Nearly every company going has an aero bike somewhere in its range. And for good reason. Our independent testing shows that the difference between a good aero bike, and a climbing bike, could be as much as 25-watts at 45kph. It’d take a lot of training to gain 25-watts.
Aero bikes are characterized by:
- Wide tube shapes designed to reduce drag
- Integrated cockpits
- Hidden, or disc, brakes
- Hidden seat post clamps
While it’s all well and good having the fastest possible aero bike, you won’t want to ride it very far if it’s uncomfortable or too heavy. Happily, the latest generation of aero bikes are impressively low weights and deliver a ride quality that’s both comfortable enough for a long day in the saddle, as well as a sprint finish.
We’ve tested the latest and greatest models, and with widespread prices, there should now be an aero bike out there to suit most budgets.
Best aero bikes 2021: Our favorites
BMC Timemachine 01 Road Four £6,999 / $7,499
Since it’s introduction in 2012, the BMC Timemachine has always been a head-turner, but there was no doubting it’s purely functional credentials, sacrificing comfort for ultimate speed.
The platform has come along way since then, and the Timemachine Road iteration is far more rider friendly, and while it retains its rapidness, the latest design manages to also shoehorn in an element of compliance, with the end result being pretty close to perfect.
Equipped with Shimano Ultegra Di2 disc brake set up, semi-intergraded cockpit, 62mm deep section DT Swiss Arc 1400 Dicut 62 wheels and fast rolling Vittoria Corsa Control tires leave you with no question as to the bike’s ambition, but with the added comfort factor, it now means it’s a lot more than just a one trick pony.
Our only grumble is with the limited 25mm tyre clearance, and the fact that at £7,000 / $7,500 it’s either the bike or a family car.
Read more: BMC Timemachine 01 Road Four review
Pinarello Dogma F12 £10,000 / $13,500
Winning the Tour De France in its first season is an impressive Palmarès and having ridden and rated the Dogma, it could probably win any race it wanted too.
There is no denying that the bike is all about performance and leaves little room for comfort. The sacrifice, however is worth it if your looking for all-out speed, as we found ourselves hoovering up Strava KOMs without even trying.
There are several build options, including an increasingly rare a rim brake option, which we tested. The brakes are direct mount, a much needed inclusion when trying to slow this machine down.
The Pinarello say that the F12 is the stiffest version yet, with the Onda fork and Torayca T1100 carbon fibre frame now 10-percent stiffer than the previous F10, as well as also getting reworked to save a further 7.3-percent drag compared to the F10, around eight seconds every 10-miles, or half a kilometre an hour.
It’s a dream of a bike, a rapid, nimble, in unforgiving ride, and of course, with the price tag, a rather expensive one at that.
Read more: Pinarello Dogma F12 review
Cannondale SystemSix Carbon Ultegra Di2 £5,499 / $7,250
The SystemSix is Cannondale’s first ever dedicated aero road bike, and the brand has come out swinging. It looks exactly the way you’d expect an aero bike to look, it’s all stark angles and chunky tubes and you’d be forgiven for thinking it’d be uncomfortable, but actually the SystemSix has a comfort is at odds it’s chunky nature.
It’s also a very fine handling bike, with a geometry that almost matches the Cannondale SuperSix Evo and hydraulic brakes that instill confidence on descents.
The SystemSix rolls on the Cannondale’s Knot 64 wheels which are tubeless ready, very stiff and spin along like a freight train. Teaming it with the much rated Shimano Ultegra Di2 for rapid electronic shifting is the ultimate partnership.
There are men’s and women’s build options at this spec, as well as a standard non-digital Ultegra and Dura-Ace Di2 and SRAM e-Tap Red AXS versions, with corresponding prices.
With two back to back years as a Cycling Weekly Editor’s Choice award winner, we cant’t speak highly enough of Cannondale’s aero offering .
Trek Madone SLR 9 Disc eTap £11,050 / $12,499.99
One of the fastest bikes on the market, the Madone is now in it’s sixth iteration and just keeps getting better and better.
Ok so the price for this baby is totally bonkers, but never fear, it won’t be of surprise to learn that this indeed it the range topping bike and there are some more modest priced versions available, all of which no doubt will be sublime to ride.
The Trek Madone SLR 9 Disc eTap specifically, however, is a technical masterpiece. It recently gained new geometry fit, and the result is a blisteringly fast bike that offers a dialled in specifically for your comfort, thanks to Trek’s IsoSpeed Decoupler, the same system that’s found on its Domane endurance bike, fitted to the top tube. According to Trek, this yields 17-percent more comfort than the old Madone and in its firmest setting it’s 21-percent stiffer.
