TOP BAGS - DO THEY WORK?
08 November 2008
Note: Many of these articles are very old, and although the technical information is still relevant the equipment mentioned may not be (for example a Stormy cooker was state of that art in 1995, but not in 2021).
If you were to blindly buy the Macpac Neve you’d probably end up taking it back and complaining, because the Neve is unlike just about any other bag on the market being only half a bag, with only the top half containing down-filled baffles and the bottom insulation being replaced by a fabric sleeve into which the sleeping mat can be fed. The principle behind the bag is sound enough on paper, after all what’s the point in carting around several hundred grams of down that will only end up being flattened when you are sleeping? By removing this excess weight it’s possible to reduce the pack size and weight by about a third, giving you a three plus-season (-5°) bag for the weight of a two-season bag (0°).
But does the idea work? Well the half bag principle has been around for years and I was very enthusiastic about giving it a go. Unfortunately when I first started using the bag I soon discovered its drawbacks. I first tried the bag a year ago in Norway, both by itself and as a liner to a synthetic sleeping bag, with temperatures hovering around freezing. When used alone the bag only really works best when you’re lying down, meaning it isn’t ideal for sitting bivvies which limits it to routes where you can fully lie out, or for normal camping, which isn’t much of a problem as 99.99% of users will be lying on their backs.
This also meant that you couldn’t sit up very easily in the bag when eating or reading, unless you unzip the bag to the waist, forcing you to sit half out of the bag, which obviously reduces thermal efficiency. You are also limited in your movement when in the bag, as you must turn inside the bag, not turn with the bag. As the hood is fixed to the mat this means if you sleep on your side you can end up eating fabric. The stiffness of the mat also means if you lay on your side you create big dead spots on either side of you as the bag is held rigid beneath you by the mat - when lying on your back this isn’t a problem as the down drapes over the body more fully. The lack of insulation on the bottom of the bag also reduces the comfort of the bag, as the bottom definitely feels colder because even when compressed the loft of a conventional bag still provides significant loft around the contact points. The lack of down also means the bag has less cushiness which most people associate with a down bag, meaning you may be disappointed if you are used to that ‘big bag of feathers’ feeling. Another problem is that with only one very thin piece of fabric between you and the mat - which is non breathable, of course - you can feel pretty clammy where your skin touches the mat. Needless to say I wasn’t totally impressed. Another factor was that my Thermarest wasn’t full length, meaning I had a gap at either end of the mat with no insulation apart from a folded fleece and, to make matters worse, this sprang a leak in the night. Overall I was left thinking that the compromise wasn’t worth it, especially considering I was in a car and could have taken a full weight bag instead.
When doubled up with another bag I began to see the potential in the design, as the other bag provided what was missing in the Neve, providing more under body warmth and comfort and allowing me sit up (there was no need to have the mat in the bag). I could see that the real potential of this type of bag is as a booster layer for winter sleeping bags - a far better option than putting two standard bags together. Unfortunately, it seemed like a bit of a waste for such a specialist and expensive bag to be used just as a liner. Overall, I was disappointed in the bag and initially wrote it off as a good idea that just wasn’t going to work.
Fortunately, I decided to persevere with the bag, coming to the conclusion that the only way I was going to get this system to work was to change my whole approach to the bag. Firstly, this is not a leisure camping sleeping bag, it’s designed for ultralight backpackers, adventure racers, Alpinists and trekkers. These people will be willing to cope with lying on their backs, not sitting up and reading and feeling a little clammy, if they are to lose a third of the weight of their sleeping bag. Secondly, unlike most sleeping bags, which require no thought apart from how to zip them up, the Neve was designed for the user who knows how to use their gear to its maximum advantage and to milk the most performance out of it as possible and it was going to take some work.
The first time I was able to give the bag another proper test was in Colorado over the winter - a place Doug Scott described as being so cold he had to climb Everest as training. This time I made sure I had a mat that fitted perfectly into the sleeve, plus a mat that offered the maximum insulation. The reason is that once you remove all the under loft of the bag you soon discover that your skinny two-season mat isn’t quite as warm as you thought thereby chilling the body. On this trip I used a full length Ridgerest (£23/400g), which is perfect, as it’s not only softer than a standard mat and highly insulating, but its snow performance is boosted as the sleeve stops snow from clogging the ridges on the bottom and thereby reducing its loft. The underside protection should be taken very seriously and I would even consider gaffer-taping sections of foam on to the main contact points to boost this (feet, backside, upper back). I personally prefer a foam mat over an inflatable mat for anything high and on snow, but if I was lower then I might consider something like a new full length Thermarest ProLite 3 (£65/552g), perhaps doubling it up with a foam mat for maximum warmth and redundancy.
Once I arrived at the first bivvy, a flat ledge cut out of a snow scoop, I must admit I wasn’t totally confident I had the right bag for the job, seeing as it was absolutely Baltic, a fact made clear by us walking clean across a lake 200m lower whose surface was encased in ice over a metre thick. Ian Parnell had a full weight standard bag with about a 600g fill and I was soon wishing I’d not chosen such a harsh spot to give this bag another chance.
