Norwegian brand Sweet Protection’s new Arbitrator full face is really streamlined at the sides, angular and futuristic-looking. It’s a two-piece convertible lid that has a unique fixing system pairing the open face portion with a full carbon chinguard.

>>> Buyer’s guide to lightweight full-face and convertible helmets

Sweet’s raft of safety features include low-density EPS foam inside (that claims better impact absorption that denser polystyrene) and also uses raised ‘bridges’ and sunken ‘channels’ to help soak up any smashes if you get too wild. A four-piece shell uses variable densities of Polycarbonate, and also hides a Zytel nylon ‘skeletal’ re-enforcing framework inside. The removable chinbar is pre-preg carbon fibre to save weight and resist heavy impacts. And all this added together yields a full DH-certified protection rating as a full face.

The Arbitrator also packs the industry-leading MIPS system with its low-friction plastic liner. Two sets of pad thickness on top of this are included, and the tensioning headband cinches all the way round the head for more even pressure distribution. These pads are really silky against skin, well positioned and especially comfy at the rear on the fit-tuning plastic dial that can also adjust the helmet’s dish.

Venting is plentiful and most effective above the ears where triangulated ports funnel air over arteries to cool blood at the temples. Testing in Italy at 30-degrees, cooling and ventilation was excellent, with good sweat absorption and cooling, so it never gets overly steamy inside.

The Arbitrator is formed from distinct upper and lower halves, rather than front and rear segments, so the way the carbon chinguard attaches is unique. The lower carbon piece overlaps the ‘open face’ portion with carbon tabs that slot inside it. The pair lock and unlock with a single rear compression lever that’s reassuringly chunky, and this locks via a small tab for extra security, so can’t get accidentally knocked open.

This design means both parts have dedicated straps. DH-mode uses a much beefier, padded ratchet system chinstrap that’s very comfy, and open face mode a lighter plastic clasp. A significant drawback to this, however, is the trail helmet’s chinstrap needs folding and stashing in internal rubber pouches before reattaching the chinguard. It’s essential to remove the lid to do this, making it slower than others to convert.