Your cycling helmet offers a great opportunity to improve your aerodynamics because it meets clean air. The way that the air is separated, passes over it, and meets again behind it is entirely down to its shape. By contrast, your rear mech, for instance, is in such turbulent air that gains are almost impossible and most brands ignore it in their aero quests. Switching your standard road helmet for an aero road model will save you around a minute on a 40km bike leg.
There’s no disputing that the coned time-trial (TT) helmet is the fastest option. In our tests the best of them can save a further minute over even the quickest of this group. But TT helmets are typically heavier, hotter and for race day only. A £250 TT helmet is a big investment when it only gets worn a few times per year.
Aero road helmets can – and should – offer a balance between TT and road helmets. That is, they have to be faster than a road helmet yet free from the compromises of weight and ventilation of a TT helmet. An aero road helmet that’s hot and heavy, yet not as aero as a TT helmet, is pointless; you may as well go for maximum aerodynamics. So while aero speed is really important here, we’re also looking for a helmet that you can train in and use on hot, hilly events.
What you’re looking for in a good aero road cycling helmet is a perfect balance between speed and ventilation. If
the former is too compromised, you might as well go for a light climber’s lid; if it’s too hot, then you’re better off with a TT helmet. So an aero road helmet option should present a happy medium.
While the weight of an aero road helmet is typically higher than a standard road lid, our wind tunnel tests at the Boardman Performance Centre in 2019 and this January reveal an aero road helmet can be 3:22mins faster than a vented lid over the 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.
We tested the helmets in both Lanzarote and Somerset; in the latter it became clear that aero road helmets also offer respite from off-season chills, proving that an aero road lid isn’t just for race day.
Time, then, to deliver our wind- tunnel and real-world results...
How we tested
No one likes a show off, but 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.
That’s why we again found ourselves at the Boardman Performance Centre’s wind tunnel under the watch of Boardman’s head of science and technical development, Jamie Pringle, this winter armed with the best of 2020’s aero road helmets. We tested each at yaw angles of 0, 10 and 20°, and at speeds of 35km/h, 45km/h and 55km/h in a fixed position on a triathlon bike (adopting an aero tuck on the tri-bars that was neither too aggressive nor relaxed).
With tunnel testing done, we then took the helmets to the volcanic triathlon hotspot of Lanzarote to access their ventilation and real-world properties. Less glamourously, tests were also carried out on the off-season roads of North Somerset.
Once used by multi-Ironman world champion Jan Frodeno, the Vanquish MIPS is unique among the competition here as it comes with a magnetic Shield Visor. The visor gives 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 (Multi-directional Impact Protection System) and comfort from the Roc Loc system (the buckle is fiddly, however). The wind tunnel results (with the visor on) saw it regularly come behind only the S-Works (it was impressive at the 0° yaw angle and 35km/h speed, and was even better in an aggressive aero position), and it doesn’t feel like a 355g lid when riding. zyrofisher.co.uk
Verdict: swift and comfy, but we could give or take the visor, 85%
Buy from www.wiggle.co.ukero-helmet
Alistair Brownlee wears the Cadence Plus, but happily there are also benefits for us age-group mere mortals. There’s MIPS safety and the addition of Aero Plugs or winter bungs, which can be placed into the ventilation channels on colder days or if you’re truly seeking an aero advantage where heat isn’t a consideration. Those ventilation channels (sans bungs) do the job on the roads, yet the internal padding is somewhat limited, and the 280g weight puts it towards the higher level here. In the wind tunnel it performed well at speeds of 35km/h and at the 10° yaw angle but, strangely for such an aerodynamic-looking lid, less successfully when riding faster at 45km/h across all yaw angles. scott-sports.com
Verdict: we like the bungs and venting, but mixed tunnel scores 84%
Buy from www.tweekscycles.com
Continue reading our guide to this year's best aero road helmets (2/3)