At 7.5kg / 16.53lbs it’s average weight for the latest aero bikes, but the performance and stiffness of the frame helps it feel agile.
Read more: Trek Madone SLR 9 Disc review
Cervélo S5 £10,199 / $11,500
The Cervélo S5 epitomises aero. There’s no doubt that it is a very fast racing machine, with Cervélo claiming that this iteration has pretty much maxed out the aerodynamic efficiencies allowed under the current UCI regulations.
The handle bar and stem system is nothing short of Star Trek film, Cervélo say the design allows the air flow to move cleanly through making a significant reduction in drag.
Now capable of running up to 28mm tires the latest model is also 25-percent stiffer around the bottom bracket and 13-percent stiffer around the head tube.
Despite it’s aggressive geometry and aero credentials, the Cervélo S5 is comfortable enough to ride, not for an all dayer — but at the speeds it allows you to ride at, you may not be out for as long as you expect.
The £10,000 / $11,500 price tag is certainly the elephant in the room, and the Sram Red eTap AXS, we we reviewed, or the Shimano Dura-Ace (as pictured above) versions are clearly the headline acts in the range, depending on where you live you might be able to get your hands one at a more modest price — about £4,500 in the UK, but the analog Ultegra spec still costs $7,000 in the US.
Read more: Cervélo S5 review
Specialized S-Works Venge £9,749 / $12,520
The Specialized S-Works Venge takes quite a different shape from the old Venge Vias, and it now has an uncanny resemblance to the Specialized S-Works Tarmac SL7 Disc — and still retains a slight aero advantage of the latest Tarmac according to Specialized. Like the Cannondale SystemSix, the Venge is disc brake only, but it takes an even more elitist approach by being compatible only with electronic gearing.
The design update improved the bike’s handling, which now feels lightening fast. It has also improved the bike’s ride quality, and it feels more plush and comfortable compared to the old model. At £9,750 / $12,520 for the full build, the Venge has one of the more expensive price tag. But for the money you get Roval’s exceptional wheels and the very good S-Works Power Crank, too. Alternatively, you can stump for a frameset only at £3,700 / $5,500.
Read more: Specialized S-Works Venge review
Other great aero bikes to consider
- Liv Enviliv: Read our Liv Enviliv Advanced Pro 2 Disc Review here
- Scott Foil: Read our Scott Foil 10 bike review here
- Giant Propel Advanced: Read our Giant Propel Advanced SL 1 Disc review here
- Ridley Noah: Read our Ridley Noah Fast Disc Ultegra Di2 here
Aero bikes: Why would you buy one?
Well that’s a very good question that, with the Cycling Weekly wind tunnel still seeking funding from the powers that be, we can’t answer with complete scientific accuracy. However, we have conducted a couple of past experiments that have compared the performances of aero bikes with non-aero bikes.
In the first of these, we put the two bikes to the test in what should be the aero bike’s home turf: the velodrome. We rode each bike (a now outdated Cervélo S5 and Canyon Ultimate CF SLX) for 10 minutes at 200W and 10 minutes at 300W, with the aero bike being 275m ahead and 1.7kph faster when ridden at 200W, and 435m ahead and 2.6kph faster when ridden at 300W.
In the second experiment we pitched an aero bike (again the Cervélo S5) against a lightweight bike (a Focus Izalco Max) on a climb, tackling Box Hill in Surrey twice on each bike, again at 200W and 300W, to see if the aero bike would still be faster even in the hills despite the Cervélo S5 being 800g heavier.
However, this time it was the lightweight bike that came out on top. At 200W, it took our test rider 9:24 to tackle the 2.5km climb on the aero bike at an average speed of 15kph, while the lightweight bike was 18 seconds faster with an average speed of 16kph.
At 300W, the lightweight bike was still faster, but the gap between the two was reduced, with the aero bike only being seven seconds slower with a 0.4kph difference in speed. This shows how much more important aerodynamics become at higher speeds, while weight is more of a factor at lower speeds.
The take home message then, is for most riders over most terrain, an aero bike will be faster than a lightweight bike. The only case where weight begins to become more of a factor is on steeper climbs where you’re travelling more slowly, and even then any time gains could well be balanced out on the descent, where the high speeds are going to make aerodynamics a factor again.
What features should I look out for in an aero bike?
At a most basic level, all aero bikes should come with tubes that have been shaped to smooth airflow, meaning that they will have a slender front profile but being extended rearwards. However, manufacturers can’t go crazy if they want to see their bikes used in races, with the UCI’s 3:1 rule restricting the ways in which they can shape the tubes.
This rule means that the depth of a tube’s profile (or indeed any other part of a bicycle) cannot be more than three times its width. So if a bike’s down tube is two centimeters wide when viewed from the front, then it cannot be more than six centimeters wide when viewed from the side.
