With elongated tube shapes and other wind-cheating features, aero road bikes provide a small but handy speed boost.
Sleek shapes make for a distinctive look.
Recent aero road bikes have alleviated the harsh ride that plagued some early models, thanks to improved use of materials.
Frame aerodynamics is still a marginal gain; if you're wearing flappy clothes an aero bike is a waste of money.
In just a few years aero road bikes have gone from The Next Big Thing to a mainstream bike option. The latest models have been tweaked to be faster than ever, according to the manufacturers, and to alleviate the harsh ride that characterised some early aero bikes.
Aero road bikes essentially draw aerodynamic features from time trial bikes into a road frame, and balance the demands of weight and stiffness into a package that, on paper, looks to be the ideal all-round choice.
At any decent speed, most of your effort goes into overcoming air resistance, so reducing a bike's drag means you'll go faster, or ride at any given speed with a lower power output. Who doesn't like the sound of that?
Most of your air resistance comes from your body rather than your bike. Wearing non-flappy clothing will help, as will losing weight. But the 20% or so of air resistance from your bike is enough for engineers and designers to focus on making road frames and products more slippery through the air. In the pro peloton aero road bikes have been quickly adopted, where the margins of victory are very slim and there has been a focus on gaining ever smaller performance gains over the years.
Weight, or the lack of it, used to be the main driving force of frame development. Along with stiffness, it was a cornerstones of bike design. These days most bikes are light, many well below the UCI’s 6.8kg weight limit (which doesn’t affect non-racers anyway), and come with more stiffness than is sometimes comfortable.
All that has made aerodynamics more important. Specialized has built its own wind tunnel, for example, and most manufacturers are testing in other facilities. Nevertheless, aero road bikes haven't converged on a perfect, slippery shape. Different engineers prioritise different ways of improving aerodynamics but there are shared design trends: skinny, aerofoil-shaped tubes, integrated brakes, and internal cable routing.
Let's take a look at the latest aero offerings.
The Orca Aero boasts lots of wind-cheating tweaks that Orbea says add up to a 27 watt advantage. Our tester David Arthur found the Orbea Orca Aero M20Team to be "a fast and great handling aerodynamic road bike with a surprising talent for smoothing out all but the roughest roads. But it is speed, not comfort, that is at the top of the list of requirements for an aero road bike, and that's an area where the Orca Aero feels very competent. It's right up there with the Trek Madone, Cervelo S3 and Canyon Aeroad, as super-quick aero race bikes.
"The handling is a highlight, and helps to set it apart from some aero bikes that can be exceedingly quick but a little lacking when it comes to the way they ride and translate your inputs into actions. The Orca Aero is fun and engaging, putting a smile on your face when you're descending or chasing a friend along an undulating ridge road."
You can customise the colour scheme and spec of your Orca Aero too, so if you want to upgrade the wheels, or have yours in pink and orange, fill your boots.
The new Bianchi Aria Disc is an aero road bike that offers efficiency, sharp handling and a responsive character, now with the additional all-weather assurance of disc brakes – in this case from Campagnolo.
The Aria Disc responds keenly to increased effort. Our 59cm sample wasn't especially light at 8.5kg (18.7lb), but it felt direct when you put in the power, a meaty bottom bracket helping to keep everything solidly in place. The Aria Disc feels as manoeuvrable as the rim brake version, which isn't a surprise given that the geometry is virtually identical. Some bikes designed for aerodynamics offer plenty of straight-line speed but they're a little compromised when you want to flick around. The Aria Disc handles sharply, which gives you options when it comes to darting about a group or avoiding something in the road.
The 3T Strada has blown us away. It's a truly stunning bike with breathtaking speed, impressive smoothness and fine handling balance. If this is the future, as some people have speculated, we're sold. Take our money, 3T. This is one of the most exciting road bikes available right now.
The Strada certainly won't be for everyone. And that's fine, there are plenty of fantastic performance road bikes currently available if the 1x11 gearing, disc brakes and tight clearances frighten you. None are as radical as the new 3T, though. What the Strada does with its unique design is offer another choice. It achieves the same aim – of being stupendously fast – but takes a different path to get there.
Colnago has joined the aerodynamic arms race with the Concept, a full blooded aero race bike that is a serious step forward from the Italian company's first aero road bike, the V1-r.
