Tangled Metal wrote:Whichever way you look at it a downmat 9 with dry bag pump is half the weight of the big thermarest.
A Downmat 9 LW is 1250g + bag/pump, a Downmat WinterUL LW (7 cm thick) is 760g + bag/pump, an Xtherm Max is 570g + bag/pump
The Downmat 9 has an R-value of 8 US = 1.4 SI, vs 5.7/1.0 for the XTherm (which is about the same as a Downmat 7).
I rode Lhasa to Kathmandu in October 2000. Overnight temperatures got down to somewhere in the region of -18°C (daytime was perfectly tolerable (+12°?), but temperatures plummeted as soon as the sun went behind a mountain). I can't remember what I used - tent, mat and sleeping bag was supplied by the trekkiing company.
On those occasions I've bivvied/camped in proper cold (Antarctic), I used a Lilo, a thicker grade yellow Karrimat (Karrimor was a good brand then), and a sheepskin. The coldest was -50°C, more usual was -30 to -35 (on the ice).