Review: Rab Sonic Ultra Zip Base Layer

Incredibly breathable and lightweight, the Rab Sonic Ultra Zip is a versatile base layer that is suited to a number of outdoor activities in most seasons.

Feature type Review

Read time 4 min read

Published Mar 18, 2024

Author Josh Raper

Josh Raper Josh is a photographer and videographer specialising in capturing outdoor brands, travel and expeditions. Having been on expeditions around the world and supported adventurers & athletes on various challenges, he is a passionate outdoorsman and enjoys exploring new places.

OUR VERDICT

Incredibly breathable and lightweight, the Rab Sonic Ultra Zip is a versatile base layer that is suited to a number of outdoor activities, in most seasons.

Weight 114g
Features Motiv™ Aero single jersey fabric, laser cut vent holes in back of the neck and underarm panels, microactive seams, bulk yarn technology, greater than 50% recycled materials, reflective branding, lock zip

Pros

  • Excellent odour control
  • Lightweight
  • Breathable
  • Quick drying
  • Super comfortable to wear

Cons

  • Fairly loose fit but not baggy, if you prefer base layers close to the skin
  • Depending on your style, some of the colours are pretty out there
  • Collar could be slightly higher

WHAT I’M LOOKING FOR

Being an adventure and outdoor brand photographer and film-maker, I tend to carry large, heavy rucksacks on some questionable terrain, in all weathers.  I therefore want a base layer I can rely on to be comfortable, breathable and nicely fitting. It also needs to have have fantastic odour control so the people I’m working with don’t start avoiding me.

I’ve bought the classic, cheap-as-chips base layers in the past along with some better quality ones from other well known brands, but these never seem to live up to their hype. They often start smelling within a few hours of use, and are quite bad at clinging to the skin when it soaks up moisture. That’s not to mention the substantial heat loss once I’ve stopped moving and the wind chill kicks in.

FIRST IMPRESSIONS

Having first tried the Sonic Ultra Zip on at home, I was instantly impressed by how it felt and the fit. It didn’t really feel like I was wearing it!

Compared to other base layers I have, this was a completely different fit in that it was a loose and comfortable without being too baggy. I already got the sense that this garment would wick away moisture effectively without clinging to the skin, particularly on those hotter days.

The quality of construction felt like it was designed to last and the ventilation holes were an added bonus, something I haven’t had on base layers before. The only drawback I noticed was that the collar was quite low against the neck, which is quite unusual for a zipped long sleeve base layer.

I was instantly impressed by how it felt and the fit. It didn’t really feel like I was wearing it!

THE TEST

Although the Rab Sonic Ultra Zip is marketed for mountain running, I would be taking on a completely different kind of test – walking the length of Hadrian’s Wall. This 135km UK-based National Trail stretches from coast to coast, from Wallsend, Tyne and Wear to Bowness-on-Solway, Cumbria.

While most hikers undertake this trail either in stages, or have their kit taken from lodge to lodge, we’d be taking the more hardcore approach carrying all of our camping, food and cooking equipment with us. With the combination of a heavy pack, mixed terrain and steep gradients, this would be the ultimate test for any base layer.

The weather was unusually cool and wet for August when we took on ‘The Wall’, but this didn’t stop me working hard and sweating a fair bit, particularly with the weight on my back. However, I never found the Sonic Ultra to become oversaturated with sweat, and my body temperature stayed fairly regulated throughout the hike.

The fabric used on this garment is the Motiv™ Aero fabric, which uses a much bulkier yarn in its construction compared to similar products on the market.  This results in a larger surface area which dissipates sweat much faster and evaporates much more effectively to keep your body temperature more regulated.

I found the laser cut holes that were positioned in high heat areas (armpits, around the upper body etc) increased the air flow and again assisted in keeping my temperature regulated and stopped sweat build up. This was also particularly useful as these are the areas that chafe or soak up sweat when wearing a rucksack. No crazy sweat patches down the spine on this garment when wearing a heavy pack! I also found I could get away with three days of wearing it before it started to smell a little bit, which is pretty impressive considering having a heavy pack on and wearing it for longer than the average mountain runner would.

Wearing a heavy pack for several days on undulating terrain, I was pretty impressed with the support it gave me and the lack of rubbing. Being completely honest, if this was your intended use I’m not sure how the Sonic Ultra would stand up to the abrasion in the long run, but with the microactive seams and reinforced construction I suspect it would handle it pretty well. As discussed previously with the unseasonable August weather, I would have liked the collar to be slightly higher to be a bit more protected from the sideways wind and rain!

WHO IS THIS BASE LAYER FOR?

The Rab Sonic Ultra Zip would suit anyone looking to be active outdoors in all seasons. Don’t be put off by any claims positioning it as a running base layer only, as this would work perfectly for any activity.

WHAT STANDS OUT?

Freedom of movement

Being true to size and not too body-hugging, this base layer moves with you without restricting movement.

Odour resistance

This base layer disperses moisture vapour away from the body rather than soaking into the fabric, doesn’t cling to the skin and massively reduces odour emitting from the product.

Thermal regulation

The Motiv™ Aero fabric uses a much bulkier yarn in its construction compared to similar products on the market. This results in a larger surface area which dissipates sweat much faster, evaporates much more effectively and keeps your body temperature more regulated.

Lightweight

It’s really hard to tell you’re wearing anything being so lightweight. Also packs down super small so very easy to pack.

It’s really hard to tell you’re wearing anything being so lightweight.

VALUE FOR MONEY

I personally believe the Rab Men’s Sonic Ultra Zip base layer offers excellent value. Its combination of durability, versatility, comfort, and being produced by a company striving to do better, is a worthwhile investment for adventurers seeking reliable and high-performance gear.

While the initial cost may be higher than some alternatives, the long-term benefits and overall quality make it a cost-effective choice for those who prioritise performance and longevity.

BASE BOTTOM LINE

I would definitely recommend this product to anyone looking to be active in the outdoors. The technical features combined with it being so lightweight and comfortable, make this an incredibly versatile base layer.

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