Giro came up with a clever pitch that illustrated their new aero helmet’s versatility, with data against its own helmets. The story? Their new helmet—which they were calling the Synthe—came out 16 percent faster at WAD at 30 degree head angle, was 13 percent lighter than the Air Attack aero road helmet, and 2 percent cooler than the Aeon. Several ProTour riders were seen in social media with boxes touting the data, but absent any look at the helmet. Interest piqued.

Giro invited LAVA to Scottsdale, Arizona Tuesday to for the reveal and road-test of the Synthe, but also see what sets the brand apart from others in terms of heat regulation and aerodynamics. And it’s compelling.

The Synthe is Giro’s marriage (or appropriately, synthesis) of two helmets with very different profiles. Giro’s Air Attack—which debuted two years ago and stands as one of the industry’s first aero road helmets when it launched—was ridden to success by Leanda Cave and Andreas Raelert in Kona, and opened the market for those that realized that few could hold a perfect head-up position over 180k on a TT bike. So for those that dip their heads, turn to grab bottles, etc., a less aggressive aero helmet was actually faster.


The fully adjustable RocLoc Air fit/stability system also serves to “float” the head off the surface of the helmet, allowing greater airflow over the head.

Meanwhile, many opted for more classic massive-vent options like the Aeon, existing on the other end of the spectrum. Forget aerodynamics; keep the head and body cool, and you stand a better chance at a better bike split, and invariably, a better run.

The Synthe exists in the worlds of both aero and cooling, serving both with aplomb. ” When it debuted, the Air Attack set the lead in industrial design, and to make gains in performance, we had to think industrial design,” said Giro brand manager Eric Richter. “But aerodynamics is something increasingly looked at with this design.”

The result is a helmet that Giro has proven in its own testing ticks the boxes in terms of cooling, aerodynamics and weight savings. And it does so in a classic-looking package.


The Synthe (center) marries the aero features of Giro’s Air Attack (left) with the ventilation of the Aeon (right).



The Synthe is part of Giro’s new design language, and on its face, the Synthe looks like a revised throwback, akin to the old “hairnet” leather helmets of the ’80s. And it’s certainly a departure from the arresting look of the Air Attack. While triathletes adapted to the Air Attack instantly, many roadies were couldn’t contend with the unconventional look. Happily, the Synthe comes back to a classic helmet look, while still delivering the aero features. It was an offhand comment, but Richter made the perfect analogy; while many of today’s classically-vented helmets like the Aeon are designed with style in mind like a Ferrari, the Synthe is an efficiency form more in line with the Prius.

And there’s nothing wrong with that. All lines are clean, tapered and simple—just like airflow likes. There’s a significant drop in overall volume of helmet as well, seen when compared side-by-side to an Aeon.

The Synthe is finished with a set of X-Static antimicrobial pads, slim webbing and a slimline buckle.

The helmet has a set of perforated panels that run laterally along the sides that Giro calls AeroMesh, which Giro says is design to improve ventilation and aerodynamics. By employing this ported panel, Giro says it helps trip up the laminar airflow across the sides of the helmet, smoothing a typically turbulent boundary layer, making wind flow off it’s surface in a smoother fashion. “I call it an air bearing,” Wesson said. “It creates a fast section. We’ve found that vents on the side can actually slow a helmet.”

Further, holes along the front edge of the panel serve as an integrated docking port for sunglasses.


We found that the sunglass port that lives within Giro’s AeroMesh panel did the trick in keeping our sunglasses stowed without bouncing loose or poking the head.

The Synthe has a total of 19 ports, with internal channeling and utilizes Giro’s RocLoc Air fit and stability system with on-the-fly vertical tuning to keep the head suspended from the helmet’s EPS foam, further increasing airflow. It weighs in at 250 grams in a CPSC-certified version (230g in CE version), size medium. For comparison, it’s not too far off the one of the industry’s lightest helmets available, Giro’s Aeon, which weighs in at 222g for the same size and certification, and comes in lighter than the Air Attack, which is 288g.

It was Giro’s testing against other brands, however, that spoke to the helmet’s status. While Giro kept the competitor brands as Competitor A, Competitor B, etc., we were able to procure those brands the Synthe tested against. While Giro created its own thermal testing capabilities, the company used four tunnels (Giro’s in-house BRG Dome and three external tunnels—University of Washington, University of British Columbia and FASTER in Scottsdale, Ariz.) to testing prototypes, and used the experience of aerodynamics expert Len Brownlie as well as Peter Ostafichuk, PhD at the University of British Columbia to pull accurate data.


The Synthe (left) has a much reduced frontal area footprint when compared to many traditonal helmets like the Aeon (left). These are both size small helmets.


Protocol was to always test at a Tour de France average speed of 25mph for road testing and 30ph for TT. Wind angle range was 5, 10, 15, and 20 degrees yaw, and two head angles were tested: a typical “head-up” position of looking up the road at 30 degrees from vertical, and a typical Ironman head position of head down, at 60 degrees.

Giro employed what is quickly becoming the testing standard of Wind Average Drag, or WAD, a calculation that considers rider speed and drag from multiple yaw angles, aggregating data for a singular drag number that permits easier, more precise understanding of a product’s overall performance.

And in their aero test (Wind average drag at 25 miles per hour in a ‘head-up” head tilt at 30 degrees), the Synthe came up with a drag number of 350.6 grams of drag. Comparatively, the Giro Air Attack 358.9 grams of drag.

