If you've seen any mountain bikers on the trail recently, you'll probably have noticed that baggy shorts are all the rage. Lycra's looking distinctly passé these days. But wait, we hear you cry, surely this is a helmet test? Yes, it is. We're drawing an analogy, and here it is. Giro's new Xen is the helmet equivalent of baggy shorts.

Allow us to elaborate. Most helmets fall into one of two categories - lightweight XCish ones and beefy freeridey ones like full-faces and all those skate-style lids. It's like having to choose between Lycra or armoured DH pants. And just as the baggy trail short bridged the legwear gap, so the Xen bridges the head protection gap. It's essentially the shape and styling of Giro's Semi jumpy lid with the vents and retention gubbinses of an E2, plus some other unique touches.

It's a lot more rounded and organic looking than many helmets, and the Semi influence shows in the depth at the back - the Xen covers more of the back of your head than we're used to. But with 17 sizable vents it shouldn't be too hot, and the Roc-Loc 4 head retention thing and all-new strap design keep it secure. New strap design? Rather than the straps emerging from inside the helmet shell and running continuously from one side to the other, the Xen's are attached directly to the shell itself. This means easier adjustment, with no pulling bits of excess strap from one side to the other. It also means that the straps are held away from the side of your head and don't get quite so sweaty. It feels a little odd at first but you get used to it, and the helmet's certainly secure although the fit's a little wider than we're used to from Giro.

As you'd expect, the Xen is noticeably heavier than the E2 but the weight manages to manifest itself as reassuring solidity rather than unnecessary heft. It's also a tad hotter. There are two culprits here - the Xen's respectably vented but it can't match the 24 air-gulping ports of the E2. And the Xen has a full-width brow pad so there's less air flowing over your forehead.

An interesting feature of the Xen that we occasionally noticed is a whistling noise when you go fast enough. We think it's the straps but we can't be sure. It's very quiet and not really distracting, though. The Xen's available in three sizes (small, medium, large) and four colours (black, blue, titanium and "Whiskey", a sort of bronzey gold colour). Oh, and there's an adjustable peak on the front, naturally.

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