R-values of sleeping pads

David,

You are correct.

Hi David,

That is one of the reasons I bought the Warmlight Down Air Mattress.

3 or 4 minutes to blow up my Warmlight on a slow day. I tried blowing up one of the Exped Down Mats in a store first and gave it up. The Warmlight is much easier to blow up.

My wife has bought the short Exped Down 7 recently and has used it for a two week + trip in august. The first few times you try to blow it up, it is indeed a bit of a nuisance. But once we got used to it, it wasn't really a problem and took just a few minutes to pump it up. BTW, Exped is releasing a new version of their down mat next year with a build in pump. Appears much easier.

Hi David
Like most new gear you get better with practice, just as you do with tents….
An often overlooked point about the Exped is that it is a lot faster to pump them up if you shut the other valve off( I have tested this)
You can also get the new pillow pump to speed up the proceedings and have a nice comfy pillow.
Keep practicing, beats sleeping on solid foam mats (IMHO)
Franco

“So am I right to consider that the combination of say a BMW torsolite with an R value of 3.5 and a Gossamer Gear pad with an R value of 2.27 will give me a combined R value of 5.77 and will techinically almost as efficient as an Exped Down Mat #7 with an R value of 5.9? Is this the case or is the math not quite that simple?”

In theory, yes you add R values. In practice you can’t. The GG Nightlight has 2.27. The torsolite has 3.5. Yet in my experiments/tests the GG Nightlight is way warmer than the torsolite. Also, thermarest claims 3.3 on their Prolite 4. Yet, again, the Nightlight is warmer in practice.
Even within the same brand, I find the 3/4 Prolite 4 to be warmer than the regular Prolite 4. Based on my observations, here’s my theories:
1. The measurement of R value is subjective.
2. Yes, R increases when 2 mats are put together but numbers don’t easily add because of other variables.
3. Just try it and see what works for you.
As an example, at 0F, I’m warm with a GG Nightlight and Thinlight together. 2.2+0.45 = 2.65. Does that seem warm? No, but it is (with a WM Antelope bag).

-Barry

I don't think the answer is as simple as adding them together. A foam mat on top of an air mat, is warmer than an air mat on top of a foam mat.
There isn't as much air movement in a self-inflator, but there will be enough to make a slight difference.

New Synth version, should be built into down versions soon:
http://www.youtube.com/watch?v=g0OZ9uOHvz4
http://www.youtube.com/watch?v=MvhD_WktMv8
down:
http://www.youtube.com/watch?v=AdMSSZyWnjQ

Review quote:"The inflation is definitely an acquired skill. For those with inflation difficulties: we discovered that having the valve unscrewed too far causes a leak around the base of the valve cover while inflating, so that 3/4 of the air leaks out for every bagful of air we pumped in. Once we discovered this, inflation only took a short time."
source: http://www.rei.com/product/763828

This is an interesting topic, but in the end, which pad offers the best R-value to weight ratio?

Interesting question considering the different pad lengths and widths i.e. Thermarest vs. Torsolite.

I use a POE Hyper High Mountain Pad

They claim R-8 & R-20 in aerogel zone. I'll probably get run off BPL with the 24.7 oz weight

http://www.pacoutdoor.com/2008/index.cfm?action=product&productID=139&groupID=25&familyID=1

GG's 3/8's inch full length under a GG 3/4 inch nightlite give a R value of 3.67 for about 13oz. That's a little bit more warth than a prolight4 at about half the weight.

> They claim R-8 & R-20 in aerogel zone.
'Claim'.
Testing showed it was nothing like that at all.