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Marathon des sables

Marathon des SablesThe Marathon des Sables is the original desert foot race and is now in its 34th year. Covering approximately 230km in the Moroccan desert, each participant must carry his or her own rucksack containing food, sleeping bag and clothes. Participants enter as individuals or in teams of three and this year about 1,300 runners will be competing.

For the Marathon des Sables, as with all desert ultra marathons, a balance needs to be struck. Running in the heat of the day, one wants the lightest load possible. On cold desert nights one wants to rest and sleep well. Desert nights can drop to a chilly 4°C, air frost temperature.

Down Sleeping Bag Selection

Our race-tuned M.Degree° K bags are ideal for the MdS. If we made just one desert racing bag, it would be the M.Degree° 200K – a Typical Operating Temperature of 4°C and a weight of just 340g – but for those who sleep cold there’s also the M.Degree° 300K (0°C), and for those who get hot or who are looking for the ultimate weight saving, the 10°C M.Degree° 100K weighs just 240g.

The 100K is really the preserve of the elite racer who’s prepared to rough it to gain the lightweight advantage – in a long, arduous event such as the MdS, the good night’s sleep gained from the warmer bags is a significant advantage in its own right.

The basic figures for the M.Degree° K bags:

Sleeping bagTOT (Min Temp)WeightPacked size
Hght x Diam (cm)
M.Degree° 100K1050240821 x 13353
M.Degree° 200K4393401221 x 13421
M.Degree° 300K-3264451621 x 13489


Sleep System

Of course, it’s advisable to have an insulated top for chilly desert evenings and mornings, so an extremely lightweight option is to combine that top with our Desert Race Halfbag. This weighs just 240g and, when used along with our Ultra Pullover, creates a warm, flexible Sleep System with a TOT of 3°C.

 TOT (Min Temp)WeightPacked size
Hght x Diam (cm)
Desert Race Half Bag337240821 x 13278
Ultra Pullover (with hood)-5/+3*23/37*260710 x 18369
Desert Race Half Bag/Ultra Pullover Combo33750015 647

* +3°C for sleeping in. Typical Operating Temperature when wearing during the day (when your movement / metabolism creates more heat than at night) is -5°C.

Additional points:

  1. TEMPERATURE RATING: Put simply these are the temperatures at which you should be able to get a night's sleep in normal circumstances. For fuller details about the TOT rating see this Technical Briefing.
  2. LINERS: A liner will add to the insulation if you choose the M.Degree° 100K but want more warmth. As always it is a trade-off between the extra weight and bulk and the warmth you gain (maybe 2°C). Silk liners at 140gm probably give the best value.
  3. FABRIC OPTIONS: The M.Degree° K bags come with 7X outer fabric as standard. Hypershell is highly wind/water resistant optional outer, adding about 15gm to the total weight.
  4. ZIPS: Zips are an option on the M.Degree° K bags, but most competitors don’t ask for one. A short zip with a draught tube adds about 40g, a full zip and tube adds about 90g. There is also the option of a footzip which adds 10g and allows air to circulate around race-battered feet. As well as weight, zips add to the packed size.
  5. PACKED SIZE: PHD stuff sacs tend to be on the loose side. All these bags can be compressed further in your sac.
  6. Also available is our Desert Race Stuff Sac, equipped with multiple lashing points and formed into a slender shape to allow easy attachment to the outside of a full rucksack.

Down Clothing selection

Wafer Ultima clothing is especially suitable for desert racing: the Pullover is 155g and the Vest is only 115g. They’re small enough to fit in a pocket, but they’re rated to 0°C (about the warmth of a thick fleece).

Warmer than that is the Ultra Pullover mentioned above as part of the Sleep System. Even if not being used with a halfbag, it’s still a very useful top for cold nights when you are – inevitably – extremely tired and therefore feeling colder, providing sub-zero warmth at only 225g. The sleeveless Ultra Vest provides the same level of insulation for the core, but tips the scales at just 150g.

The next Marathon des Sables starts on 3rd April 2020.