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Mountain Equipment’s Down Sleeping Bag Revolution

British brand aims to make the sleeping bag great again with a completely reimagined, overhauled range for spring 2017

This is Matt Fuller. Matt is an expert in down. In fact, Matt is arguably the world’s leading expert in down use in performance sleeping bags and clothing. He has a PHD in – you guessed it – down and how it performs.

Which is all very interesting and means Matt can talk the breast feathers off a goose at outdoor industry dinner parties, but what really matters this spring is that Matt, aka ‘Doctor Down’ is the driving force behind a radical overhaul of Mountain Equipment’s down sleeping bag range.

New From The Foot-Box Upwards

Not just a tweaking or redesign, but a completely new array of bags covering six different categories, using brand new designs, fabrics, features and genuinely innovative thinking and priced between £200 and £800.

Why? Essentially, says Matt, down sleeping bags have remained pretty much the same for the last 50 years bar the odd relatively minor tweak. His mission, which he chose to accept, was – in a nut-shell – to make sleeping bags great again… or more practically, simultaneously both lighter and more compact and also warmer, which is a pretty good trick if you can pull it off.

Not Just The Small Stuff

What does that mean exactly? Mountain Equipment has gone back to basics, down basics, with some fascinating results. People have calculated how much down to use in particular baffled compartments for optimum performance before now, but Matt has taken things a stage further.

Take the density of the down you use. It’s not just about warmth to weight ratios, though they obviously matter. Too little down and you don’t get the insulation value you need. Too much and you’re adding weight and bulk you don’t need.

But the density of the down also impacts on how suited it is in certain areas of the bag. A collar baffle, for example, needs to be able to mould to the contours of your body to retain heat flexibly. Down destined for baffles on the underside of the bag needs to be dense enough not to move easily aside under bodyweight leaving cold spots. As Matt demonstrates below.

Optimising the right density of down in the base of the bag is crucial. Too little and it will simply be displaced by your weight, too much and you're adding pointless weight and bulk to your sleeping bags. This is just right...

Water Resistance?

And then there’s resistance to water. ME doesn’t feel there’s a need for water resistant down in sleeping bags – it prefers to rely on water-resistant fabrics where needed – but intriguingly, down density even dictates how down reacts to getting wet.

A low-density fill acts a bit like a snow-globe when water hits, swirling around and letting the whole compartment get wet. Denser fills though tend to restrict the wetness to the surface layer of the down, so the bulk of it stays largely dry and effective. You always wanted to know that, right?

The Design Process

It’s not all theoretical. Working with outdoor equipment designer Pete Dolman over a period of 18 months, the bags went through ‘tons of testing’, both by Matt and Pete and with ME’s sponsored athletes like Nick Bullock.

There were lab tests too. In the cold chamber at Leeds Beckett University, and using the thermal mannequins which form the basis of the ubiquitous sleeping bag temperature rating system.

To cut a long story short, what started with computer modelled fill distributions and down densities, finished off with the prototype bags being used for real in harsh mountain environments from Scotland to the Himalaya.

Fabric Choice

Which fabrics to use for which type of sleeping bag is, it turns out, almost as important as the down itself. An expedition bag which needs to be relentlessly tough and durable, for example, gets Gore’s latest Thermium fabric, a completely windproof and highly water-resistant material that’s also very breathable for the protection it gives.

Ultra-lightweight bags, like those in the new Fire range – more about those later – use a fabric that’s not the absolute lightest available, but is still very light, but not at the expense of strength. Who wants a disposable sleeping bag after all?

And then there are the small things…

Nothing radical here, but a secure internal zipped valuables pocket hasn't been forgotten in the rush to innovate.
This cunning neck fastener uses magnets. Quick and easy to engage, but very secure it opens only in one direction.
These are the easy to use neck cords. Look carefully and you'll see one is flat and one rounded so you can tell them apart and adjust the opening to suit even in the dark
Main-zip baffles have been redesigned so they don't merely but together, but overlap giving an area as warm as a non-zipped section
Storage sacks supplied with every bag are red and cube shaped for easy storage. Neat!
All bags come with a waterproof stuff-sac with roll-over seal, but this is a clever vent hole which lets you expel excess air before completely sealing the bag.

Sweating The Small Stuff

It;s not just the fundamentals, like fabrics, down baffle shapes and down density though, ME has also put a load of effort into getting the little details just right. You can see some of the neat new features above.

Take the side-zip baffles. Existing ones often just butt together creating inefficiencies. The new design is fully over-lapping one that is as effective as a non-zipped area of the bag. Then there’s a neat, new, magnetic neck fastener – no fiddling with interlocking plastic, the magnet takes the strain and holds things securely shut.

Hood adjustment cords allow you to tweak front and back tension to suit and the clever bit is that one cord is flat and the other rounded, so you can still tell the difference in the dark, clever stuff.

And finally even the storage and stuff-sacs get the treatment. The red storage sack supplied with every bag is cube shaped for easier storage about the house. Meanwhile waterproof stuff sacs have an ingenious little vent hole that takes the hassle out of expelling excess air as you fasten the roll-over top. Properly neat and thoughtful.


Meet the new Fireflash, the warmest bag at its weight in the whole world says ME

Meet The Fireflash

We could go on about the cleverness, about how the bags are filled by sophisticated robots with down quantities calculated to the nearest 0.1g, about how each baffle is optimised for down density, warmth, recovery from compression and so on, but you’ve probably got the idea already.

What it all adds up to though, is a bag like the new Fireflash, the warmest of ME’s newly launched ultra-lightweight bag range. It’s Doctor Down’s favourite weighing bob on 1000g with and amazing 650g of that being ethically-sourced 800 fill-power down.

But while it’s light, it’s not masochistically minimalist. You get a pretty much full-length zip, ME’s EXL elasticated inner system, a proper hood and proper toe-box plus slanted box-wall baffles throughout.

The light, but tough Plasma 10D outer shell looks amazing in a sleek, fabric way. And the temperature rating damage is – according to ME’s own sleep rating – around -10˚C for comfort limit and -28˚C for extreme. In other words, a four-season bag what weighs a kilo. Price is £460.

There are lighter bags in the Fire range too, but chances are that the revamped Helium range and the Helium 400 and 600 bags in particular will be the biggest sellers. They too, by the way, use those slanted, box-wall baffles throughout, no stitch-through cold spots.

Helium v Helium

We thought we’d compare the 2016 and 2017 versions of the Helium 400. Used on Mountain Equipment’s figures, the overall weight is near identical at 855g for the new bag versus 860g for the old version.

The new version uses 385g of down, the older one 400g. But where it gets interesting is that the new bag’s official test figures are 3˚C comfort, -3˚C limit and -19˚C extreme, while the 2016 equivalents are 4˚C, -2˚C and -18˚C. Not ground-breaking, but an interesting demonstration that attention to detail has made a measurable difference.

More Information

The new bag range will be on Mountain Equipment’s web site shortly and in the shops in the next couple of weeks. See also ME’s excellent Down Codex site which explains the lengths the brand goes to, to make sure its down is both ethically sourced and traceable.

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