Gear Review: Zpacks Arc Blast 55L backpack

Words and pictures by Andrew McCluggage. Find Andrew on Facebook using the button below.

As an outdoor writer and photographer, I spend a lot of time on the trail. Long days with a fully-laden pack is part of my job so I am constantly looking for products which help me lighten the load, without a reduction in performance. Often one of the heaviest things a backpacker carries is the backpack itself and the differences in weights between products can be large. The very lightest packs are light because they incorporate the lightest products available and these are pared down to the bare minimum. Very light materials tend to be very thin. And very thin material is often not very durable.

The holy grail of backpacks is therefore one that is light and durable and still performs well. I have used a lot of packs over the years and have never found the very lightest packs to be very good. Sometimes the straps are too flimsy to be comfortable. Sometimes the material just does not last very long. Well the Zpacks Arc Blast 55 has changed everything for me.

Over here in Europe, I had been hearing great things about Zpacks, a US manufacturer, for a few years now. So, I was very keen to get my hands on one of the packs. I chose the Zpacks Arc Blast 55 which has a good reputation in the US as an ultralight option for multi-day treks. Normally, I travel long-distance trails with a 45-litre pack which requires very careful packing to ensure that overnight gear and food fit in. The Arc Blast 55 would give me a little more space and yet at 569g it was still much lighter than 45-50 litre packs from other manufacturers. 

Zpacks Arc Blast 55 Backpack on the South Downs Way

​First Impressions

As you unwrap the new pack, it is the Dyneema outer which is immediately striking: it crinkles loudly and it is very thin. The straps and buckles are also very thin but seem to be well designed. The diameter of the carbon frame is very small too so I was keen to see how that would hold up. The overall weight of the pack is astonishing: it feels like there is barely anything there when you lift it in its empty state.

Zpacks Arc Blast 55 Dyneema Material


The pack comes flat and it is up to the user to set it up. The ‘arc’ in the frame is produced by tightening up a few straps: the first time you do it, it is nerve wracking as the frame is so thin. However, you soon get confidence that it is strong enough. Fitting the pack to your back is quite complicated but there is a good video on Zpacks’ website which clearly shows you how to do it. Once fitted properly, the pack feels snug, secure and comfortable. There are few manufacturers which give such good guidance on fitting.
I am 183cm tall and I chose the medium size: apparently almost nobody goes for the large. It fitted me well but only just. I think that anybody slightly taller than me might find the medium to be too small.


To test the pack, I walked England’s South Downs Way, 160km of beautiful flint and chalk trails through the South Downs National Park. I took full camping gear and had a base weight (excluding food and water) of 6kg. With food and water, I was topping out at 9-10kg each day.

Comfort: Over 7 days I found the pack to be extremely comfortable. Although the padding on the straps and belt is thin, it is good quality and I had no problems with it. I suspect that it might be less effective for heavier loads but most people who buy this pack will be ultralight backpackers who have a small base weight so this should not be an issue.

Durability: it is fair to say that the material is very tough. Rubbing on rocks and trees seem to cause it little problems. However, after 160km I did notice some very minor wear around the bottom corners of the pack. Presumably this was caused when setting the pack down and it should be minimised by giving the pack a little more care in future.

Water-proofing: the material is very waterproof, much more so than any other pack that I have ever used. There are a few places where a small amount of water does get in but this is a minor gripe as the pack scores far better than its competitors in this regard. I would still carry a dry-bag though on longer trips but that is no issue as good ones weigh a mere 20g.

The Zpacks Arc Blast has comfortable straps
The Arc Blast’s carbon frame
View of the inside of the pack


  • The huge net pocket at the front of the pack is excellent: I used it for my rain jacket and drying wet items of clothing. It held up very well but in forest terrain you would need to take care not to catch it on branches.
  • Roll-top closure: European trekkers will take a while to get used to the roll-top closure which is quite unlike traditional packs. However, I have to say that I am a complete convert. It saves weight and is very waterproof. You may miss having a pocket on top but this is easily remedied by carrying a small dry-bag inside to contain the items that you need to access quickly on the trail
  • Side pockets: there are two and they are well-designed, making it easy to reach for a water bottle or other items


The Arc Blast 55 is now my ‘go-to’ pack for long-distance treks. It is easily the lightest pack that I have ever used. In fact, it is almost unbelievably light. Yet I found it to be stable, durable and very comfortable. Unlike most other packs, it is almost completely waterproof. Despite the lightweight construction, it performed extremely well. At $325 it is not cheap but if you like to travel ultralight then it is a price worth paying.

But can I not find any faults at all? OK then, I have just one: please Mr Zpacks can we have a whistle on the sternum strap?! Honestly, that is the only fault I can find with this exceptional backpack.

Andrew is from Northern Ireland but the Alps are his HAPPY PLACE. He loves trekking, mountain biking, labradors and brewing beer (in no particular order). Oh and he also loves Blink 182 which makes him feel like a teenager: sad but true!

After 20 years as a corporate lawyer, Andrew decided to do something interesting.

He started off writing walking guidebooks for other publishers. In 2018 he started Knife Edge Outdoor Guidebooks to design and publish better guidebooks.

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