In an attempt to continue to improve the aerodynamics of their bikes while staying within this rule, many manufacturers now use kamm-tail tube profiles. This means that the tube retains a traditional aerofoil shape at the front, but with the back half lopped off to give it a flat back.
A lot of people say that aero bikes now all look the same and a possible reason is because of the use of popular dropped rear stays, which the industry has collectively decided is the most aerodynamic shape. Helpfully, it’s also comfortable, too.
Integration is the latest big trend when it comes to aero bikes, with the latest aero bikes such as the Trek Madone aiming to hide as much hardware as possible within the frame.
The key to this is cable routing. The sleekest aero bikes keep the gear and brake cables hidden for as long as possible, routing them through the handlebars, stem, and frame before they emerge close to their partner components, usually on the backside of the tubes to keep them out of the wind. At the next level down from this the cables are not routed through the handlebars and stem, but do at least enter the down tube behind the head tube to keep the cable entry out of the wind.
Integrated rim brakes used to be very common on aero bikes and when the first models emerged a few years ago most manufacturers decided that the optimum aero position to stick the rear brake was under the bottom bracket, although the aerodynamic benefit of this was questionable.
Now, however, the market has moved a long way from integrated brakes, and disc brakes are the most common stoppers that you’ll find on aero bikes, with some models even being disc brake specific. The bike brand’s argue that they’ve managed to design the latest models around the rotors, or generate more aero savings across the frame.
However, possibly the most important part (or parts) of a seriously sleek aero bike are the wheels. According to Kevin Quan of Knight composites, a 95mm deep rim (which is admittedly incredibly deep) will save a typical rider 35-watts compared to a standard box section wheel at time trial speeds.
While 95mm is probably a little deep, most aero bikes do come with chunky rim profiles, typically between 50 and 65mm deep. Other than aero benefits, deep wheels are stiffer and faster rolling as a result. Oh, and they look amazing, too.
There are, of course, other areas that aero bikes can maximise efficiency. Nearly all models now come with either an integrated bar and stem that are designed in an aerodynamic shape, or ones that are capable of running cables internally.
How easy are aero bikes to live with?
Yes, for most people on most terrain, an aero bike will be faster, but if you’re considering buying one, you also have to weigh up what day-to-day life will be like with your new pride and joy.
It used to be the case that the more aerodynamic the bike, the more difficult it was to live with, mostly because of complicated internal cable routing. This does make altering cable length or raising and lowering stack height a bit of a pain because it involves cutting cables to do so. However, many modern aero bikes now come with split spacers, which makes this process a lot easier.
Traditional integrated brakes used to be a bit of a faff, too, but this nuisance is now transferred to disc brakes. While sitting in a more accessible area, the more power brakes have a new complication depending on how au fait you are at bleeding a hydraulic system.
Finally, if you’re going to get the most out of your aero bike, then you might occasionally find yourself riding in the dark. In this case, aerodynamic seatposts and handlebars can make it a little tricky to fit lights, while the seatpost design may also limit the saddle bags you can use.
How else can I be more aero?
Before you rush, wallet open, to your local bike shop in search of the latest aero bike, it’s worth considering that there are plenty of other much cheaper ways to make some aerodynamic gains.
The vast majority of the wind resistance that you have to overcome while cycling is caused by, well, you, so your position and clothing choice can make a big difference to your speed. Riding in a low, crouched position with your hands on the hoods, elbows bent, is roughly 20 per cent more aerodynamic than riding upright with your hands on the tops.
Similarly, tight-fitting aerodynamic clothing and an aero helmet can also make a significant difference. The benefits might not be as stark as with changing your position, but if you’re riding along with a baggy rain coat unzipped and flapping in the wind, then you can wave goodbye to any gains that you might have got from your expensive aero bike and flash deep sections wheels.
How much should I pay for an aero bike?
With aero bikes now being available at almost all price points, it’s more a case of how much can you afford to pay rather than how much do you need to pay.
At the top-end of the scale, it’s not unusual to see aero bikes pushing hard against the £10,000 / $10,000 barrier, which should be enough to get you a cutting-edge frame matched with some pretty tasty components and deep section wheels for a seriously aero machine.
However, for a fraction of this price, you will often be able to pick up a bike with a frame that might not have the same high-quality carbon-fibre (so will be usually be less stiff and heavier), but will at least have the same shape tubes which will still be subject to the same laws of physics.
Wheel choice is also important when considering how much to pay for an aero bike. If you already have aerodynamic, deep section wheels, then there’s no point in paying more money for an aero bike that comes with similarly posh wheels. Instead, buy the bike with the cheaper wheels, take these off to use as training wheels, then put on the deep section wheels that you already own for race days.