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Item # GIR0402 Past Season Colors

5 5

Community Rating | 21 Reviews

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  • Matte White/Silver, S ($249.95)
  • Matte White/Silver, M ($249.95)
  • Matte White/Silver, L ($249.95)
  • Matte Red/Black, S ($249.95)
  • Matte Red/Black, M ($249.95)
  • Matte Red/Black, L ($249.95)
  • Blue/Black, S ($249.95)
  • Matte Black, S ($249.95)
  • Matte Black, M ($249.95)
  • Matte Black, L ($249.95)
  • Matte Titanium, S ($249.95)
  • Matte Titanium, M ($249.95)
  • Matte Titanium, L ($249.95)
  • Matte Black/White, S ($249.95)
  • Matte Black/White, M ($249.95)
  • Matte Black/White, L ($249.95)
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Item # GIR0402


Cooling comfort.

In the never-ending quest for helmet lightness, one fact makes us rest easy: Even the most feathery helmets must pass the CPSC safety standard for impact resistance. If, for example, you've ever picked up a Giro Prolight or Aeon helmets, you know why this is a concern. It seems impossible that a near-weightless thing like these helmets offers adequate protection. Amazingly, though, they pass the CPSC testing just fine.

The Prolight tips the scale at 200 grams, nearly 50% lighter than most alternatives in its $200 price range. Its lightness comes thanks to several factors, the most noticeable of which is its lack of fit adjustment hardware. Its Roc Loc SL is made from elastic and offers none of the fine-tuning of other Roc Loc models. Furthermore, the strap buckles beneath your ears are fixed and non-adjustable on the Prolight. And while this might seem like a reasonable price to pay for lightness, if you ever choose to wear a cycling cap or winter hat beneath your helmet, the resulting tightness around your head is a bummer.

Enter the Giro Aeon. With the Aeon, Giro's goal is to offer the next generation of superlight helmet design. The Aeon marries the breathtaking lightness of the Prolight and the fabulous ventilation and adjustability of the Ionos.

At 218 grams (size Medium), the Aeon is in the same weight class as the Prolight, but it offers far more fine-tunability to the fit. It comes with Giro's all-new Roc Loc 5 retention system. For starters, the indexed Micro Dial lets you adjust the tension with a two fingered twist. And itsGiro Aeon Helmet  Detail three position bracket allows 15mm of vertical adjustment in the retention basket -- enough to fit any head shape comfortably. In another improvement over the Prolight, you get clever strap management. The retention basket has strap holders to ensure that they'll be right where you want them by the time the helmet falls into place on your head.

The Aeon uses in-mold construction to fuse the foam liner to the abrasion and puncture resistant polycarbonate shell as other Giro helmets. However, Giro uses a low-density EPS liner for the Aeon that performs the same important task of absorbing impacts, yet it's 15% lighter than the foam they used previously. Giro took advantage of that weight savings by foregoing the composite reinforcement found on the Ionos. Instead, a thermo-formed SL Roll Cage reinforces the Aeon for maximum safety, yet it's 49% lighter than the Ionos' composite sub frame.

The Giro Aeon Helmet has 24 massive Wind Tunnel vents to suck cool air in the front and flush warm air out the back, even at relatively slow speeds. The Giro Aeon is available in the sizes Small, Medium, and Large and in the colors Highlight Yellow/black, Matte Black, Matte Black/white, Matte Black/color fade, Matte Black/yellow Livestrong, Matte Blue/black texture, Matte Red/black, Matte Titanium, and Matte White/silver.

Tech Specs

[skeleton] Thermoformed SL Roll Cage
Adjustable Vents:
Fit Adjustment:
adjustable chin strap, Roc Loc 5
Claimed Weight:
222 g
Recommended Use:
road cycling
Manufacturer Warranty:
1 year

Size chart


Adult Cycling Helmets
 SMLXLAdult UniversalWomen's Universal
Head Circumference 20 - 21.75in
(51 - 55cm)
21.75 - 23.25in
(55 - 59cm)
23.25 - 24.75in
(59 - 63cm)
24 - 25.55in
(61 - 65cm)
21.25 - 24in
(54 - 61cm)
19.75 - 22.5in
(50 - 57cm)
How to Measure:
For best results, use a tape measure to measure around your head where your hat would fit comfortably.

Reviews & Community

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Giro Aeon Helmet

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Here's what others have to say...

3 5

What's with all the stars?

  • Familiarity: I returned this product before using it

I see a LOT of road cyclists with this helmet so I thought I'd give it a shot. Don't see what all the hype is about. Looks okay but not great (I tried the black). Maybe one of the colored ones would look nice if it matched your kit. But in terms of breathability the mavic plasma or the catlike mixino both breathe better (hence only 3 stars). In terms of comfort I had no complaints.

5 5

The best for a reason

  • Familiarity: I've put it through the wringer

I ordered a POC Octal to be quirky/cool/different and match my two Cervelos. I couldn't get over the mushroom vibe no matter how light it was so I returned it for the Giro Aeon. Also toiled over the Catlike, but couldn't be happier I went Giro.
I got it in fluorescent orange to stick with the high-viz theme and it definitely passes the test. Bright, light, most comfortable helmet I've ever owned.
It gets breeze to my scalp through my mop of hair and has no compatibility issues with my Oakley Radarlocks. It's a close fit but as long as everything is properly adjusted, you'll forget you're wearing shades or a helmet. Can't say enough good things about the Aeon!

3 5

Adjustment knob breaks off

  • Familiarity: I've put it through the wringer

Overall a good helmet. However, I've owned three of these, and the adjustment knob has broken off each one within 3-4 months of use. I never adjust the fit while riding, and I am understandably cautious when I do turn the knob. Mechanics at my local bike shop say that manufacturers discount longevity in order to make low weight claims. Come on, people. A stronger knob might add 3-6 grams. It's worth the weight.

