Private project
2021-2022
2021-2022
Need
The idea came from my own need for specialized backpacks. I was looking for two different backpacks. One smaller backpack that could be used for climbing, shorter alpine adventures as well as short super-light hiking during the summer. The second needed to work as a light, stable and comfortable backpack for longer trekking and backpacking in northern Sweden as well as in southern Europe.
Goals & Restrictions
The goal for the smaller bag was a very lightweight frameless bag at ~500g and a volume of ~20L, the aim for the larger one was a lightweight backpack at ~1000g with an internal frame and a volume of ~40L. The smaller one should be stable to carry at loads under 6kg and the larger one should comfortably carry a load of ~12kg for extended periods of time, but also be able to carry up to 18kg without too much discomfort. This requires a balance between lightness and carrying comfort where all choices of materials and design has a significant impact on the outcome as the margins are relatively slim.
Another significant restriction is budget and time. This limits the amount of prototyping and testing that I can perform. The fabrics used for lightweight backpacks are often expensive at 30-70€ per meter and testing by sewing takes a lot of time.
Sketching
The idea to achieve lightness was to keep it simple in construction and design. I realized early on that I could avoid zippers in favor of a foldable roll-top-design which provided both sufficient water protection and adjustability in volume.
In order to work around the problem of cost and time consuming sewing, I used a lot of sketching and scaled down paper models. This is to a certain limit beneficial in the purpose of creating patterns but is less suitable to predict stretch and movement in the actual fabric.
Evaluation of Ideas
Simpler sketches of how the smaller backpack is intended to look and how to construct it. This showcases the construction of the bags main body and internal sleeve for a soft foam pad to create some rigidity.
Material
As the smaller black backpack was seen of something of a learning-project, the choice was mostly impacted by availability and cost. I decided to use a simple and thin nylon fabric with an inner PU-coating as the main fabric, polyester mesh as secondary and a 6mm EVA-foam for rigidity.
The white bag was seen as a second step and therefore I put in some more money and thoughts into the materials. I tested multiple varieties of fabrics for the bigger backpack. I looked into some of the more commonly used fabrics for lightweight backpack like DCF (Dyneema), X-Pac, Robic-Tsunooga. At the time the newer and arguably more improved fabrics like Ecopac and ULTRA were not yet commonly available. The main fabric had to be waterproof, durable, readily available and easy to work with, and preferably not too expensive. I estimated that I would need about 1-1,5m which would be 1,5-2,25m2 of main fabric.
By comparing test pieces of fabrics against each other, the choice came to be the X-Pac VX21. It was readily available, good price-point, highly durable and very easy to work with. The closest competitor was the much more supple Robic-fabric, unfortunately it only came in black and would have created a very dark inside of the bag. Together with its PU-coating which could more easily be worn off over time rather than the laminated alternativ in the VX21, the choice became evident.
The white color was chosen to create a lighter interior of the bag and to later make it easier to see the contents of the bag. The VX21 was the heaviest fabric among the ones considered but was chosen due to being more favorable in other aspects.
The white color was chosen to create a lighter interior of the bag and to later make it easier to see the contents of the bag. The VX21 was the heaviest fabric among the ones considered but was chosen due to being more favorable in other aspects.
I still needed a thinner fabric for details that did not necessarily had to be waterproof, so I utilized the Robic fabric for the outside of hipbelt as well as for the shoulder straps. The mesh netting for the pockets was a simpler fabric with some stretch and which fit the purpose. The 3D-mesh was a later inclusion in the process and it helped to improve comfort in carrying and moisture dissipation from shoulders and back.
Hardwear pieces was easier to select than fabrics. Based on the sketches that, I had made I picked out the pieces that seemed to solve the problems the easiest. Most of the time it was a straight forward choice based on need, compatibility and quality.
Assorted test pieces of different X-Pac varieties intended to be used as main fabric.
The chosen materials for the white pack: VX21 X-Pac as main fabric, Robic ripstop as secondary fabric (not shown), 3mm 3D-mesh, webbing of different widths, shock cord (not shown), EVA-foam of different thicknesses, net fabric and shown plastic components.
Manufacturing
To create the patterns I started out with sketches that were transformed to small scaled down paper models to test the shapes. A second stage of models in full size was later produce to see that if the loosely drawn up patterns would work together in full size.
The fabrics I used were all easy to work with, especially the VX21. The process of pattern making included just as much mental imagination of how the pieces were to be sewn together and in which order as the time it took to actually create the raw patterns. Everything was later cut and sewn together fairly easily, except the shoulder straps which turned out to be a more intricate step in the process.
Product
The bags were both finished and functions very well judged by the initial need they were created to fulfill. Both bags have later been used on both shorter and longer self-supported trips. The bags were relatively simple to make and great for each of their different applications.
Everything included the weight of the small one turned out to be 440g, and for the large one 1180g. As the bags are tailor-made with a fixed back length, I had the possibility to avoid some heavier components like an adjustable back length. Even though the fabrics are completely waterproof, the bags are not due to the seams. The process of seam sealing a backpack is both time-costly and difficult. Instead a special cotton thread that swells up in contact with water was used and hinders additional water from entering the bag. To be completely sure, a waterproof bag liner is used on longer and rain prone trips.
Details of both bags, load-lifters to the left, equipment loops to the right.
Evaluation
On our way to the summit of Glittertind, with just the essentials in the bag and the other gear left in camp.
The goal was to create two comfortable, capable and lightweight, which I would see as mostly fulfilled. I have continually used both of the bags, especially the white one which I have brought along on several longer trips. The small one fulfilled all the qualities that I was looking for but the cheaper fabric has shown to wear a lot faster than expected and therefore a more durable fabric would have been better.
For the white one, durability have not been an issue, more the opposite. The VX21 fabric is sturdy and thick and is for the most times too much for the intended needs. The weight turned out be well above the 1000g that I set out to go below. I blame this on a partly overbuilt construction, excessively heavy fabric and design choices.
With the lessons learned from both of these bags I see a possibility to create a second generation of the large bag with lighter and more adequate fabrics like ULTRA 200 and different design choices such as a redesigned hipbelt construction . This would improve on both user experience, weight and comfort, with the effect of a higher production cost.
