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Item # GIR0138

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Item # GIR0138


The Phase doesn't cover your ears, so you can hear the shop monkeys begging you to wait for them.

The Giro Phase Bike Helmet features tons of venting to keep your melon cool during those mid-summer rides that you regret letting yourself get talked into. It's kind of nice to drop those spandex-clad über-climber bike-shop buddies that talked you into coming, though. It looks like they could have saved the $300 that they spent on their helmets for a helmet like yours that actually vents.

  • Acu-Dial fit system for a custom fit
  • 27 oversized vents keep the air flowing
  • Snap-fit 2 visor keeps sun and debris from getting into your eyes

Tech Specs

[shell] polycarbonate, EPS (foam)
Fit Adjustment:
Acu Dial 2
Recommended Use:
MTB, touring, urban, commute

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 Phase Helmet

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Here's what others have to say...

5 5

I like it

I have a very big head and this helmet fits very well. I also got a great deal on it so it couldn't be beat.

5 5

Phase Helmet

This helmet is great, my head is strangely sized and most helmets do not fit me very well (either too snug or too tight); however, this helmet is very easy to adjust (via roll wheel in the back) and is probably the best fitting helmet I have ever owned. Performance wise, I have not tested its head protection capabilities, but it feels great during hot days as there is lots of ventilation.

5 5

Giro Phase

Have only had this out on a few rides so far but it seems like a great helmet. Very light, tons of vents to keep the dome cool, easy to adjust and secure on the head. Overall good helmet and a great deal.

5 5

Great buy!

Great air flow, light, great looks, great comfortable fit and great safety rating! My helmet from now on! definitely recommend it!

4 5

Great value

  • Familiarity: I've put it through the wringer

Bought one of these from another site early this season and have over 1500 miles on it. It's light enough, vent well and even ponytail compatible. Starting to stink from summer wear, plan to replace it with another one or maybe two. Great value for the price.

5 5

Excellent Bucket

Excellent brain bucket, I think I might have the phase ii, not sure. Either way great helmet, the adjuster deal is best compared to others I think. I got burnt on the extra pad liners, not sure if it's supposed to come with them or not. I did not order it from here thought so nothing related to Huck n Roll.

I need to go back to the shop where I got it and check see about an extra set a padding.

4 5

Giro Phase

I took my new Phase (made by Bell Sports according to a sticker : ) out to a local trail park for about an hour today. It was sunny with a little bit of wind. I did not really notice it during my ride, which was great. I have not smashed it into anything yet, so I can not comment on that.

My head is about 22.5 in around so I got the medium (55-59 cm). It came with the height adjustment maxed out (in the 3rd position) and I turned the Acu Dial to about 75% closed. It is a good fit.

I did not see a side on view, so I am posting one. Too bad I was the only one around to display it : )

Giro Phase
5 5

Comfortable, worked when I needed it

Great helmet if you have a big head, adjustment is easy, just a little tricky at first to get it to stay at the size you want. I have a big head, especially the ridge on top, and it fit great. Ventilation was great too. Also did it's job when I needed it too, flew over the handlebars and nailed a rock with my head, broke the helmet, head wasn't too bad. I would buy it again.

5 5

A Helmet.....

....is really just a helmet. This one works great, but makes my head appear more mushroom-like than others. Still gave 5 stars as it does what it should.

Responded on

I remember flashing back to Mario 2 the first time I saw myself in it : )

5 5

Nice, comfortable and light helmet.

Aight, this is my first real mountain bike helmet, but I'm going to review it. I have a gigantic head, like I wear a size 7 5/8 hat, but this helmet fits me perfectly. I also was astonished by how light it is. It literally weighs less than a newspaper. And it just looks awesome. It's a great helmet, if your hesitant, don't be. It's fully worth it.

4 5

great fit and good look

tried on a number of lids at local store. most made my head look like a muffin top. retention cinch in back holds lid in place during bumps and drops where you do not want to have it cover your eyes. glad i bought it.

5 5

Dig the Giro Phase Helmet

I have a big awkward head. This is one of the few helmets I found that is adjustable and makes my odd noggin' just about bulletproof when riding. I chose this helmet over a few others because of the great coverage in the back of the head. It does weigh a little more than similarly priced helmets in this category, but a few extra grams of helmet for more coverage is a small price to pay when you fly over the handle bars.