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Do you need an aero road bike?

By Bruce Lin

If you get more aero, then you’ve effectively become faster. You’ve probably heard before that wind resistance is the main force riders have to fight against. This means that improving your aerodynamic efficiency gives you an unquestionable speed advantage.

Watch a modern professional bike race and you’ll likely see a number of riders on the sleek and slippery aero road bikes with advanced stealth-fighter-shaped frames.

Specialized Venge aero road bikeEngineering modern aero bikes is an intensive, technical, and expensive process. Beyond ads and marketing, the world of aerodynamics is mysterious for everyday cyclists. Beyond feel and perception, it’s hard to know for sure how much difference an aero bike will make in everyday riding.

So if you’re looking at spending a few thousand dollars on your next bike, how do you know if an aero bike is worth considering? Can you be frugal and make yourself more aero on your current bike? Here’s what you need to know. 

You don’t need to be fast to experience aero benefits

World Tour pros aren’t the only riders who benefit from improved aerodynamics. Your average rider can still gain valuable speed and time. I spoke to aero expert Mio Suzuki, Senior R&D Engineer leading aerodynamics at Specialized, who talked to me about the testing she’s done with riders of different levels. The magic number is surprisingly low — only 13mph.

Specialized Venge wind tunnel aero testing “One of the findings we’ve made is that from 13mph and up, aerodynamics will come into play pretty significantly and have a very positive effect,” Suzuki says. “That sort of speed is pretty average for a rider who’s not competitive. Obviously, for professionals averaging 20-to-30mph, aerodynamics are important. But when measuring the time difference when moving from point A to point B, you still see noticeable aero time gains at much lower speeds.”

Suzuki explained that when looking at graphs tracking power and speed, it’s hard to tell if weight or stiffness makes any difference. But it’s easier to see when an aero bike is used because there is a quantifiable speed differential. Other than fitness, aerodynamics is the most important single factor that influences your speed on a road bike.

“We track data and make calculations for every category of rider to try and understand the effect of aerodynamics in a lot of different riding scenarios,” Suzuki says. “We have pretty detailed graphs and analyses of a lot of different situations. For your average everyday rider, like me, who’s often riding at 15mph, there's no question it will definitely make you faster.”

Aero bikes don’t compromise ride quality

In the past, reviewers liked to criticize aero bikes for having poor ride quality (either too noodly or too stiff) due to the shape of the frame tubes. But bike makers have put a lot of time, effort, and money into aero bike design and manufacturing to make them feel and ride like non-aero bikes.

Specialized venge cobbles comfortPhilippe Gilbert had no problem riding his aero Venge on the cobbles.

“A lot of manufacturers, including Specialized, are getting smarter about how to construct aero bikes,” Suzuki explains. “It’s definitely a design goal to make an aero bike that still rides like a traditional round-tubed bike.”

Carbon technology has progressed to the point that manufacturers can produce bikes of nearly any shape that exhibit the classic traits of lateral stiffness and vertical compliance. By controlling the carbon lay-up, the possibilities for precisely controlling ride quality are near limitless. When buying aero bikes made in the last five-to-ten years, riders should have few if any concerns about ride quality. 

Even with aluminum bikes, clever hydroforming and welding now allow manufacturers to add stiffness to key points like the bottom bracket and compliance to areas like the seat stays.

“Compared to 10 years ago, aero bikes have evolved quite a bit. They don’t necessarily have the exact same ride feel,” Suzuki says. “But our engineering and manufacturing techniques make it so that aero bikes that too stiff or too noodly, as you say, aren’t really an issue anymore.”

Aero bikes can still climb

Weight is a big deal for riders interested in climbing, and aero bikes generally weigh more than their non-aero counterparts. But the difference may not be as big as you think.

When it comes to weight, advances in manufacturing have brought aero bikes very close to “traditional” road bikes. For example, let’s compare two Specialized road bikes — a 2020 S-Works Venge (left) and a 2020 S-Works Tarmac (right) — that are the same size, with similar builds, and equipped with the same wheels and tires.

Specialized Venge vs. Specialized tarmacThe Venge weighs 15 lbs 15 oz while the Tarmac weighs 14 lbs 12 oz. Okay, one bike is a pound lighter. That might seem like a lot, but for most riders, the overall aero benefits will outweigh the climbing benefits. 

Consider that the rider makes up the far larger percentage of the overall weight of the rider and bike combo. A single pound really only matters to riders who exist at the extremes of weight or performance. (To learn more about the effects of bike weight, check out our Does Bike Weight Matter article.)

Also, aerodynamics still come into play on climbs. Suzuki points out that the 13mph speed where aerodynamics make a positive difference is mainly quoted for flat terrain, but it’s applicable to climbing as well. The wind resistance at 13mph is the same going uphill or down. Less wind resistance will increase your speed uphill. Only on very steep gradients are you moving slow enough for weight to be a bigger factor. 

