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Aero road helmets: 7 of the best tested on the road and in the wind tunnel

Aero road bike helmets are an ultra-smart compromise of standard and TT cycling helmets, and should offer both aero gains and sound ventilation.Matt Baird tests 7 of the best

Best aero road helmets reviewed

The popularity of aero road helmets has exploded in triathlon, sending the long-tailed TT helmet towards the margins as savvy triathletes have realised that aerodynamics, comfort and ventilation could come in one helmet package.

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While the weight of an aero road helmet is typically higher than a standard road lid, our wind-tunnel tests at the Silverstone Sports Engineering Hub in late 2020 and at the Boardman Performance Centre in 2019 have shown an aero road helmet can be 3:22mins faster than a vented lid over a 180km Ironman bike leg, a healthy saving for those vying for age-group honours. Much of this, of course, depends on an athlete’s abilities to keep their head in the same aero position, but the drag penalties of moving one’s head aren’t as high on an aero lid as when riding in a TT helmet.

An aero road helmet should also provide better ventilation than a TT lid in summer racing and, as our year-round testing has proven, some protection from those beastly easterlies in the winter. Other key factors are the effectiveness of the retention system for comfort and fit; the ability of the buckle to be unclipped (especially with cold post-swim fingers); and the helmet’s often-overlooked modus operandi, safety. All of the helmets here have passed the relevant European safety tests, but also look out for added safety features such as the MIPS system.

  How we tested the aero road helmets

We’re proud to say that we’re the only publication worldwide to regularly test our aero helmets in the wind tunnel. The reason is that nearly every brand claims to produce the world’s fastest helmet, but still refuse to release the raw tunnel data from their own tests.

As our wind-tunnel results show, some helmets only perform at certain angles and speeds so, while a helmet may technically be the fastest at a 20° yaw and riding at 55km/h, that doesn’t mean it performs across a range of wind directions and riding speeds. Given that the vast majority of a 180km Ironman bike leg is spent riding below 10° yaw (98% at IM Arizona, 72% at Kona, for example), the 0° and 5° angles especially were the key focuses for us.

In addition to our Boardman wind-tunnel tests from 2019, we aero tested the Kask, Smith and Spiuk at the Silverstone Sports Engineering Hub under the watch of aero expert Stephen Roche (thebiketailor.com) in 2020. We tested each at yaw angles of 0, 5 and 10°, and at speeds of 35km/hr and 45km/hr on a tri bike with the mannequin for added reliability

LIMAR AIR SPEED

£179.99

LIMAR AIR SPEED

Limar have made a concerted effort to move into the tri market in the last couple of years, attracting British ITU racers into the fold and adding a magnetic buckle on the chinstrap for added transition appeal for cold, post-swim fingers. Limar’s own positive tunnel testing has only extended to athletes riding on the hoods, yet our tri-bar Boardman tunnel analysis confirms that this is one swift lid, regularly coming second behind the S-Works or Giro (especially at the key 45km/h speed and 0° yaw angle). In terms of safety, there’s no MIPS protection but the retention system is secure, while venting from the 12 channels on hilly, sticky days is acceptable. Weight is a decent enough 259g. 

Verdict: Plenty of tri appeal and success in the  wind tunnel too, 90%

S-WORKS EVADE II

£250

S-WORKS EVADE II cycling helmet

Specialized have spent plenty of time in their own Californian wind tunnel with the Evade II and our own Boardman tunnel results reaffirm this aerodynamic development (the Evade was the fastest overall on test in our Boardman tunnel sessions, especially at the speed of 45km/h but impressive across a range of yaw angles). The 12 deep, internal air channels are an improvement over the original (as is the new addition of the MIPS safety system) for warmer high-intensity riding, and the magnetic buckle is great for transition speed and numb finger use. Weight with the MIPS safety system is still a lean 262g but we’d prefer more adjustment with the side straps, which are oddly fixed in place. 

