Tuesday, June 11, 2013

Giro Air Attack aero road helmet

May 20, 2013

The original Giro Air Attack, circa 1989.

All the way back in the mid-80s, aerodynamics was already coming into play as Giro founder, Jim Jentes, applied airfoil technology from NASA to his helmet designs. In 1989 Giro released the first plastic shelled helmet called Air Attack, and later that year it was ridden to victory at the Tour de France atop Greg LeMond. 25 years later, and the new Air Attack has more similarities with its ancestor than just the name. 

On a recent visit to Giro headquarters in Grass Valley, California RBA got a first-hand look at Giro's past and present, in addition to how and why the Air Attack was re-created for 2013. 

The design phase of every helmet begins with a 2-D sketch and then a handmade half-scale foam model that has intricate detailing of both shaping and vents. 

The Air Attack name isn’t new to Giro at all; it was the name of their first helmet featuring a polycarbonate shell introduced way back in 1989, which went on to a Tour de France victory by Greg LeMond that same year. As it turns out, when Giro was wind tunnel testing for the Air Attack reincarnate, (they tested about 100 different helmets) the late-1980s Air Attack’s round profile yielded some impressive numbers of its own. After having a good idea of what fared well and what didn’t in the wind tunnel, Giro’s Senior Industrial Designer, Greg Marting went to work on designing the new Air Attack. "The helmet begins with a 2-D sketch, and then we make a half scale 3-D foam model by hand”, explained Marting. The design room is filled with foam models spanning the past decade of helmet designs, with each one impressively accurate in perfectly detailed venting and shaping. 

The Air Attack's design is a balance between aerodynamics, weight, ventilation, and even aesthetics. Inspiration for design comes from a myriad of places. 

Achieving the sought after aerodynamic gains required a significant re-think of Giro’s popular road helmet designs. Giro’s Engineering Manager Rob Wesson explained how the gains were achieved, “The aerodynamic benefits over a standard road helmet are in most part due to its smooth, rounded shape and minimal vent openings. By eliminating sharp corners, edges, and pockets you greatly reduce the re-direction of air over and around the helmet; thus reducing its drag. The second aspect of the Air Attack that contributes to its aerodynamic benefits is its profile. By rounding out the back the way we did, we can achieve more consistent drag numbers regardless of a rider dropping their head when they are tired, looking around from side to side, or course and wind direction changes.”

After a design is settled upon, a full-scale clay model is made that can be windtunnel tested and easily manipulated with the addition or removal of material. 

Once the design is set, a clay model is made to scale. From there it can be wind tunnel tested and manipulated by adding or removing clay. While helmet production ceased in Giro’s Santa Cruz location in 1995, the rapid development of 3-D printing now allows them to print a production-replica helmet that weighs about one fifth of what the clay model does, and can have graphics or paint applied to it. 

  With 3-D printing becoming more cost effective within the past few years, Giro can now create a wearable (although it has no protective ability) helmet that's much lighter than a clay model in a fraction of the time it takes to get a production sample. The $30,000 machine uses a cartridge that feeds a plastic line into the printer and about 30 hours later, voila, a helmet!

After receiving production samples, the last step is, well, breaking them. In Giro’s test lab the helmet gets strapped onto a machine to simulate a fall from six and a half feet high. Multiple surfaces are used for the tests, ranging from a flat surface to a curb, in order to see how the helmets fare with different impact zones. Giro tested multiple Air Attacks to show us how they fared. In each test, the helmets had micro-cracking of the inner foam in a few inch radius of the impact—exactly what it’s intended to do for impact displacement. 

With a dummy head in the Air Attack, it gets dropped from six and a half feet on either a flat surface or a curb in order to simulate a crash. 

Side by side, the difference in design between the Aeon (left) and Air Attack is dramatic.

Ok, so Air Attack is purpose-built, and we realize that. But the first time you look in the mirror with one on you’ll think you’re about to head to the skate park; and there were plenty of people to remind us of that fact. Granted, the Air Attack looks slightly bulbous on your head, partly due to the rounded, bowling ball shaping, but also because it does sit slightly higher than Giro’s other road helmets. The Roc Loc Air retention system is designed to allow a 3mm gap between your head and the shell in order to achieve unabated airflow through the limited venting. 

An optional visor attaches securely to the helmet via three magnetic attachments. Giro did state that any difference in aerodynamics between using the visor versus using sunglasses is negligible.

Is it faster? We can’t confirm or deny Giro’s findings of the Air Attack having 49 grams less drag then the Aeon, which translates into 17 seconds faster over 40km at 25mph. In a 600 meter sprint at 40mph, it would give you a two bike length advantage, which is why just about every pro sprinter that has the option of an aero helmet is wearing one. While these numbers are considerable if you’re Pro Tour level rider who can achieve, and maintain, those kinds of speeds, for the rest of us, the benefits are going to be smaller since the slower you go the less of a benefit you’ll get. 
One thing we noticed with the Air Attack was that it’s warmer than an Aeon. Giro says that the difference between both helmets is two degrees Fahrenheit when riding at 25mph. This very well may be, but it’s a noticeable two degrees. When the temperatures were below 75-80 degrees Fahrenheit we didn’t have a problem using the Air Attack on long rides, but as the mercury went up we found ourselves looking for more ventilated head protection options. 

Long before aero-road was even a thing, Giro made a ventless version of the original Air Attack at Greg LeMond's request. 

The Air Attack has a purpose, and it’s not for an everyday application, at least we don’t think so. If you’re in search of marginal gains, and don’t mind paying for them, then look no further than Giro's latest lid. The best application for the Air Attack will be criteriums, triathlons, certain road races, of course, most Strava KOMs. Ok, so it has a lot of applications, but reserve its use for the days when the mercury stays south of the 80-degree range; that is unless you’re going to be going 25+ mph the entire time. 

Price: $200, $240 (with visor)
Weight: 276 grams (without visor)
Sizes: Small, Medium, Large

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