Some tech articles found online will try to list specific gradients where aerodynamics are no longer a factor (e.g., at 8%+ weight will matter more for average riders). This may have some basis in fact, but Suzuki is hesitant to make specific claims like this.

“Rider weight, gradient, and a bunch of other variables all factor into climbing speed,” Suzuki says. “Because of that, there’s no way to say, universally, that there’s a single point where bike weight gains will be greater than aero gains.”

What advice can you take from this? Well, since aero bikes aren’t significantly heavier than comparable non-aero bikes, then weight should only be a major concern if your primary focus is climbing on very slow and steep climbs. For all the other times when the gradient eases and speeds rise, aero bikes will net greater speed advantages. Both Suzuki and I would likely choose an aero bike over a non-aero bike for our everyday riding. 

Note that the importance of aerodynamics is transcending specialists bikes like the Venge and many “traditional” road bikes like the Tarmac are also starting to apply wind tunnel testing and aero shapes to make them better all-rounders. Though the current Tarmac isn’t as aerodynamic as the current Venge, Specialized’s most aerodynamic road bike offering, it’s nearly as aerodynamic as the first-generation Venge that helped ignite the aero bike boom in 2011.

Aluminum bikes can be aero too

Specialized Allez SprintAero bikes aren’t always synonymous with high-end carbon dream machines. The Specialized Allez Sprint is one of the most popular road bikes for competitive road racers because it combines a robust and budget-friendly aluminum frame with aerodynamic efficiency that surpasses the first generation Venge.

The belief that carbon bikes are more aero than aluminum bikes comes from the reputation carbon has for being easy to manipulate. It can be manufactured into any shape an engineer can dream up, opening up more aero possibilities. But the Allez Sprint has shown that more traditional bike materials can still be competitive.

“In general I’d say it’s easier to make an aero carbon bike because of the shaping. But that doesn’t make it more aero,” Suzuki says. “Aluminum manufacturing technology has evolved a lot. If an aluminum frame can be made with an aero cross-section at the key points then I would say an aluminum bike could be just as aero or more. It all comes down to design. The Allez Sprint shows that.”

Other manufacturers are following suit. The main competitor for the Allez Sprint, Cannondale’s CAAD-series, has just come out with the aero aluminum CAAD13. As we said before, aero is transcending categories in the bike industry and it’s becoming clear that many future budget aero options will be available to satisfy more riders. 

Aerodynamics are still a bit of a black box

The regular consumer can’t test bike aerodynamics because we don’t have access to wind tunnels or the necessary instruments. It’s not a simple as putting a bike on the scale. So are we reliant on manufacturer’s claims and magazine tests?

Specialized wind tunnel aero testing“I’ve done a lot of aerodynamic tests,” Suzuki says. “Knowing all the care we place into what we measure and how we measure things, I would like to say that the numbers and performance I can put out are trustworthy. As an engineer, I want true information.

“How is everybody else doing it? I can’t say for sure. I like to think everybody else is honest. Specialized is lucky because we own our facility. That means we can do as much wind tunnel testing as we want. If you don’t own a wind tunnel, then you have to go somewhere else and rent time. You pay per hour for usage of the tunnel so you have to carefully prioritize what to test and how to stay in budget. That might restrict the number of bikes or configurations they’re able to test.

“This is why you don’t see people and journalists just gather up 100 bikes to go compare in a tunnel. I’ve seen magazine tests and their results and they try to do their due diligence to compare bikes in a fair way. I’ve seen good tests and I’ve also seen questionable results. The questionable part being the protocols they follow.”

Unfortunately, we don’t live in a world where we have an easy way to test and compare bikes for ourselves. Most cycling publications provide nothing more than riding impressions for aero bikes. You could do some form of home testing with a flat road and a timer, but Suzuki warns that the results will be very subpar. It’s unlikely that you’ll extract meaningful data for the minute differences between two frames. The wind tunnel is the only precise and reliable tool.

If this concerns you, then consider that reputable aero manufacturers, such as Specialized, Trek, and Cervelo, sponsor pro riders and invest significant time in the wind tunnel. It’s in their best interest to actually make competitive bikes. If you want something effective, then looking at brands that actively discuss and showcase their wind tunnel testing may be prudent.

You can improve aerodynamics on your current bike

If you don’t want to purchase a new aero road bike, but you want the improve the aerodynamics of your current set-up, there are three key components to consider upgrading — your wheels, handlebars, and helmet.

Zipp aero wheel wind tunnel testingPhoto courtesy of Zipp Speed Weaponry

“Definitely wheels,” Suzuki says. She emphasizes their importance. “Aero wheels are a great, great, great investment. They are what contact the air first and everything comes behind them. With wheels too, I would highly recommend doing research because just because something is deep doesn’t mean it’s the best wheel.”

