OMM Rotor Smock (Primaloft Aerogel Version)

Special Mentions

[ * below we've bolded the relevant condition for the item reviewed here ]

Over time we've come across a number items that have really impressed us and we'd like to draw attention to, but ...

• either they don't quite fit into our rather strictly defined / narrow categories, or
• they are, or are highly likely to be, our top-rated recommendations, but may require some more testing, or
• due to their high price-point, they cannot compete with our existing recommendations (mainly on the value score), or
• they will become our top choice, but only if and when our existing recommendation becomes unavailable (i.e. this item is the current heir in waiting but is just marginally edged out by our current recommendation).

Normally, these Special Mention (SM) "reviews" don't get a rating score and may receive less in-depth coverage, but this is not the case here. Instead, once this item has gone through its winter test, we'll likely flip this SM review to full review status and the item will be featured in our catalogue.

Intros out of the way, we'll proceed with our look at OMM's Rotor Smock, and as always, we're looking at the item from the point of view of long distance trekking over tough terrain.

Test subject: Chest 42", Waist 33", Height: 5ft 8"
Test item: Size = Large, Model 2024, Colour = Blue
Kit Tests: Summer / Winter (pending)
Disclaimer: None required (item not provided by manufacturer)

Datasheet

Manufacturer's Page

 

Scramble Review

Contents

• Introduction
• About OMM
• The Cut of the Rotor
• Features
• Packability
• Any Negatives?
• Conclusion & Product Images

 

Introduction: Solid As Hot Air

What's written in the section below is largely copy and pasted from our review of the now discontinued Haglofs LIM Barrier Jacket. OMM's Rotor Smock is something of an analogue; much of what we wrote regarding the Barrier carries over to OMM's Smock. We'll use the Barrier as a reference throughout and highlight similarities and differences as we look over OMM's Rotor Smock. 

At Scramble, as most of our official testing takes place on the wettest parts of a wet isle, we're big fans of synthetic insulation and treat down as something of a softy that requires the protection of its more hardy, petroleum-based sibling. There's a lot of unwarranted, over-promising hype in the outdoor industry (especially regarding synthetic insulation), but every once in a while there's a new technology (or a new use for an old technology) that makes a substantive difference and is worthy of praise. One such leap is Primaloft's integration of a strange substance  called Aerogel which has been embedded into their proprietary, polyester-based synthetic Gold  insulation. Primaloft call this synthesis "Cross Core".

So, What Is Aerogel?

We'll let NASA explain: 

Aerogel is a porous material in which the liquid component of a gel has been carefully dried out and replaced by gas, leaving a solid made up almost entirely of air. It long held the record as the world’s lightest solid and is also one of the most effective insulators in existence. While its inventor published his discovery in 1931, aerogel remained impractical for many decades due to its fragility and brittleness. NASA turned to the material to keep rocket fuel at cryogenic temperatures and worked with industry to create the world’s first practical, flexible aerogel blankets in the 1990s. Since then, aerogels have become widely used as insulation in subsea systems, oil refineries, industrial buildings, homes, refrigerators, jackets and shoe inserts.

For those who want to dig deeper into the strange properties of aerogels, the science channel Veritasium made two excellent mini-docs on the topic: "World's Lightest Solid" and a follow-up called "I Waterproofed Myself With Aerogel", both are interesting and well worth a watch.
 

Synthetic insulation just got a lot lighter

What's important for our purposes is that Aerogel is like solid air.  Trapped air is a great insulator and since Aerogel in Primaloft's Cross Core is more than 95% air, you're getting a large insulation boost with a very low weight premium.

The pitch from Primaloft (which so far in our testing seems about right) is that to convert the grams per square meter from Primaloft Gold Cross Core (Aerogel infused) into the traditional Primaloft Gold for an equivalent warmth comparison you need to add 50% (i.e. multiply by 1.5).  So, a 40g/sm Primaloft Cross Core jacket should be equivalent to a 60g/sm Primaloft Gold jacket (such as Mountain Equipment's 2014 Compressor). 

