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Bottom edge of polystyrene is prone to dents and dings
The Giro Aeon was a former winner of our Editors' Choice Award and has lost its crown to the Giro Synthe. At 225g, the Aeon is the lightest helmet in our field of eight road cycling helmets. It's actually the lightest cycling helmet we've ever tested, so we awarded it a perfect score in our weight metric. The super low weight of the Aeon also makes it one of the most comfortable helmets in our test, only being outscored by the Giro Synthe and Lazer Z-1. The Aeon's 24 large vents combine with minimal yet adequate padding to make the Aeon an extremely airy helmet. The only area where this helmet suffered was in durability. It is less resistant to dents and dings than other helmets because its polycarbonate shell leaves much of the delicate polystyrene exposed.
The Aeon (pronounced Eon) replaced the Giro Prolight a few years back as Giro's uber light top shelf helmet. The Aeon is a major improvement over the last generation of Prolight. For starters, it uses Giro's RocLoc5 retention system, which is super lightweight yet provides enough security for much heavier helmets. The Prolight used a flimsy retention system which relied on an elastic band for tension. The Aeon also provides a bit more rear coverage than the Prolight.
At $200, the Aeon is just slightly more expensive than the average of the eight helmets we tested, which ranged in price from $80 to $300. The Aeon is our absolute favorite helmet, but if you are looking for the best value, you should check out the Giro Savant, which shares many of the Aeon's qualities while retailing for just $90.
New Colors Since our Tests
Giro released new colorways for this helmet, such as the one pictured above since our tests. Otherwise, the 2017 model we tested is the same as the 2018 model.
Our Analysis and Test Results
Hands-On Review
The Giro Aeon is a performance-oriented, in-molded bicycle helmet designed with weight and ventilation as a priority. This helmet scored highly in all of our tests except the durability test, where it proved to be a bit delicate, earning one of the highest overall scores. It became our testers' favorite no-nonsense performance helmet, especially for longer rides.
Performance Comparison
Luke Lydiard sprints towards home in the Giro Aeon.
Credit: McKenzie Long
Comfort
The Aeon is one of the most comfortable helmets we tested. The consensus was that its comfort is largely due to its very minimal weight. The Aeon is the lightest helmet in our test. In fact, this helmet is so light that it is hardly noticeable at first and quickly fades from your attention so you can concentrate on the road. One of our testers wore the Aeon during a 100+ mile Gran Fondo and completely forgot about the helmet, which allowed him to fully concentrate on the cramps in his legs.
The Aeon uses very thin, narrow padding on the inside of the helmet, similar to the Giro Synthe. Despite the minimalism, we found this padding to be plenty adequate to pad between this featherlight lid and the head. The padding is covered in X-Static material, which is supposed to cut down on funkiness. The padding dries very quickly once you remove the helmet, so we don't see much need for antimicrobial material, but we think it's a nice touch.
The Aeon is the lightest helmet we tested at 225g.
Credit: McKenzie Long
The most comfortable helmet in our test is the Giro Synthe which took a rare perfect ten in our comfort test. The Synthe keeps it comfortable, not by shaving grams like the Aeon, but with the awesome Roc Loc Air fit system. The Roc Loc Air suspends the helmet off the EPS foam and provides a pressure point free fit.
Adjustments
The Aeon uses Giro's RocLoc5 retention system, which became one of our favorites when we used it on the Giro Xar, which was part of our Mountain Bike Helmet Review. The RocLoc5 is also found on the Giro Savant. The RocLoc5 system uses a very low profile, yet plenty burly, rear retention band, which is adjusted with a small click wheel. The wheel is about the diameter of a dime and protrudes both above and below the band. This wheel is easy to locate and operate even with full finger gloves on. It allows for controlled micro adjustments of band tension in both directions and informs the user which way it is going with a loud click to tighten and a quieter click when loosening.
The Aeon uses Giro's lightweight yet secure RocLoc5 retention system to keep the helmet in place. The Giro Atmos, Savant and Xar also use this well designed system.
Credit: Luke Lydiard
The band can also be adjusted vertically into one of three positions using a simple plastic sliding mechanism. Vertical adjustment allows the band to get a good grip on the occipital lobe and ensure the helmet stays put no matter how hard you hammer. We watched one video from Giro in which they show that the height of the rear band can be adjusted while wearing the helmet. We think it's more likely you will set the height once to conform with your head and never mess with it again.