Just like with aero frames, some brands put more effort into wind tunnel testing than others. Zipp and ENVE are great examples of high-quality wheel manufacturers that prove their wheels out in the wind tunnel. There are even budget options with extensive engineering and testing behind them.

Because handlebars are at the leading edge of the bike, aero handlebars can also make a significant improvement in your efficiency. Cervelo has done wind tunnel testing that has shown that handlebars contribute up to 30% of a bike’s overall drag at zero degrees of yaw.

Aero helmets began gaining popularity around the same time as dedicated aero bikes. In 2011, the same year the Venge was released, Mark Cavendish won the 2011 World Championship road race wearing an adapted Specialized aero road helmet with its vents covered. Aero helmets have since been adopted by the peloton and regular riders. Many aero helmets sacrifice very little in terms of ventilation for their aero performance so they are a convenient way to get an extra edge.

Good bike fit makes you more aerodynamic

If you're on the fence about aero bikes, then consider getting a bike fit instead. When discussing wheels, Suzuki was quick to bring up riding position and bike fit. According to her, they are as important to your performance as aerodynamics.

“If I were to put it all in order,” she says, “I think wheels and bike fit would be my two top things. Bike fit is really an underrated secret. In terms of aerodynamics, the rider position affects efficiency quite a bit. We do a lot of testing, particularly with professional athletes, in the wind tunnel. We’ll have their hands on the hoods as a baseline posture. Then we have them hold the drops so their back angle decreases into a bit more aggressive position. We have seen as much as a 10-20 watt difference between hands on the hoods versus in the drops. That’s super-significant."

Getting as low as possible on your bike has a very positive effect on your aerodynamic efficiency. The less your body is exposed to the wind, the less wind resistance you have to fight against. Suzuki warns, however, that this isn’t a prescription to slam your cockpit as low as possible.

“You might be able to get into a perfect, aggressive position, where your back angle is low and you’re out of the wind,” she says. “But what if you can only hold it for five seconds. If it’s not sustainable for two hours, or whatever the entire duration of your ride is, then it’s meaningless."

Andy Pruitt retul bike fitAndy Pruitt fitting a rider. | Photo courtesy of Retül

Instead, it’s better to get properly fit into the lowest sustainable position to maximize both efficiency and power. Andy Pruitt, one of the world’s foremost cycling fit experts, echoed this sentiment when I spoke with him last year. Pruitt is the founder of the CU Sports Medicine and Performance Center and has worked extensively with numerous pro riders and teams dialing in their bike fits.

“Rarely is the most aerodynamic position sustainable,” Pruitt says. “So a rider’s position will end up having to creep upward and get more comfortable to be more sustainable. Ultimately, if you’re more comfortable, you’re going to be able to go faster and harder for longer, rather than fighting to stay in some aerodynamic position.

“In some cases, bringing the handlebars up a bit actually can allow you to relax your elbows, which is not only more comfortable, but it can allow you to get more aero. A great example is this rider Lars Bak. In his case, raising the handlebars two centimeters actually lowered his back angle four centimeters because he could relax into the front end of the bike.”

Suzuki also says that riders don’t need to worry too much about wasting the benefits of an aero bike by riding in a more upright and comfortable position.

“It doesn’t completely negate the aerodynamics of the bike,” she says. “The leading edge of an aero bike still offers a lot of benefits, particularly if it has aero wheels too.”

This is another strong argument in favor of aero bikes. If you aren’t capable of adopting an aggressive, low position, an aero bike can act as an equalizer to help you get back some of the speed you may have lost. 

 

Are you riding or thinking about switching to an aero road bike? Does aero matter to you? Let us know in the comments!

Photos courtesy of Specialized Bicycle Components.


3 comments


  • Great article; very in depth. It is interesting I have an older Cervelo R3 and an S3. The R3 is slightly lighter (and more comfortable). But most of my PR climbs have been on the S3 – like 11 out of 12.

    Twain on

  • Optimized body position on a bike can never be considered a static “one position-fits all” thing. The rider needs to be able to observe and react to constant changes in wind, gradient, and road surface conditions. Aggressive low positions have their physiological limitations and are less effective on tailwinds, false flats and climbs. i.e. try climbing a 10% grade in the supertuck position. While wind tunnel testing may imply an efficient position on a flat road with a modest head wind, at the end of the day, the rider will need to rely on experience, intuition and trial/error to figure out how to modify that position in real time to optimize speed.

    Jon W on

  • I see a lot of testing of a single rider in a wind tunnel. For time trialing, or a rider “off the front,” this may be an effective test. I would like to see how aerodynamics of a bike within a peloton are affected. Has anyone done that kind of testing?

    Greg Braun on


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