Perhaps a better comparison would be with Bergan's old hoodless Uranostind jacket, which had 60g/sm of Primaloft Gold insulation throughout and weighed 365g (size large).  The OMM Rotor Smock (L) weighs just 238g.  If we multiply 238g by 1.5, we get 357g, which tells us that most of the weight savings are coming from the Aerogel insulation (we can guess that just around 8g are coming from fabric, zip and other design choices).  Ultimately, Primaloft Gold Cross Core allows manufacturers to make top end synthetic jackets about two thirds of the weight of those we were getting just five or so years ago.
 

OMM: Not Just For Runners

OMM (The Original Mountain Marathon) is an event that takes place over two days in October in the UK and it's been running since 1968. OMM began producing their own outdoor clothing and equipment (such as waterproof jackets and trousers, backpacks and sleeping bags) adapted specifically for the event. Though the marathon is just a two day unsupported affair, it's easy to see why OMM's gear would fit so well with what we do at Scramble.  We probably move a little slower and certainly carry a lot more in terms of supplies (food mainly), but apart from that, it's all very familiar territory.

When OMM make gear for their race participants, it's likely to be minimalist, lightweight and extremely packable - their Rotor Smock is just that. What we have here is quite elemental with a simplicity that belies some thoughtful design combined with premium materials. OMM clearly know what they're doing.

The Rotor Smock has a superior cut to Haglofs' LIM Barrier.

The Cut of the Rotor

Compared to the LIM Barrier, the cut of the Rotor is less boxy, slightly more "athletic" but still somewhat forgiving. There's a good degree of room at the shoulders and for me it's almost an ideal fit.  It's not quite as long in the body as the Barrier, but still long enough to easily cover my arse. When sizing for a jacket like this, we always make sure we can fit a lightweight down gilet or pull-on (like Crux's Halo or more current Turbo or Montane's old Starlight) underneath. We also make sure light insulated jackets (like the Rotor) will fit over our recommended winter layers (Brynje Mesh + Megmeister Crew + Rab Borealis Tour + Mountain Equipment Echo).

Side note:  Prior to picking up our samples, we contacted OMM to discuss sizing as we were concerned they may have aimed their products specifically at trail and fell runners and thus, for me, a size XL may have been required. OMM's largest size for the Rotor Smock is XL and we can't recommend items if the "sizing window" is too limiting. We were correctly assured this wouldn't be a problem (more on this later).

When you first get hold of the lightest of the aerogel infused jackets, they almost feel bereft of any insulation at all and you wonder how these things are going to keep you warm.  Yet they do - the "tech" actually works! I remember the first time I wore the Barrier jacket I had a strange feeling, as though I was somehow cheating and getting away with it.  The same goes for the Rotor Smock.
 

Features

The Rotor uses a lightweight, wind-blocking, taffeta-like 22g/sm polyamide ripstop face and liner fabric. The outer is treated with a fluorocarbon free DWR. 

The hoodless Rotor has a reasonably high collar which helps seal in the warmth and is comfortable and snug. The smock has a deep "half-zip" that finishes at the sternum and zipped kangaroo hand-warmer pockets (so your hands can meet in the middle) which are fleece lined for extra warmth (useful for drying wet hands). The only other features are velcro wrist adjusters and a single hem cinch at the hip.  

I admire OMM (and Haglofs with their Barrier Jacket) for sticking to their guns. It must have been tempting to feature the obligatory zipped chest pocket or an internal pocket for everybody's smartphone. But no. Warm hands, warm bodies and nothing more.

OMM have stuck to their minimalist principles and made a highly effective ultralight insulated jacket.

Zips

All the zips on the Rotor Smock are reverse coil YKK zips which prevents them snagging as the zip teeth point inward and thus avoid the surrounding fabric. Each zip features a funky OMM zip pull.

Simple reverse coil zips on the chest and hand-warmer pocket zips.

The main zip is backed by a wind baffle. At the neck is a zip housing (or "garage").  What does exist on the Rotor is finished to a high standard and the zips are no exception.

