Rab Ascent Bivi Bag Review

Many people would favor better and sturdy four-season tent over winter bivi sack for winter camping or backpacking. But many forget that these bivi sacks can give better and closer protection in extreme weather conditions. Bivi is advantageous over other winter camping gear because of its lightweight feature that helps to avoid the bulk load in your camping backpack.

Who can easily use Rab Ascent Bivvy Bag

The bivi market is flooded with options of different brands, sizes, qualities etc. Rab Ascent bivi bag is one of the best among the bivis out there. It is a single person, lightweight, waterproof bivi that can assist you and protect you from colder climatic conditions during your normal winter outdoor camping or your alpine expedition trips. The bag will not take up too much of your limited backpacking space and us much easier to transport compared to a tent. It could be ideal while you walk, bush craft, climb mountain or do lightweight ascents.

In Short – Rab Ascent Bivi Advantages and Disadvantages


  • Compresion and package: It is very simple since the bivi can be compressed and packed in the sack that comes along with the package. This also makes this bag lightweight, easy to use, pack, unpack and can be expanded to desired size.
  • No-see-um zipper: will glow in the dark, makes closure easy and provide adequate privacy. The hoops can hold the sleeping entrance open at all times.
  • Mosquito mesh: Provides good protection from insects and other unwanted guests. It can be removed as per requirement.
  • Waterproofness: Design with 100,000 mm H/H waterproof base makes it perfect for rainy and snowy climatic conditions.
  • Sidewalks and Foot Box: Designed in such a way as to minimize the bag loft and provide more spaces to the sleeper.
  • Internal collar and hood draw cord: Keeps the bivi closer around the neck to give better climatic protection.


  • May not withstand extreme cold
    The bivi can give adequate comfort for up to -5 degree Celsius. As per the manufacturers, this bag can give comfortable sleep for a temperature of -12 degree Celsius. But in certain cases, this might change.

Is Rab Ascent Bivi Pack Size Big And Light Enough?

The bivi measures 31.5×100.4×23.6 inches and weighs around 600 grams. It is quite roomy with a dimension of 2250×700 mm. This is designed for solo-trekking or mountaineering and makes a wider profiled sleeping bag. Rab Ascent Bivi pack size comes with a low 13 x 25 cm, which makes it an easily portable one.

The package comes with two storage sacks with the options of carrying it in a large or small sack. This gives you choice of compressing the bag to conserve space and for de-compressing it for long term storage.

With the use of highly breathable and durable three layered Pertex Microlight lightweight and waterproof fabric on the upper part of the bag, the bivi has considerable less weight.

Weather and Water Resistance Of Rab Ascent Bivi Bag Is Never A Problem

The Rab Ascent bivi bag is a very comfortable sleeping bag that keeps you optimally warm. This is a high performing, down filled bag that is ideal for daily use and in colder climates. It holds a U-shaped zippered opening that has an in built mosquito net. The bivi is made of 100,000 mm H/H laminated nylon waterproof bathtub base.

How Breathable is Rab Ascent Bivi Bag?

The Rab Ascent bivi bag is highly breathable. With the use of Pertex Microlight fabric on the exterior and ultra-light and densely woven fabric on the interior, this bag provides good circulation. The duck down filling is incorp.

Decision Based On This Rab Ascent Bivi Review – Yes or No?

Our Rab Ascent bivi review above shows that this bag makes an ideal choice for seasonal trekkers and mountaineers or for general outdoor adventure seekers. It can give a lightweight appeal with a waterproof and highly breathable fabric to keep cold outside and comfort inside. Some Ascent bags come with poles to keel the sleeping system clear. But during worse weather, you could even use the internal collar and hood draw string for additional warmth. This bivi will make a great investment if you are planning for regular winter outings that do not go much beyond the manufacturer’s temperature limits. So, It’s a big YES to Rab Ascent Bivi bag!

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