We’ve already brought you the scoop on Rab’s new for Spring
2010 clothing, but at the same time, the company
has also completely redesigned and improved its range of down sleeping bags
with improved construction and down.

Serious Research

Rab’s been making down bags for almost 30 years now so the guys know a
thing or two about how to make them work, but a couple of years back,
they decided to go back to basics with a research project at Leeds
University. The aim of the project was to work out the absolute optimum
amount of down to use in any given sleeping bag chamber for the best
balance between warmth and weight.

The results of the research mean that Rab now knows exactly how much of
any particular fill power down to put inside each baffled compartment
of any of their bags, so when bags are being filled, the down is
precisely weighed out for each chamber. Not too much, not too little.
‘The golden ratio’, Neil Mcadie of Rab calls it.

Hood has neater internal
drawcords for 2010

Other crucial factors are the weight of shell fabric – the lighter the
fabrics used, the easier it is for the down to achieve maximum loft and
the more insulation it will give – and the construction of the bag.

Differential cut and chamber shapes are both important as is the
direction of the baffles, so for example, chest baffles may be vertical
to reduce down slippage. Another factor here is that Rab uses mesh
side-walls inside the chambers both to save weight and because the mesh
grips the down and stops it slipping around inside the bag.

The final ingredient is the down itself. This year’s top-end bags use
new 850+ fill power, US-rated down, the best the company has ever used.
Neil Mcadie says that 850+ is the maximum possible in their experience.
The company has switched to US ratings partly because it’s expanding
into the American market.

Rationalised Range
Rab’s exiting range had grown organically becoming quite
hard to understand in the process, so this year, all that’s been
simplified with easy to understand categories and less overlap:
top-end, super-warm bags are ‘Expedition’, then there’s ‘Andes’, still
very warm, ‘Alpine’, where weight becomes more of a consideration, and
‘Neutrino’ which is all about weight savings.

Expedition and Andes bags
have longitudinal chest and foot baffles to
reduce down migration within the chambers.

The bags are colour coded – red is very warm, orange next step down and
yellow less warm.

Below that level, the cooking Atlas bags are replaced by ‘Ascent’ and
‘Explorer’ bags, still made to Rab’s high standards, but with less
highly specced fabrics and fill and at a more affordable price.

Expedition Bags
Do what they say on the can: these are the warmest Rab
bags out there, use 850+ eastern European goose down and Pertex
Endurance coated and water-resistant fabric. To put things in
perspective, the 2105g Expedition 1200 has a comfort rating of -29˚C
and a limit of comfort of -40˚C.

Features include longitudinal chest and foot baffles, a generous cut –
80cm across the torso – so you can wear down clothing inside the bag
for extra insulation, anti-snag webbing tape and lots more. The bags
are hand filled at Rab’s HQ in Derbyshire. Sizes: 800, 1000 and 1200.

Andes Bags
The Andes series bags are similar to the
Expedition ones in fabric, cut and features, but use 800+ fill power
down instead. There’s some crossover, the Andes 1000 is a little warmer
than the Expedition 800, but mostly they’re slightly lower specced
bags, though still very warm.

Colour coding means
redder bags are warmer – this is an Expedition 1000.

The Andes 800 – also available in women’s version – has a comfort limit
of -21˚C for example. Andes bags come in 800 and 1000 sizes with
a women’s option for the 800. Big mountain bags.

Alpine Bags
The alpine range, as you might guess, is aimed more at the
alpine climber where weight is a serious consideration. In 200, 400 and
600 versions, they use highly water-resistant Pertex Endurance outer
fabric and Quantum inner and the same 800+ fill power down as the Andes.

Alpine 400 bag (top) and
Neutrino 600 – outer fabrics differ, down is the same. Production
Neutrino will not have reflective piping.

Baffles are horizontal on chest and foot and cut is 5cm closer to save
weight. The 200 weighs just 745g, comfort limit 0˚C and even the 600
tips the scales at 1185 grammes for its comfort limit of -14C. Aimed at
lightweight mountaineering use.

Neutrino Bags
Neutrino has always been Rab’s lightweight flagship range
and it carries on this year in 200, 400 and 600 sizes. Inner and outer
fabrics are Pertex Quantum, their current lightest fabric for weight
saving and better loft. Down is 800 again and there are women-specific
versions of both 400 and 600 bags.

Colour coding again on
Alpine and Neutrino.

Compare a Neutrino 400 and an Alpine 400 and the Neutrino is slightly
lighter at 920g compared to 970g, though the Alpine sleeps around 3˚C
warmer thanks to the water-resistant outer fabric. It’s less breathable
though, which means more regular airing than the Quantum-shelled bags.

Aimed at lightweight, all-round use.

Cooking Bags
Last but definitely not least, it’s goodbye to the Atlas
series and hello Ascent series
bags. They use 650 fill power down and Pertex Microlight fabric and
come in 500, 700 and 900 versions. There are women’s and XL versions of
the 700, should be ideal for general all-round use right up to serious
high mountains with the 900 version.

Ascent 900 and 500 – more
colour coding. Or you could read the labels…

You’re not losing that much in performance terms either. An Ascent 900
weighs 1795g and has a comfort rating of -11C while a far more
expensive Expedition 800 weighs 1640g and is comfort rated at -15C.

Finally there’s an Explorer range of adaptable travel-esque bags,
squarer shape and all round zip and the minimalist Rab Top Bag lives on
in two different forms, more about that shortly.

In the shops about now, full details of the entire range at www.rab.uk.com.