X-Bionic Energizer MK2 base layer – review

Feature packed, science heavy and genuinely superb in practice

If you like your bike clothing to come with an insane amount of features, then you’ll weep tears of joy when you pick up any item from X-Bionic as even the socks appear to have the entire text of Infinite Jest on the packaging.

If you’re not familiar with them, X-Bionic are a Swiss/Italian company (‘Swiss engineered, crafted in Italy’) established when Professor Bodo Lambertz created the ‘X-Technology Think Tank’, the minds that came up with all the innovations here. Fifteen years later the company has collected more design awards than most people realise even exist, and have backed up their claim to have ‘redefined the world of functional clothing’. The level of research and design that goes into their products is impressive, and even the Energizer MK2 base layer here has an intimidating array of features. But while the kit might have more buzzwords than you can shake a thesaurus at, don’t knock it, it performs like nothing else

First up, X-Impact. This, basically, is compression. The claim is that the reduction in muscle vibration from the compressive clothing stabilises the muscles and helps to stave off fatigue for longer. This one comes with ‘mid’ compression, which is a skin tight fit without that crushing feeling you get with full-on compression gear. Whether or not you buy into the performance-enhancing benefits, it’s impossible to deny that the fit is fantastic, exceptionally comfortable, and the lack of movement that comes with such a snug fit is particularly important for the second major feature of the clothing.

The 3D Bionic Sphere system on the front and the back manages sweat like nothing we’ve ever used before. It also plays a role in insulation and making sure you stay warm, even when you’re recovering after a hard interval

One of the fundamental goals of all X-Bionic’s clothing is sweat management. There are a number of fancy-sounding features, one of the most prominent being the 3D Bionic Sphere System. In short, rather than totally removing all moisture, it’s designed to leave a layer of residual sweat on the skin. Small enough, in fact, that the body doesn’t register it as damp. According to X-Bionic, we can only perceive sweat once it begins to bead and roll down the body, so by trapping that thin layer of moisture and then removing excess sweat – in ‘SweatTraps’ – before it builds up, you won’t have to deal with that uncomfortable damp feeling than comes hand in hand with riding hard. These SweatTraps are under the arms, too, and go to work removing sweat there. The Energizer also doubles up as an insulating layer, helping to cool you by removing excess sweat while you’re working hard, and trapping warm air while you’re recovering so you don’t cool down too much. On the new kit, they’ve increased the size of the Sphere System panels by 50 per cent, meaning even more effective sweat reduction and temperature regulation.

If you’re wondering what the different coloured sections on the elbows are, they’re yet another feature, this one being called ExpansionRibs. This is another insulation feature, and X-Bionic say that the ribbed elbows keep heat in better than conventional sleeves, as well as expanding and contracting with arm movement, rather than being pulled tight and loosening. The ribs also store heat, which isn’t lost as you move your arms around, helping to keep your arms warm.

The ribbed sections on the elbows allow the Energizer to move with you, unlike some base layers which are tight and loose depending in what position you’re holding your arms. The ribs also trap heat, keeping you warm.

But how well do these features work? Well, it’s very difficult to quantify, but from a purely subjective viewpoint this is definitely the best sweat-managing base layer I’ve ever used. Not only does it do that effectively, it actually keeps you feeling dry. In multiple multi-hour rides I didn’t once have that horrible, damp, sweaty feeling no matter how hard I was working. Other fast-wicking materials reach a point where they simply can’t cope, but I haven’t been able to push this base layer past that point yet, which is really rather impressive. Using this on rides around and just below ten degrees, with only X-Bionic’s ‘The Trick’ long-sleeved jersey as an outer layer, I was very surprised how warm I managed to stay. Obviously it depends on what you have as outer layers, but I’d be happy using this all through winter as, even outside of the thermal qualities, the way it keeps you dry is worth the price alone.

With it being such tech-heavy clothing the price of X-Bionic’s kit, as you may have guessed, tends to fall at the upper end of the spectrum. In fact, looking through their kit is an interesting mental illusion. You’ll see a £200 set of bib tights here, a £150 long-sleeve jersey there and when you see this base layer, at £67, you might think that it’s a bargain. But if you step back for a moment and take a deep breath, you’ll realise that its sixty-seven pounds for a base layer. It’s not cheap kit. If you’re looking for a benchmark, X-Bionic’s kit comes in at a very similar price to Rapha albeit with a heavy focus on technical features and, on the flip side, styling that isn’t quite up to the high standards of their British counterparts.

The whole fit is very impressive and the compressive nature of the material makes it extremely comfortable with no extraneous movement

Speaking of style, it’s the look that’ll probably prove the most divisive part of X-Bionic’s kit. The great thing with the base layer is that it’s almost always underneath, so it doesn’t really matter, but the outer layers have a similar aesthetic and one that – especially in the case of the bib tights – may well polarise opinion. And that might be part of the trouble X-Bionic have when trying to sell their kit. Although it works superbly well, if you’re dropping serious money on kit there’s a stylistic expectation as well as a functional one and that might be the one area in which it falls down (though styling is subjective – ed.)


It’s easy to write off a lot of X-Bionic’s tech as marketing nonsense until you’ve tried the clothing. But once you’ve ridden in it, you’ll realise it’s legit. The Energizer MK2 –despite its, erm, quirky name – is honestly the best base layer I’ve ever used, and something that I’ll be happy to ride in all through the autumn and winter. If you don’t fancy the long sleeves, there’s a short sleeved version as well, and also a sleeveless ‘light’ version for when it’s hot.


– Keeps you amazingly dry and manages sweat very impressively
– Regulates body temperature very well
– Excellent fit and compressive qualities mean it’s highly comfortable


– Doesn’t come cheap

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