The Bike List

X-bionic XQ-1 Arm & PK-1 Leg warmers (£40 & £50)

Tested by Jon Adams, tester for The Bike List

Swiss company X-Bionic are renowned for making highly technical underwear and bike-specific clothing, and the Energy Accumulators (their name for arm and leg warmers) fit perfectly into the range and convert short-sleeved tops and shorts into long-sleeved jerseys and full-length tights.

Like other X-Bionic clothing, the warmers have lots of different patterns and weaves, and when positioned correctly, these fit over your joints and muscles to give insulation when it’s cold, cooling when it’s hot, and a little bit of compression to stop the muscles wasting energy by bouncing around. For more on this side of things, have a read of our bib shorts review where we go into greater detail on the science side of X-Bionic’s kit.

The first thing you notice about the arm and leg warmers is how comfortable they are. The fabric hugs your limbs without feeling tight – a bit like a gentle support bandage – and though they’re thicker than Lycra-based warmers, they’re not restrictive in any way when it comes to moving. The warmers aren’t fully windproof, but the weave is tight enough to keep most of it at bay, and over the elbows and knees, the fabric concertinas back and forth in a ribbed pattern. This extra fabric allows you to fully extend or contract the joints without losing any of the insulation around it, and also serves as an effective ‘hinge’ so you get complete freedom of movement and the same warmth whether your knees and elbows are fully bent or locked in-line.

Even around the top of the thighs the leg warmers don’t feel tight – the ribbed and elasticated design simply hugs your legs and keeps them in place without the need for any silicon grippers. It’s the same story with the arm warmers – there’s no silicon band or cutting in of the fabric to keep them in place – you simply pull them up to where you want them and leave them be.

The arms and legs are specific to each limb, so you have to get the left one on your left leg and the right one on the right. The warmers are labeled inside the top band to assist with this, but it’s a bit subtle if you’re in a hurry, so something a bit more obvious would be nice. In both cases, “TOP L” is printed into the fabric, so you know which way up they go and which limb they go on.

In the same place on the Right garments are the washing instructions, but just remember 40° synthetic and the job’s done. On the washing side, these things bounce back like new no matter how many 40 degree cycles they take on in the machine. We’ve hammered them through summer and winter for a full six months and countless wash-wear cycles, and they look and feel just like they did when we first opened the box.

In use, we found that the legwarmers extended the working range of a pair of X-Bionic bib shorts down to just above the freezing point. Considering the same shorts were equally comfortable in the summer at 28°C, you begin to see how effective all those different weaves and patterns are at keeping you cool or keeping you warm. The arms aren’t quite as useful, simply because it’s a bit impractical in the winter to wear a short-sleeved shirt and arm warmers, and then layer up with more over the top. They’re great from spring to autumn use though, and though at £40 they’re a bit more expensive than most brands, the comfort, insulation and ease of fitting and removal makes them worthwhile.

On top of that, the wet weather performance makes them a serious contender for commuters and tourers, too. Though they hold onto some sweat to provide a cooling film of water next to your skin, they don’t really wet out beyond that point, so even in fairly persistent rain, you just get the same sort of damp feeling you’d experience on a hot day. This is true of X-Bionic’s shorts too, but wearing the legwarmers with a brand that does wet out won’t be so successful in the rain.

The only real downsides to these Energy Accumulators is the pack size and the lack of retro-reflective flashes. Because of the wads and waffles in the design, they’re heavier and more bulky than Lycra or Windstopper warmers, and this tends to see them being left at home for those ‘just in case’ rides when you’re starting out in shorts but think it might get chillier at some stage. For the days when you know you’re going to need them though (windy, wet or sub 10°C), they’re the ideal extension to shorts and short sleeves. The complete absence of any retro-reflectives is a bit of an oversight, and we’d like to see some added to the design to aid visibility for night riders.

Overall, X-Bionic’s arm and leg warmers are excellent and a great intro to the brand for those nervous of splashing out on more expensive items like bibshorts or jerseys. The legwarmers will see more use than the arms, so that’s the starting point to go for, but the arms will be the natural addition if you buy into the whole system.

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X-Bionic says:

Scientists have discovered that endurance athletes use up to 97% of their energy just regulating their own body temperature.
This means; keeping cool improves performance. Sweating is mankind's own natural and effective system for cooling down. Reduced muscle vibration with increased compression and support for muscles and joints. Conceived to meet the requirements of cyclists and to optimise movement while stimulating blood circulation.

 Legs are at high risk of injury when they are cold. X-BIONIC Leg PK-1 Energy Accumulator insulate systematically, because legs lose their heat differently in specific areas. When the knee bends, conventional leg warmers lose insulation as the fabric is stretched. Not with these. Bending the knee, a system of chambers and channels unfolds, like an accordion. The ExpansionKnee inproves its ability to insulate rather than thinning out. At the same time, X-BIONIC Partial Compression minimises muscle vibration and provides welcome support for muscles and joints. This ensures that the legs remain temperature-controlled and retain their power - even on icy cold days.

X-BIONIC Partial Compression: Conventional full-surface compression crushes the blood vessels, preventing adequate blood supply to the capillaries, so that the blood is not cooled by perspiration. X-BIONIC Partial Compression leaves the capillaries open and does not crush them. Your body’s natural cooling system is supported, enabling you to enhance your performance.

X-Impact Technology for improved nutrient supply: These rather special leg warmers have a stabilising influence on the blood vessels. By supporting these vessels, the circulatory system is unburdened and oxygen and nutrient provision is improved. Through improved return flow of the venous blood to the heart, muscles and organs have quicker access to performance-enhancing oxygen and nutrients.

X-Impact Technology for reduced muscle vibration: By stabilising your muscles and reducing vibrations, you’ll conserve your energy reserves and optimise your performance. This is achieved without restricting your freedom of movement.

ExpansionKnee: This clever system protects and insulates the knee. The high-tech knitted structure folds, rather like an accordion, ensuring that penetrating cold doesn’t cool the knee. Even when sharply bent, the insulating property is maintained through warm air stored in the inner chambers. The flexibility of the ExpansionRibs and the elasticity of the yarn allow a frictionless freedom of movement.

AirConditioning Spot: The knee hollow perspires quickly and heavily. Here, a fine, circular knitted fabric has been incorporated to quickly dissipate excess sweat in order to avoid the risk of chilling.

AirConditioning Channel: This ventilation system continuously carries away excess heat and moisture, ensuring a comfortable ride or run.

Self-Adjusting Cuff: Fits any size of leg without constricting or slipping.

SkinNODOR: This specially developed yarn inhibits the growth of bacteria using nano-technology, thus reducing any unpleasant odour.


• 78% SkinNODOR
• 13% Polyamide
• 6% Elastane
• 3% Mythlan
• Sizes: S/M, L/XL, XXL

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At a glance

Verdict Comfortable and effective insulation layers that boost the performance of shorts and tops without making you overheat.