When buying a road bike ﷽helmet, your primary motivation most likely relates to safety. In the event of a crash, the added pౠrotection offered by a certified helmet can be the difference between walking away with little more than your ego bruised and, well, not walking away at all. 

But there isn't a simple answer to whether one helmet is safer than the next. There are a select few third parties that perform indepe🍰n☂dent tests, but at an industry level, all we know is that they've met the relevant local authority's minimum standard, which, brands tell us, is a low bar. 

As a result, choosing which helmet to buy is often a balance of other factors. Ventilation is important for those who live in warmer climates. Weight will be a key factor for mountain goats who spend their lives riding uphill. The fashion-conscious will prioritise how it looks, but for the majority of ꦉus, the important metric will be aerodynamics. Who doesn't want to go faster for less effort?

Around a decade ago, thꦜe category of aero road helmets sprung into life, and these days some take an unambiguously aero approach to their design, with long tails and closed-off frontal profiles. Others 𝔉take a more subtle approach, with a more rounded rear and a few vents up front. 

Given their go-faster intentions, it's not uncommon for an aero helmet to be launched with claims of being some watts more aerodynamic than that other helmet, or any number of seconds faster than something else over a 40km time trial. Those comparisons usually relate to𝓰 a brand's outgoing model or other products in the lineup; rarely will they call out the competition. 

As a result, there isn't much information out there that compares acrossꦗ brands, such as the Specialized Evade against the Trek Ballista, or the Met Manta against the Giro Eclipse. 

Luckily, that's where we come in! 

We took 23* different helmets from 18 brands to the wind tunnel for a back-to-back test to find out ♏w🗹hich was fastest (and which was slowest!). We also ran some additional tests on sunglasses, gloves and more, which we'll share in the coming weeks. 

*We actually took 24 helmets, but one was an unreleased helmet that launches later this year. We tested it under the promise of keeping the results to ourselves until then. I'm afraid that's all you'll hear about it until it does. 

Before we get into the data, a quick interlude to say th📖at this feature is not sponsored and we paid the normal commercial rate for our wind tunn൩el access. This content was made possible solely and entirely by our paying subscribers.

The helmets

Of all the helmets we took, the majority were described as aero helmets by their respective brand and fell somewhere on the spectrum between 'all-out aero' (such as the Trek Ballista or S-Works Evade) and 'aero all-rounder' (like𒀰 the Giro Eclipse or POC Ventral). 

A small number would be classed as 'vented' helmets, because we also wanted to get a 🍃feel for the difference between the 'vented' and 'aero' categories as collectives. In alphabetical order, they are as follows:

Aero helmets

• ABUS Gamechanger 
• Carnac Evo
• Giro Eclipse
• Julbo Sprint
• Kask Elemento
• Kask Utopia Y
• Lazer Vento Kineticore
• Limar Air Atlas
• MET Manta
• Oakley ARO7 (tested twice - with and without visor)
• POC Procen Air (tested twice - with and without visor)
• POC Ventral
• POC Ventral Tempus
• Rudy Project Nytron
• Scott Cadence
• Smith Ignite
• Specialized S-Works Evade III
• Sweet Protection Tucker 2VI
• Trek Ballista
• Van Rysel FCR 

Vented helmets

• Specialized S-Works Prevail III
• Trek Velocis
• Uvex Rise Pro

Each helmet was size medium.

The decision process for choosing which helmets to test was based on our research of each brand's best available option(s💟) on the market at the time of testing; wꦚhat's being used in the WorldTour; and which helmets we think people will consider when deciding to buy. 

It was limited, to a point, by what we could get our hands on. For example, we wanted to include the Ekoi Aerodinamica but our multiple attempts to contact the brand went unanswered. We also tried to get the 168澳洲5最新开奖结果:new Kask helmet (the one that g𝔉oes down over the 🦄ears), but neither Kask nor Ineos had a spare they could loan us.

The test

We took the helme꧋ts to the wind tunnel at the Silverstone Sports Engineering Hub, testing the aerody𒐪namic performance of each helmet. 

Naturaౠlly, the test was standardised, meaning t✱he same conditions were met for each data capture. These included the same bike (Pinarello Dogma X), rider, kit (Santini Viper skinsuit, Velotoze overshoes, Oakley Radar glasses), wind speed and more. 

