The best aero road bikes: save watts with the fastest aero bikes available

(Image credit: Trek)

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Best aero road bikes you can buy today
Aero road bikes explained

The best aero road bikes will give you a dose of free speed with their aerodynamic performance better than ever and saving you energy at all but the lowest speeds. Their aerodynamic gains are more important than the benefits of riding the best lightweight bikes on all but the steepest climbs.

Modern aero road bikes are also much more comfortable than their predecessors and many have reduced the significant weight of those bikes close to the UCI's 6.8kg weight limit in top spec builds.

Trek Madone SLR

Best for aero tech innovation

Specifications

Brake: Disc

Frame: Carbon

Sizes (cm): 47, 50, 52, 54, 56, 58, 60, 62

Weight: 7.4g (Madone SLR 9 Red eTap,56cm, claimed)

Reasons to buy

Innovative features

Radical design aesthetics

Head-turning looks

Reasons to avoid

High price

Non-adjustable frame stiffness

Narrow bar tops may not be for everyone

But the Dogma F manages to reach a more competitive weight via small gains in parts like the 3D-printed titanium seatpost clamp, which together add up to a 265g reduction from the Dogma F12 and puts a top spec disc brake retail build at around 7kg. The Dogma F is not just light though, it's razor sharp, fast, and comfortable with it. It's also one of the few high spec bikes that's available with rim brakes, not just discs.

The CF SLX level frames are equipped with mid-level electronic groupsets, but still boast a power meter and quality wheelsets, while the entry-level CF SL frameset is specced with Shimano Ultegra and DT Swiss ARC 1600 wheels. Smaller size CF SL bikes come with 650b wheels to keep the geometry similar to larger sizes with 700c wheels. Canyon quotes a bike weight of 7.8kg for the most basic CF SL 8 Disc spec, dropping to 7.2kg for the CFR Disc Di2.

The Scott Foil is another aero road bike that has had a recent makeover. Scott says that the changes have made the new bike lighter and more aero. Although the cut-out for the rear wheel makes it look as if the wheelbase has been reduced from the older model, the geometry is essentially unchanged. According to Scott the redesigned frame with its deeper tube profiles will save you over a minute over its predecessor over a 40km ride at 40km/h.

What makes a bike aero?

The heart of an aero road bike is its aerofoil-shaped tube profiles. In fact, truncated aerofoils are used, which have the front end of a classic teardrop shape, but cut off the rear end sharply. This results in an aerofoil (like a plane's wing) that's as much as eight times longer than the actual tubing. Air behind the rear of the tube "completes" the aerofoil shape and results in the air flowing smoothly around the tubes.

This creates a frame that's significantly more aerodynamic than a classic round tube profile, reducing the effort required to keep the bike moving at all but the slowest speeds.

In addition, modern aero road bikes hide the brake hoses (and gear cables if these are present) within the bar and stem, routing them directly into the head tube.

As with round frame tubes, there's drag developed by exposed cables that's disproportionate to their width. This front-end integration and fitting bar-stems that are aerodynamically optimised save yet more energy.

Finally, an aero road bike will almost always be fitted with deeper section wheels, which are more aerodynamically efficient than shallower rims. The sweet spot tends to be between 40mm and 50mm deep, where there are significant watt savings, but the wheels are not too hard to handle in crosswinds.

Why do aero road bikes cost so much?

There's a significant amount of resource required to develop a modern aero road bike. That usually starts off with computational fluid dynamics (CFD) studies of airflow over the design and iteration of the design elements to optimise aero efficiency.

Life size 3D-printed models of the bikes are then usually tested in a wind tunnel, which is a pricey, labour-intensive process. Airflow may be modelled at different wind speeds and wind yaw angles to ensure good aerodynamic performance in a range of conditions.

There may be several iterations and designers may perch mannequins on the prototype frame to see the effect of the rider on airflow. Some mannequins can even pedal, as this movement can alter the results.

It's all additional work and cost over developing a traditional round-tubed bike, in addition to ensuring it passes all the relevant safety standards too. It has to be shown to be comfortable to ride and stiff enough for efficient pedalling as well.

Are aero road bikes uncomfortable to ride?

The initial crop of aero road bikes from around 10 to 15 years ago had a, not unmerited, reputation for being jarring to ride and heavy. Modern aero bikes have overcome this though, with designers learning how to maintain aerodynamics while building compliance into the frame. The ubiquity of disc brakes has seen a trend to wider, more comfortable tyres too.

Bike weight has decreased as well, with top spec modern aero bikes routinely approaching the UCI's magic 6.8kg weight limit, even with the disc brakes that are now the norm.

In most ride conditions, aerodynamics are more important than bike weight, so an aero road bike is usually a better choice for most riders, even on hilly rides. It will be faster on the way back down too.

Why do all aero bikes look the same?

A result of the focus on aerodynamics and the need for designers to keep to the UCI's rules on frame design is that there's limited scope to innovate in frame shape. The same physics apply to airflow over every manufacturer's frame.

Features like deep aerofoil sections, horizontal top tubes, a deep bottom bracket area, dropped seat stays, integrated hose routing and sharp frame junctions have the same effect for all bikes and so feature in the majority of designs.

Having said that, there's still room for innovations like the Trek Madone's split seat tube that can potentially stir things up and change the aero calculus.

Would an aero/lightweight bike be a better choice than a full aero road bike?

Some brands offer both a lightweight bike and an aero road bike, so you may have a choice if you've decided on a particular bike brand. The majority of lightweight bikes now include some aero features though, just not as extreme as a full-on aero bike, so there's less energy saving. In general they retain a significant weight advantage.

Examples of lightweight bikes which have had the aero treatment include the Bianchi Specialissima, the Merida Scultura, the Scott Addict RC and the Trek Emonda. Other brands have merged the two categories: take the Specialized Tarmac SL 7 and the Pinarello Dogma F for example.

For many riders, the combination of aero and light weight may be a compelling alternative to the all-out aero road bike.

Paul has been on two wheels since he was in his teens and he's spent much of the time since writing about bikes and the associated tech. He's a road cyclist at heart but his adventurous curiosity means Paul has been riding gravel since well before it was cool, adapting his cyclo-cross bike to ride all-day off-road epics and putting road kit to the ultimate test along the way. Paul has contributed to Cyclingnews' tech coverage for a few years, helping to maintain the freshness of our buying guides and deals content, as well as writing a number of our voucher code pages.