce turbulence and keep airflow attached while the fork features a greater than normal axle-to-crown length and a wide stance to open up space around the front tyre to improve airflow.
Quintana Roo boasts that 7.3kg (16.1lb) builds are available – so, again, we’re talking light but not the lightest. “Aero performance was the top priority,” it says.

What next?

Essentially, we have a situation where most brands have made their lightweight road race bikes more aero and their aero road race bikes more lightweight over the past few years. Some brands, such as Specialized and Trek, now take the view that they can build an aerodynamically efficient road bike that can hit the UCI’s 6.8kg minimum weight limit for racing, so there’s no point continuing to offer two separate platforms.

2024 Colnago Y1Rs (credit: Colnago)

But, as we’ve seen, other brands see value in pushing the limits of new UCI regulations. For example, the removal of the UCI’s 3:1 rule certainly influenced Colnago's decision to develop the aero Y1Rs. If that means a slight weight penalty – yes, slight – in return for improved aero performance, that’s a sacrifice they’re willing to make.

Where next? It’s a difficult one to call but one thing’s certain: despite a lot of talk about its impending demise, the aero road bike is far from dead.