Forclaz Trekking Sleeping Bag MT900 5°C Down: a no-frills down bag that gets the job done at a reasonable price

Forclaz Trekking Sleeping Bag MT900 5°C Down: first impressions

Decathlon has been behind some of the best bang-for-your-buck outdoor gear in recent years. Its line of hyper-considered and extensively tested trekking tents all offer exceptional value for money, and I’ve been nothing but impressed by everything I’ve tried. But does that apply to sleeping bags? Earlier this year, I visited Decathlon at its production facility in the French Alps to find out about how they design, test and validate products. And came away with a shiny new MT900 5°C sleeping bag from their trekking brand Forclaz to test.

Costing £149.99 when bought directly from Decathlon in the UK, the Forclaz MT900 5°C sleeping bag is a down-filled, 3-season sleeping bag that sits at the intersection between big-brand-feel and price. Unlike its line of backpacking tents, however – such as the Forclaz MT900 Trekking Tarp Tent which comes in at less than half the price of most big-brand competitors – Decathlon’s 3-season sleeping bag is only a little cheaper than big-brand alternatives. So, how does it perform in comparison?

Forclaz Trekking Sleeping Bag MT900 5°C Down: in the wild

I’ve had my hands on a Forclaz MT900 5°C sleeping bag for all three seasons now. That means I’ve been able to put it up against the full gambit of conditions it was built for, ranging from temperatures hovering around its 5°C / 41°F limit all the way up to balmy summer nights where the mercury remained well above 16°C / 61°F. I’ve used it in dry conditions, windy conditions and outright monsoon-style conditions during a snap summer storm in Dartmoor National Park in England. So it’s safe to say that I’ve given it a fair crack of the whip.

The first thing I appreciate about this bag is its size and weight. Coming in at just 830g / 1.8lbs, it weighs less than a liter of water and packs down to about the same size as a rugby ball. That means it lends itself well to ultralight trips and adventures where pack space is a premium, such as bikepacking, fastpacking or UL backpacking trips. In fact, the only bag I own that is lighter than the Forclaz is the Sea to Summit Spark 7°C which just happens to be half the weight. That being said, it also happens to cost twice the price and is considerably less warm, so I found that I’ve continued to use the Forclaz MT900 5°C sleeping bag on UL trips throughout 2024, despite having a much more ‘premium’ bag on my shelf.

Inside the large version of the bag, Decathlon has stuffed 370g / 13oz of 700 fill-power, RDS-certified and traceable insulation. This comprises 90% gray duck down and 10% gray duck feathers. This is wrapped together inside a cozy polyamide shell with vertical baffles that feels great against your skin, reduces cold spots and ensures an even spread of down throughout the bag.

Another thing worth noting about the Forclaz MT900 5°C sleeping bag is the quality of the zipper. In all my many nights, it barely snagged and was easy to loosen whenever it did. This never cut into the material or caused any damage whatsoever, which can often be a problem with lightweight sleeping bags like the Forclaz MT900 5°C. What’s more, featuring a soft polyamide internal baffle, the zipper is also fully protected against drafts and comes with a handy internal stuff pocket for keeping things like your phone safe and warm through the night.

Finally, it’s worth mentioning the stuff sack, which is easily the best of its kind I’ve come across. The sack provided with the Forclaz MT900 5°C is a dry bag that comes with two clips for extra compression. This means that you can safely carry your down bag through the worst conditions out of the box, and you don’t need to buy an additional dry bag for use in damp conditions (as is so often the case, even with premium lines).

Forclaz Trekking Sleeping Bag MT900 5°C Down: warmth

I’d say that the Forclaz MT900 5°C sleeping bag is mostly good down to 5°C / 41°F. When combined with a warm pad, such as the Thermarest Neoair Xlite NXT, I didn’t have any issues down to 7°C / 45°F, so I’d happily take it down a little further than that when combined with some base layers and maybe a thin jacket. But I do run cold! As ever, however, I find it incredibly difficult speaking about the warmth of a bag, as what’s warm for me might not be warm for you. In a welcome move, however, it’s nice to see that Decathlon has listed the comfort temperature as a part of this bag’s name and not the limit temperature, as is so often the case with sleeping bags. So top marks to Decathlon there.

One last thing of note is the cut of the bag. Unlike your usual mummy-style sleeping bag, the Forclaz MT900 5°C comes with an anatomical hood that is tight over your head. Unlike regular mummy bags, which gently taper from the widest point around the shoulders up a narrow rounded tip above the head, this bag is cut like a down jacket, meaning it’s cut inwards sharply around the shoulders and more naturally shaped around your head. I found this to do a great job at keeping in the warmth, though the more restrictive cut of the bag did take some getting used to. Over its use, however, I grew to love it, and it meant that I actually made use of the hood of the bag for a change, rather than just resting my head inside an open cavern, as is often the case with regular mummy bags. Additionally, due to the tighter cut around the shoulders, I also found that the bag moved more with me as I rolled around at night, which was a welcome revelation as a wriggler.

Overall, I really like the Forclaz MT900 5°C and find it to be an excellent option for a great price. Granted, at £150, it’s pricey for Decathlon, but I think you’ll have to spend considerably more to find a comparable 3-season down bag from any of the big-name brands out there.

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