Arc'teryx Nuclei SV Parka Long Term Review

The Nuclei SV (as in “severe”) is the big brother to the Nuclei FL (“fast & light”), intended for seriously miserable conditions and weighing almost double that of the FL at 600g in a Medium. It is the replacement to the old Dually in Arc’teryx’s line up. If you read my review of the Nuclei FL in VL#42 you’ll know it was hands down my favourite piece of static insulation (thanks to the type of synthetic fibres used), and that my only gripe with it was the lack of a double zip. So, being the big brother, this jacket had a lot to live up to. 

Fit:

The first thing to mention about the SV is the sizing. Arc’teryx classifies their gear using acronyms like “FL”, “LT” and “SV” based on the use case, but they also change the fit and sizing a bit. So a size Large in the SV will be much bigger than the same size in an FL. For those who want a standard “throw it over all your other layers” sized parka, I would order your usual size. But for those who don’t plan to wear as many layers underneath (more likely in Australia), maybe consider sizing down. For reference I wear a size Large in the Nuclei FL, and can easily layer a size Medium Nuclei SV over it (not that you would need to). In terms of cut, it feels as expected for a winter belay parka (boxy), very similar to the cut of a Patagonia Das parka. The hood is also helmet compatible (of course), but can still be synched for use without one.

Features:

The SV features the same Arato face fabric as the FL, but in a slightly thicker 15d (instead of 10d), which never ceases to amaze me in both weather resistance and durability for such a light denier fabric. The SV has two internal drop pockets (handy for keeping climbing shoes warm), a chest pocket, waist cinch, fleece-backed handwarmer pockets, a double zipper, and a push-stud at the bottom of the zipper—a few more features than the FL. After spending many hours belaying people in cold gullies, I can confirm all of these features are a welcome addition. But the real secret sauce is in the insulation. The SV shares the same type of Coreloft™ Continuous insulation as the FL, but multiple layers have been used at the front, back, and upper arms to maximise warmth. While I don’t want to get too bogged down in specifics about synthetic insulation, I do want to mention that insulations like Coreloft Continuous (which is very likely a rebranded Climashield Prism) are significantly different from the type of synthetic insulation (short-staple) typically seen in jackets like this, and offer some unique advantages when it comes to loft retention and resilience to packing out.

Function:

For those who have worn a Nuclei FL, the easiest way to think about the SV is that it feels like you’re wearing two FLs, both in terms of warmth and bulk (and pretty much weight). Unlike the FL, I can’t see too many people stuffing it into the included stuff sack (which is a tight squeeze) and clipping it onto their harness. Obviously this piece shines for frigid winter belays when things might get a bit damp (which is usually the argument for synthetics over down), but even when things are dry I would still pick the SV up purely for how damn wind resistant it is. The SV can comfortably handle temps going into the negatives (with correct layering), so using it for winter cragging in Australia makes you feel like you’re wearing a suit of armour. The SV essentially fits the same niche as the Patagonia Das parka, they perform almost equally on paper, but given the type of insulation in each jacket my personal choice is hands down the Nuclei.

Final Thoughts:

The Nuclei SV is a beefed-up version of much loved the Nuclei FL, offering almost double the insulation and a couple of extra features for winter belaying comfort. For those heading into damp conditions (or just those who prefer synthetics) it’s an excellent alternative to the typical down belay parkas on the market, boasting a competitive warmth to weight with the added benefits of a more durable synthetic fibre than most. If you’re looking for a static piece for winter use, I can’t think of anything I’d want to wear more than this!

Overall, I’d rate it 4.75 out of 5 blue offsets.