We loved Montane's Spine jacket, and felt that for running in harsh conditions it would be hard to beat. Well has its replacement managed that tall order? Bridget Glaister and Rob Greenwood zip up to investigate.

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I don't think I've ever tested a jacket to the extremes I tested the Spine Jacket. In April 2022 we published our review, by which time I'd already used it loads, but in January 2023 I put it through the ultimate test* when I completed the Spine Challenger South. The weather throughout was apocalyptic, possibly the worst I'd ever been out in, but what surprised me was how enjoyable the race was - and I put a lot of that down to the fact that I was dry.

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Thanks to my attachment to that shell I was worried when I heard a rumour that the Spine Jacket was being discontinued, but heartened to hear that it was to be superseded by the something else - namely the Phase Nano Jacket**. The two share almost identical DNA, with the differences actually being quite subtle; however, the brilliant news is that Montane have managed to improve on what was an already amazing jacket. 

*ok, the ultimate test would have been doing the Full Spine, but forget doing that... 
**maybe I'm biased, but I still think that the Spine Jacket is a substantially cooler name...

In Use

Much like the Spine Jacket, the Phase Nano is designed primarily for runners.

From a runner's perspective it ticks virtually every box: it's lightweight; extremely breathable; soft and silent in use; and - perhaps most importantly - extremely waterproof.

It's not often that all these elements come together, but in the Phase Nano they do, and it's because of this that its application also extends far beyond running. If you're after a lightweight waterproof for hillwalking or backpacking, then look no further, because each of the aforementioned attributes are just as applicable. If you're intending on more technical use, such as scrambling, climbing or mountaineering, the main limitation is its lightweight 13 denier face fabric. I've found this has stood up to a remarkable amount of wear, but I've definitely avoided using it around rock, and if you're heading to a rough environment I'd recommend buying something more burly. Montane now offer various jackets in the Phase collection, including the Phase Lite and Phase Jacket, both of which fit this criteria far better than the Nano does.

Rob: My primary usage has been running, although it's come with me hillwalking a lot too - sometimes when I'm expecting to wear it, other times 'just in case'.

The Phase Nano is definitely a jacket that deserves to be worn though. Running in waterproofs is often a pretty awful experience and something to be avoided at all costs, but the Phase Nano's balance between waterproofing and breathability means that the prospect of going out wearing it is one that I actually look forward to. Gore Tex Active is - in my opinon - a massively underrated membrane. On grim days its level of breathability has often led to me ditching the windproof, which is something I never thought I'd say prior to reviewing the Spine Jacket, as I'd always favour a windproof as a result of their superior breathability; however, the Phase Nano achieves this and saves you taking two jackets.

Bridget: Owing to a foot injury my Phase Nano was initially tested on mountain biking days out and worn from start to finish on the rides rain or shine - so I can assure you that you aren't going to find a more breathable jacket. It allows great freedom of movement when picking the bike up too. Once back out running in the hills the hood got tested in typical awful conditions and it fixes nicely in place to move with the head and the wide peak keeps the rain out of your eyes. I've always been out with my running pack worn on top, and the lightweight material copes well with this; plus it makes no annoying rustle.

Fit

Rob: The men's Phase Nano has a very similar, possibly even identical fit to the Spine Jacket. It's a close fit, but an active one, offering pretty much perfect freedom of movement, and with next to no hem lift. Much like the Spine Jacket it feels quite snug for its size. This isn't to say that it's too small, because I'd still say it's true to size - it's more to say that if you expect to wear it with a few layers on underneath then you might consider going up a size. 

Bridget: My women's Phase Nano jacket is a slightly more generous fit than the Spine Jacket, not so you need to change your sizing, but it feels better for the extra room. There's further improvement in the cuffs, which are now much easier to pull over my chunky watch, I'm pleased with that upgrade. I like the hood, apart from that it takes me a while to suss out working the mechanism when releasing the bungee, but that's what you get with the minimalist features to a certain degree. 

Features

The nice thing about the Phase Nano is how limited the number of features actually are - it's a very uncluttered jacket. That said, the features it has have all received some subtle upgrades, which once you look at them are actually quite noticeable. 

The pockets are a good example of this, with the shift from a mesh liner to a waterproof one. This was one of our very few criticisms about the Spine Jacket, as the mesh lining meant you had to remember to close your pockets in the event of it raining. Whilst we'd still recommend you try your best to remember shutting your pockets in the rain, it's not longer quite as necessary. 

The hood has received a similarly positive update, with the fairly simple elastication on the back being replaced by a proper volume adjusting cord/toggle. The side adjustment has also been changed so that the elastication no longer runs the whole way around the rim of the hood, but instead along the sides. There's logic to this change, as it adjusts the volume where you need it adjusting without creating a pinch point at the top. It effectively lowers the wired peak that runs along the top, creating a smaller space to protect you from the worst weather.

The zippers have also changed, becoming more minimalist, which I have mixed feelings about. The zippers featured are quite slender/tapered, which makes them a bit more fiddly compared to the slightly chunkier zippers that were featured on the Spine. In cold conditions they are a bit more difficult to operate, particularly if you've got gloves on.

Summary

The Phase Nano is a worthy successor to the Spine Jacket. It does everything that its predecessor did, but improves on certain areas, and refines a few others. Most importantly it still provides that brilliant balance between weight, waterproofing and breathability. It is, in our opinion, the ultimate running jacket. At least for now.