The Concept has all the capability to dice with the fastest in a race situation. Its stiff frame, deep-section wheels and lightweight give it an insatiable appetite for speed. It's quick in all circumstances: climbs, descents, flat and undulating roads – the bike shines everywhere. This is an exciting bike to ride fast, and like all good aero road bikes it encourages you to ride flat-out.
That firm ride, and frame and fork stiffness ensure the Concept accurately follows your inputs, whether through the handlebar or pedals. It reacts positively whether you're blasting an uphill sprint finish or bombing through a curving descent.
The Concept isn't just for racing. It provides adequate composure and comfort, allowing you to tackle long distance rides at a few notches below race pace and not be dealt a hammer-blow to the lower back the moment the tyres encounter anything but a super-smooth surface. The front end of an aero race bike can often be overwhelmingly harsh, but the special headset and fork steerer tube that Colnago has developed mean the Concept is smoother up front than would normally be expected on an aero road bike.
Merida has updated its Reacto to be, it says, lighter, more comfortable and more aerodynamically efficient than before. It has done this by slimming down the tube shapes and introducing a lower seatstay connection with the seat tube, among other things.
Merida – a Taiwanese brand although much of its engineering is undertaken in Germany – says that the new Reacto is more aerodynamically efficient than the previous version by about eight watts at 45km/h. That equates to around 5%.
Comfort has been increased through redesigning the seatstays and giving the S-Flex seatpost a slimmer cross section and a bigger ‘window’ – a notch that’s cutaway to allow more downward movement.
For 2018, Merida is offering disc brake versions of the Reacto for the first time.
Boardman's Air 9.2 (£1,749) is just the ticket if you're looking for a fast bike with a good spec. It's a great package and the performance is impressive.
Some aero bikes can be a handful, but thankfully the Air 9.2 is a neutral ride most of the time. Considering the amount of side profile, it's really not that much of a handful in the wind. Okay, our reviewer had a couple of interesting moments getting hit by a 30mph sidewind on one ride, but it's generally pretty predictable.
It's fast, it's firm but not uncomfortable, and it responds well under power. There are a few minor niggles – the brakes aren't the best, and some of the components are worth an upgrade to get the best out of the frame – but if you're looking for a fast bike for racing, triathlon or even time trialling then it's very much one to consider.
Buying the Storck Aerfast Platinum is a massive outlay, but boy, oh boy do you get one hell of a return on your investment. It's a sub-6.5kg race weapon, with aerodynamics that work in the real world, and it offers comfort levels to challenge most endurance bikes.
Taking plenty of things it has learnt from its astonishingly good Aernario, Storck has pushed the design even further down the aerodynamics route, and what it has created in the Aerfast is a bike that's not only unbelievably fast, but light and stiff too.
If you're in the market for an aero bike, speed is going to be topping your list of priorities, and that's where the Aerfast truly excels. At lower speeds the Storck feels like any other bike to ride, any other superlight bike that is, but as you ride faster it feels like a permanent tailwind is nudging you along, a friendly hand on your back as you watch the numbers climb on the Garmin – with little more effort required than there was 5mph ago. It's a wonderful feeling, and one of which you never tire.
Cervélo has redesigned the S3 Disc to smooth out any penalties that might occur from adding disc brakes. The result is a frame that it claims is 9% stiffer, a touch more aerodynamically efficient, and lighter by 40g compared with the regular rim brake model.
There's a lot to like about the Cervélo S3 Disc. If you want pure speed with the reassurance of hydraulic disc brakes, it's a very good option: it's extremely fast and the handling is lively and direct – just what you want from a race bike – but its composure on rough roads falls some way short of its key rivals. If you're willing to overlook its lack of comfort, it's an explosive bike.
Aero and discs? It's getting more common as bike makers figure out how to mount disc callipers without adversely affecting aerodynamics.
Ridley calls its collection of speed-enhancing aerodynamic features FAST. It includes a tube shape that combines an aerofoil profile with a groove that helps keep the air flowing smoothly over the surface to reduce drag. For 2019 tube shapes have been further refined, there's a new integrated bar, stem and fork system that hides the cables completely, and the fork tips have sprouted 'F-Wings' to improve airflow over disc brakes.
As for the discs, Ridley believes they're simply a better way of stopping.
Developed in collaboration with Team Sky, the Dogma F10 is the bike upon which Chris Froome won the 2017 Tour de France. The F10 uses FlatBack tube profiles – a Kamm tail sort of shape with a rounded leading edge and chopped off tail, and Pinarello has shaped the down tube so that you can mount a water bottle without ruining the aerodynamic performance. Up front the fork is derived from the company’s Bolide time trial bike with aerodynamically shaped legs and a crown that's integrated into a recessed down tube.
