Companion forum thread to:

Western Mountaineering Summerlite Sleeping Bag REVIEW

I wish I had a WM bag in my kit [note 'ars3nal' was considered profanity!? huh??]; maybe some day. For those few hikers like me who do not like the feeling of a tight mummy bag and like to stretch, roll around, cross legs, etc.. MontBell might be an option. It was my choice; 'stretch baffles' constrict gently to maintain maximum loft, or expand to give 75% more internal volume (compared to this Summerlite). Stretch baffles also automatically make more room for extra layers, such as a synthetic lofting pants/jacket combo, without compressing it much.
1lb 7oz for a 0'bag:
https://www2.montbell.com/america/asp/products/Spg_shosai.asp?cat=1101&hinban=2321663

The WM Megalite is the marginally heavier, more roomy version of this bag. I'm not "lean" like the author, so that pretty much made the decision for me as far as one vs the other :)

Yes, the Megalite is definitely an option if you want, or need, the extra room. The only other difference (besides dimensions) between the Megalite and the Summerlite is that the Megalite has a neck collar, while the Summerlite does not.

Brett, i have a WM Highlite - short length bag. excellent bag in quality of construction and performance.

has a few weak points on design however, viz. poor hood design, wt. saving half-zip makes getting into the bag (particularly when in a tight bivy sack) a bit of a challenge (but all that wriggling activity contributes to initial warmth!!), quite tightly cut - again to save weight and increase warmth of the 7oz of down fill. i'm not going to get into diffs b/t MB 725FP down and WM 850FP down. if interested, search the Forums, this has been discussed a number of times.

i have come to prefer the MB SS bags to the WM Highlite.

Why?

a) well, of course the SS system
b) full zip
c) much better hood
d) perhaps better for extending range by wearing high loft insulating jacket due to the SS system. in fact, when wearing hi-loft ins. jacket, the MB bag might actually be warmer than the Highlite since the SS permits wearing the jacket with little or no loss of loft of bag or jacket (admittedly, this is more of an assumption on my part, because while i've done this, i really haven't done side-by-side comparison testing). in the Highlite, it is a tight squeeze even w/o wearing a high loft jacket to increase the temp range, hence my prev. assumption that wearing a BMW Cocoon inside of the Highlite will result in compression of the insulation of either the jacket and/or the bag (so, will there be any net gain in insulating ability???).

downside of the MB is the few ounces of extra weight of the MB bag in order to get a somewhat similar temp rated bag - again, though, this might be offset a bit if using a lighter MB bag and wearing a hi-loft layer in the MB bag.

I am 5'6" and 160 lbs. I have the regular length AlpineLite which is a wider version of the UltraLite Super (both 20 deg F bags), thinking that a little extra room would be nice for additional insulation (down jacket or summer down bag on really cold nights) and storing shoes and water bottles inside. At times I have wished that I had gotten the 5'6" UltraLite version since my feet have felt cold, and the extra width has left me feeling cool...even with the legendary understating of WM bag temperatures. Sometimes there is just too much space. However, when I was shopping for the bag the UltraLight did seem a bit too tight.

Has anyone else had trouble with limited space or excessive compression on the narrow WM bags?

Tom

Tom, I'm not quite as slim as I should be at 6' and 205#. I have the WM HighLite. It too is a slim cut bag. Measurements are listed by WM as shoulder - 60", hip 52", and foot 38".

It is snug. I've only had 2 nights out where I've needed to wear insulation to bed using a GoLite Coal jacket with hood. I would say that I don't have a 1/2" to spare. Another couple of inches in the shoulders and hip would feel better to me. I don't know that it would make the bag perform any better. I agree with WM's claim that the MegaLite warms quickly.

As PJ pointed out the hood could be a little better. But overall, I'm pleased with the weight and great warmth of this bag. My long bag weighs 16.9 oz. There have been some compromises to make it this light -- a short zipper and no draft collar for instance. Those are OK for what I seek in a 3 season bag.

Don

Did you have any problems with your legs (the feet specifically) getting cold at night in the Sierras. I see that most of your insulation is torso and head and wondered without insulation under the feet did you have a problems?

Randy

Randy -

I had no problems with warmth at all. In the Sierras I frequently camped low, at 8000 or 9000 feet, but I did spend a few nights at or above 11000 feet. Sometimes I'd put my pack under my feet, more for comfort than for warmth. The footbox on the Summerlite is nice and square, and well filled with down. It is a darn good bag - though I have not tried the MB stretch bags.

Don,

Have you used any of the lighter bags from Marmot and if you have how do they compait to WM's?

Randy

Thomas, i too am a wide-body, albeit a very short wide-body. i can use a WM Highlite - short length, which is a very fine bag (both in quality of construction and performance), but can barely move inside, making zipping/unzipping downright difficult. The tight lower body is fine, it's just that, IIRC, 59" shoulder girth. Also, WM is generally spot-on in their claimed lower temp ratings, and i consider myself a cold sleeper (though i need non-hi-loft layers to get to the Mfr. claimed lower limit of range).

i prefer the Montbell SuperStretch bags over my WM bag. However, to get equivalent warmth in an MB vs. WM bag, the MB will weigh more, IMHO.