Verdict: light, lean and proven gains in the wind tunnel, 93%

GIRO VANQUISH MIPS

£219.99

GIRO VANQUISH MIPS

The Vanquish MIPS is unique among the competition here as it comes with a magnetic Shield Visor. The visor provides good clarity but there’s a clear gap between that and the face, giving us concerns about detritus flicking up. Which is a shame, as the helmet offers sound ventilation via its 10 well-placed vents, there’s MIPS (Multidirectional Impact Protection System) and comfort from the Roc Loc system (the buckle is fiddly, however). Our Boardman wind tunnel results saw it regularly come behind only the S-Works (it excelled at 0° yaw angle and 35km/h speed, even better in an aggressive aero position), and it doesn’t feel like a weighty 355g lid when riding. Very high RRP, however. 

Verdict: swift and comfy, but costly and we’re not set on visor, 84%

VAN RYSEL RACER

£39.99

VAN RYSEL RACER cycling helmet

 Largely blown your tri budget on a race spot and flights to Ironman Lanzarote? Then you could do far worse than picking this forty quid Decathlon creation as your lid of choice, given it offers fine ventilation and superior aerodynamics in crosswinds. While it performed poorly at 0° yaw angle (i.e. into direct headwinds), the wider the wind angle, the better the Racer performed. Our recorded segments even showed it beating the S-Works at 20° yaw angle when riding at 45km/h. The ventilation is amongst the best on test here yet it loses marks due to the firm front padding, a tricky to adjust retention system and straps that have a tendency to loosen. We also prefer the other four available colours. 

Verdict: fine venting,  aero gains in winds, disappointing  straps, 88%

KASK UTOPIA 

£219

KASK UTOPIA cycling helmet

The Utopia is the helmet of Team Ineos and the official helmet of Ironman Europe, the former suggesting exhaustive R&D, the latter a huge marketing pot. And it’s the R&D we’re interested in here, with the Utopia reaching the promised land in our 2020 Silverstone Sports Engineering Hub tests – beating both Smith (easily) and Spiuk (much closer) at every speed and yaw angle. Onto the asphalt and we’re a sucker for Kask’s leather chinstraps, while the multi-directional ratchet system and thick internal padding aid both fit and comfort. Ventilation via the nine vents is only satisfactory and we’d like a horizontal pad across the forehead to prevent sweat streaming down. Weight is a lean 235g. 

Verdict: swift and sleek, just sHort of our own helmet utopia, 90%

SMITH OPTICS TRACE

£210

SMITH OPTICS TRACE cycling helmet

Of all the helmets on test here, the Trace is the most confidence-inducing when it comes to safety. That’s due to both the MIPS and Koroyd beehive core, also seen on helmets from Endura and, to a greater extent, the custom 3D-printed offerings from Hexr. It’s the helmet that we’ve got the most usability out of in 2020, joining us on both trail rides and road slogs. It’s durable, the ratchet is efficient and the internal pads are plump. Anecdotally, we found midsummer ventilation compromised by the beehives and, despite Smith’s claims of aero dominance from testing in 2018, it was consistently out-performed by both the Kask and Spiuk in our late 2020 Silverstone wind tunnel tests at every speed and yaw angle. 

Verdict: versatile, safe and pricey, and outdone in the tunnel 72%

ASPIUK PROFIT AERO 

£130

ASPIUK PROFIT AERO cycling helmet

Given they made our first-ever tri-suit, we’ll always have a place in our tri heart for Spiuk. If their UK tri exposure has reduced since 2008, the Profit Aero comes with the backing of ITU World Champ Mario Mola and with plenty of multisport flourishes. These include a magnetic buckle and Boa retention dial for T1 speed, while the brand’s aero focus has produced a helmet that delivers in the wind tunnel, coming only marginally behind the twice-the-price Kask (especially at 0° yaw angle). The nine vents are effective enough, but the limp padding and frustratingly fiddly straps show where some cost compromises have been made. Only two available sizes also limit the chances of perfecting your fit. spiuk.com

Verdict: Good price,  great shell, less  impressive strap 83%

Find out how you can improve your cycling aerodynamics here

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Images by Steve Sayers