Cumulus Quantum Models – Pretty Impressive On Paper

Comparing the Cumolus 350 ( 665g) to the somewhat similar sized WM Ultralite (820g) , the Ultralite has an extra 100g (3.6oz)of down , about 30% more . The claimed temperature rating is similar so I find the Comulos specs unbelievable ( I don't believe them…)
Franco

I'm certainy no expert in this field at all, but the feedback from this forum suggests that WM bags are conservative on their ratings.

If you look at this taken from Cumulus website, surely there is more to a bag's true rating than just the amount of down being used in 2 'similar' bags produced by different manufacturers

'Differential Fill means that the quantity of down in the base is less than the quantity in the top of the sleeping bag. At Cumulus we employ a ratio of top: base = 3:2 (discounting the hood, neck and zip baffles). Hence the base has 40% of the total insulation instead of the 50% it would have if there was no Differential Fill.
The compaction of the base restricts loft and reduces its insulation value so the difference in warmth between 40% and 50% is quite insignificant. On the other hand, having 60% in the top gives a big warmth benefit compared with having 50%, since no compaction means that the extra down traps a fully proportionate extra quantity of air and loft is increased by a fifth'.

As I said, I really am no expert, but given that the WM Ultralite does perform better than it's advertised rating, surely the above paragraph, if it is deemed factual rather than just 'sales talk', might indicate that the Cumulus advertised ratings are possible.

Of course if the WM Ultralite is constructed as above, it sort of swings back to your disbelief and my concerns

The WM Ultralite has continuous fill baffles, which is probably why many find it 'conservative', because the down can be shifted to the top for colder conditions. It also gives it a bit more flexibility for warmer conditions, when more of the down can be shifted to the bottom of the bag.

It's also good for side sleepers. If more of the fill is on the top of the bag, that's going to make the back colder if sleeping on your side.

The ratings on the Cumulus bags may not be far off truth. Instead of using Chinese down they are using top grade Polish down. They rate it at 870 loft, and from what I know of Polish down that is probably NOT on the new inflated scale. It is likely to be on the old scale.

My 2c: I have not tested the bags.

Cheers

"Differential Fill"
That is clever, I wish I had thought of this ( about 50 years ago, 'cause everybody else has done that since….)
No I don't buy it. 3.6 oz of extra fill is not made up by the possible debatable difference between the down used by WM and Cumulus.
But I would be very happy to be wrong on this point.
Franco
As a dedicated tosser (and turner) the 40-60 does not work for me, however the WM continuous baffles, as Pamela has already explained , can do that, in fact if really cold ( has happened with my Ultralite) you can get most of the down on the top and hold still till you warm up. Best to have a good mat for this .

If you look at the Cumulus 450 with the same fill weight as the WM Ultralite you have a temp rating of -10 rather than -6. The down being used is a factor.

If you care to look at this site PHD Designs
and choose to custom make a bag using the guided route method and go to box 8 ‘Fill Weight & Quality’. from here you can see that the difference in temp rating for 450gsm fill using 800fillpower & 900fillpower is roughly 3.6degrees.

That explains the diffrence between Cumulus 450 rating -10 and the WM Ultralite -6.

Okay the fill rating of the Cumulus is not 900 but 870, but then the 2 bags are not identical either.

It suggests to me that the Cumulus range is worth further investigation.

It is quite possible the Cumulus bags are rated accurately, given that WM bags are under-rated, and as an owner of a polish down duvet I would also agree that it is the highest qualtiy stuff around. The differential cut and 60:40 design are so not novel that it makes the bags sound suspicious though! I would go so far as to say that those two features are 'standard' design features in all good down bags.

Anyway, none of the cumulus range are lighter than the conservatively rated WM PODs in terms of warmth to weight ratio, so their design is nowhere near novel enough to make them the lightest. Imagine if WM had used polish down in their POD series !

Oh yeah, and at 59" shoulder width, they are 3" narrower than the PODs…

So if I just want a bag that goes down to a true -6, and we work on the fact WM is overkill as it is conservative, will the Megalite be good down to -6(21)? as it has a rating of 30. Is that pushing it just too much?

EDIT – Allison what are PODs, please excuse my ignorance.

Darryl, a POD is a "top bag" that WM launched a few years back (no down on the bottom of the bag). They never really took off because WM designed them to mate with only their own weird and heavy mat, and the attachment wasn't very good. With a few minor modifications to the mat attachement, we now mate them securely with any mat we want. The POD 30F weighs less than a pound (mine is 435 grams), and the POD 15F weighs 750g.

I think how cold you could push a Megalite would depend on many things, including what else you have to wear in the bag, whether you are in a tent or tarp, bivy bag etc…but with the right layering system it should be fine.

My friend that manages a local outfitter was told by the Western rep that Western's down actually tests at 910 plus.

