Free 2-Day Shipping on Orders Over $50

Detail Images

  • Giro - Side
  • Giro - Side
  • Giro - Fathom Helmet - Matte White/Black
  • Giro - Fathom Helmet - Matte Black/Gloss Black
  • Giro - Side -
  • Giro - Side -

Current Color

  • Giro - Fathom Helmet - Matte White/Black
  • Giro - Fathom Helmet - Matte Black/Gloss Black

Giro Fathom Helmet

35% Off
sale $97.47 $149.95

Free 2-Day shipping on orders over $50. Learn More

Select a Size:

Select options
  • Select options
    • S
    • M
    • L

    Select a Color:

    Select options
  • Select options
    • Matte White/Black
    • Matte Black/Gloss Black

    14 Reviews


    Mountainous Atmos.

    If you’re a multi-bike rider, you’re probably familiar with how light, breathable, and comfortable road helmets can be, and have probably wished your mountain helmets could compete. Maybe you’ve even taken to wearing road helmets off-road, and deflecting the inevitable comments about spandex, shaved legs, and Lance. Well, the Giro Fathom can’t do anything about your riding partners’ senses of humor, but since it’s an Atmos with a visor, you’ll be just a bit more incognito. It gets the same, thermoformed Roll Cage SL, the Roc Loc 5 adjustment Giro helmets are famous for, and 26 vents to keep you cool, even on long, exposed, hot climbs.

    • Roc Loc 5 adjustment system
    • SL Roll Cage maintains helmet’s integrity in the event of a crash
    • Removable Visor
    • 26 Wind Tunnel vents move air in, through, and out of the helmet
    • Item #GIR007J

    Tech Specs

    Shell Material
    in-mold polycarbonate, Thermoformed SL Roll Cage
    Impact Foam
    23 Wind Tunnel vents, internal channeling
    Fit Adjustment
    Roc Loc 5
    yes, removable
    Recommended Use
    cross country
    Manufacturer Warranty
    1 year

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    super light

      I've been looking for a new mnt biking helmet for awhile. I have a hard time finding one that fits because I'm in between S and M sizes (56ish cm). Small sizes usually are too tight in temples, while mediums do not tighten enough to feel secure. I ordered this helmet in size Small and it fits well, I have room to add one thin layer if it's cold and it can be tighten securely around my head even with a pony tail. It's very light, which is great for me since most of my riding is xc. (I wonder is it compromises safety though?) With a few simple adjustments it stays comfortably secure without bulky weight or extra bells and whistle. It's a little costly, which is the main downside of this helmet.

      Perfect for all situations

      • Familiarity: I've used it several times

      I'm a newbie when it comes to biking, but I can say that this helmet seems good for all situations, from a chill ride to a more demanding activity.
      I really like how light and the level of ventilation this helmet provide!
      It's really confortable, awesome fit and it also look good.

      Light and Tight

      • Familiarity: I've put it through the wringer

      I've been wearing Giro helmets for years and am thrilled to have upgraded to this one. The size adjuster is smoother and has more settings than prior helmets. Tons of venting and it is so light that you barely notice it's there. I just hope it offers the same protection if i bump my cabeza!

      Long time Giro user looking elsewhere

      • Familiarity: I returned this product before using it

      I've been a HUGE proponent of giro helmets and have been wearing them exclusively for the last 10+'years. The mediums fit my head like a glove and I am currently running a synth on the road (love it) and Giro Montaro for mountain.

      I ordered the fathom for a lighter XC helmet and out of the box this does NOT fit like other giro helmets as it is extremely shallow and provides very little coverage. Additionally, I was never able to get the straps to lie flat against my face, the buckle is extremely off center and and the fit is generally off. The visor is crooked (and tiny) and the helmet had a super cobby unfinished look with excess foam etc. This is the WORST effort I have ever seen from Giro. Very disappointed.

      Just starting to test

      • Familiarity: I've used it several times

      Because of a very wet spring here in Utah I have not had the chance to use this much. The fit seems good so far. I will update this as I get more rides in.

      Now if have several rides in the mid summer months with this helmet and it is working great. Light and airy. I am stoked.

      Light & Cool

      • Familiarity: I've used it several times
      • Fit: True to size
      • Height: 6'6"
      • Weight: 228lbs

      Live in hot and humid Houston. I replaced an older Giro road helmet with a real visor that blocked the morning sun, that helmet also routed the sweat in the front around your face and no sweat drip on glasses and face until the pads wore out.

      The new helmet is smaller looking lighter and well ventilated, fits well and adjustable. It is cooler than the old one.

      Only negatives are the visor is useless for blocking morning sun.
      I removed it and went back to using a chopped cycling cap for morning sun and there are vents in front that do help cool better but you do get sweat drip.

      Great XC Helmet

      • Familiarity: I've put it through the wringer

      Love this helmet for XC riding. It is so light, comfy, and airy that it feels like I'm not wearing anything.

      The Roc Loc 5 is awesome and easily adapts to headshape, hairstyle, and head coverings. You could for sure wear a bandana or skullcap under this helmet and still be comfortable. But then again I don't know why you would, it's just so well ventilated! I've definitely taken a few hard spills and it's showing no signs of damage.

      If you're looking for a go-to lightweight XC style helmet, this is it! You won't be disappointed.

      I'm a Large in most head apparel (I guess I'm filled with hot air) and this helmet was no different.


      Great XC Helmet

      Awesome and well vented XC helmet

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

      Rode with the helmet during an Israeli spring heatwave (+30 c). Awesome ventilation, immediately you feel the air flowing all over your head. Trumps previous specialized S-works helmets with good ventilation themselves. The giro isnt as lite as the S-works but also not as expensive. If your helmet needs to be safe and vented, this is definitely the helmet for you!
      Giro could learn from specialized when it comes to strap endings and length that are very long and dont really solve dangly straps. I personally dont find this a big deal as the rest of the design is very aesthetic.

      Great warm weather MTB Helmet

      • Familiarity: I've used it several times

      Living in FL, I prefer a helmet that has a lot of venting, is lightweight, and is comfortable. The Fathom does all three while still providing better protection than using a straight-up uber-light road helmet. The new wider straps and roc-loc retention make this thing very comfortable too.

      A couple other little features I like are the removable visor and the small rubber plugs you put in the visor holes on the helmet to give it more of a finished look with the visor off. Also dig the extra set of pads.