Michael Cheifetz,

I also wonder how well this flow idea works...

We don't expect much heat to flow through the insulation on top of us or we would get cold. If we expect the 3 or however many inches of insulation on top of us to severely restrict heat flow and keep us warm, how much heat do we expect to flow 8, 15, 22 inches down our legs?

The only difference I can see is that the insulation on top of us is capped by a nylon shell and the insulation running down the baffles is not.. Well, there are the flow gates..

By 'extremity', I figure they mean legs. My arms stay in the torso touching zone.

Anyway,I am not sure I buy this reason for this type of baffle.

All this talk of flow has a Jack Johnson song stuck in my head

Edited by Tan68 on 01/25/2013 06:00:12 MST.

Sorry for the double post. I have trouble with the page timing out during submission. I go back to the thread, hit refresh, see no post, so I re-post,and then I see multiple posts...

Edited by Tan68 on 01/25/2013 03:15:22 MST.

I don't know that I buy into the design myself.

http://www.insotect.com/insotectflow.php

Depending on how often the flow gates are spaced I don't see that it uses much less baffle material. But it does make it harder to add more down to say just the top third of a bag or quilt (where most people need it) unless they make flowLESS gates too. ;-)

Personally I have hotter feet and a cold torso when I sleep. I would rather keep my precious body heat where it is, not send it down to my feet. I beta tested two winter bags that used this and they were not as warm as my "traditional" bags.

Of course the whole design is to get away with less down in the first place. Light weight rules you know...

I also tested a winter bag with the Insotect baffles last year, and, while it wasn't a bad sleeping bag, I am very skeptical about any supposed benefits from heat moving up and down the baffles. The whole think stinks of snake oil to me.

As Mike Cheifetz has already said, the human body does the work of transferring heat from the core to the extremities. What more can an insulated tube do than keep the air around your body from getting as cold as the air outside the bag?

The Clymb is offering the bag for $379.98. Not sure if that's been the standard discount for this bag but at least it puts it in the same ballpark with the Feathered Friends Swallow (unless similarly discounted).
http://www.theclymb.com/brand-event/173287/show-product/260723?f=mi

Even cheaper direct from SD right now. $349.99

http://www.sierradesigns.com/p-474-cloud-15.aspx

Sierra Designs has only the regular size on sale. The Clymb's price is for the long version.

Jerry - good comment on the solar value of a dark sleeping bag cover - that makes a huge difference in colder air temps.

Looks like a nice bag despite the light cover - competitively priced. Wonder why it's not sporting the DriDown. The EN rating is 30* for woman and 19* for men.

The comparison needs to be made to the Marmot Plasma 15 - very well designed hood, draft collar & footbox wrapped in a Pertex Quantum cover - one degree warmer on the EN rating - though cost wise you need to wait for the sale prices.

I've been watching for the Plasma 0* for about a year - I see they finally now have those available - I'd start waiting for the sale price but my 2006' 900 down Quantum cover Lithium is in perfect condition and weights the same even though I added 1.5oz of 900 to the draft tube - I also like the fuller cut for ventilating and ability to add layers without as much compression.

Edited by SanJuans on 01/28/2013 20:59:12 MST.

At the Sierra Designs website today (2/8), one currently finds the Dridown Cal 13 and the women's Dridown Clo 18, which may be the successor bags, both of which have the vertical baffles. No trace of the Cloud 15. Guess it drifted off.

Edited by swimjay on 02/08/2013 22:24:05 MST.

How will 900 fill power down handle the condensation? Last thing I want at 15 degrees is a compromised sleeping bag.