Question about “true rating” of MontBell SS UL #1

add another overbag to get another 15-20F … then add vbl and clothing

trying to get -11F out of a 15F bag is quite a stretch … at those temps you have no margin for error

I have always found MB bags optimistic with respect to their warmth rating, despite the restrictions of EN testing. Having said that, Eric is right. Personally, in winter conditions I want a bag that is rated to the expected temps, lest you get into a situation that causes hypothermia or worse. Extreme cold is not an environment to try out some UL tactics that may or may not work for you.

Ure: I have always found MB bags optimistic with respect to their warmth rating, despite the restrictions of EN testing.

+1

"I have always found MB bags optimistic with respect to their warmth rating, despite the restrictions of EN testing."

Also agree. I am a Montbell retailer, (and Valandre) and have tested several of their bags and jackets. While I like their design, I have been disappointed in their warmth ratings as David stated.

I suspect that it could be due to the use of immature down, but that is only a guess.

Valandre', by comparison, uses mature goose down, and I have found their ratings to be spot on.

del

SS UL #1, I don't know, but I have two MB bags — UL down #3 and the Thermal Sheet — and I find them spot on at 30 and 50F respectively. I always sleep wearing long silk base layer plus liner socks — for comfort and to keep body oil / grime away from the bags.