If you’re looking for a way to lighten your hiking pack this summer, Rab’s new Mythic Ultra sleeping bag line makes a serious case for mummy bags. If you were hesitantly thinking of switching to an ultralight quilt to save weight, this new bag might make you pause and reassess. Like UK-based gear maker's award-winning Mythic G down jacket, the Mythic Ultra sleeping bags use goose down and titanium—yes, a titanium sleeping bag (sort of, we'll explain!)—to make a seriously light sleep sack.
The Mythic Ultra line features three bags rated for 32, 20 and 10 degrees. The technology doing the heavy lifting is called Thermo Ionic Lining Technology, or TILT. It coats the interior lining with titanium particles, creating a silvery look but leaving a familiar soft feel. Theoretically, it also reduces radiant heat loss by reflecting body heat back toward you the same way a space blanket does. Because TILT handles some of the thermal work, Rab loaded less down into the bag (though it's still using 900-fill here, the good stuff) which helps the bag save on the scale.
It's worth noting that the actual effectiveness and physics of reflective tech is often ineffective when positioned next to skin, so the efficacy of TILT could vary. All the same, it’s an impressive attempt to make mummy bags compete in the same world as quilts without some of their downsides, like draftiness.
Courtesy Rab
All three of the new Mythic Ultra bags are filled with 900-fill hydrophobic European goose down and have a unique baffle shape not seen on other bags that Rab calls L.O.F.T 3D. This uses helix-shaped baffles that prevent down from migrating and keep loft even across the bag. Baffle preferences vary, but as long as they’re not sewn-through they should be effective at mitigating down migration.
The 10D Pertex Quantum ripstop outer is pretty standard for ultralight gear but it is thin, so this bag will require some babying. Fortunately, Pertex Quantum is known for being stronger (and more wind resistant) than other fabrics. Fragile shells are par for the course in the ultralight backpacking game of saving grams above all else, so you should expect to be careful with anything this lightweight.
Whether or not TILT is the magic heater I want it to be remains to be put to the test, but there’s no denying that the Mythic Ultra line brings some seriously premium bags. Ingredients like 900-fill goose down and a 10D Pertex Quantum shell are what you want to see on the spec list for a piece of ultralight gear, and the bags should provide plenty of campers with a lighter pack and great night’s sleep.
Courtesy Rab
Here's how the line breaks down.
Mythic Ultra 32°F
Weight: 1 lb 1.6 oz
Price: $525
The lightest of the three at just 500g, and the one that competes most directly with quilts. It packs down to just 6.3 x 11.8 inches and uses a super-short ⅛ length zip to keep weight to an absolute minimum (zipper teeth = excess grams folks). Ounce for ounce, this is the sleeping bag that competes with backpacking quilts.
Mythic Ultra 20°F
Weight: 1 lb 8.7 oz
Price: $625
This is the three-season sweet spot. At 700g with a comfort limit of 21°F, this bag covers the vast majority of backpacking conditions while still packing down to 7.1 x 11.8 inches.
Mythic Ultra 10°F
Weight: 2 lb 0.45 oz
Price: $775
The coldest and most capable of the line. At 920g with a 10°F limit of comfort and a packed size of just 7.9 x 13.8 inches, it pushes into shoulder-season and genuine cold-weather territory without taking up your entire pack.
