Review: Rab Muztag Alpine Shell with eVent DVStorm

It’s been a few years since I last donned any kit from Rab, that respectable gear company out of the UK. The last shell of theirs that I’ve put into the mountains was the Myriad, and it remains one of my top choices today. There have been some changes in the last two years though, not least of which is the introduction of eVent’s new DVStorm fabric. The new fabric coupled with Rab’s design expertise has created a rather special new jacket known as the Muztag.

Rab Muztag Jacket Features:

• 3L DVStorm fabric
• Helmet compatible hood
• Wired hood peak
• Velcro roll-down tab for hood storage
• YKK Aquaguard front zip with internal storm flap
• Twin YKK Aquaguard zippered chest pockets
• HH: 10,000mm
• MVTR: 40,000 g/square meter/day
• MSRP: $300

Breathe freely, if a little damply

First of all, let’s explore the foundation of the jacket – namely, eVent’s DVStorm fabric. eVent touts this fabric as the ideal lightweight option for moderate conditions. So, for my location up here in Washington, this jacket offers itself as the perfect companion for summer ascents of glaciated terrain, but I wouldn’t risk it in the winter or in very inclement weather. The flipside to its lightweight cred is a truly remarkable level of breathability. It’s so good that I can use the jacket for aerobic pursuits like mountain biking — a rare feat for something that can also do alpine duty.

Before we jump into the meat of the review, let’s briefly discuss some of the rationale behind having a jacket this breathable. First of all, we have to acknowledge that any time we say that fabric is ‘exceptionally breathable’ or something to that effect, we’re also essentially making a negative comment about water resistivity. There’s a tension between how water resistant a fabric can be and how well that fabric breathes. Manufacturers do their best to get around this, but it’s the fundamentally constraining factor behind all waterproof/breathable fabrics.

Now, just to be clear… I prespire a lot. On a recent trip to Mt. Baker to do some crevasse practice, we hiked up the unforgiving Railroad Grade wearing full packs. All the while it drizzled gently on us, so I pulled out the Muztag to fend off the moisture. As the day wore on the jacket’s DWR had done a fair job of fending off the rain (except for the spots where my pack touched the jacket) and I was reasonably dry. Then, the rain really started hammering down and before long the fabric was overwhelmed. Mind you, Rab coated the fabric with an exceptional DWR but, nonetheless, the downpour was much too much.

Do I think that this is a bad thing? No, I don’t, and here’s why. For people who sweat heavily like I do, there are no highly waterproof fabrics that can effectively deal with the microclimate generated by my sweat. What’s more, virtually all waterproof/breathable fabrics on the market today will wet out if they spend a day in heavy rain. So, from my point of view, why not have an exceptionally light and breathable shell that will no doubt wet out in the rain, but on moderate days promises to both keep me fairly dry and handle my sweat?

What’s more, light fabrics like eVent DVStorm dry more quickly than heavier laminates. Essentially, my reasoning is that I’m happy to be using a light shell that can deal with my sweat on aerobic pursuits but might wet through in inclement weather, acknowledging that a more waterproof shell would simply wet out due to sweat. I trust the Muztag to keep me dry in moderate weather, to not wet out from within on aerobic climbs and to dry out quickly when it does wet out.

And now for the features

Alright, so that’s my take on the fabric and the various performances trade-offs that are made. The Muztag is cut like a classic alpine shell with a fairly generous waist for layering and Rab’s signature longer sleeves for unimpeded reach. I’m wearing a Medium and it fits my 5’11”, 185lb frame like a charm.

As befits a lightweight shell, the features list is sparse but largely complete. There are two waterproof pockets that are set high and above the harness for easy access. There’s also a full hem drawcord for managing the hem of the jacket when wearing a harness. Rab included a fully adjustable, helmet-compatible hood that can roll down to stay out of the way when not needed. I was particularly impressed that Rab still chose to include a wired peak for added strength in high winds – it really drives home that they intend this to be an alpine shell, not matter its light weight. It’s still minimalist, though – the only touch for comfort is a slim strip of felt at the chin.

Beyond things like water resistivity and breathability, the eVent DVStorm fabric doesn’t necessarily have a tremendous amount of charm. It’s a fairly loud fabric (ie, crinkly like a chip bag) and it doesn’t have very much inherent stretchiness. These, it seems, are the opportunity cost of such a light, breathable fabric.

Finally, as would only be appropriate, I have to complement Rab on their attention to detail. They were the first to turn me on to the importance of having good wrist closures and, once again, the Muztag has great ones. They’re a rubberized material that has the Rab waves laser-cut into them. I’ve found that, more often than not, good wrist closures go along with a quality garment – it’s a detail, but it counts.

The Good

• Dare I say class-leading breathability?
• Rab’s characteristic cut yields great range of motion
• Excellent DWR is a good first line of defense
• Hood is fully adjustable, helmet-compatible and up for high winds
• Very light overall – 12oz is respectable for a midweight alpine shell

The Bad

• The fabric is rather crinkly and loud
• The fabric tends to wet out quickly, as a result of its breathability

Bottom Line: Rab Muztag Jacket

As I fleshed out above, the Muztag is an ideal jacket for me. Frankly, if it rains in the Pacific Northwest there’s a good chance that the jacket I’m wearing will wet out by the combination of sweat and rain. So, why not have a lightweight jacket that dries quickly and, for those rare times when the rain is only moderate, will still keep me dry? More generally, the Muztag is an excellent offering for anyone seeking an exceptionally breathable shell to take into the mountains, provided it’s not monsoon season.

Buy Now: Available from Backcountry.com