The Aeon's RocLoc5 retention system adjusts up and down into three different positions via a simple sliding mechanism.
Credit: Luke Lydiard
The RocLoc5 retention band is a million times better than the weight saving elastic band found on the Roc Loc SL retention system at the rear of the now discontinued Giro Prolight. While the rigid band and click wheel likely add a few grams, we think that the added security is well worth the weight. The only retention system which we like better than the RocLoc5 is the Roc Loc Air system, also for Giro.
Weight
At 7.94 ounces (225 grams) in a size medium, the Aeon is the lightest road bike helmet in our test. The Aeon's super light weight not only saves energy on the road, but also means it is more comfortable on the head. This is one of those helmets you completely forget you are wearing, leaving you open to focus on more important things, like how many gu packets you should be eating.
The Giro Aeon is quickly forgotten about on the head and allows you to concentrate on the road ahead.
Credit: McKenzie Long
Style
The classic looks of a heavily ventilated helmet never go out of style (at least in our opinion). The Aeon is designed around weight savings above all else, and for many riders that makes sense. The Aeon does not have rubber sunglass grippers in the vents like the Giro Synthe, but lets face it - that would add extra grams. The Aeon also lacks a MIPS liner, which would once again add weight. The Aeon is a gram counters dream, and due to this, it eschews many features found on other high-end helmets.
Ventilation
The Aeon took the second highest score in our ventilation test, just behind the Specialized Airnet MIPS. Giro designed the Aeon with 24 vents to allow cool air to flow in the front and hotter air to exit the helmet. These vents are distributed evenly around the entire helmet and give it a rib cage-like look. The Aeon's thin but adequate interior padding is shaped so that it does not interfere with airflow through the vents at all. The POC Octal also scored highly, matching the ventilation characteristics of the Aeon, and is also a good choice when the mercury rises.
The rear of the Aeon is packed with vents which allow hot air to escape and give it one of the highest scores in our ventilation test.
Credit: Luke Lydiard
Durability
Durability is the Aeon's only weak point. Lightweight and durable tend to be mutually exclusive features on anything bike related. The Aeon is the lightest helmet in our test, so we weren't too surprised that it didn't hold up to day-to-day abuse as well as other helmets in our test. Its low score was matched by the Giro Savant and the Bell Overdrive MIPS.
The Aeon's polycarbonate wraps slightly around the edge of the polystyrene, protecting the foam from everyday wear and tear.
Credit: Luke Lydiard
The Aeon's polycarbonate shell is very thin and it dented very easily. Our biggest complaint with the Aeon, however, is not the thickness of the shell, but the lack of coverage this shell provides around the edges of the helmet. We discovered that helmets hold up much better against day-to-day abuse if the polycarbonate shell wraps completely around the bottom edge of the foam. The Aeon's shell just barely covers the outer edge, but still leaves a lot of foam exposed to dings when the helmet is off your head. The Aeon and Laser Z-1 also have a number of pointy areas at the rear of the helmet which are prone to cracking should you drop the helmet from a small height or let it roll around in your trunk. The most durable helmet we found in our test is the Smith Overtake. The Overtake's polycarbonate shell wraps fully around the bottom edge of the polystyrene to protect it from dents and dings.
Best Application
Use this lightweight helmet for any type of road biking, road racing, or cyclocross racing.
Conclusion
The Giro Aeon is our favorite helmet for long days in the mountains. It is the lightest cycling helmet we've ever tested - our size medium test helmet weighs just 225g. The Aeon has ample vents and comfortable yet minimal padding, which also makes it one of the most ventilated helmets we've ever tested. The RocLoc5 retention system is super solid and more than adequate to keep this featherweight rig securely in place while you make a solo break from the peloton.
The Aeon's one weakness is its ability to stand up to dents and dings from everyday use. As is expected from any super light cycling product, the Aeon is a bit on the delicate side. It is CPSC certified to protect your head from cycling crashes, but needs to be treated with care when off your head. We recommend the Aeon for road racers as well as performance-minded recreational roadies who value light weight, comfort, and ventilation in a helmet.
Other Versions
This helmet has been released in at least 13 different colorways, so finding one to match your kit should be easy. It is available in three different sizes, which we found fits very similarly to the Giro Savant. We've grouped all of the manufacturer's size guidelines onto one handy sizing chart over in our Buying Advice article.
