Gear Review: Big Agnes Bellyache Mountain SL 17 Sleeping Bag

Lightweight and affordable, this bag will keep you warm and dry in a variety of weather.


ThiLight, warm, and affordable for a bag of its rating, this mummy uses 700-fill DownTek and vertical baffles (a lightweight construction that channels warmth from the core to extremities) to provide comfort right down to its rating. On 20°F nights along New Hampshire’s AT, I stayed cozy and detected no cold spots—even at my feet, which often feel chilly in other bags. The DWR-treated nylon shell fabric and water-resistant down (which is coated with a hydrophobic polymer) take the worry out of wet weather. The cut is efficient but not confining. $300 to $340; 17°F; 2 lbs. 7 oz. (reg.); 3 sizes;

Best For

Three-season hikers who want lightweight warmth

Tester Data

» Seth Urich (other testers: Kristin Hostetter, Jonathan Dorn, Brian Mockenhaupt)

» Duration Feb. to Nov.

» Locales/conditions CA, ME, NH, WY; 20°F to 60°F

» “Unlike previous BA bags, this has insulation on the underside, yet it still packs to volleyball size.”