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Mammut's Sphere UL and Light Pump Sleep System on Mt. Rainier

Posted Wednesday, July 3, 2013
Gear Reviews

Enjoying a post-climb nap time with the Mammut Sleep System

It seems that the "blue bubble" may have finally arrived in Washington.  After a largely damp and gray May and June, we hit a blue streak last week.  Under clear skies I headed out with a team to explore "Rainier's Wilder Side"--the Emmons Route.  By the numbers, about 70% of Rainier aspirants climb via the Muir/DC Route, 20% climb via the Emmons Route, and 10% climb via other routes. So Rainier's Emmons Route tends to be a quieter, wilder way up the mountain.  

A few of the reasons that the Emmons Route is quieter than the Muir/DC Route are:

  1. It requires about 1000' more vertical feet of climbing.
  2. There is no climbers' hut at Camp Schurman (there is at Camp Muir), requiring everyone to bring tents (and tent-weather appropriate sleeping bags)--so heavier packs.
  3. Approaching Camp Schurman typically involves an overnight camp on the Inter Glacier, adding to the overall length of the climb.

All of these reasons made an early-July Emmons trip an excellent place to test out Mammuts Sleep Systems.  With freezing temps predicted in the 14K range, I opted to go light and bring the Sphere UL Spring bag and the Light Pump Mat UL.  Together, these two pieces weigh in at just over a kilogram (1080g)--about 2 pounds.  I typically sleep a bit on the cold side, so I was a bit concerned about how I'd feel with the Sphere's 29F rating.  When considering sleep systems, people often focus only on the bag, and forget about the integral role that a sleeping pad plays in reducing conductive heat loss (especially when camped on snow, as we were).  With a stout 4.1 R value of insulation in the Light Pump Mat UL, I knew I could rely on the pad to take up any slack.   

In the end, there was no slack to be taken in:  surrounded by the Sphere's 240g of top-quality 850 fill down and supported by the Light Pump's cushy margin of R-value, I slept with the bag partially unzipped most of the time.  And in our crowded tent, I appreciated the non-slip nature of the Light Pump's "squareTX" fabric gripping my sleeping bag, particularly as the snow began to melt underneath.  I also appreciated that the squareTX fabric is much more rugged than many other air mattresses on the market, allowing me to rest easy without the worry of popping it--and all that R-value, coupled with the ruggedness, still only weighs a total of 560g.   Conditions were very dry during our time on the route but the warm temps meant that inevitably a bit of snow was tracked into the tent--no problem though, as the Sphere UL is coated with an effective "prolightTX" water-resistant fabric.

If you go onto Mammut's product page, you'll see that we market our bags and pads under the heading of "Sleeping Systems."  That's exactly how one should consider their bag and pad combo, as a combined sleep system--taking into account both the temp rating of the bag and the R-value of the pad.  Together the Sphere UL Spring (rated to 29F) and the Light Pump Mat UL (4.1 R-value) provide a reliably warm summertime alpine sleep system with a combined weight of only 2 pounds.  In the coming weeks, I'll be up adventuring in the North Cascades and this system will definitely be in my pack.  This sleep system will also be a fixture in my pack when doing spring, summer, and autumn overnight rock and alpine objectives in the Northeast (Huntington Ravine, Katahdin, Adirondack High Peaks, and the like).  Taken together the Sphere and Light Pump are two pounds of pure sleeping joy!

As always, you can see more pictures of recent climbs (including this one up the Emmons Glacier) at the Adventure Spirit Rock+Ice+Alpine Facebook Page.