And “Competitor A” “Competitor B” and “Competitor C?”

The other helmets tested were the Specialized Evade aero road helmet (359.2g), the Louis Garneau Corse aero road helmet (360.5g), the Poc Octal (378.8g), the Specialized Prevail road helmet (380.1g) and the Bontrager Oracle (380.5g).



Thermal testing also came out to Giro’s advantage, and much of their design comes from the results of the company’s thermal testing head form, which the company calls the Therminator. In fact, Giro says it’s the only company to this point to quantify their thermal features. With 24 thermocouple sensors around a headform heated to a typical rider head temp of 100 degrees (and a snake trail of cables running off the form, relaying live data to a computer in the control room), Giro can identify literal hot spots by isolating any one of the sensors, and re-design vents, ports and such to determine the effect. Before our media test in Scottsdale, we touched the aluminum headform and yup—it was like our heads during a hot ride in the Arizona desert. “The forehead is most important,” said Giro lead designer Rob Wesson. “That’s where we get immediate feedback; if it’s cool there, it’s going to feel cool.”

And contrary to past helmet designs, a cool helmet isn’t the one with the biggest vents anymore.

“In the past, vent count was the theme. We’re now beyond that. Venting isn’t what we want to talk about,” Richter said. “Core temp and head temp We want to talk about cooling your body. In the air conditioning industry, they call it cooling capacity, where they measure rate and range of temperature change. We do that, instead of measuring positive or negative space in a helmet.”

With the tunnel tested at an ambient temp of 73 degrees (plus or minus one degree), the Synthe came out at at a 30-degree head tilt. A time of 30 minutes per helmet was enough time to show separation between helmets.


Giro design engineer Rob Wesson fits up a Synthe for our test with the Therminator thermal reading device at FASTER Wind Tunnel in Scottsdale, Ariz.

While the thermal testing versus other brands of aero road helmets, we were intrigued to see a plot that existed waaaaay up on the chart. We had to ask: what was that data point? It was Giro’s own dedicated aero helmet, a typical helmet we see on course in Kona: the Selector. And that chart was proof positive that yes, an aero helmet is great against the wind, but keeping your head and body temp thermoregulated over the course of a ride (and setting up for the run) may be the bigger consideration. It can pay big dividends with the right helmet choice… or result in big fireworks if you blow up by overheating. Choose wisely; some claim to not find issue with traditional aero helmets in the heat. But for those that do, helmets like the Synthe ought to be highly attractive.

One other aero note as it relates to triathletes: Giro said the Air Attack was 16 grams better than the Synthe in drag with head down at a 60-degree head angle (a typical head-down position we hold in the course of an Ironman). Giro said that for reference, 20 grams of drag equates to about a 20-second advantage over 40 kilometers of riding, so it’s not an insignificant consideration. “That said, every rider is a unique equation,” Richter said.


Wesson shows the media live findings of the cooling effects of the Synthe on the Therminator thermal testing headform at FASTER wind tunnel.


Is the Synthe worth a triathlete’s look? It may well be. As Richter said, every rider is a unique equation. That is, every athlete holds their head at a certain pitch. Whether that works for you aerdynamicslly is for you or your coach to decide. As we learned, the Air Attack may be a better choice for the rider who hangs their head in a pronounced fashion.

That said, the savings of seconds may be secondary to thermal regulation in a hot race like Cozumel, Kona or Lanzarote, in which case the Synthe is going to be every bit as cool as the Aeon vented helmet—with much better aerodynamics. Were I racing Kona, and choosing among the three, I wouldn’t even think twice: with heat regulation as my primary concern versus a few seconds that I may save, the Synthe would be my choice. It’s plenty aero, but much cooler.

Out testing was timed perfectly: in the heat of summer, Scottsdale, Arizona. We went for a short hour and a half ride, but with temps slated to reach 107 degrees F, we departed early, and still felt heat in the 90s.

And yes, it’s cool. Giro’s work with the Therminator seems to do the trick, but I’d also attribute the cooling effect to the RocLoc Air, which physically suspended my skull from the helmet, furthering the effect of air flow over my head. And with a shaved head, I was quite sensitive to it. Long story short, the helmet is cool, much cooler than the Air Attack would be in similar conditions.


Taylor Phinney of the BMC Racing Team was one of the early testers of the Synthe.

Aero? We’ll have to play with that when long-term media test units are made available in a month’s time, since Giro is still fine-tuning this lid before they go to production.

The sunglass port worked admirably—at least for us. Giro admits that they won’t work for all glasses (some temples with hard angles or odd pitches will prove challenging, but our Oakley Radarlock sunnies popped in there, no problem, and the arms didn’t tap our head at all. I would suspect many Oakley and Smith sport optics will work just fine, but perhaps some Rudy Project temples with articulating temple ends or many sunglasses with pronounced L-bend armpieces will find it either challenging, or won’t work altogether.

Dipping low and simulationg riding in the aerobars, the browline is slightly raised, meaning clear, unobstructed view up the road. No sweat.



The Synthe will price at $250, and will come in a collection of color options, including one limited-edition black with blue and red trim. Giro said the company would likely be doing color-matched helmet/footwear colorway pairings as well. While we will see riders from IAM, Katusha and BMC debuting the Synthe in a few weeks at the Tour de France, it’s scheduled to be made available to the market sometime in December.

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