Leatt MTB 4.0 Enduro V21 Convertible helmet ticks plenty of boxes by being pretty lightweight, packing a rotational impact protection system (Leatt’s 360° Turbine Technology) and also different polystyrene densities for superior energy absorption in a crash. The turbines are the little squidgy wheels inside that can twist if the helmet takes a glancing blow in a similar way to how a MIPS liner slides across the scalp in the event of an angular impact. An adjustable visor, fast-fastening magnetic Fidlock chinstrap clasp and plenty of vents pack in the features, plus a well-dialled, angular and low-profile shape sees it sit close to the skull and look great in both full or open-face modes.

Leatt MTB 4.0: do-it-all helmet that has you covered for both trail and downhill runs

Ventilation is excellent – even in summer, the V21 never cooked my noggin like a boiling hot full-face can, and on uplift days I found myself often keeping it on in the van; something I never do with a ‘proper’ mountain bike full face helmet. Cooling might be aided by how there aren’t a ton of dense or cushy pads inside, but the well-shaped interior still feels comfy enough and fits my head without any hot spots or annoying jiggle or wobble when riding, so long as I cinched the rear retention dial reasonably tight.

In terms of open-face performance, you’d be hard-pressed to notice the top half isn’t a ‘specific’ trail helmet as it’s as light, stable and comfortable as top-tier half-shells from other leading brands. This isn’t automatically the case with some of the wonky, top-heavy and hard-to-convert enduro helmets I’ve tested for mbr over the years.

Just about the only minor complaint is that the MTB 4.0 must sit marginally lower than some at the brow, as certain brands of goggles are pushed slightly down the bridge of the nose. And, as this is an expensive bit of kit, a purchasing consideration might be if you already own a nice-open face lid, considering something like the iXS Trigger (a fixed rather than convertible ‘enduro’ full-face minus the rotational protection) that’s noticeably lighter at just over 600g and a chunk less cash.

At £280, this new Leatt MTB 4.0 Enduro V21 convertible helmet is definitely at the premium end of the price scale, but it’s the best convertible helmet I’ve used to date, with a rock-solid chin bar, the reassurance of a DH rating and an open-face mode that’s good enough to be your everyday helmet – that means it’s truly two products in one, which takes considerable sting out of the cost.