Klim Aggressor -1.0 longsleeve top in monument grey

 

The Aggressor -1.0 is a very lightweight, very stretchy, highly perforated top. It's the millions of tiny holes in the fabric that allow the liquid sweat to escape from the body. Actually, under the arms, where we tend to perspire even more profusely, the holes are even larger.

 

What Klim tells us is that their Aggressor shirt is infused with 'chemical-free cooling technology'. Now I am not a fan of such mumbo-jumbo, but what I have ascertained is that Klim has created its own version of Coolmax. Klim calls their version Coolcore, and basically what it means is that the individual fibres are channelled rather than smooth and round, to allow moisture to better pass along them. 

 

In essence, this works on the same basis as Merino wool whose fibres are similarly 'grooved'.

 

The result is that sweat will pass to the outside of the Aggressor shirt faster, where it will evaporate more quickly, thus enhancing the cooling effect. And because it's about the nature of the fibres as opposed to a chemical treatment, this effect won't fade over time however often the garment is washed.

 

Klim further bangs on about low-profile seams for comfort and non-abrasive neck roll and sleeve cuffs; again to the same end. And all that sounds useful.

 

There are no NASA style technologies at play when it comes to staying cool on the bike; or indeed in any activity where an increase in your body temperature is likely to cause you to sweat.

 

We want as much sweat as possible to be able to wick away from the skin as fast as possible. It's that simple.

 

When it comes to a base layer, you want to be wearing something made of Merino wool or synthetic fibres, as opposed to something made of cotton, to ensure the sweat doesn't get absorbed. And you want the material to be heavily perforated to speed up the wicking process.

 

Something like Coolmax, or in Klim's case Coolcore, will allow the sweat to pass through the fabric more quickly.

 

And so, as far as we're concerned, the Klim Aggressor -1.0 would seem to hit all the right notes. It will do what a base layer is meant to do; and it will do it well.

 

Getting hot and sticky on the bike is never nice; and that's why Klim has also gone to such lengths to ensure that the Aggressor is as comfortable as it can possibly be.

 

In really hot weather we reckon the Aggressor -1.0 is as good as a base layer gets.