The appeal of an aero road helmet is its promise to help you go faster with the same amount of effort. We tested these helmets at the FASTER wind tunnel in Scottsdale, Arizona – the same tunnel Giro used in developing its highly acclaimed Synthe – at yaw angles of 0, 5, 10 and 15 degrees, and with a single head angle. Recorded values were averaged for a final composite score.
Instead of using the industry-standard 30mph wind speed, though, we tested at 20mph. Higher speeds might very well exaggerate differences in aero performance, but according to FASTER’s director of biomechanics and technology Aaron Ross, you can’t predict airflow on a linear scale. We experimented with a few of the helmets at 30mph and the rankings actually changed slightly.
Most importantly, cyclists don’t spend all day riding at 30mph. We asked the folks at Strava to pull the average speed of its entire, massive rider database to get a real-world idea of how fast we’re really going. As it turns out, male cyclists ride at just 15.6mph on average; for women, it’s 13.4mph. Even if you assume that the typical aero road helmet buyer moves faster than that – say, in a racing situation – we decided to evaluate these helmets for all-around use since that’s how they’re more likely to be ridden.
[Editor's note: FASTER asked us to clarify their position on aero testing, so their comments are at the bottom of this article.]