Giro Merit Spherical Dirt Helmet Review

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The Giro Merit Spherical Dirt is one of the newest additions to the brand’s ever-expanding helmet range. Designed as a do-it-all trail riding helmet, the Merit’s trump card is the inclusion of something called ‘MIPS Spherical’ for added crash protection.

  • Brand: Giro
  • Product: Merit Spherical Dirt
  • Price: £189.99
  • FromGiro UK
  • Review by: Ross for 4 months
Giro Merit Spherical Dirt

Constructed from an in-mold polycarbonate shell with EPS liner, the Giro Merit Spherical Dirt features a full lower ‘Hardbody’ coverage. This basically means there is no exposed EPS on the bottom of the outer shell of the helmet, thus giving extra protection and helping to stop things getting damaged in transit and storage etc.

The Merit Spherical Dirt also benefits from what Giro calls ‘Progressive Layering’. This is the use of two different materials to help manage the energy of an impact. One layer is EPS, which is perfect for high speed crashes, while the other layer is a lower density EPP foam. The EPP foam has rebound characteristics that deal with “more common, low speed impacts”.

While MIPS has become a common site on everything from trail to full-face DH helmets, MIPS Spherical isn’t as widely seen yet. Where MIPS uses an internal ‘slip liner’ to protect from rotational forces, Spherical takes it one step further and is in effect two helmets in one, connected to each other by elastomers over a slip liner. Think of a ball and socket joint, and you get the idea. 

The idea is that the outer layer is designed to rotate around the inner liner during a crash, helping to re-direct forces away from the brain. An added bonus is that there are no hard plastic surfaces or slip planes in direct contact with your head, increasing comfort.

MIPS Spherical in action

While protection is paramount with a helmet, it also helps if it breathes well. The Merit Spherical Dirt uses a combination of 15 big vents, and Giro’s proprietary Wind Tunnel ventilation technology to keep things cool when you’re working hard. Wind Tunnel ventilation is a series of internal exhaust channels that are designed to funnel fresh air from the vents and over the rider’s head, getting rid of hot, stale air and replacing it with cool freshness. 

Everything is kept in place using Giro’s tried and tested Roc Loc Air Fit system. This is like Giro’s Roc Loc 5 retention system that offers a BOA like tightening system and fore/aft adjustment with just one hand, but it also incorporates their Air Fit system which suspends the helmet slightly off the top of the skull enabling more airflow and cooling than a standard system.

Up front you’ll also find an adjustable screw in visor for keeping low sun out of your eyes. All this tech and protection comes at a cost of £189.99.


My head measures around 58/59cm which puts me at the top of the sizing for the size M, but that’s the helmet size I always wear, and the one I went for with the Merit Spherical Dirt. The size is actually spot on and there’s plenty of adjustment for getting it fitted right and tightening things up if needed, and it certainly doesn’t feel small.

I’ve also got a more oval than properly round head and Giro helmets always tend to fit my head shape well, and the Merit is no different. With some brands that offer a rounder shape, it can feel as though the helmets sit a bit ‘wide’ across my temples and above my ears, leaving a gap, but not the Merit which offers a good, snug fit with no hotspots.


I really like the Merit. Not only does it look good but it fits me well. The pads are comfortable and I’ve had no issues with anything rubbing, or encountered any hotspots, despite wearing it on some, long, hot days out.The RocLoc retention is simple and easy to use and lets you easily micro-adjust the fit, whether wearing gloves or not. And when used in anger, it stays put, with no movement or wobbling around.

Considering the amount of tech involved in the Giro Merit Spherical, it still manages to post a more than respectable weight, coming in at 368g on my trusty kitchen scales (to put that in perspective, the Smith Engage MIPS coms in just 10g lighter at 358g and my Fox Speedframe Pro weighs in at 390g) and along with the sorted fit, that light weight helps make it genuinely ‘fit and forget’ comfortable. 

The big vents and internal channelling do a good job of keeping air flowing, helping to keep you cool when working hard and really let air flow through when descending. Even during the hot summer weather we had (sigh) I never found the Merit to be overly hot and it remained cool and comfortable.

I’m quite picky when it comes visor position and really don’t like having it in my vision when I’m descending, and while the visor on Merit doesn’t have a huge amount of movement (you’ll struggle to get goggles under there if that’s your bag) there’s more than enough to get it out of view, and it also stays where you put it.

I’ve used a few different pairs of glasses while testing the Merit, from Sweet Protection, Madison and Smith, and they’ve all fitted well, with the arms working well with the retention system.  The peak on the Merit is also designed to store your glasses under but I found I preferred to poke the arms through the rear vents to store them when I had to take them off. 

Fortunately, I can’t comment on the full on protection that the Merit Spherical offers as I’ve managed to not properly bin it for a while. But, given that I’ve crashed in plenty of other standard MIPS helmets and survived, I’m happy that the protection will do what it needs to. 


The Giro Merit Spherical Dirt is comfortable, looks good and has plenty of safety tech. It’s not the cheapest helmet out there but then you only get one head. If you’re looking for a good looking open face helmet, with leading edge head protection, then the Merit should be top of your list.

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Review Info

Brand: Giro
Product: Merit Spherical
From: Giro UK
Price: £189.99
Tested: by Ross Demain for 4 months
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Ross Demain

Ad Sales Manager

Ross pairs his childlike excitement for bikes with a complete disregard for the wellbeing of his ribs, or his rims. Best known for riding cheeky trails, his time is also spent trail building in his local woods, drinking beer, eating pies and entertaining his two children.

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