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The Giro Aries Spherical combines both a physical and mental edge to create a unique advantage among the best road bike helmets.

It’s a comfortable, well-ventilated, well-made helmet with conventional and innovative elements. Together they give me the sense that I’m riding a cooler, lighter and safer helmet, even if there’s little if any, meaningful performance difference between the Giro Aries and its top-of-the-line road bike helmet competitors.


While straightforward, the Giro Aries uses a full complement of proven adjustment mechanisms that fit my head shape easily and well and that I could envision would do likewise for those with a rounder or more oval head than mine.

There is about 40mm of width adjustment in its plastic, sturdy circumference strap at the back of your head. That allows me to better align the strap’s shape to the contour of my own noggin even before I start to dial it in.

Many helmet brands have done away with this width adjustment. Instead, some use a thinner, more pliable circumference strap that easily adapts to your head shape (Trek). Others use a strap of similar material and strength as the one in the Giro Aries inside a shell that is more aligned with so-called “intermediate oval” head shapes at the middle of the bell curve (Specialized) or favoring western (oval, intermediate-oval) or Asian (round) shaped heads.

Giro Aries Spherical

The Aries width and height adjustments and clearance between the front strap and shell combine for an optimum fit for your head and sunglasses and a comfortable sense that the shell is lighter than it actually is.

The Aries uses a small-diameter Giro branded dial to tighten or loosen the circumference strap. The dial, width adjustment, and a simple, sturdy, snap-in height adjustment with three options about 5mm apart are all cleanly integrated into the rear cradle.

I found the height adjustment key to bringing the front brow of the helmet up to allow for my largest sunglasses.

The Giro Aries Spherical straps also seem to draw on old-school design. They are anchored well inside the shell, come together under your ears with an up/down, forward/back clip, are made of a pliable material that lays comfortably against your face and neck that has a Goldilocks “just-right” length and connects with a basic clip under your chin.

File this under “it just works.” It actually works quite well.


A 1-inch, 30-millimeter tall, quite comfortable, and sweat-absorbing pad with open slots about halfway up sits against your forehead. It’s attached to the circumference strap, which sits about 3/8″ or 5mm from the shell.

With that pad design, the various fit adjustments I described earlier, and the circumference strap all dialed in, I don’t feel the presence of the helmet’s shell the way I do with other helmets. I feel the forehead pad and the one sitting at the top center of my head, but I don’t feel the shell.

It was a strange feeling at first, almost as if my helmet wasn’t connected to the pads or if I hadn’t adjusted it tight enough. (I had.) But I got used to it after a couple of rides, and I was left with the sensation that the helmet was much lighter than it was.

In fact, the Large size, CPSC versions of the Giro Aries (316 grams actual) and its leading competitors, the Trek Velocis (306 grams actual) and Specialized S-Works Prevail 3 (320 grams claimed), essentially weigh the same. It’s just that the Aries feels lighter. So that’s one of the mental advantages I mentioned at the top that favors this helmet.

Physically, the Giro Aries’ shell has large, front-to-back vent cutouts across the top of the helmet. Those line up with good-sized rear vents to exhaust the air. These vents are so large that if my hair were thinning, I’d definitely be working sunscreen into my scalp on sunny days.

On the warmest and most humid days, both on hot paved roads and off-road at slower gravel riding speeds, the Giro Aries Spherical vented my head quite well. And the forehead pad absorbed any sweat. In regular summer and spring weather, I was cool enough in the Aries that I just never thought about venting or where the sweat was going.


While all of the top road bike helmets get good ratings these days in the Virginia Tech Helmet Ratings, the Giro Aries Spherical ranked #1 among 115 road, MTB, urban, and multi-discipline helmet models that received their best, five-star rating.

That’s another mental advantage for the Aries.

But Aries doesn’t use the plastic sliding layer inside the helmet shell that you see in many MIPS helmets. Instead, it has a shell within a shell design where one moves across the other like a ball and socket. This gives you a slip plane – the top shell moves independently of the bottom upon impact – but in a different way than five-star helmets that don’t score quite as well.

It is “powered by MIPS,” and the MIPS logo is displayed on the helmet. I assume this means it is one of a growing range of MIPS or MIPS-approved designs.

Having taken a fall wearing the Giro Aries Spherical helmet on a gravel ride, I can personally attest that this design worked to keep my head from concussing. If only Giro or MIPS could work some kind of ball and socket design into a jersey that could have avoided the sore ribs I’m still recovering from as I write this review…

The same Spherical design is also used in Giro’s aero road Eclipse helmet and standard Aether model. While also getting five-star ratings, the Eclipse ranks #45 on the list while the Aether comes in at #83. Go figure.

Unlike the Aries, the shell within a shell design in the Eclipse (review upcoming) feels more like an extra shell layer. While still providing enough airflow, the upper one partially covers the vents of the lower one, likely to provide better aerodynamics.


Beyond the fit, comfort, and safety functionality I’ve gone through above, I will tell you that the Giro Aries plays very nicely with all sorts of sunglass friends, from modestly sized to goggle-sized ones. Properly adjusting the helmet height makes room for tall sunglasses and brings the brow down to reduce the gap between the tops of smaller ones.

You can also easily and securely dock sunglasses of various sizes both right-side up and upside down.

The Aries also looks and feels very well made. While not flashy, I really like the attention they’ve given to the straps and how they’ve integrated the ball and socket shell design into the helmet with clear plastic cross struts that you wouldn’t notice without looking closely.

On the form side of things, the Giro Aries Spherical has a traditional helmet shape that looks clean. Along with basic black and white options, the helmet comes in black and red, black and green, sky blue, and turquoise, all with matte finishes.

You can order it for US$300, £220, €280 using these links to Competitive CyclistBTD (BikeTiresDirect)Performance BicycleSigma Sports, and BikeInn, all stores I’ve vetted and recommended for their competitive prices, high independently verified customer satisfaction ratings and good, enthusiast-level product selection. 

Compare the Giro Aries Spherical to other top road cycling helmets for road and gravel.

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  • Hi Steve, thanks for the great article. I bought one of these helmets and wasn’t sure how to adjust the vertical fit. The Giro website suggests that the vertical fit can be adjusted just by sliding the Roc Loc 5 fit system with the helmet on, but I couldn’t get this to work. It looks to me as though the adjustment fitting has to be pulled out of one position and pushed into another, is this correct?

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