>Western's down actually tests at 910 plus.

I wonder which testing method they use? I won't disagree that WM makes very high quality bags for the weight, but 910 is higher than most of the best European goose down and approaching eider down.

They rate it at 870 loft, and from what I know of Polish down that is probably NOT on the new inflated scale. It is likely to be on the old scale.

Yes I assume it's 870 EU, which is about 970 US. PHD does 900 EU down.

You can go back and relisten to Western Mountaineering podcast.
Gary stayed there if I recall correctly that their method for down measuring is conservative and their source for down is Poland and Hungary.

Having 2 different measurement systems is a minefield. You have to reasearch what you are actually buying. It's too easy for worldwide manufacturers to quote the inflated US method. Just because it is quality Polish down means nothing. The same down can be manipulated to give different readings, depending on how it is tested.

From the Cumulus web site :
Polish goose down has been tested and certified by the International Down & Feather Testing Laboratory, Salt Lake City, Utah, USA to a MINIMUM rating of 680 cu in and 800 cu in respectively. Our newest 'diamond grade' white down scored 870 cu in, after steam conditioning.

Same lab same test that WM is using. WM claim sample testing between 800 and 830 but choose to stick to the 800 figure since they have observed that the higher figures drop quickly once the bag is in use.
Franco

That's the type of thing i'm meaning Franco. Why is a European manufacturer using US tests? How many EU buyers just assume that the figures they see are EU testing figures? They are getting an inferior product from what they think they are buying.

Franco

Yes well spotted.

I did use PHD Mountain software, and as I am inexperienced, i couldn't quite fathom out what the problem was, but the figures never quite added up to me. If I am correct in my thinking this company is being deceitful, and I have managed to find a forum thread that states that one of the 500gsm bags he received was 100gm heavier than it ought to have been.

Your findings together with other posters on this thread along with my own findings make Cumulus products a non viable option for me. Any company that needs to 'massage' it's figures in this manner would not get a penny of my hard earned cash.

EDIT: I just spoke with Cumulus and asked them to explain why this bag has a rating on a scale from the US (bear in mind I really don't know exactly what I'm talking about here). All I can say is that the guy on the other end waffled on about how 'it is more complicated than that' trying to imply that my concerns were not as I thought they were. The guy I was speaking to then received help from another colleague and came back and told me because the calculations are made in metric and imperial it is very hard to describe how they have attained their results, again reiterating that it's more complicated than that.!!!!!!!!!!!!!!!!!

http://www.downsleepingbag.co.uk/shop/sleeping-bags-c-84.html

> Our newest 'diamond grade' white down scored 870 cu in, after steam conditioning

! So do I need to steam condition my bag before each use to get it to loft? This whole system of measuring loft seems like a farce to me. Why not blow dry your down to get extra air into it too, maybe even add some helium to boost your FP rating?

Well all I can say that the price of the membership for this forum has opened my eyes in many areas. Although I’m not at the stage of replacing toliet paper with smooth stones yet, this thread just shows difficult it can be making purchases for the inexperienced.

Hopefully on Saturday I will be able to view a WM Ultralite to see what all the fuss is about, although I must admit with the current economic climate as it is it would be nice to buy British. With that in mind I have approached PHD Mountain Software who seem to be incredibly helpful and very transparent in what they can and cannot offer. In particular the custom made bags will allow me to have a wider fitting as I feel (prior to trying) that the WM Ultralite may be too restrictive for me. Anyway a big thank you to all here for gently moving me away from what looks like a ‘bad apple’.

I wouldn't go as far as to say Cumulus bags are 'bad'. Maybe not as 'good' as they at first appear to be.

I wouldn't say PHD were transparent either. Try and find out how much down they use in their UL bags and garments. It isn't on their website, and they won't tell you if you e-mail them. ;)

Mike

Thanks for PHD info. Surely if you go to the Do Your Own Sleeping Bag page and choose guided route and then choose -5 as a temp rating and choose the Minim you can see the quantity they are using and what grade too. For example the Minim 400 is using 400gm of 800fillpower down. Sorry if I being thick but am I right for I every time I think I’ve got it worked out another angle is added to the equation.

Re: Cumulus, I can’t stand deception. I couldn’t care a jot if the bag was the best thing out there. A British company has no right quoting US ratings to suit. We both know if it were the other way around (US figures gave lower numbers) Cumulus would either choose not to use them or would explain the lower figure. My 5 minute conversation with them did not install any confidence in them with me.

EDIT: Mike I agree they don’t show quantity of down on their clothing, nor on their standard bags (although by using my method it is possible to find out exactly what is being used, and of course change that amount too).

I also noticed (and emailed) RE: amount of down in PHD products, with no luck. With the exception of the DIY bags, it seems to be a closely guarded secret!