The Bike List

X-Bionic Bike Bib Tight Short £160

Tested by Jon Adams, tester for The Bike List

Every once in a while, a product comes along that actually makes you think again. You always expect manufacturers to stir up a bit of hype about their brands, but when something actually delivers in a significant way, it's really noticeable, and X-Bionic's kit is a case in point. The Swiss clothing company made its name with very techie-looking thermal underwear, and over the past few years, it has expanded into cycling-specific clothing using the same kind of clever knitting technology which uses different weaves, fabric weights and elasticity for different areas of the body.

The Bike Bib Tight Short is a very distinctive pair of bibs that looks and feels different to everything else on the market. Instead of the usual Lycra-panelled finish with breathable mesh braces, you have a textured, stretchy fleece-like fabric with all kinds of different patterns and thicknesses built in. There are ridged sections where the fabric concertinas back and forth on itself, there are cord-style ribbed sections and there are waffled patterns of varying densities. The chamois area is made of different stuff again, and from the outside, it has a neoprene-looking finish. I hasten to add that it's not neoprene, but it has that kind of texture and feel.

The whole package immediately looks very high tech, and very expensive. You won't be surprised to learn that both these are true, and with a price of £160, you need to be very serious about your shorts to invest. Before we go on to the performance and comfort offered by these bibs, though, let's take a look at the fabric technology employed, as that helps to understand where your money's going.

What the X-Bionic bibs offer can be broken down to three main things: insulation - to keep muscles warm when it's cold, body cooling - to keep your temperature down when you start to heat up, and compression - to stabilise and support the muscles. All the various weaves, knits, fabrics and panels contribute to this, but we'll run through them to explain the science.

The areas over the thighs and hamstrings and, to a lesser extent the hips and buttocks, feature insulation pads to retain heat and prevent excessive cooling in these important muscle groups. The inner thighs however, offer a zero-insulation fabric, as this area generates a lot of heat and doesn't need any help. You've probably put your hands between your legs to warm them up, and that's because it's part of the body that runs hot. So, in a nutshell, the areas that need to be kept warm are insulated, but once you get too warm (the point at which sweat starts to run) the insulation does the opposite job. To cool you down, the concertina'd and wadded parts of the garment's weave actually hold water. Instead of simply lifting perspiration off your skin and sending it through to the outside world like a regular wicking garment, the X-Bionic kit hangs onto some moisture and leaves a film of coolant (aka sweat) next to your skin. This is why you sweat in the first place - to cool down - so by keeping hold of the water, the garment is enhancing what your body is trying to do.

The third thing it offers is compression - the art of stabilising muscles so they're not wasting their energy jiggling about and bouncing around. X-Bionic call it Partial Kompression though, because if you compress a muscle too tightly, you constrict the blood vessels and reduce performance (the blood is the fuel for the muscle, so you don't want to squash the supply pipe that's carrying it).

That's more than enough theoretical stuff for now (remember, this is a pair of shorts, after all) so what happens on the bike in the real world? Well, in the summer I wore these shorts when it was 28°C and I was perfectly comfortable. I also wore them in the winter with X-Bionic legwarmers at 0°C, and they actually remained comfortable. Not quite as warm as fleecey, winter tights, but perfectly acceptable. I had more layers on my top half and head in the low temperatures, but the same shorts that were fine in the summer really did double as winter legwear when bolstered with the right legwarmers. This is the strongest indication I can give of how effective they are in performance terms - all the body-mapping, sweat-trapping, muscle compressing science stuff is fine, but you can't feel any of it happening when you're pedalling. The fact that the same garment keeps you comfortable with about 30 degrees of variation in temperature is testament to the technology doing its stuff, though, and that's something to applaud.

Next to this impressive body temperature regulation, the other thing we can assess is on-the-bike comfort. And this is another area where the shorts really stand out. They are supremely comfortable - at least as good, if not better than anything else at the premium end of the market. The ribbed, stretchy construction means they hold everything in place but nowhere do they feel remotely tight. If you want to pull on a pair of legwarmers, you can roll the legs with real ease right up to your groin, but they'll hug your quads and hamstrings snugly when you roll them back into place. It's a bit like having a luxuriously thick, stretchy crepe bandage enveloping and supporting you - it doesn't feel tight anywhere; it just feels... err ... great!