The first thing I did was place any unused clothing between the sleeve and the mat, meaning I reduced the clamminess of the mat and thereby using what I already had to gain insulation. I then boiled some water and filled my Nalgene bottle and got into my bag. I carried a small pair of down boots, which I put on after warming my feet on the bottle and replaced my damp socks (down boots make very good emergency frostbite mitts). After loosening my leg layers I stuck the water bottle between my thighs, which warmed the blood running down to my feet and meant I could still grab it for a drink in the night. Next I took off my soft shell top and draped it over my legs and took off my down jacket and draped it over my body, lay down and zipped myself in. In my pocket I had a load of honey-roasted nuts that I nibbled, knowing their fatty content would keep me warm. The hood of the bag isn’t thick, but with my balaclava and thick hat on this wasn’t a problem. Anyway I fell asleep and slept warm and comfortable all night even though the temperature was probably far lower than the bag should have been able to cope with, in fact, Ian complained of being cold in the night, even though he had as many layers on as I did. Waking up warm and refreshed I was suddenly convinced that the idea worked - especially so when I stuffed the bag (which was nice and dry), into its tiny stuff sack and dropped it into the bottom of my very small rucksack.
What else has this bag got to offer? Well best of all is the bag’s Epic fabric shell, which really makes the bag stand out. Epic has been around for several years, but still isn’t found on that many products, which is a shame as I think it’s a really great fabric. Unlike most other highly water resistant fabrics which use a breathable PU coating or laminate, Epic repels water because every polyester fibre is encapsulated in an ultra thin polymer, which repels water molecules. This means that the fabric is not only highly water resistant, but also far more breathable than PU water resistant fabrics. Another bonus is that Epic is also far tougher than equivalent fabrics such as Dri-Lite and Endurance, as coatings reduce the tear strength and, unlike many of these PU fabrics, Epic seems to retain its water resistance over a longer time. The fabric is also softer and easier to compress, making the bag easier to stuff away and, most importantly, loft when taken out of its stuff sack. I’ve been using and testing encapsulated fabrics for about 10 years now and they seem to be getting better each year and although on clothing they often need regular re-energizing by a ride in a cool tumble dryer, on sleeping bags this isn’t so necessary, unless you’re a very dirty user. The water resistance of the bag came home to me one day when I hung it out on the line to air out after a trip. An hour later I suddenly noticed it was pouring with rain and rushed out to take it off the line fully expecting to just find a damp rag hanging off the washing line. Instead I found the bag as I had left it, fully lofted and covered in beading-up water droplets. Yanking it off the line I took it inside and found to my surprise that it was bone dry. In January I used the bag on a open bivvy at the base of The Diamond in Colorado and due to the amount of clothing I had inside the bag I was unable the close the rather slim Macpac bivvy bag I was using, meaning I had to leave the top of the bag exposed. That night there was a great deal of spindrift blowing around and by morning the bag was covered. To my surprise I could just brush the snow off as none of it had melted out and dampened the shell, an important plus point as when winter camping it’s not always possible to totally protect your bag from the ingress of snow and ice.
Other features of the bag are a minimalist hood and chin baffle (rather than a full neck baffle), both of which are effective. The foot of the bag has a very nifty down-filled pocket into which you can slip your feet.
A full-length zip runs down the bag, which seems a bit like overkill for a bag like this and I’d have preferred a half zip instead. The bag has radial down baffles that cover the upper body and are very effective at reducing down shifting, often a problem with plain horizontal baffles, and the premier 750+ goose down is well-located in the baffles meaning there are no cold empty spots.
My overall conclusion is that this bag, along with other bags of this type, are perfect for the weight conscious user who isn’t prepared to suffer totally (i.e. sleep in a bin liner), but who is willing to put some effort into making a lighter alternative work. The conditions under which I’ve used the Neve have often been extreme
(Diamond and Troll Wall in winter), nevertheless I think that if it can perform there with some work then it can perform in less extreme situations, such as ultra distance backpacking, multi-day Alpine routes where nights are spent in tents, snow holes or on good flat spots. This bag is only really of use for about 10% of outdoor users, but for those people this bag and other bags of a lower fill weight offer them big savings in the load they must carry.
If you’re facing a night in a bag that you think isn’t warm enough then here’s a great tip. You’ll want to wear the main insulating piece, be it a down jacket or fleece, well don’t, as there is a better way to boost your warmth. Instead take it off and cover yourself with it like a blanket inside your sleeping bag, tucking the arms inside the jacket to boost the insulation value of the jacket, also by having your arms close to your body means you also gain more heat (a little like why mitts are warmer than gloves if you know what I mean).
By doing this you are not only exploiting 100% of the fabric (i.e. you’re not lying on a third of it), you’re also creating more dead air space around the body. The same can be done with the legs and if you have a spare fleece you can slip your feet into the legs and drape the body of the fleece over your legs. If you have insulated trousers with full length zips then unzipping them and laying them over your legs can also provide a more useful level of insulation. If you don’t have a pair of down booties then mitts can do the same job if your feet aren’t too big.
Rab’s excellent Quantum Top Bag (£130/200g fill weight/400g total weight) is a real gutsy performer and designed for the user who really knows what they are looking for, built without a hood or side zip a clever user, protected in a tent (and with a close partner), could push this minimalist bag down to zero. It is also a perfect booster layer for a winter bag.
Western Mountaineering make their Pod 15 (£300/325g fill weight/750g Total) and Pod 1 (£250/250g fill weight/600g), both of which are designed for a custom foam mat (400g), which is a good system which can be detuned by the use of a lighter mat in milder conditions.
Mountain Equipment make two top bags, both of which come with their own inflatable mats. These are the down-filled Classic Integral (150g fill weight/1,300g total with mat) and synthetic Firewalker Integral (£100/1900g with mat), but unfortunately I think neither bag nor mat is high spec enough to appeal to the extreme user, which leaves the bags out in the cold a little as I think these users are the only people who will put up with the bags’ downsides, in fact, I think ME would have been better making an offshoot of their awesome Dewline bag instead.
PHD also make some very light top bags as variations of their Minimus (£148) and Pigolo (£120) bags as specials, with the Pigolo coming out as perhaps the lightest summer weight sleeping bag on the planet at around 250g.