What is the right helmet for me: Aero or vented?

Although a helmet's primary function is to protect your head in the event of a crash, helmets have also become a well-engineered piece of performance gear that can provide aerodynamic gains. Modern helmets are shaped to channel airflow around the head and shoulders in a way that creates a smooth path for the air to follow. One of the ways this is done is with smaller or reduced vents in the helmet. This makes cooling more of a struggle, so at some point swapping the aero helmet for a more vented one is going to offer more in terms of performance, but where exactly is this point?

• Read more: GCN Show: Helmets make cyclists appear ‘less than human’, so what should we do?

The helmets in question

For this dive into understanding helmet performance, we will be looking at the latest offerings from ABUS with the Gamechanger 2 and the Airbaker models. These can be seen in the pro peloton used by both Alpecin-Deceuninck and Movistar, fear not if this is not a brand you are considering as the advice is transferable to all brands when comparing aero to vented helmets.

© Velo Collection (TDW) / Getty Images

Both Movistar and Alpecin-Deceuninck use Abus helmets

Is there any difference in safety?

If there are any differences in the safety performance of both helmets, it is negligible and will come down to factors such as an aero helmet having more surface area rather than any purposeful design differences.

For all helmets sold in territories such as the EU, North America or Australia there is a safety certification that all helmets have to gain to be able to be sold as a helmet. This does not mean that all helmets will offer the same level of protection but a premium helmet manufacturer will offer a similar level of protection across their range.

Most premium helmets now also feature some sort of integrated slip-plane lining like that of a MIPS system that allows the shell of the helmet to rotate separately from the cradle. This technology has been reported to greatly reduce the risk of concussion in the event of a crash.

Is there a difference in price?

This very much depends on how you approach the subject, for most brands a comparable aero helmet and vented system is going to cost about the same, with the aero version costing a little bit more. What is notable is that aero helmets only start to feature in a brand's product range from the mid-higher price points whereas a vented helmet is going to be offered all the way down to their base range. So if you are on a budget a vented helmet is going to be the go-to choice.

Comparing the two

© Velo Collection (TDW) / Getty Images

Abus have a range of helmets which they offer to Movistar and Alpecin-Deceuninck

Weight

Firstly both helmets are different in their construction leading to a measurable weight difference. The Gamechanger 2 helmet weighs in at 265 grams for a size medium, with more material being used than on the Airbraker that tips the scales at 210 grams for the same size.

Although it is not a crazy saving between the two models it is noticeable when handling them, and as Ollie can attest to after his Tour de Stations 1000km ride, there does become a certain point when any extra weight for your neck to support starts to matter.

Performance

The weight saving mentioned above has an incredibly negligible impact on performance, with the 55 gram difference equating to a saving of around one solitary second over the course of a long alpine climb.

Using the aero helmet at speeds in excess of 16 km/h will see this deficit flipped in favour of the aero model thanks to its savings in efficiency.

For speeds under 16 km/h using a lightweight vented helmet offers a marginal gain in terms of weight saving and thermal regulation. So for those lucky enough to ride long steep alpine passes on a regular basis, opting for a vented lightweight helmet could be a wiser choice.

• Read more: Stefan Küng finishes European Championships ITT with a broken helmet after crash

As an all-around helmet that will offer the best performance on a mix of terrain, the maths tells us that the aero offering will be the one to go for. Taking a sportive such as the L’Etape du Tour as an example, the difference between both helmets could be as much as two minutes across the full duration of the event.

Cooling

© GCN

Venting is the easiest way to increase cooling from a helmet

At this point, you might be wondering why you would ever want to go for a lightweight vented helmet over an aero one if there is such a performance gain to be had. Well, like most things, it isn’t quite that simple and cooling is a huge factor in the overall feel and performance of a helmet.

Although it can be harder to measure and will differ a lot from person to person, the effect that a helmet can have on a rider's thermal regulation can be a massive performance inhibitor.

• Read more: Do you really need a fan for indoor training?

For rides that take place in warm climates, the ability to stay cool and regulate your body temperature can have a major impact on your performance. If you overheat you will lose more performance than any aero gains can give you. Having more vents allows more airflow through the helmet to carry away built-up heat which not only physically cools you but also can make you feel more comfortable. There have been multiple studies published in the field of sports science that show, that if you feel comfortable on the bike, the psychology of this can lead to better performance.

The test

To find out if there are any discernible real-world differences between the helmets Alex Paton sets out to ride the famous Sa Calobra climb in Mallorca with both helmets. During these tests, Alex will ride to a fixed power, with his core temperature and heart rate being recorded as well as Alex’s own perceived exertion.

Although during the test the air temperature was 30ºC it was a very dry heat, which humans are able to cope with far easier than if it was a humid 30º as it is the process of sweat evaporating that cools us down. The more humid the air, the less capacity there is for the air to accept evaporating moisture.

The results

During Alex’s first attempt with the lightweight vented helmet, his core body temperature remained at a stable 37.2ºC. Interestingly for the second test with the aero helmet, although the effort started with a core temperature of 37.2ºC it rose to 37.3ºC and then shortly after the effort due to some thermal leg crept up even further to 37.5ºC showing just how much the added ventilation of the lightweight helmet aided Alex’s thermal regulation.

It was also visible that after the test with the aero helmet, Alex was considerably more sweaty meaning that even though there was only a 0.3ºC change in core temperature, his body was having to work harder in order to keep him cool, something that would cause real differences over the course of a long hot ride.

As far as perceived effort from Alex’s perspective, it was noticeable that with the aero helmet, there was more heat build-up and he could feel the decrease in airflow when compared to the more vented helmet.

In conclusion

© GCN

Both helmets have their place but the environment you ride in is going dictate which one is the better choice

The right helmet for you is going to depend on a range of factors but mostly it comes down to the terrain and conditions in which you ride. For riders in cooler climates like here in the UK that don't have long climbs or incredibly hot weather, an aero helmet is going to provide more benefits than issues. For a rider in southern California, a lightweight helmet with more ventilation is going to be beneficial for the long climbs and the hot weather.

Ultimately, there is no right or wrong helmet; they will both do the job of protecting your head in the event of a crash and both will not hinder your ability to complete a long tough ride in any conditions. However, in terms of comfort and performance, you have a choice that is best matched to your type of riding.