Make an Ultralight 50L Backpack (£30 / 480g)

Background

I liked the weight and strength of the GoLite Jam pack but found it to be a litte uncomfortable for carrying loads that did were not completely rigid. I wanted to see if I could create an ultra-light pack that had all the 'essential' features and load-carrying ability of a conventional pack.

I've found it hard with the ultrlight packs to get them to transfer loads efficiently and comfortably to the hips. With this pack I succeeded.

One concern was that the ultralight packs (such as the GoLite) did not seem to worry about comfort at all but I have always felt that comfort and fit were actually vital to walking day-in-day-out.

This article is really about designing a pack that is the lightest you can live with. My pack includes features that you might be able to live without. Where I need features I have done them in a lightweight way.

Design

This pack is based on what was right for my body and the trips I was planning. As it happens the pack is far too big - It does handle loads from 30-50L but in practice 30L is all I need. The pack was constructed over a few weeks and in that time all my gear shrunk and so less volume was required.

I'm not going to give patterns and precise dimensions because this is one of those times when I think it would be useful to do what I've done - find a pack that fits you well and use that as a rough template.

The total cost of the bag was far less than any commercial equivalent even if I did have to buy 1m lengths of some of the more unusual fabrics and have most of it left over...

Materials

• Main Body - approx 1x1.5m of Silnylon in a cylinder
• Back and base - 250d Cordura with 3mm padded mesh pads
• Hip Pads - 500d Cordura with 3mm padded mesh
• Side Pockets - Kit Mesh edged with 2oz PU-Coated Nylon
• Front Pocket - SilNylon Bullfrog pocket.
• Shoulder Straps - 50mm thin nylon webbing backed with 3mm padded mesh
• Hip belt - 25mm webbing with 25mm double buckle
• Shoulder strap fastenings - 25mm webbing with ladder-lock buckle
• Bag closure - 20mm webbing with captive buckle
• Fitting loops - 10mm webbing

Construction

This section will lay out the details of how I constructed the bag and the issues I had with it. It took about 3 days elapsed to build this bag. That is a lot of work.

Construction is given in the order that I did it - which was not always ideal.

Construction - Shoulder Straps

The purpose of a shoulder strap is to stabilise the load and to spread it over your shoulders. My shoulder straps never actually carry much weight. The thik padding you see on shoulder straps may look very pretty but it adds weight and is not particularly functional.

The shoulder strap is 50mm webbing. I've extended the width by stitching a 7cm strip of 2oz PU-Coated Nylon to the webbing and then slicing out the middle to leave a thin strip either side.

The shoulder starp is backed by an open mesh fabric that is itself bonded to a 3mm layer of open-cell foam. This mesh is fitted to help with comfort and to help with removing sweat from under the straps.

The straps are constructed inside-out and then pulled through themselves like socks to produce neat edges. The edges have then been hemmed with a single line of stitching.

The buckle loops habe been attched to both the top and the bottom of the webbing in such a way that they do not touch on any part of the body.

Every 10cm or so on the strap I have placed stitched perpendicular to the strap to completely ensure that the mesh and the webbing act as as a signle piece.

Construction - Hip Belt

The hip belt is constructed in a similar way to the shoulder straps.

1. Stitch some 25mm webbing to a piece of 500d Cordura. Arrange it so the webbing is on the OUTSIDE of the cordura (away from the body.

2. Stich the mesh onto the hip belt sections so that it is inside out. ONLY stitch the long edges!!

3. Pull them through so that everything is the right way around.

4. Stitch around the edges to produce a clean (and stable backing).

Note 1: The mesh is not stitched for the last 3cm nearest the pad.

Note 2: The pad size itself is about 3-5cm larger than the external size would suggest in order that it can be fixed to the pack...

Construction - Back and Padding

The back-panel and base panel are a single piece of 250d cordura which has been cut 4cm wider than nominal width in order that the seams can be done.

I have used the 3mm padded open mesh to create 3 pockets. These pockets have then been stuffed with pieces of closed-cell foam cut from the cheapest camping mat that I could find. [Camping mat foam is designed to carry your body-weight without collapsing and so it works well for back padding.

This design is a little flawed and really needs a central triangular patch as well... YMMV.

The pockets are constructed by stitching 3 pieces of the padded mesh to the back and stitching each one on only 3 sides. The stitch used is a Zig-Zag stitch (to flatten the edge) AND a straight stitch (to provide a clean pocket shape for the pad.

3 pieces of foam were cut to just-slightly oversize so that they would be a very tight fit when installed. The foam was inserted and scrunched a little so that each pocket could be sealed. The foam was then unscrunched to produce a smooth pad that does not move around.

The Shoulder straps are attached to the INSIDE of the back-panel using a Flag Stitch AND some random lines of stitching. This stitching carries a lot of weight and so I've done several lines of stitching where the strap joins the fabric.

