Sharing loads of safety technology with Giro’s flagship Manifest helmet, this Merit Spherical lid saves you £50 by omitting a few features. Like me, you can probably live without a bulkier, magnetic Fidlock chinstrap clasp anyway, but there are also differences in the shell construction and the way the ‘Spherical’ layers are structured that allow for this cost saving too.

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Inner and outer layers rotate and can float against each other

The Merit still uses Giro’s sophisticated multi-layer construction (developed with MIPS), where two separate helmet sections rotate independently of each other. Like a ball and socket joint, an inner and outer shell are connected via small elastomers, with the outer piece able to twist and slide separately to the part in contact with your skull. The two sections use foam liners of different densities too, with EPS in the outer zone and a slower-rebounding EPP in the inner one, to better absorb impacts of different velocities.

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The design means one layer (held in place by Giro’s sorted retention system) grips the top of your head, and the outer shell of the helmet is held in place by the chin straps. The set up eliminates the sometimes clammy and hard edges of a traditional MIPS plastic slip-plane liner (that can also impact on cooling and airflow), but still allows energy absorption from glancing impacts to help prevent damage to the brain.

Giro’s Spherical technology uses a MIPS-based design to redirect impact forces and protect the head

While both lids share the excellent, height-adjustable, Roc Loc tensioning dial headband with its rubberised foam padding, Giro’s pricier Manifest has a separate upper outer shell. This is able to rotate over the lower portion above the ears, rather than the concentric layers. It is made possible by that lid’s ‘Aura’ reinforcing arch, which is a polycarbonate band reinforcing the top of the helmet. Giro can then use massive vent holes on top of the crown to pump air in, rather than relying entirely on an in-moulded outer shell for structural integrity like most lids.

Omitting this piece of the puzzle means the Merit’s lengthways vents are much smaller on the top, and its air ports are also less gaping all over. Ventilation is still on par with most rivals though and there are also effective dual vent slits on the forehead (that feed through both layers of the Spherical design) to channel cooling air onto the brow.

The Merit Spherical helmet uses a regular strap buckle rather than a magnetic closure

Giro’s layered set up doesn’t creak like some MIPS lids can, and the Roc Loc cradle wraps the entire circumference of your head and combines with an excellent interior shape and pad placement to keep the Merit super stable when riding. Air flow is pretty good, but this lid isn’t the absolute coolest on boiling days, and while the thinner Ionic+ pads are very comfy and grip your head well, they don’t mop up and hold onto as much perspiration as thicker linings if you’re a heavy sweater.

The Merit is also not as deep-dished as lids such as the Troy Lee A3, if you have a longer skull and want a lid that sits lower at the ears and forehead. If you need to run the chinstrap short, it can niggle against the side of the jawline, rather than sitting centralised directly above the throat.