Brynje Super Thermo Zip Polo Shirt 3/4 Neck base layer – review

A mesh winter base layer seems somewhat counter-intuitive. Surely you want more material to keep you warm, not less? The result here, however, is very effective.

Brynje is a Norwegian firm which can draw upon 75 years of experience in manufacturing base layers for use in cold conditions, be it Edmund Hillary’s first ascent of Mount Everest in 1952 or the Norwegian military. The base layers are also becoming increasingly popular in cycling circles, too.

The Brynje base layer range is broad and includes winter and summer, long sleeve and short sleeve, synthetic and merino base layers. This one is the catchily-named Brynje Super Thermo Zip Polo Shirt 3/4 Neck and it’s designed for winter use.

The theory

Brynje’s base layers may not be cycling-specific but the goal remains largely unchanged, regardless of the activity: to stay warm and dry during physical activity. Brynje’s original base layer was made from mesh and the theory behind a mesh construction is the same now as it was then.

The key principle, according to Brynje, is that nothing breathes, insulates or dries like air. The goal when we pull on clothing before a ride is to maintain a stable – and comfortable – core temperature. Not too hot, not too gold  – the Goldilocks zone – and the base layer is key to that by drawing perspiration away from the skin and allowing it to evaporate, rather than remaining close to the body where it can subsequently have a cooling effect. Therefore, a base layer needs to breathe and wick moisture away from the skin, and also dry quickly (or, in the case of merino wool, at least retain heat when wet).

But why mesh? Firstly, there is significantly less material to dry and in this piece Brynje use a hybrid Meraklon polypropylene yarn called Isolfil which absorbs very little moisture. That’s only half the battle, however, and in winter insulation is key and the mesh construction is at the heart of that. The mesh traps pockets of air and uses the body’s natural heat to warm the air, while also allowing the skin to breathe, thus improving the rate of sweat evaporation.

And in practice?

The theory is all well and good, but does it work on the bike? In short, yes. Very well. We’ve used the Super Thermo through the back-end of last winter and the start of this season, in temperatures ranging from close to freezing to around ten degrees. On warmer days when we’ve been overdressed, it’s managed perspiration effectively, and on freezing days (and with the right combination of layers) it’s helped keep us warm and comfortable.

The Super Thermo is very good at moving moisture away from the skin. The fabric itself retains little or no moisture and that helps maintain a consistent body temperature on a ride, when your work rate is likely to vary considerably, whether going into the red on a climb, freewheeling on a descent or after the cafe stop. By keeping your skin as dry as possible, as well as the layer that is in direct contact with it, you will go a long way to staying warm and the Super Thermo helps you do just that, aided by the pockets of air trapped by the mesh construction. We’ve found the Super Thermo to be better at dealing with moisture transfer than almost any polyester winter base layer we’ve tried.

In fact, in our experience it’s likely to your other layers that struggle to move moisture away as quickly as the Super Thermo, and so from time to time you may feel the slightly damp (and cooling) interior of a jacket or jersey come in contact with the skin. Either way, that’s better than the clammy feeling some base layers have and, by and large, the mesh provides an effective barrier between the two.

Sizing is fairly accurate, with a size small providing a close but not restrictive fit here, and there’s plenty of stretch in the mesh material. The cut isn’t cycling-specific so it’s a little shorter in the body than many base layers but it still tucked into bib shorts or tights just as you’d expect. A standard ‘closed’ fabric (i.e. not mesh) is used on the cuffs and that ensures a snug fit. Same goes for the neck, while the half-length zip, which has a large toggle easy to use with gloves, can be opened to let in a little more air if you’re running too warm.


All in all the Super Thermo is an excellent piece of kit which does a great job at keeping you warm and dry – the two key tasks of a winter base layer. The mesh look may not be for everyone but it’ll largely be hidden from view and when it works this well, who cares?

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