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Giro Synthe MIPS Helmet

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Item # GIR00AA

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Item # GIR00AA


Your brain deserves the best protection.

The original Synthe was a ground-breaking helmet for Giro, combining the best of both aerodynamics and ventilation to create a lightweight helmet that slices through the air while keeping riders cool and comfortable. With the Giro Synthe MIPS Helmet, Giro follows the general trend in introducing the industry-leading Multi-Directional Impact Protection System (MIPS) safety technology into its top-end helmet.

The big draw with MIPS is its ability to reduce impact force and decrease concussion risk in the event of a crash. MIPS consists primarily of a strategically anchored, thin liner on the inside of the helmet that looks exceptionally simple, but serves a rather complex purpose. That little liner is designed to move independently of the helmet shell to essentially redirect impacts and reduce force on your brain compared to standard, non-MIPS helmets. If you do happen to crash, MIPS technology reduces your risk of concussion and dramatically increases your chances of walking away without a head injury.

On the outside, the Synthe retains all the awesome features that made its non-MIPS predecessor so well-loved in the peloton by cyclists like the US's own Phinney. Wind tunnel testing shows that it's more aerodynamic than the Aeon, while giant vents and Aero Mesh Panels funnel air across your dome for a massive cooling effect — a rare combination of fast and comfy.

Giro uses Featherweight Webbing straps with a Slimline buckle to hold the Synthe MIPS firmly in place without any of the pesky irritation or distractions that can plague thicker strapped helmets with bulky closure systems. The Roc Loc Air fit system features two-way fit tuning that's easily adjustable on the fly and is ponytail-compatible, making this helmet extra convenient for those of us with long hair. Giro even integrates eyewear docking ports into the Aero Mesh Panels for safe storage of your favorite sunglasses when the clouds come out to play.

Bottom line, the Giro Synthe MIPS Helmet brings together a tough-to-beat combination of wind-cutting speed, cooling temperature control, and top-line safety features to get you safely down the road.

  • An all-purpose aerodynamic road cycling helmet
  • Proven at the highest levels of cycling
  • In-Mold construction increases impact resistance
  • Adjustable fit cradle accommodates ponytails
  • Generous ventilation so "aero" doesn't mean stifling
  • An optics perch holds your glasses while you climb
  • Giro has set a new standard in understated, functional cycling design

Tech Specs

Shell Material:
In-Mold polycarbonate
Impact Foam:
25 Wind Tunnel vents, internal channeling, Aero Mesh Panels
Fit Adjustment:
Roc Loc Air
Recommended Use:
Manufacturer Warranty:
1 year



Claimed Weight

Claimed weights are provided by the vendor.

Have questions? Chat with a Gearhead

[medium] 270 g

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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Superlight, well ventilated.

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

When I first pulled this helmet out of the box, and saw almost no padding whatsoever inside and no extra padding in the box, I thought for sure that my review was going to end up being a negative one, and yet it isn't.

Giro's current top end road helmet (I'm not counting the Vanquish aero helmet), is one of the lightest and most comfortable I've ever had the opportunity to wear, because while the padding is minimal, it's perfectly situated.

A lightweight helmet is really important to me as well. I have degenerating discs in my neck, and relatively weak muscles. Because of this, any extra weight on my head can put stress on my neck muscles when trying to hold my head up in riding position. On today's inaugural ride in this helmet, I barely noticed the weight of the helmet at all.

My lack of fitness, on the other hand, I noticed right away, and while there were lots of times I was struggling on the bike, none of them were neck related. To me right now, that's worth a 5-star review.

And the added benefit of MIPS protection would bump it to a 6-star review if I had that option.

Very Nice

  • Fit: True to size
  • Size Bought: Small

The helmet was awesome in every way but was too small so I returned it. I purchased it on sale, size small (clearance?) and it's definitely worth it if you have a small head.

One of the Best!

  • Familiarity: I've put it through the wringer

Bought this helmet as a gift. Here is what they had to say about it - "One of the best helmets I have ever used. The fit is great and the ventilation is really awesome. Very comfortable even after hours in the saddle. I've been using this helmet for road rides, road races, and cx races. Love knowing I have the extra protection of MIPS."

An excellent helmet!!!

  • Fit: True to size
  • Size Bought: small

I used this helmet for a year and a half to two years and it has been exceptional. The small size fit my 21.5" head perfect and when I recently had a bike crash it kept my head safe and it did not move from it's original position at all.

Avg. ride time: 7h 28m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Synthe MIPS

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

I loved my original Synthe Titanium and rode it for several seasons. Had to replace it after a crash in the fall and decided to upgrade to the MIPS for extra safety. Fits exactly the same as the original and breathes just as well. I don’t plan to ever switch from this helmet except for future renditions. Couldn’t care less about the Aero claims, but I guess it’s a plus.

Nice Helmet

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

I couldn't decide if I wanted to put that much money in a helmet, but I am glad I did. Researched several different helmets and finally decided on the Giro Synthe MIPS. I have been wearing a Giro Atmos II and wanted to get a helmet with MIPS. It is one of the most comfortable helmets I have worn and is very easy to adjust. The helmet looks great and I could not be more pleased.

Avg. ride time: 58m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Synthe MIPS Titanium

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

Great colour. Helmet is nice and light. I also have a Foray and this fits the same. The Synthe is a beautiful helmet and has MIPS but I'd have to say the cheaper Foray is much the same as the Synthe and way better value. I had a crash with a Foray and wrote the helmet off but my head was good and the Foray didn't have MIPS. Personally I'm not so sure that MIPS is the great miracle life saver but maybe it is.

