Phantom Sleeping Bag (courtesy, Mountain Hardwear)

Do you have a question of your own?

I used to have a single sleeping bag that I used for summer, winter, Rainier, and lowland camping. It was the REI Mountaineer—a bag they stopped making many years ago. I don’t know what the temperature rating was, as back then bags were basically “thick” or “thin.” My guess is that it was a zero-degree bag. And it was fine in the winter and up high. Everywhere else, it was pretty miserable to use. Especially if mosquitoes were buzzing around and the options were A) Zip up in bag and par-boil, and B) Unzip bag and become a human sacrifice.

So it would be with the Mountain Hardwear Lyell ($350). It’s certainly a lot of bag for the money, with 600-fill down, a waterproof shell made with Mountain Hardwear’s proprietary Conduit material, and a thick collar around the hood to keep drafts out. But it’s really a winter-only bag. Even an expedition-type bag. It’s okay for a winter trip in Rainier, perhaps, but if you climb Rainier or Hood in the summer, then it will be way too much.

So I tend to think an “all-around” bag such as what you are looking for is more in the 20-degree range. That will get you around during the spring, summer, and fall; will work well up to 11,000 feet or so on Rainier (during summer months); and could pull light duty in the winter with a bivy bag and an extra set of long underwear.

In Mountain Hardwear’s lineup, that would include the Phantom ($355), a +15 bag that uses 800-fill down and superlight nylon shell material to drive the weight down to just under two pounds (the Lyell weighs in at three pounds, four ounces). Marmot’s Helium ($359) is almost identical in every way—weight, temp rating, fill material (slightly higher fill rating for its down), and shell. Or there is Western Mountaineering’s Ultralite ($355), a 20-degree bag that shaves the weight to one pound, 13 ounces and features WM’s famously high-quality construction. That would be my choice, to be honest.

To boost the warmth a little, add a Rab Vapour Barrier Liner ($40). This waterproof shell goes inside the bag and works by preventing cooling through evaporation off your skin. As a bonus, they also keep your bag drier because skin moisture can’t work its way into the insulation and freeze or condense. A Cocoon Thermal Liner ($60) also adds degrees, taking a 15-degree bag down very close to zero.

The 2008 Summer Outside Buyer’s Guide is now on newsstands. Look for it online soon.

RECENT QUESTIONS Can I use crampons on trail-runners for day-summit attempts? What’s the best way to keep plenty of filtered water on hand for a large group? Is a freestanding tent worth carrying the extra weight? Is military-style gear, specifically backpacks, suitable for everyday use? What’s the best super-light raingear for an extended backpacking trip? Search the Gear Guy

GEAR GUY FEATURES Check out the bio of Douglas Gantenbein, aka the Gear Guy. Readers' Mailbag: The Gear Guy digs into some of your more bizarre, obscure (and let’s face it, downright weird) posts from years gone by to see if he can make sense of it all, or if it’s just time to run up the white flag. Previous column: Beat the Cost of Gear. The Gear Guy reports from the 2005 Outdoor Retailer summer trade fair, with his rundown of ten products to watch in 2006, plus the inside scoop on what shook down at the bi-annual gearapalooza.

MORE GEAR The Outside Gear Blog 2005 Buyer's Guide State of the Art: 2005 Bikes