Content and images by Jefe Branham   I like to make things. Sometimes because I can’t afford the real deal and sometimes because no one makes just what I want or need. I have been sewing my own gear for years. Most, if not all, of my bike bags are homemade. I also make my own sleeping systems. This consists of a simple “bivy-bag.” Basically a waterproof sleeping bag, or an insulated bivy. Simple, light, easy to throw onto the dirt at the end of the day(s) and easy to pack up so I can get rolling after resting. Over the years, I have been creating these “bivy-bags” lighter and lighter with the available materials, and insulation has been getting better and lighter as well. I have been scheming this latest design for years. Due to the cost of some of the fabrics, I never got around to building it. Recently, I took the plunge and ordered hundreds of dollars worth of materials that came shoved into two small padded envelopes. It was a shock to see how so little material can cost so much money, but that is the way manufactured ultralight gear works these days, right?  I did a lot of research and no one makes a sleep system similar to my design. The basic design is this: A waterproof breathable Cuben Fiber top, 17 g/m2 Cuben bottom, with a top layer only of ClimbaShield Apex as insulation, lined with breathable Momentum 45 and a sleeve on the bottom to hold a thin foam pad in place. This project meant a few firsts for me.  I was going to use only a “quilt” style top layer of insulation. I was also using Cuben fiber for the first time and that meant using special double sided tape as well as stitching to hold it all together. The goal was a sub pound (454 gram) sleep system including the pad. I modeled the whole thing off of the bivy-bag that I used in my 2011 Tour Divide run. I also used this system many times since and the size is about perfect and it works great. So, I measured the model bag several times, made a lot of notes, got out the new fabric and started cutting. began cutting I made the outer shell first. Taping, then sewing the waterproof breathable Cuben to the non-breatable Cuben bottom. My plan was to tape, then sew just on the outside of the tape so that the seam would remain waterproof. However, the needle was getting gummed up going through the tape and kept snapping the thread. After a few tries and some thought, I figured out that WD40 cleaned residue off of the needle… so I got a Qtip, soaked it in WD40 to sit just right on the thread feeding into the machine and I was back to stitching. stitching the shell after taping Taping was interesting and tricky to do in tight spots or the curves of the footbox. I ended up liking the tape a lot and will use it in the future as it is clean, waterproof and pretty strong. Cuben Fiber is cool stuff, I will definitely use it again for future projects. taping the curves of the footbox was the hardest part, but wasn't too bad After  getting the shell done. I moved on to the upper liner of Momentum and Apex.  I cut them to size, stitched them together at the edges, and then stitched them to another bottom piece of non-breathable Cuben. I did not quilt, or sew through any of the insulation. Apex is made for big panel projects like this, and my last bivy bag was made the same way and has held up great, so no quilting= less sewing, less cold spots. insulation stitched to the liner along the edge only, no quilting Once the liner was together I simply sewed them together at the head of the bag while adding in a simple shock cord/ toggle closure.  Of course, I left the two bottom pieces of Cuben separate so I can slip a thin foam pad in between, and thus the pad stays put and can not shift from under me while I sleep. insulated upper and sleeve bottom with foam pad in place The whole project took me a good part of a day to complete. It was smooth sailing for the most part. Best of all the bivy-bag came in under a pound at about 450 grams with the pad! Next comes the fun part, testing! total weight bivy and pad, sub pound! Yes!


  1. Nice thinking Jefe. I am looking forward to the “comfort level” follow-up on this story.

    btw: When I first saw the photo I thought you had stuffed a Ken doll in a paper sack. LOL. Great modeling.

  2. So Jefe, no sleeping bag, correct? You just get in and you’re good. How breathable do you think this will be? How do you deal with rain? Looks right for light and fast.

  3. Daniel Landes

    You are the coolest mother fucker on the planet. always was and prolly always will be. proud to know you.

  4. Just got done with the Colorado trail with tent and down sleeping bag, getting passed by bikepackers the whole way and was building this bag in my head, but with tyvek and micropore…cool project. How much was the total cost?

    • Cost for the bivy bag was about 250-300$ I think. Hard to say exactly with left over fabric and insulation being used to make other projects. I thought the B/B worked quite well, could use some refinements, but would be on my gear list for the TD was I to do it again. I was not inside it for more than 4-5 hours at the most but it breathed just fine, kept me quite dry even in the nastiest conditions I’ve ivied in in years. Could be made much cheaper and a bit heavier with GoreTex Paclite, used that martial for a previous B/B and it is still a great bag but added about 100-150 grams??? Thanks for the interest everyone!

  5. Rad. The sleep system for the dude that doesn’t sleep. Nice tinkering

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