The Synthe wins

    The Synthe is simply brilliant, and I mean that literally. You could almost miss it, which is why I love it so much. The other big hitters in the high-end helmet game (Octal, Z1, Protone, Overtake) are the figurative extroverts of the cranial protection world, and for some, this is a positive, but for the vast majority of the population, your fashion taste may be called into question. "He looks like a marshmallow." The Synthe's is always going to be the safe and classy option.

    In the modern day, any helmet over $200 is going to be fantastic. They all ventilate well, they're all held to the same high safety standards, and they're all shockingly light. The Synthe differentiates itself by being delightfully straightforward. It employs the same, mind mindbogglingly simple tightening system as it's entry level siblings, instead of some contrived, bizarre systems that some of it's competitors use. (I'm looking at YOU Lazer.) One of my only gripes with this helmet is that the "sunglass garage" doesn't really work, or at least, not much better than sliding your shades into the vents.

    As far as the MIPS/non-MIPS debate in concerned, yes, this helmet is slightly heavier than the non-MIPS version. Yes, it does not ventilate as well. Yes, it will occasionally catch some hair. At the end of the day though, even a marginal safety gain is worth it when you're talking about your head, and I say that as a guy who didn't even have that may brain cells to begin with. Just go for MIPS, be stingy when it comes to bottle cages, not your brain.

    Really, you can't go wrong with the Synthe, and especially now, when they're on mega sale. Just go for it.

    If you have any questions, feel free to reach out to me directly at (final note: the Synthe pairs wonderfully with an Oakley Jawbreaker)

    Not as good a fit or feel as the Aeon

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

    I am going to buck the trend of unlimited praise for the Synthe. I mean, of course it is a nice helmet. But I got both it and the Aeon and ended up preferring and Aeon for a couple reasons. First, the fit of the Synthe is not as good for me--and fit in a helmet of this quality is enormously important. I did not find the adjustments worked for my head, which is large and not as round as the Synthe shape. The only way I could get a good fit was to tighten the Synthe to the point of unpleasant pressure. The Aeon, by contrast, is more the traditional Giro shape, a little more long fore-to-aft and narrower side-to-side. The second aspect is what my wife spotted as soon as she saw me with the helmets on-the Aeon looks better. The Synthe is round, sits very high, and is more like wearing a mushroom. The Aeon, again in the traditional style of Giro, is less round, sits closer to the head, and looks, well....faster! As for MIPS, to my mind, the jury is still out on its actual value and how to best implement the concept. In the meantime, my new Aeon is comfy and beautiful.

    Avg. ride time: 2h 29m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Light & Comfortable

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

    This helmet is perhaps the nicest and most comfortable I've ever had to wear. It is nearly infinitely adjustable, allowing me to custom fit the straps and cradle.

    Saved my brother-in-laws life!

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

    I was stoked when my brother-in-law started to get into road biking so I surprised him by buying him this helmet to help him look the part and be safe. He said it's much lighter weight and more aerodynamic than his old helmet and it doesn't even feel like he's wearing anything. I was even happier I bought it for him b/c it literally saved his life when he crashed his bike earlier this week. It's a great helmet and I bought him another one to make sure he continues to be safe!

    As advertised

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

    Helmet is indeed very light. You do forget you have it on.
    I have been wearing Giro helmets since 1992 and the tech has come a very very long way since those days.
    So far the warmest day I rode in was in the mid 80's and ventilation was good enough. I never felt it being warm. It was on rolling to flat terrain. I have not done any climbs in the heat, yet.
    The fit. It has changed slightly. I have been wearing Giro large size helmets for as long as I have owned them; however, this helmet is just a tad narrower than other Giro helmets I've owned. Enough to notice but not at all uncomfortable. I compared it back to back to my Atmos to ensure I was not crazy. And yes, it is indeed narrower.

    Lightweight + good ventilation + MIPS

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

    Accurate fit per sizing chart (medium), looks good, colors are tasty, nice strap and clasp

    Awesome Helmet

    • Familiarity: I've used it several times

    It looks good and it feels good. It seems to help prevent sweating on the brows/forehead and wick any sweat off the side. I usually have issues with helmets accumulating sweat that drips into my sunglasses – but so far, I haven't had that issue with the Synthe. I forget it's even on my head.

    Great helmet

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

    Great fit right out of the box, with very little adjustment needed. Unlike all of my other helmets, the buckle stays put, so the chin strap doesn't loosen and constantly need adjustment. Light weight, fits great. Thanks for the sale price, too!

    Avg. ride time: 8h 39m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Sweet helmet

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

    The Giro Synthe Mips is a slick helmet! As others have noted, the size adjustment fits a wide range of head shapes, it's plenty light, and also well ventilated.

    I haven't tested out the crash worthiness yes (knock on wood!), but I've left behind a long wake of broken Giro helmets that demonstrate the quality of build and protection.

    Nice Fit

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

    Everything is pretty good, it looks great, it fits good, well ventilated


    • Fit: True to size
    • Size Bought: M

    I have an odd shaped head and buying a helmet without trying it on is a real risk (yet minimized by great customer service). Luckily most of the homies are running the Synthe and for a good reason. The fit is massively adjustable due to an intelligently design ratchet system that conforms to all head types, even the [more aero] head shapes. On long rides with my previous helmet I'd end up with mass headaches as a result of how the ratchet system pulled.

    one of the best

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

    I've owned more Giro helmets than I can remember, in general they have it right. The Synthe fits very well and is comfortable even after several hours on.

    Avg. ride time: 8h 46m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    How does this fit in comparison the a medium Aeon? The Medium Aeon is a perfect fit for me - if I went to a Large, it would way too big.

    Hi Thomas,

    I would stick you in a Medium on this helmet as well.

    I think you'll find the medium in this helmet will fit just fine.