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  • In-Mold technology bonds the helmet's tough outer microshell to the impact-absorbent expanded polystyrene liner, creating a light, cool and strong helmet
  • Acu-Dial fit system can be adjusted with a single hand for a comfortable, secure fit
  • Highly tuned, 27-vent design provides superior cooling
  • The Giro Phase Bike Helmet features a detachable visor for added protection from sun, rain and the occasional branch


View all Giro Mountain Bike Helmets

REI membership


Best Use Mountain Biking
Helmet Style Mountain
Head Circumference
20 - 21.75 inches
21.75 - 23.25 inches
23.25 - 24.75 inches
Vents 27
Visor Yes
Weight Unavailable
Gender Unisex
Rated 5 out of 5 by from Life Saver Awsome product! I've had this helmet for the past few years and it has been absolutely fantastic! I've ridden many many miles on my mountain bike and moved along to road biking. It always vents great and hugs your nogin really well. I've recently started biking to work and had a chain drop and flipped off my bike earlier this week. I stumbled away with a smashed helmet, concussion, and some whiplash... but if I weren't wearing a well fitted helmet I would have definitely not walked away! This helmet seriously saved my skull and my brain contents!
Date published: 2014-08-07
Rated 4 out of 5 by from Nice Helmet, but the straps really annoy me I bought this helmet on sale so I didn't get to try it on first. Its a very nice helmet, light weight, comfortable and the tightening system works great. However, the slider on the sides of the straps bugged the heck out of me. They sit perpendicular to your face and flap around and hit you in the cheek when your going fast. I looked at other Giro helmets to see if any of them were different but Giro uses the same straps on all their helmets. I returned this helmet because of the straps, and it just didn't sit low enough on my head for my liking. I decided to go with a Fox helmet now which looks better IMO and sits much lower on my head. Overall, great helmet for the price, just keep in mind the straps if your considering Giro helmets.
Date published: 2014-09-30
Rated 4 out of 5 by from Love the easy adjustment in lieu of inserting pads I was looking for a new helmet after the pads on my old one got so old that they were turning to powder. (OK, I should have replaced it long before that happened, but I didn't). This is great; one turn of the little knob at the back and it cinches down on my head. This will make getting ready for a ride s-o-o-o-o much easier. Also happy that it has lots of ventilation
Date published: 2014-08-24
Rated 5 out of 5 by from Good Buy Have worn helmet in windy conditions on open trails and in deep woods on singletrack. Gives great protection and ventilation.
Date published: 2014-01-24
Rated 1 out of 5 by from Fits like a yamaka (not a good thing) For me, this helmet fit so strangely I had to return it. It was like trying to strap a thick plastic yamaka to my head. It was just okay if I was not riding my bike, but it's a bike helmet so....I wore it to work one day and it kept falling to the back. I worked with all the adjustments to try to get it to stay still. It seems like the front is sloped too much for me. If I had more of a Neanderthal-shaped forehead, it might have worked. It didn't grab my head in the right spots.
Date published: 2016-07-17
Rated 4 out of 5 by from Good at being a helmet, minor defects in padding The helmet works well with the harness/adjustment system. Plenty of room in the back for ponytail. Adjusts to fit over skullcaps for cold weather commutes. The fit-kit foam pad inserts, however, have junk adhesive, leading to some discomfort on the top of the head. Be prepared to not use the foam stick-on inserts, or to replace them with an after-market kit.
Date published: 2015-03-12
Rated 4 out of 5 by from Giro Phase - not bad for the price I got this on sale for $15 !!!! It's comfortable and very adjustable and worth at least $30. The only con is the comfort pads don't continue across your brow so expect to get sweat right down your nose and into your eyes at the worst time. Other manufacturers have figured this out and the fix is so simple, I wish Giro would wake up...
Date published: 2016-03-30
Rated 5 out of 5 by from Saved my skull today Comfortable helmet. Today it saved my skull from splitting apart on the pavement. I plan to buy a new Giro helmet to replace my current helmet, which suffered various cracks from today's collision impact.
Date published: 2016-05-19
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