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Item # GIR007F

Cooler, lighter, but still a classic.

If you're into road cycling, then chances are good that you've owned, or known someone who's owned, an Atmos. It's been a staple of ours and our riding buddies for so long that it's hard to imagine not seeing one bobbing up and down in the group. Now, Giro has made the risky decision to release the Atmos II. We're happy to report that the original design remains largely intact, but there is one key addition that ups the ante for safety across the industry: Giro's Thermoformed SL Roll Cage.

The SL Roll Cage is the skeleton that gives form to the helmet's EPS liner. It keeps the helmet together under impact, acting like a second shell to maintain the helmet's structural integrity and disperse impact. The added strength also means that Giro can add negative space to the Atmos II without sacrificing safety, so it's more ventilated and lighter than its predecessor. The Atmos II still takes advantage of Giro's In-Mold Composite reinforcement, which permanently fuses the outer shell and SL Roll Cage to the EPS foam liner to enhance the effectiveness of all three.

In an age of mass production, Giro's Roc Loc 5 Fit System makes the Atmos II fit like a custom one-off. You can custom tune the fit tension as well as the fore-aft tilt of the helmet in seconds with one hand. Though other helmet manufacturers have similar adjustability options, none of them even come close to the weight savings that the Roc Loc system offers; it's almost 40% lighter than comparable systems.

Keeping your head cool during even the hottest, most critical road races is something that Giro has focused a great deal of attention on. Giro helmets are developed with a proprietary Wind Tunnel Ventilation System that combines 26 vents in the shell with exhaust channels within the belly of the helmet leading to the rear. Fresh, cool air from the front is strategically channeled around the head to help evaporate the sweat before exiting through the rear exhaust openings. It's a natural cooling system that you'll appreciate every ride.

  • Roc Loc 5 adjustment system
  • 26 vents with exhaust channels that lead the air over the head and out of the back of the helmet
  • X-Static pads inhibit bacteria growth

Tech Specs

Shell Material:
in-mold polycarbonate, Thermoformed SL Roll Cage
Impact Foam:
26 Wind Tunnel vents, internal channeling
Fit Adjustment:
Roc Loc 5
Claimed Weight:
[medium] 270 g
Recommended Use:
road cycling
Manufacturer Warranty:
1 year

Size chart


Adult Cycling Helmets
 SS/MMM/LLXLAdult UniversalWomen's Universal
Head Circumference 20 - 21.75in
(51 - 55cm)
20 - 22.5in
(51 - 57cm)
21.75 - 23.25in
(55 - 59cm)
21.75 - 24in
(55 - 61cm)
23.25 - 24.75in
(59 - 63cm)
24 - 25.55in
(61 - 65cm)
21.25 - 24in
(54 - 61cm)
19.75 - 22.5in
(50 - 57cm)
Head Circumference 20 - 20.75in
(51 - 53cm)
21.25 - 22in
(54 - 56cm)
22.5 - 23.25in
(57 - 59cm)
23.5 - 24.25in
(60 - 62cm)
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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Perfect as Expected

  • Familiarity: I've used it several times

This is my first Giro road bike helmet, as I just started roading. I have a an Athlon mountain bike helmet an absolutely love it, so this selection was a no-brainer. No hot or pressure spots, light and comfy, and the RocLoc works well for me. Love the Atmos II!

One bad flaw, IMO

  • Familiarity: I've used it several times
  • Fit: True to size

I had read nothing but good, no great, reviews on this helmet and decided to get one while they were on sale. I have always had Giro helmets and was expecting good things. However, there is one flaw in this helmet that I am surprised I have not heard about. In the middle of the forehead, there is a gap without a sweat pad (the pad is two pieces - a right and a left). Because of this, sweat just pours right down the middle of my head and down my nose. I had to go to a Halo headband which is OK but it only moves the problem to later in the ride. Other than that, great helmet. I will be moving to one of the new MIPS helmets later this year.

Light and Comfy

  • Familiarity: I've used it several times

I love this helmet. It is lightweight and comfortable. With the easy adjust wheel in the back of the helmet, I can snug it quickly to my head and forget about it. It has plenty of vents to keep you cool when things get hot which I am looking forward to in the summer heat, and the helmet itself has a classic and stylish look. I am very glad I ended up getting this helmet.

Avg. ride time: 11m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Great Helmet

  • Familiarity: I've put it through the wringer
  • Fit: True to size

Looks great. Doesn’t look too big or small on your head and is very light. Very comfortable and you won't even be able to tell you have it on.

A must have

  • Familiarity: I've used it several times

Lightweight and comfortable. Exactly what one needs when riding. Need to play with the straps to get the right adjustment but you will be happy you have it.

