Arc’teryx Nuclei SV review (vs Dually)

Maybe it’s because I’m getting old. Or maybe I’ve just gotten too comfortable and haven’t been practicing enough suffering – but I sure do like a nice warm jacket these days when the temps drop.

The Arc’teryx Dually has been my go-to stupid-cold weather parka for years, but lately I’ve been known to pull it out of the closet at barely zero. (Yep, I’ve definitely gotten soft!) However, for Fall/Winter 2021 the Dually is no more, replaced by the Nuclei SV, a jacket that is nearly half the price — so is it just half as good?

In recent years I have migrated most of my insulation to some type of synthetic. I find the synthetics wet out less, and dry better if they do, compress pretty much just as well as down, and most importantly perform on par, or at least very, very, close, to quality down that’s paired with a quality shell fabric.

But the Nuclei SV seems to push this even further: it’s not just warm but it has this uncanny ability to ‘heat up’ just like the best down out there, and radiate that heat back. The first time I felt this I figured it was just too warm and I was sweating too much, so I tried it again on a much colder (-15C) day. Same thing. Within a couple of minutes of putting it on, the Nuclei SV is not just keeping me warm, but it feels like the insulation itself has heated up and is sending that warmth back towards me.

To ensure I wasn’t imagining things, I pulled out the Dually for the next belay. After a few minutes I was warm, but I wasn’t feeling that amazing warm hug of the Nuclei. And I felt something else, too — I was getting clammy. I wish I had the instrumentation to measure parameters like this, but I swear the Nuclei is not just more down-like in behaviour than the Dually, it is also much more breathable. This breathability feels like it adds to the overall feeling of warmth as your sweat evaporates more readily. The overall warmth difference between the two parkas feels negligible, but it’s in all the other areas that we have seen progress and innovation in the past ten years that the Nuclei SV pulls ahead.

First off, the commonalities in design. Both parkas are cover-the-butt length in the back, they have dual-slider zippers, hem snaps, two hand pockets, and dual inside drop pockets. They’re both hooded, obviously, and each comes with a stuff sack.

Where they differ in design is the incremental improvements I would like to see in all garments. The Nuclei SV’s hood is bigger, easier to pull on, and warmer than that of the Dually. The hand pockets are bigger, and better positioned. Same goes for the inside drop pockets. And there’s a zippered outside chest pocket, too.

But the most noticeable difference only shows up when you start packing the jackets into their respective stuff-sacks. When you start stuffing the Nuclei SV into its stuff sack, a funny thing happens: the fabrics trap so much air that the jacket puffs up. Ever rolled up an air mattress? You start getting to the end and there are pockets of air that only have one point of escape: the tiny valve. Same thing with the Nuclei SV: air gets trapped inside and as you’re stuffing the jacket, it creates these air balloons. It’s quite remarkable, actually: a jacket so wind-proof that it actually prevents air from escaping. No wonder it feels so warm. (By comparison, the Dually doesn’t exhibit any such behaviour.)

This is how the parka naturally ‘puffs’ up when packing into the stuff sack.

This incredible outer fabric is Arato 15r, which is remarkably durable for such a low-denier shell: I’ve already managed to scrape the sleeves and shoulders on some sharp Rockies limestone a couple times yet there is no visible damage. The liner is Arato 10r, and I can only presume this is why the jacket puffs up so much: both the inner and outer fabrics are incredibly tightly woven and airtight.

Inside, the Nuclei SV adopts the Dually’s construction method by stacking two layers of Coreloft Continuous 90 (90g/m2) in strategic areas. That means you have a single layer of the insulation at the sides, on the lower arm, in the underarm area, and in the hood for better breathability, but two layers at the front, back and upper arms for additional warmth. Functionally, this gives you the best of both worlds and I am seriously impressed with how well the Nuclei SV regulates body heat and humidity.

In terms of warmth, well, it has yet to drop much below -15C here in the Rockies so I can’t comment on very cold weather performance. It is more than warm enough to wear over just a couple of light layers in those temperatures. Comparing it to the Dually back-to-back, the Nuclei SV feels warmer, has a better cut, and the hood is next level warm — and it’s quite large so it very easy to slides over a helmet. Taking into consideration that I would typically wear the Dually only around -20C and below, I am expecting similar performance from the Nuclei SV once winter sets in properly.

Back to that hood for a bit: it is superb, and possibly the best insulated hood on any Arc’teryx jacket I’ve used (and that includes the new Alpha Parka, which does have a great hood, but the Nuclei SV’s feels roomier and more protective). It’s large enough that it easily slides over a helmet, the adjusters are located in the brim for a tight cinch, and it actually extends quite a bit out for a very deep fit and superb coverage. I find that just throwing the hood on, without even zipping up the jacket, is more than enough at -5 or -10C.

My Men’s Medium Nuclei SV weighs in at an even 600 grams — exactly as quoted by Arc’teryx. The stuff sack adds another 12 grams. Compare that to a same-size Dually at 720 grams, plus a 14 gram stuff sack. A hundred-odd grams doesn’t sound like much, but the Nuclei S just feels so much lighter. There’s a bulk and a heftiness to the Dually that I’ve always felt but it is especially pronounced when you have a Nuclei SV to compare it to.

About the only gripe I have is that the main zipper sliders do not come with any kind of toggle that would be easy to grab with gloves on. All three pocket zippers come with the latest in overly-over-designed Arc’teryx pull tabs, but strangely the one zipper you really want to open and close on a regular basis does not. An easy fix with some thin cord, but a surprising lack of detail.

I guess I could also complain that the only colour available is not a bright orange or lime green or some other flashy and bright colourway but at the same time the “Timelapse” blue is a nice shade. I would just prefer my alpine apparel in brighter colours.

In terms of cost, the Nuclei SV retails for $450 Canadian. Compare that to the $800 the Dually sold for and all of a sudden the Nuclei SV seems like a bargain, especially as it outperforms its predecessor in every category I can think of. It actually reminds me of the original Patagonia DAS Parka — all the warmth and belay comfort you want, but at a much lower price than most of the competition. Come to think of it, it outperforms the current DAS Parka for a hundred bucks less.

The Nuclei SV is the standout belay parka for the Fall/Winter 2021 season. Yes, Arc’teryx’s own Alpha Parka (review coming after it gets really damn cold) is the headline grabbing one, with high-tech fabrics and an eye-watering price tag, but for most of us that just want a really warm parka, the Nuclei SV is it. I cannot recommend it enough.

As always, a huge thank you to Arc’teryx for sending along a sample for testing and review. I couldn’t create this content without support from the brands that make this gear.

And, of course, thank you to Veronica for taking all the detail and comparison photos, and to Chris S. for the ‘action’ shot.

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