The chamois is a foam number and its construction looks rather simplistic in comparison to those of high-end brands like Assos, Gore or VauDe. The thing is though, it works perfectly in conjunction with the 'bandage-style' outer fabric, and this ensures that the pad gently 'hugs' you in all the right places, so nothing shifts about between standing and sitting positions, and you never seem to have to readjust your undercarriage - even on a long ride.

With the legwarmers, the shorts shrug off rain just fine too, making overtrousers overkill in anything short of a deluge. The legs will hold that fine film of water to keep you cool when you're sweating, but that appears to be the limit for the fabric, so even in persistent rain, you don't really seem to get any wetter than the damp feeling you'd get on a hot day.

As regards care, they seem to put up with anything. You can subject them to all sorts of abuse on the trail, then wash the hell out of them and they bounce back like new every time. Just throw them in a 40° synthetic cycle, then hang them up anywhere and they'll be ready to go in the morning.

Aside from the price, the only downside to these shorts is the lack of retro-reflective flashes. There are none at all, so night riders will need to ensure that their top half, shoes and pedals have some reflectives on. As for that price tag, the best question I can ask is whether I would be prepared to pay £160 for these? After six months of use in all weather conditions and temperatures, they still look and feel like new, and the comfort is unmatched. I don't honestly know whether they enhance performance like it says in the marketing blurb, but I do know that they'll cover a really wide range of temperatures, and they're the first pair I'll reach for when I'm off on a ride.

It'd need to be an incredibly special pair of bib shorts to make me want to fork out £160, but the X-Bionic Bib Tight Shorts offer the comfort, versatility and hard-wearing quality to do exactly that. A luxury item, of course, but quite brilliant and highly recommended if you're serious about your riding.

Buy from

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.

3D-BionicSphere®-System works from its position on the chest and the back. without the sensation of wetness or heat. no risk of over-cooling during recovery. The cooling is activated only when the body's temperature rises and sweating begins. If no sweat is present, the system serves as insulation. The 3d-bionicSphere®-System only begins to cool once you are sweating.

HeatPipe Cooling, the heatpipe Micro-System uses the sweat for additional cooling.

3D-BionicSphere®-System for the back the high metabolic rate of the cyclist and the resultant heat creates a circulation of air within the X-Bionic® Shirt itself, air which is conducted to the back section of the garment, where the 3d-bionicSphere® ventilation channels go about their task of keeping the cyclist cool and dry. Temperature and humidity regulation takes place at various levels within the system, keeping the cyclist cool.

Two-Step Front 3D-BionicSphere®-System Innerlap AirConditioningZone'™ woven mesh with zero insulation function allows air to circulate and aids cooling as soon as you start to sweat.

Loose fit leg The wide active drawstring fits to every leg size without slipping or constricting. The trousers support over the entire surface, so that no tight elastic is needed to keep the trouser leg in place.

During the event

Sweat forms a fine film of moisture on the skin. Drops are absorbed by the Sweat Traps and conducted into the Evaporation Surface Expander. The evaporation occurs in 3 ways, activated by body heat: On the skin, for cooling. In the SweatTraps, to process excess moisture In the Evaporation Surface Expander, where the excess is finally evaporated.

During recovery

Cold ambient air represents no over cooling risk factor, because the warm air inside the Inner Air Channels form an insulating cushion. During recovery, the cooling-down process is interrupted by the lack of sweat. The air in both channels serves to warm and protect, using the body's own warmth to create a body aura: an air-conditioned protective shell that wards off the influence of cold.


  • 77% SkinNODOR
  • 11% Polyamide
  • 4% Elastane
  • 8% Mythlan
  • Colours: Black/Anthracite

Find out more:

At a glance

Verdict Expensive but supremely comfortable and unique bib shorts that keep you cool in warm weather and warm in the cold, thanks to the different densities and weaves of the stretchy thermal fabric employed.