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Giro Insurgent Spherical helmet review

The Insurgent Spherical really packs a punch when it comes to safety tech

Our rating 
4.5 out of 5 star rating 4.5
GBP £350.00 RRP | USD $350.00 | EUR €390.00
Giro Insurgent Spherical helmet - full face mtb helmet

Our review

A comfortable and well-priced full-face helmet that comes with more safety features than you'd expect for the cost
Pros: Packed with the latest safety tech; very comfortable with secure fit; well-considered features; decent weight; great price
Cons: Padding not as plush as some; only three sizes
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Giro’s Insurgent Spherical full-face helmet is aimed at downhill and enduro riders or racers.


It’s packed to the brim with a host of safety tech designed to keep your head better protected in a crash.

Giro Insurgent Spherical helmet construction

The Insurgent Spherical helmet uses a fibreglass outer shell, rather than a more expensive – and potentially lighter – carbon-fibre equivalent.

There are three sizes – XS/S, M/L and XL/XXL – which isn’t as many as Giro’s direct competition, but it does supply additional padding to help tailor the fit.

Safety first

The ‘Spherical’ in the helmet’s name refers to the safety tech. Foam liners move over each other to help dissipate impact force in the event of a crash.
Andy Lloyd / Our Media

Inside the shell are two foam liners of different densities, connected via small elastomers – one sits against the shell of the helmet and the other sits on top of your head.

In the event of a crash, these liners work a little like a ball and socket joint, with the outer liner rotating over the inner liner to redirect some of the impact force.

This is the Spherical MIPS technology and features on a whole host of Giro lids, including the Manifest, Merit, Tyrant, Eclipse and Helios.

The outer liner is made from EPS foam, which Giro claims is well suited to high-speed crashes. The inner liner is made from EPP foam, which is better suited to slow-speed impacts. This, according to Giro, is known as ‘progressive layering’.

While I’ve seen Spherical safety tech before, Giro’s new Flex Gasket is new to me. At the rim of the helmet, you will spot the 70mm sections of this softer material on either side. The idea is that it will compress if it comes into contact with your collarbones and help reduce the force of the impact.

This is similar to Collar Bone Suspension System as seen on the Troy Lee Designs D4 helmet.

A D-ring closure with padded strap is used to securely tighten the Insurgent onto your head. There’s also EPP foam lining the chin bar.

The adjustable peak is fixed in place with tool-free, breakaway bolts and includes a neat little extra – a tab in the centre of the peak. This helps anchor the peak in place and control how it’s adjusted.

The peak also includes an additional mounting hole for GoPro/action cameras.

Keeping you cool

Brow ports across the front of the Insurgent help draw air in to cool you down.
Andy Lloyd / Our Media

Because the Insurgent is designed for enduro riders and racers (you may have seen Bex Baraona and Richie Rude wearing these in the Enduro World Series) as well as downhillers, Giro needed to ensure it considered ventilation and weight during the design process.

My M/L sample weighed in at a very competitive 1,040g. That’s impressive considering just how much safety tech is included, plus the fact it uses a fibreglass rather than a carbon outer shell.

20 vents around the Insurgent Spherical will help keep your head cool. There is also internal channelling that runs throughout the inside of the inner foam liner.

Despite the lattice-like covering at the front of the chinbar, the two slit-vents at the front are wide and should help with air intake when you’re really gasping.

The Ionic+ padding is anti-microbial and easy to remove when you need to give the lid a wash.

Giro Insurgent Spherical helmet performance

Exhaust ports work alongside internal channelling and front vents to help draw air across the top of the head.
Andy Lloyd / Our Media

To gauge how the helmet felt, I wore it when riding downhill and also on the climbs. This included during weather conditions ranging from mild, early autumnal days through to bitter, rainy days where the mercury sat close to zero.

To get the fit just right, switching to the fatter 30mm cheek pads helped the Insurgent Spherical properly hug my head.

This isn’t something I’ve had to do when wearing the likes of the Troy Lee Designs D4 or Fox’s Rampage Pro Carbon, which have a wider range of sizes.

Giro’s approach of supplying an alternative pad kit gets around this issue, though. And, while the end result might not feel quite as slick, it’s still impressive nonetheless.

With chunkier cheek pads in place, I had no issues with the helmet shifting about or dropping down while riding, even on really rough trails.

The padding is comfortable, and the shape and sizing of the M/L Insurgent Spherical (designed to fit heads with a 55-59cm circumference) worked well for my head.

I’d argue it’s not the plushest padding I’ve tried, but it’s still incredibly comfy when riding.

While the D-ring closure takes a little longer to cinch compared to a standard clip or magnetic FidLock clasp, I prefer how secure it feels and how easy it is to adjust the strap’s tension for a close fit.

The D-ring closure is a classic and works well. A popper at the end of the strap helps keep things tidy once it’s done up.
Andy Lloyd / Our Media

A popper at the end of the strap helps tidy any excess strap once you’ve done it up.

Considering the amount of coverage on offer, the venting is reasonable – but don’t expect it to be as open and breezy as lighter full-face or convertible enduro-style helmets.

That said, with the Insurgent Spherical in place even on milder autumnal days, I managed to do a fair amount of pedalling without drowning in sweat, even on the climbs.

When working really hard, sucking air in and bellowing it out through the gaps in the chinbar doesn’t feel restrictive or limiting. Also, the sound of your breathing doesn’t reverberate around the helmet as it can with other lids.

The field of view is unrestricted, too, with the peak offering enough adjustment to be shoved out of the way so you can’t see it while riding. And the Smith Squad XL goggles I paired with the helmet fitted perfectly.

How does the Giro Insurgent Spherical helmet compare?

The Troy Lee Designs D4 helmet is a more expensive lid than the Spherical.

In recent years, I’ve worn the Troy Lee Designs D4 full-face helmet more than any other, so I will use this as my comparison with the Insurgent Spherical.

At £500, the D4 costs more than the Insurgent Spherical. Why? Well, the carbon shell accounts for some of that, along with the fact that TLD offers the D4 in six different sizes and, like the Insurgent Spherical, it’s packed full of safety tech.

But, if any of the three Giro sizes work for you and you’re not bothered about the carbon factor, the Insurgent Spherical is close competition (if not edging ahead) when it comes to safety tech.

At 960g (medium), the D4 is lighter – but we’re talking just 80g. And, in terms of venting, it’s pretty close, although the D4 has the very slight edge here.

For me, the D4 offers marginally plusher padding and a slightly better fit overall, but I’m more than comfortable in the Insurgent Spherical and feel just as safe. The fact it’s £150 cheaper is a plus.

Giro Insurgent Spherical helmet bottom line

Below the Giro logo, you’ll spot the soft ‘Flex Gasket’ material. This is designed to squish a bit should the helmet come into contact with your collarbone, lessening the impact force.
Andy Lloyd / Our Media

The Giro Insurgent Spherical full-face helmet is a great option for the cash, packing in plenty of safety features and some great rider-friendly touches that make a difference on the trail.

It may not come in as many sizes as the current market leader but, if you try the padding supplied, you can tailor the fit relatively easily.


This leaves you with a lid that fits well and feels really comfortable for prolonged stints on the hill. The weight is competitive and the venting is good, too.

Product Specifications


Price EUR €390.00GBP £350.00USD $350.00
Weight 1,040g (M/L)
Brand Giro


Features Sizes: XS/S, M/L, XL/XXL
Colours: Matte Harbour Blue; Matte Black/Gloss Black; Matte Black/Ano Lime; Matte White/Ano Blue
Helmet type Mountain bike full-face