One of the best bike helmets ever made

  • Familiarity: I've put it through the wringer
  • Fit: True to size

I have been riding for nearly 40 years.
Have used so many different helmets, but, hands down for the protection, style, weight, comfort and fit and, the price, specially, if it is on sale, the Giro, Atmos, helmet, is hands down, the best helmet that Giro has ever designed and created.
I have been using it ever since it first came out.
Unless you think about it, while riding, you do not really, "feel it."
This one is a true classic.

Given as gift - but he's raved about it

  • Familiarity: I gave it as a gift but have feedback to share

No sense re-inventing the wheel - right? Gave this as a gift to replace the dad-in-law's nappy old one. Fit, style, use exactly the same as they were before and he's as happy as can be. One of the best things about Giro helmets are how adjustable they are, and the Atmos is no exception.

nice and simple.

  • Familiarity: I've used it several times

I dont ride my road bike all that often but i love this helmet for the fact I can't tell its even there.very light , comfortable well made helmet

Avg. ride time: 5m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

amazing adjustability

  • Familiarity: I've used it several times

Great helmet, super light weight and amazing adjustability.

amazing adjustability

Don't even know it's on

  • Familiarity: I've used it several times

So far i am loving this helmet, super light weight, comfortable on my head to the point where i forget it is there. I don't think there is better helmet for the price, would recommend to anyone looking for a great road helmet.

Comfy, light and does a great job

  • Familiarity: I've put it through the wringer

1. Comfy

2. very light

3. amazing adjust-ability

4. does a great job when you land on your head in a crit race - see attached pic

Comfy, light and does a great job

My Giro Aeon saved my noggin after a head collision with railroad tracks. I also have an Atmos which I also am pleased with, though I need some replacement pads. They offer a decent crash replacement discount if you contact them as well.

Unanswered Question

Always wore a large, measured my head at 22.75 inches so I ordered a medium. My head fits and everything seems great but I'm freaking out cause it looks to small and the back of my head seems exposed compared to my old $50 trek helmet. Any feedback from users will be appreciated.
Cheers, Mike T

Simple does it.

  • Familiarity: I gave it as a gift but have feedback to share
  • Fit: True to size

Sometimes a helmet is just a helmet. And there's nothing wrong with that. The strap isn't as soft as some, the shell isn't as obnoxiously "aero" as some, and the body isn't as minimalistic as some. It's not the most advanced (read: expensive) helmet, but it disappears once it's on, and that's what matters most. It's a classic for a reason.

Version II is better than ever

    Giro designs some of the best high-end helmets in the sport (atmos, aeon, synthe). Excellent gloves and aero covers too.

    I purchased my first Atmos helmet 12+ years ago. It was one of the first modern, really good looking, highly-vented, in-mold composite bike helmets made.

    Pros: Very, very well ventilated. Light weight. Strong. X-static (silver fiber) pads naturally inhibit sweat odor. Awesome looks. Affordable $$.
    Cons: none.

    This is a great Summer road helmet. The classic for a reason.

    Note: Make sure any helmet fits your head *shape* correctly (more round or oval). This is very important and true with any company's bike helmet. The only way to know is to try 'em on.

    Avg. ride time: 4h 59m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    If it aint broke, don't fix it

    • Familiarity: I've put it through the wringer

    I've been using the Atmos now going on ten years, still my favorite! Great lightweight design, comfortable fit and plenty of ventilation for those hot days in the saddle. I often forget I'm wearing it sometimes. This will be my third one, and I'll probably re-up again when the time comes.

    If it aint broke, don't fix it

    Same great helmet as it was 10 years ago

    • Familiarity: I've put it through the wringer
    • Fit: True to size

    This design certainly isnt new, but it shows how great it was when the original Atmos came out quite some time ago. Great ventilation, solid retention system, a fit that works well for me, and all at a lower price as this helmet has succeeded by others with snazzier options. I also own the Synthe and love it, but if you want the best helmet for your money this is it.

    Great helmet at a good price

    • Familiarity: I've used it several times

    I bought this helmet to replace an older Giro helmet I've had for several years now. The Atmos II is lightweight, better ventilated than any other helmet I've owned, and priced right. The Roc Loc adjustment is great, but I think my head is sized weird - so the medium is too small, but the large is a bit too big. The adjustment system does cinch around my head well - but it still leaves a gap on each side of the helmet and it doesn't feel that secure. The thin straps are unobtrusive but the ends were a bit long - which I easily solved by cutting the excess strap material and singing the ends. The foam on the bottom lip of the helmet is fairly exposed though - so one concern I have is the long-term durability of it.