This is the mummy version of the Serpentes False Bottom Sleeping Bag. It’s narrower in the torso than the fetal position systems with a smaller differential cut. It’s meant to bend with your legs rather than allow room to curl up inside.
The Serpentes Sleeping Bag is a full sleeping bag with a false bottom. This is a full sleeping bag that wraps all the way around the sleeper, just without the insulation in the bottom where it is compressed and has limited effectiveness in a traditional bag. 12″ of the total torso circumference is the false bottom. This design pushes weight savings well below traditional bags and even below quilts, but performs totally draft free like a full sleeping bag. Venting is accomplished with the top drawcord. It has horizontal baffles, a differential cut, a puffy draft collar, and super dense 160% overstuffed chambers.
The Serpentes takes the false bottom design a step further. One limitation in weight reduction of the Wren false bottom is that the top circumference needs to be large enough for the user to slide their shoulders in. Once in, there is extra insulated area here that just gets cinched together. The Serpentes has a false bottom that extends up to the top, with snaps to cinch it together once in. With 6″ of the top width as false bottom, the system is large enough to get in but the insulated width is only what you need when it’s cinched down. This reduces weight by removing unnecessary insulated area and 6″ of shock cord. The Serpentes also uses Argon 49 7d shell fabric, 1000fp down, ultralight shock cord, and ultralight baffle fabric. Unlike the Wren, it has no pad strap attachments. Since it is such an ultralight focused system it also uses the older Timmermade temperature rating system. The new system is a very conservative rating and really overshoots the insulation needs of the average person in an effort to provide a comfort rating for everyone at the set temp rating. The Serpentes rating system is aimed at achieving a comfort rating for the average person so that the ultralighter can better dial in the level of insulation they need without carrying too much. This system was used for many years with an extremely high success rate for keeping folks warm. However, it should be noted that there isn’t a big cushion built into this system for colder sleepers and they may want to consider adjusting their temp rating.
It is important with any sleep system that it is paired with a sleeping pad rated to similar temperatures. It is especially important with quilts and false bottom bags and it should be noted that pads that utilize empty spaces are generally not suitable for these types of sleep systems.
See https://timmermade.com/sizing/sizing-sleep-systems/ for information on sizing.
This should be used with a Waterbear Balaclava or it can be used with other types of head insulation. https://timmermade.com/product-category/sleep-systems/balaclavas/
This can be paired with an overbag to manage moisture and boost it’s temperature rating. https://timmermade.com/product-category/sleep-systems/overbags/
See the “Technology” section on this site for information about this system’s features.
Cory –
I got the false bottom in 20*. I have spent plenty of nights in it now and I’m super impressed with it. Spending nights close to 11,000 feet this summer in the Sierra hasn’t gotten down to it’s rating, but I anticipate the bag performing as expected. In fact, I was worried I would be sweating due to lack of mechanical ventilation with a zipper. There’s something interesting here though, whether intended or not: one can position the bag to expose the false bottom, aiding in ventilation. One night the false bottom was indeed a false top and I slept so comfortably. The bag has the perfect amount of stretch. Super stoked on it!