5 5

Giro fan forever...

  • Familiarity: I've put it through the wringer

The Aeon saved my life, literally. I was t-boned during a ride... Before that, it was an extremely comfortable, super light weight, and excellent looking helmet! I would not hesitate to get another and in fact, I just did! Thanks Dan and Competitive Cyclist! Going for the orange one for visibility ;)

5 5

Legit Brain Bucket

This is a nice lid. Was looking at Specialized helmets, but the Spec lids didn't fit my head quite right. However, the Giro lids fit comfortably, and are also stylish.

3 5

Does not hold sunglasses well

  • Familiarity: I've used it several times

I just got this helmet a couple weeks ago. Very comfortable and light. I love the adjustment mechanism. The large size does not hold my oakleys at all. It might seem like a silly thing but i'm so used to putting my glasses in my helmet for the long climbs simply with one hand and easily reaching for them when I need them. I would think that would be a design consideration with a helmet of this level. I might return it but I do feel a little guilt about this as I've been using it for a couple weeks now. Really want to really like it.

Responded on

Agreed. That was a big disappointment for me and I am still living with it. Take advantage of the awesome return policy competitive cyclist has and get yourself a helmet that holds your sunglasses.

5 5

Feels Good, Looks Good Too

  • Familiarity: I've put it through the wringer

Love the design and look of this helmet, and all the great color schemes that it comes in. This along with its super lightweight and a perfect fit make this my favorite helmet from Giro, and my favorite helmet I've ever owned.

Feels Good, Looks Good Too
5 5

Great helmet but costly

  • Familiarity: I've put it through the wringer

I've been riding with my Aeon for about 18 to 24 months. Without a doubt the lightest, most comfortable helmet I've ever used. Also the the best able to keep my melon cool. This is important as I live in South Florida and regularly ride in 90 degree temps. This helmet's only downfall is it's high cost. Easily 50 to 70 dollars more than several other high end helmets. Helmets wear out (the Roc loc on mine took a dump recently) and replacing it is a substantial cost. That said, if money isn't a problem you will have a difficult time finding a more comfortable helmet than the Giro Aeon.

5 5

One of the very Best

I purchased my first Giro "Atmos" helmet over 10 years ago. It was one of the first modern, really good looking, highly-vented, in-mold composite/Kevlar reinforced bike helmets. Fast forward to today... Giro based in Santa Cruz CA designs some of the best high-end helmets in our sport (atmos, aeon, and air attack).

If you can afford it, the Giro "Aeon" helmet is a fantastic Summer helmet: extremely well-ventilated and -amazingly- light. The ultimate light-weight warm-weather cycling/racing helmet?

Note: Make sure any helmet fits your head shape (and size) correctly. This is very important and true with any company's bike helmet.

5 5

Light & Right

  • Familiarity: I've used it once or twice and have initial impressions

Santa just brought me a new Aeon, and I've taken advantage of a couple of warm-ish days to ride with it. The first ride, I had to tap my head a couple of times to make sure I had a helmet on - it is that light and comfortable. I've been riding with Giro buckets for 10+ years and this is definitely their best effort. It adjusts very easily, and the straps are light and comfortable. Even with my 7 7/8ths head, I could fit a wool training beanie underneath. Fortunately, I've never had to test my Giro crashworthiness out it any serious way, but it's nice to know it's there. Take a look at one if you are thinking of a new helmet.

5 5

Great Helmet

  • Familiarity: I've put it through the wringer

This is my 2nd purchase of the Aeon. My first safes my noggin (only slight concussion )and had a slight dent in it. This helmet is awesome. Very light weight and comfortable. When I saw it on sale on Backcounrty for an incredible price I grab it up ASAP. I previously purchased a pair of Sidi's and saved $100. Amazing ; Thanks Backcounrty for having the best on sale/ close outs.

5 5

Great support from Giro

  • Familiarity: I've put it through the wringer

I won't reiterate what others have said. Light, adjustable, ..
What I would add is that Giro sent me a replacement RocLoc kit NQA when mine broke. Excellent support

4 5


  • Familiarity: I've put it through the wringer

The helmet is amazingly light compared to the Ionos. The only thing I don't like is my sunglasses, Rudy Project Rydon and Oakley Flak Jackets don't seem to stay in the vents when I try to store them there. On the Ionos I had no problem.

4 5

The best Giro Helmet

  • Familiarity: I've used it once or twice and have initial impressions

It is very expensive so I only buy them when it is on sale. Backcountry had some color for sale at 40% and it was worth it. It so light and comfortable. I love the x-static padding. I would recommend the helmet but just too expensive to pay for full price.

5 5

What helmet?

  • Gender: Male
  • Familiarity: I've put it through the wringer

Yes that was my reaction because I didn't feel wearing one. I bought this helmet to replace my old Prolight and this one fits way better. The Prolight seemed to be a bit narrower from side to side, so if I need to wear any sort of cyling cap or thermal cap in the winter, it felt very tight. While the Aeon is about 20 grams heavier than Prolight in size M, I just simply feel lighter wearing the Aeon due to its so comfortable fit. And the loc 5 retention system is great, it creates a comfortable snug fit and can be adjusted on the ride using 2 fingers. My only concern is the durability of the loc 5 system, it's a very minimal design for light weight so I don't know if it last for the life of the helmet, but only time will tell and I hope I'm wrong on these. Highly recommended.

5 5

Simply the best

  • Familiarity: I've put it through the wringer

This helmet,by far, is my favorite helmet to date. Its super comfortable and the fit is outstanding. The retention straps are easy to adjust and the helmet is well ventilated. I like the low profile design as well as it provides a little more aero properties. Highly recommended.

Simply the best