Create an Internal Frame in your U/L Pack
The one thing that I really miss from my ultralight packs is an internal frame. I have found that even with the relatively light loads of 5Kg base weight and under that without an internal frame it is very difficult to get the pack properly stable and comfortable - lots of small things in a pack does not compress down too well!
After playing with my own pack design (45L, frame, padded back and 350g leanweight) I realised it would be very easy to add a frame to my OMM 25L without much effort or weight.
Here is a picture of the finished article:
This project is also one that can be hand sewn.
What I have done is take two strips of scrap fabric (in this case it is 0.75oz Spinnaker fabric) that are approximately 6cm x 55cm.
They have been folded over to make two tubes and then the ends of both tubes folded over and stitched to seal them.
Finally I have stitched the tubes to the seam edge of the pack (on the inside) at 4-5 places including of course the top and the bottom. (Use a 14 or 16 Leather needle if machine stitching through the seam). For best results stitch the entire length of the pocket.
So far no frame right!
To create the frame what I then do is insert one section of my tarp pole in each tube. This creates a rigid frame to the pack - perhaps too rigid. I have of course been able to cheat. My tarp pole sections have been cut to fit in the shortest pack that I use - this one.
If you do not carry tarp or tent poles that are more-or-less the right length then the alternative is two 45cm lengths (Your pack may vary) of 6mm aluminium tubing (total weight < 50g) or you could buy a 1m length of Carbon Fibre tubing (<20g) and use that. If 6mm is too soft, 8mm will be pretty stiff.
Either way, for a maximum of 50g on your pack weight you can add a good working internal frame. This is about the same weight as is lost from removing a few of the unused gear loops and toggles from a pack.
Note 1: After extensive testing with my own pack I have decided that 6mm Aluminium tubing is optimal. The main thing about the tubing is that it is soft enough to bend. This means that over the course of a day or so you will end up with two aluminium tubes that exactly follow the curve of your back - which is just what you want.
Note 2: I have found it useful to add Velcro to the top of the tube pocket so that the top can be folded over. This stops the tube moving during use.
For a tougher version of the tube pockets you can add a little strip of tough fabric - such as cordura to the bottom of the pockets and also to the top. For a luxury finish you can also attach Velcro to the top of the pocket so that it can be folded over and completely lock the tubing into place.