Do you need an aero road bike?
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.
Engineering
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.
“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.
Philippe 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.
The
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
Aero
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?
“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.
“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."
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.”