We ensu🌼red each helmet was sitting level before eaꦆch run, and the straps for each helmet were clean against our model's face without any strap 'tail' (which could flap and skew the results). The wind tunnel itself was also put through a taring process before each capture to ensure accuracy. 

The protocol was designed by myself, with guidance from aero experts Cౠasper von Folsach in the run-up and Huw Williams on the day. 

Pedalling the bike was Cyclingnews ไTech Writer and amateur racer, Tom Wieckowski. We wanted to try and get as close to a ꦍreal rider as possible, so we accepted the (financial) cost of running longer captures with a real person to get a more realistic result, rather than using a static mannequin.

Tom's position on the bike was captured in an initial baseline test, and then an outline of that position was projected onto the floor in front of him for the rest of the day. This provided an accurate cue for Tom to remain in position during subsequent runs. We also tested for positional drift, which comprised multiple tests with the same he🔯lmet to work out how much difference there could be between two identical setups, and thus how much blur we should accept in our results. 

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We tested each helmet at 40km/h (24.85mph). This is reflective of good amateur-level racing speeds, but the resulting CdA data will be valuable at all speeds. In the results below, I have extrapolated the data to provide 🐬the power required at 30, 40 and 50km/h, the speed expected at 250, 350 and 450 watts, and how those speeds relate to a 40km time trial.

Each data capture was performed in five-degree increments from 0 to +15 degrees yaw. That means four capture points of 🌞0, +5, +10 and +15 degrees. Helmets are symmetrical, so there was no need to capture the data at negative yaw angles too. Each helmet was tested in a sweep in the same positive direcౠtion (0 to 15) for consistency and held for 30 seconds per capture. 

The wind tunnel itself was operated by professional Engineering Technician Huw Williams and is designed to accou♒nt for any changes in temperature or air density in its results.

Holding the bike in place was a set of stanchions, and no corrections were made for these, since they were the same across all tests. We're primarily interested in the difference between helmets here, not the absolute values.

Some caveats

We've tested the aerodynamics here, so we have the CdA figure for each helmet at four different angles of yaw. With the average figure, we've done some calculations to solve for power (watts) at different spee🍒ds, for speed at different powers, and the time saved over a 40km course where all other factors remain equal. These calculations do not fact🔯or in additional losses such as drivetrain friction or rolling resistance, but we're only interested in the differences here, rather than absolute values.

Our rider Tom's positional drift equated to 1.19%. As a result, each resultඣ within 1.19% of another should bear thisꦯ in mind, as it could simply be a result of this. We will continue to share the testing results as they were received for simplicity.

The results of our testing are representative of just that: our testing. We understand that helmet brands might see different results based on different tests or different protocols. We don't intend to claim that our results are the final word in helmet aero testing, but rather an additional stream of independent, unbiased testing and information for Cyclingnews readers. 

We understand that the aerodynamic performance of a helmet can differ from person to person depending on how it interacts with the body. We sat Tom in a reasonabဣly relaxed 💧'hoods' position, reflecting an all-day riding position, so that the helmet would sit higher away from his body to minimise this connection. 

We also understand that there are other factors that come into play when buying an aero road bike helmet. For example, how well it will protect you in the event of 😼a crash, how comfortable it is, its ventilation properties, its weight, its style, and how well it plays with glasses are just some of the other factors you should consider when deciding which to choose.

The results

For each helmet, we will list the CdA for all four yaw angl🌠es, along with the averag🅷e and an accompanying line graph. We will order the helmets using the average from fastest to slowest. 

We will then use it to calculate the power required to ridไe at 30km/h (18.64mph), 4🔜0km/h (24.85mph), and 50km/h (31.07mph) using the following calculation: 

We wil🌃l al▨so calculate the expected speed if riding at 250 watts and 350 watts using the following calculation: 

We will then apply this speed to calculate how long it would take to cover a 40km course. The calculation for this assumes ideal conditions and so factors such as wind, elevation, cornering, drivetrai🌊n efficiency, rolling resistance, acceleration, etc are all totally equal. Again, we're highlighting the differences here, we're not interested in absolute valu🐓es. 

The results in brief

Detailed results, ordered by average CdA

1. Poc Procen Air (w/ Visor)