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.

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.

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!

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.

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

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 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!

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.

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

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.

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.

Firstly, it is the most comfortable helmet I have ever used and I ride year round in Arizona. Secondly, I got to personally crash test this helmet at 40mph. No head truma. The whole inner web works just as advertised! So glad I was wearing this helmet. When it comes to protecting the gray matter between your ears this is helmet is worth every penny.

excellent fit,comfortable,definitely as efficient cooling as previous helmets

This is my first Synthe and my first helmet with MIPS. NOT my first Giro, tho. Giro helmets have always fit me well and this one is no exception. It seems to have a bit less wind noise than others I have owned (Atmos, Spec Piranha, original Giro with the lycra cover). This helmet seems a bit more aero, but that's a lil hard to tell, really. I've not worn this on super hot, humid days yet, so can't speak to the a/c factor. Definitely seems to be worth the money at this discounted price.

The fit on this helmet is awesome. It literally fits like a second skin.
I was a little freaked out with the lighter gauge material on the straps. However, after using the helmet for a few rides the straps just disappear. I completely forget there’s a helmet on my head. Once adjusted properly they are very comfortable.
Other people have commented that the helmet is a little warm. I don’t find that to be the case. Perhaps it’s because I use Headsweats under my helmet to keep the sun off of my scalp. The cooling seems to be about the same or better than my previous Giro Ionos helment.

I have had the MIPS and regular Synthe and they were great. I was hit by a car from behind and barrel rolled and the ambulance drive said it aill, the helmet saved your life--the nurse in the ER wanted to know the band so she could buy the same model. I was wearing the MIPS and I can't say enough good things--no concussion or head trauma. BEST HELMET.

I love the Giro Synthe. I own both MIPS and non-MIPS versions now. I can confirm that the MIPS version fits just slightly, slightly smaller than the non-MIPS version. So if you're on the fence sizing-wise, go with the larger size.

I love the aerodynamics and quietness of this helmet. If you compare the Synthe to previous top all-around road helmets (S-Prevail, Giro Aeon and before that, the Giro Ionos), helmets I rode in for years, there is no comparison. The Synthe is significantly quieter, especially when you put your head down during hammertime.

By the way... Greg van Avermat won the Olympic Road gold and 2017 Paris-Roubaix wearing... the Giro Synthe helmet.

Great helmet, still keeps the head cool. the Ionis feels a bit more comfortable. I guess a touch less comfort is a small price for the increase in safety if the bean hits something.

1 - I usually run a Small non-MIPS Synthe so ordered the same for this one, but it's too small. The MIPS mechanism really does take extra space so size up appropriately if your on the upper end of a size.
2- As mentioned in other reviews, the MIPS version does suffer on the air circulation side, so it is warmer.

All in all, not sure that the MIPS is worth it, the human scalp also offering a natural slip plane in case of a crash.