The MB SS system will avoid the cold spots that might be caused by larger air volumes next to your body. It also allows ease of movement inside the bag while excluding the extra air next to your body, even at your feet - sort of a "win-win" situation.

Figure a MB SSDH #3 will be 23oz with 0.5oz more down (lower fill power, but let's not get into that issue here) as cp. to the WM Summerlite.

The SS system allows shoulder girth ranges, IIRC, from ~53" to ~71" with its GENTLE, non-compressive SS system. It's very easy to layer a hi-loft jacket (and pants, if so desired) to extend the range of the bag w/o compressing either the hi-loft clothing or the bag's insulation. Under these circumstances you might be able to take a slightly heavier (than its WM counterpart) down further than you would with the tighter fit of WM. Though as Shawn Basil has recently pointed out in another Thread, he achieves better results by laying his hi-loft clothing on top of his bag to extend the range, thereby eliminating compression and loss of loft.

The SS system avoids the issues some people have of a roomier cut WM bag and heating that extra air, particularly at the footend.

MB prices are comparable to WM prices.

Just a thought.

Randy -

I have a Marmot Atom that I am testing now. I did a short Spotlite review on it a few weeks back - look over at the spotlites.

The specs on the Atom are very similar to the Summerlite. But the Atom uses sewn-through construction and has a half zipper. I've got more testing to do before I weigh in on the comparison between these two bags.

I may do a side by side comparison article in 2007. I am specifically interested in the performance differences between the baffled construction of the Summerlite and the sewn-through construction of the Atom. It is the collective common wisdom that sewn-through construction creates "cold spots" or is generally inferior. But how much? Is this really significant? Do other aspects of construction and design overcome these differences? I'm working on some ways that we might be able to quantify and test this - specifically by comparing the performance of the Summerlite and the Atom in some type of controlled test. No guarantees yet that we will be able to complete that test - but it is under consideration.

Would you readers find that comparison interesting?

Sure.

[BT, how's that for a short post!!!]

Hello Don,

What I saw recently that interested me was that someone had placed two different sleeping pads on top of a thermal imaging sensor so that you actually see that cored foam did leak heat more than a solid sheet. I would like to merge the two ideas together and be able to see where sleeping bags leak heat and how much of a difference draft collars and hood openings help conserve heat.

Randy

Randy -

You nailed it. That's exactly what we are looking at doing. But if we do that, we'll try to keep it controlled enough to make the data valid. Otherwise, we probably won't do it.

PJ - Impressively short post. You've left little room for future brevity improvements :-)

Don

Edited by don on 12/21/2006 11:22:20 MST.

Randy-There is an alternative source for the information you are seeking, if they sell their bags to EU countries. If they do, ask the vendors for a copy of the Informative Appendix for their bag's EN 13537 Test. Non uniform heat losses are clearly quantified by the 20 manikin segments.

Edited by richard295 on 12/21/2006 11:28:31 MST.

Thank You, Richard

Don:
I would be interested in a side by side by side comparison with the MB SS #4 rated to 37 degrees. Sewn through vs baffled vs SS with compartmented baffling. The weights of these bags and prices are close enough that most of us would, I think, consider each in a purchase decision matrix. When I hold my MB bag up to bright sunlight I can see how they have constructed the individual squares for max loft to work with the SS system. Very impressive. And for those of us who take your caution that if you are not slim or a toss-n-turn sleeper an altenative should exist to the narrow cut mummy.
Addendum:
Check my User Review of the MB SS#4 bag which I updated.

Edited by mitchellkeil on 12/21/2006 12:18:31 MST.

I think that the MB SSDH #3 is a better match when comparing against +30-32F rated bags, since the MB SSDH #3 is rated to +32F. Sure it's heavier, but also has 9.5 vs. 8.1 oz of down (the Summerlite has 9oz - if i remember the review spec correctly), and i'm not sure that the #4 will perform well, but then, i'm a cold sleeper.

However, comparing similarly Mfr rated bags (hence the #3 vs. the #4 in this comparison) is probably the way to go.

Ideal would be to compare BOTH the #3 AND the #4 with the Atom and Summerlite.

Do you disagree Mitchell? If so, please let me know.

Edited by pj on 12/21/2006 12:59:05 MST.

PJ:
Because of the rating method that MB employs, both the #3 and #4 intersect with the WM bag and Marmot bag. The sweet spot temp that MB uses for the 8 hours of uninterupted sleep would suggest the #3 would be the better fit. But much does depend on the sleeper. But you are right that 9oz of down is very close to the amount for each of the other bags. Since I sleep warm, I tend to think of the #4 as my 32 degree bag and it is closer to the actual overall weight of the other two. So perhaps we need a side by side by side by side comparison (or a side to the 4th power comparison.)Regardless, a comparison should be made between MB bags and these other lightweights because of the issues I and others mention in the previous posts.