One of the benefits of a smock is that it maximises the area that can hold insulation and conversely, less real-estate used for zips means less heat loss. All else being equal, the smock will always be a little warmer than its full-zipped jacket counterpart. 

Let's turn the Rotor inside out and see if there's anything else going on ...

Inside

The lining is silky smooth and made using the same "PointZero" downproof outer fabric.

Two areas where the Rotor beats Haglofs' LIM Barrier are the cinch and velcro adjusters at the wrist and hem.

There are three areas where the Rotor Smock is superior to Haglofs' Barrier:

1. The Rotor is a better cut / fit
2. The Rotor has velcro adjusters at the wrist (pic #2, above) versus the Barrier's lycra (this is far better at sealing in warmth), and
3. The Rotor features a single shockcord cinch at the hem (pic #3, above) versus the Barrier's non-adjustable semi-elasticated lycra binding.

In addition, the Rotor Smock has (what I initially thought was something of a gimmick) a feature I ended up using every single night over the 13 nights of the Summer Kit Test trek ...

Not A Gimmick At All:  The Pillow

The Rotor Smock packs away, inside out, into its "kangaroo" pocket. Once packed, it can be zipped up to form a pillow, with a fleece on one side (for colder nights) and a taffeta-like nylon on the other (for warmer nights).  Genius ! And like I say, I really didn't think much of this prior to the kit test, but once I'd used it, I was sold. It's not a reason to buy the Rotor (there are plenty of good reasons for doing so), but it's certainly a nice added bonus and definitely not a gimmick.

The pillow is a really nice and useful feature.

And that's pretty much all there is to the excellent OMM Rotor Smock.
 

Packability

Below is the LIM Barrier jacket packed away (left) and pictured on the right is the OMM Rotor Smock. Both pack down remarkably small for how warm they are, but the LIM Barrier has the edge. The reason for this is probably the Rotor's fleece pocket lining.

The Rotor Smock almost packs down as small as the LIM Barrier (we'll blame the fleece, but wouldn't want to do without it).

 

Any Negatives?

There are no negatives regarding the actual Rotor Smock.  It's an ideal piece of minimalist design and we wouldn't want OMM to add or remove anything.  Instead we'll use this section to make some recommendations to OMM (and to a degree, other manufacturers who use Primaloft Gold Crosscore in their apparel).

A Word to The OMM

Firstly, this is not the first iteration of the OMM Rotor Smock. The original version used 40g/sm of Primaloft Gold (no Aerogel Crosscore) and it's why we ignored it back in the day. It took us a while to realise that the Rotor Smock had been updated and sufficiently enhanced to meet our thermal criteria for a lightweight insulated jacket. But why did such a major upgrade go under the radar?

When manufacturers make changes (even minor changes, like those we've just made to our Towers) they absolutely should reflect this via some kind of versioning (especially where the overall design / outward appearance hasn't changed much).  

We made some slight alterations and went from "Tower" to "Tower V2" so customers know they're buying something different (no matter how small the difference, outdoor manufacturers could learn a little from software developers).  In addition, retailers may update their specification while still clearing stock of the older model (obviously they shouldn't do this, but a lack of versioning makes this more probable) and this can result in mis-selling (whether intentional or not).  

Rab used to make the Boreas softshell.  They made changes to the fabric and the design and changed the range name to Borealis.  OMM should simply have released the Rotor Smock as Rotor Smock V2 or Mark II or Rotor Smock Crosscore or whatever. So, OMM (and any other manufacturers who do the same), in the future when changes are made, like upgrading the insulation by 50%, please change the name (or some element of the name) to reflect this.

In addition, OMM should, in their marketing, explain what Primaloft Gold Crosscore is. It's a profound advance in synthetic insulation and we think the industry (including OMM and Haglofs and many others) aren't doing a great job of informing the public. In our view this is one of the reasons why Haglofs discontinued what was an excellent product; they may blame "the market", but they're partly responsible. Afterall, if this was a car, say a VW Golf and the latest upgrade did 50% more miles to the gallon or went 50% faster, I'm pretty sure VW would be screaming about it.