The hip belt pads are attached in a similar way but the mesh has been put onto the outside of the fabric and the cordura has been stitched onto the inside of the fabric.

The pads have been fitted through a slot cut into the back-panel on what will be the final seam-line.

Construction - Side pockets

The side pockets are pieces of kit mesh that are about 50% wider than the final pack depth.

The base of each side pocket has been hemmed with some 2oz PU-Coated Nylon and this has been pleated to remove the extra width.

The top of each pocket is constructed in the same way BUT the 2oz PUCN is formed into a little tunnel and into that tunnel is fitted some 25mm elastic. The elastic is about 50% of the width of the 2oz PUCN and is stitched very firmly to each end of the tunnel.

Construction - Front Pocket

The front pocket is a bull-frog design. This means that the fabric is much wider than the pack at the top and about the same width as the pack at the bottom. My pocket is about 1/3 of the overall pack height. I've made it with SilNylon.

The pocket is closed with a zip that is fitted at the widest point. The top of the zip is fitted to the final piece of the front pocket which is a bit of fabric that has been pleated to reduce the width down to the pack width. [Not a fantastic piece of design and not 100% waterproof).

Construction - SilNylon Body

The main body of the pack is a single piece of Silnylon. It forms a tapering cylinder for most of the pack length but on my pack was not wide enough at the base.

On the inside of the silnylon are stitched two 2cm rails of cordura which are used as anchor points for the pocket seams and the compression strap loops.

Inner Cordura Rails (looking down the pack)

Outside of Cordura rails - note single line of stitching to hold it in place

Pocket Stitching (Pocket seam has been folded in on itself for neatness

The internal strips follow the line that would have been taken if the pack had been made up of panels. It is stitched where one seam would have been.

The pocket should be fitted to the body first. The base of the pocket is going to align with the base of the fabric.

The side-pockets should also be part-fitted so that their bottom seams are tacked in place AND their side-seam where they meet the pocket is also stitched. Make sure that the elastic is on the seam and has several rows of stitching to hold it.

When you are finished you should have a complete bullfrog pocket attached to a piece of silnylon and two side pockets that are half-fitted.

Construction - Compression Straps

I have fitted two types of loops for compression straps:

The simplest, lightest and weakest consists of 5cm of 4mm nylon cord that has been sealed and then stitched several times onto the outside of the cordura rails. It's not going to last for 20 years...

The second type consists of 6cm of 10mm nylon webbing that have been stitched as showing above. They are designed to take the weight of attachments such as sleeping mat loops and walking sticks.

Construction - SilNylon Body / Cordura base attachment

The base is attached to the SilNylon using a few lines of stitching. The pack is turned inside-out, a little bathtub is created from the Cordura and this is stitched several times with reinforcing being added to the corners.

Construction - SilNylon Body / Cordura sides

For the sides I have put the seam stitching on the OUTSIDE of the pack. (This makes it a bit easier to seal). The seam are single stitched and then rolled back onto themselves and stitched again. I've also used the resulting seam as an attachment point for compression loops.

Where the side seam meets the hip pads I have stitched through the lot to create a strong bond.

Construction - SilNylon Body Roll-Top closure

One of the simplest, lightest and most waterproof ways to close a pack is by using a roll-top closure. For a roll-top to work it must be stiffer than the thing that is closing and must be rolled at least 3 times. The 'proper' way to do it is to use a semi-rigid strip of plastic to act as a stiffenner. I didn't have any and so used 20mm webbing instead.

To create the closure I stitched a loop of webbing onto the outer edge of the Silnylon. Onto that loop (at opposite sides) I have fed a buckle. The buckle is held in it's own little loop created by stitching in some slack.

Construction - Internal Backpack Frame

On this pack I have done two things to help with the load carrying.

I've created an interior pocket by stitching a patch of Silnylon between the two back seams. Into this I have inserted a piece of cut-down cheap camping mat. This adds stiffness, supports the main back pads and helps to keep the pack load in place.

The second thing I have done is to fit two thin pockets that run the length of the seam. Into these I have added a strip of 6mm aluminium tubing. This allows the pack to develop a contour that matches my back and also transfer the load very effectively to the hip belt. Full construction details can be found here.

The pockets have been made of SilNylon. The base of the pocket is reinforced with cordura. The top of the pocket is reinforced with cordura and has velcro so that when folded over it stays put.

Construction - Finishing Touches

1. My pack includes a carrying handle made out of 20mm webbing that has been stitched onto the top of the back-panel.

2. Onto the Right-hand hip pad I have used a ladderlock buckle and some 20mm webbing to create a miniature belt onto which things can be hung. I find it great for hanging my compass and map pocket etc.

3. Underneath the pack I have added some loops for a trekking pole and a camping mat. See here (mat loops) and here (pole loops).