The second-generation Aeroad CF SLX has been inspired by the work that Canyon did on its futuristic Speedmax time trial bike, with razor sharp aero tube profiles and an optional one-piece handlebar and stem. Much of the company’s focus was on reducing the Aeroad's frontal surface area, so along with the new cockpit there’s a narrower hour-glass shaped head tube to help reduce drag. Other changes include a variant of the Trident tube shape used on the Speedmax, and a seat tube that hugs the leading edge of the rear wheel.
The Aeroad CF SLX is available in both rim brake and disc brake models.
If you're going to fly, you need to be able to rein in that speed. Disc brakes give finer modulation of speed with less effort at the lever so as you're whooping into Alpine hairpins you can brake later and waste less valuable speed.
As well as its aero frame, the Venge Vias has an aero handlebar and stem. The almost complete lack of external cables further reduces drag.
The Foil arguably kicked off the whole aero road bike trend, bringing aerodynamic design that was once the preserve of time trial bikes to regular road bikes. For 2018, Scott added disc brakes, arguing along with other manufacturers that you can go faster if you can slow down better. That's on top of the last series of updates to the Foil that saw the down tube lowered and wrapped around the fork crown, and a smaller rear triangle and internal seat clamp in the top tube.
Don't make the mistake of thinking this is an uncomfortable aero bike. Mathew Hayman rode over a few little bumps on his way to winning Paris-Roubaix in 2016.
Once an all-round lightweight race bike, the Madone has had a complete aerodynamic makeover. It features a version of the Isospeed decoupler borrowed from the Domane to provide some comfort and it’s wrapped up in a frame with Kamm tail shaped tubes. Like Specialized, Trek has also developed its own brake callipers that are designed to integrate with the fork and seatstays. The head tube features flaps that open and close to accommodate the movement of the brake when the fork is turned.
For 2019 has a hugely updated Madone road bike with adjustable IsoSpeed (a shock damper at the top tube/seat tube junction), a new geometry and disc brake models. The rim brake version is lighter while the disc brake version has no aerodynamic penalty, according to Trek..
Giant has added disc brakes to the Propel Advanced lineup for 2018, claiming that the flagship model, the Propel Advanced SL Disc, has the highest stiffness-to-weight ratio of any bike in its class and a lower drag coefficient at a wider range of yaw angles than the rim brake version.
“One of the key breakthroughs is a new truncated ellipse airfoil shape – a design that lowers drag at a wider range of wind angles than traditional teardrop frame tubing,” says Giant. “Engineers also found that, with proper integration, a disc-brake design can actually improve aero performance compared to rim-brake configurations.”
As well as a stunning paint job, the top of the range Propel Advanced SL 0 Disc has a full Shimano Dura-Ace Di2 groupset and Giant's own SLR 0 Aero Disc wheels with a 42mm deep front rim and 65mm rear.
The Propel disc range starts at £2,999 with the Propel Advanced 1 Disc.
French brand Lapierre gave its Aircode bikes a major update for 2018. The frame profiles were refined, and are now shaped using a combination of NACA and Kamm tail profiles. The down tube, for example, transitions from one to the other to keep drag low while increasing lateral stiffness at the bottom bracket. Other changes include a revised geometry, shorter chainstays and fork rake that has been reduced to bring it closer to the Xelius SL. There's also a new aero seatpost, direct mount brakes and 'TrapDoor technology' whereby the Di2 battery is housed in the down tube for better weight distribution.
Lapierre has integrated the fork crown into the down tube to bring the front wheel closer to the frame. It’s also using a direct mount brake calliper which allows the fork crown height to be lower than with a standard brake.
Bianchi took the Oltre XR2 as its starting point for the XR3's design and then altered many of the tubes and features, resulting in a very different bike. The head tube is new, for example, the aero design fairly similar to that of the XR4, and the seat tube is new too, although it is still cut away around the leading edge of the rear wheel.
The Oltre XR3 features Bianchi's Countervail technology, Countervail being "a patented viscoelastic carbon material with a unique fibre architecture that cancels up to 80% of vibrations while increasing the stiffness and strength of carbon frames and forks", according to Bianchi.
The Oltre XR3 is nimble and sharp handling, and it offers a ride that's smooth by aero road bike standards.
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Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.