Finally, we've recommended to OMM, that they should open up the sizing window a little for those who want to pack light in winter.  The Rotor Smock will work as a belay / short stop jacket in sub zero temperatures.  It would be nice if they offered something like a half size up from XL (XL+ or XL Belay) for those who may want to have additional layers underneath their synthetic smock. At present, the XL ceiling on the Rotor Smock is potentially limiting.  It's not a deal breaker, but for larger types in cold climes it could be. 

 

Conclusion

Primaloft's integration of Aerogel into their premium synthetic insulation has finally bridged the gap between synthetic and down.  When you look at some of the premium down pull-ons like the Crux Turbo (£230) for example which uses 75g of 900 fill power goose down, the weight difference minimally favours the OMM synthetic (Large Rotor Smock = 238g, Medium Turbo = 235g). 

It's hard to know which is warmer, but my guess is that they're roughly on a par.  What we do know is that for wet conditions, we used to pay a significant weight premium for synthetic and those days are now behind us, at least for jackets that use Primaloft's Cross Core insulation.

By adopting Crosscore, the Rotor Smock hits our target of 60g/sm equivalent of premium (e.g. Primaloft Gold) synthetic insulation, which is where we feel meaningful insulation begins for the static user. We wouldn't want to go any lighter than the Rotor Smock (at 40g/sm of this Aerogel infused insulation). But at just 238g for a size large, the Rotor is genuinely ultralight.

We're hoping to test the Rotor Smock in conjunction with a quality down pull-on to see how this combination will perform in sub-zero conditions. But at present, the OMM Rotor Smock is a fantastic ultralight option for cold summer nights and the adjacent seasons and when combined with a mid-weight (133g/sm Primaloft Gold) smock or jacket like the Belay from Keela, you've got ~200g/sm of Primaloft Gold equivalent (which in our view takes the static user down to around -20℃).

Everything on the Rotor Smock is finished to a high standard and though, with a full RRP of £180, it's not cheap, it's still very competitive against jackets pushing "traditional insulation" to its lightweight limits, such as:

• Patagonia's £190 Nano Puff ( 60g/sm PrimaLoft Gold Insulation Eco, at 340g size Medium, now with a polyester face fabric! ... not a sensible choice), or
• Rab's £190 Xenair Alpine Light ( 60g/sm PrimaLoft Gold Active+,  at 310g size Medium)

... and in our opinion the Rotor Smock should also be measured against some of the pricey high-end down pieces too.

We need to complete our winter testing, but as we're familiar with this insulation, having tested the similar Barrier in all seasons, we expect the Rotor Smock will become our recommendation in the Lightweight (<400g) Insulated Jacket category.  

An outstanding, high quality, minimalist and genuinely ultralight insulated pull-on with some old fashioned NASA tech thrown in, the OMM Rotor Smock with Cross Core Aerogel is definitely worthy of a special mention.  We've been looking for a jacket we could wholeheartedly recommend in this tricky lightweight insulated category. We thought we'd found one in the LIM Barrier, but Haglofs prematurely discontinued it. In our view, Primaloft Cross Core is the future of synthetic insulation and we hope OMM will continue to back the Rotor Smock. We'll happily put our money on a little "solid air" over "blown into baffles to mimic down" and we'll be more than happy to recommend the Rotor Smock as our top pick in the "Lightweight (Under 400g) Insulated Jacket" category. 

 

Product Images

 

Rating (out of 10)

* The value score is derived from two factors:
1) Competitive Market Price (CMP). This represents our judgement of a competitive online price point if we were to stock the item. e.g. if we feel we would need to sell an item at 40% off (i.e. 60% of its full RRP) to be competitive, then our CMP score will be 6/10.
2) Customer Value Price (CVP). We then make an honest appraisal of the maximum price we would be willing to pay for the item (and we're mean). So if we'd pay 80% of its RRP our CVP score would be 8/10.
We then average the two scores to get our final value score, which in our example would be 7/10.

 

Last Updated: 09/12/24