anyone ever try a thermal bivvy

[Mongo]

So I just got back from a few days of riding around when going over k falls got a lil to wet and cold for me and decided to turn around in Eugene and hitch back to oakland. My last ride took me all the way to Concord and kicked me down one of these .

http://www.adventuremedicalkits.com/product.php?product=146

after getting home I just wanna go back out around those mountains and try it out. Just wanted to know peoples experiences with these.

 

[DoctorApocalypse]

Interested to hear how well it works. I've got the military modular sleeping bag w/ the patrol bag, intermediate bag and gortex bivy, used together it's supposed to be good down to -50, but it's really bulky to carry. So if this thing works well combined with a regular bag, I might look to give it a go.

 

[Bl3wbyyou]

I actually had one of those things.The older model without the vent on the bottom.Keeps you pretty warm just itself but you will sweat like a pig inside of it.But if you were to strip down then get into it would be pretty good.I would just use those space blankets and throw a few of those in instead of that whole bivvy thing.It doesn't breathe well at all.

Though the new version is much better so i hear.

 

[wizehop]

Looks comfy as all fuck, but chances are it aint as sexy as the pic makes it out to be. I have a basic bivy and I use a military sleeping bag inside it. It is comfy as fuck, but also bulky as fuck...

So if this thing pans out for you (although why the fuck would they give it away), you need to let us know so I can lighten my load come winter months.

 

[anotheridiot]

It relies on body heat so it will not make you warmer unless you use it inside of your sleeping bag which i don't recommend obviously. They work well enough to keep rain off of you but as others have mentioned it doesnt breath so condensation build up on the inside is still going to get your bag a little wet.

Pros: Good for a few uses when caught in weather, light weight, small pack size.
Cons: Does not breath, does not add warm when used with a sleeping bag as the body's heat is trapped in the sleeping bag, bright silver cover is eye catching on any somewhat exposed ride.
Source: Used one while riding the sunset line in November, fucking froze my ass off and this thing did little help the situation.

 

[Mankini]

Yeah. I think they suck. I slept in one for one night in the redwoods. Cold, clammy, and just bad in general. They'll keep you alive, I guess. But I wouldn't trust them in anything under 30 degrees.

 

[outskirts]

The new model, the SOL Escape Bivy does breathe somewhat, you get very little condensation. I have one and it works great for summer, the new model is also available in a green color. I have to say mine is holding up quite well. It is great if you just need a barrier from the wind and some of your own body heat reflected back. The only draw backs are that you will have to take care with it so as not to tear it, or wear it out, so don't sleep directly on the ground, get some cardboard or something. Also you have to crawl into the thing because the zipper only runs a third of the way down the thing, which prevents it being opened all the way up to be utilized as a blanket. Over all though, the new model is great lightweight piece of gear.

 

[etpyh]

It relies on body heat so it will not make you warmer unless you use it inside of your sleeping bag which i don't recommend obviously.

Cons: Does not breath, does not add warm when used with a sleeping bag as the body's heat is trapped in the sleeping bag.
Source: Used one while riding the sunset line in November, fucking froze my ass off and this thing did little help the situation.

Doesn't pretty much every sleeping bag, etc. relie on your body heat? I mean there are some, that heat up electrically, but those are not what we are talking about here I guess. It's just about keeping enough of the body heat around you to be comfortable. If this thing refelcts heat form your body, or isolates you from the cold outside, it will "make you warmer". Or am I missing something?

 

[travmhid]

Doesn't pretty much every sleeping bag, etc. relie on your body heat?

The guy you were responding to seems not to have understood how a thermal bivy is intended to work. You are right, sleeping bags trap your body heat... but the primary function of a thermal bivy is to act as a VB (vapor barrier). So unlike what that guy said, putting it inside your sleeping bag is exactly what you want to do--and condensation buildup on the inside is exactly why you want to use it.

Basically, vapor barriers reflect heat back onto you and contain moisture created by your body... moisture that would otherwise get into your sleeping bag (reducing its effectiveness) all while making you colder through evaporative cooling, which is the process by which your body cools itself through the evaporation of sweat. Basic technique: Sleep naked in the VB which is inside your sleeping bag, with your sleeping bag inside a wp/b bivy; your clothes can be used over your sleeping bag or inside of it (outside the VB, obviously) for extra insulation. When you wake up in the morning you'll be soaked inside the VB but your bag/clothes will be dry because your moisture has been contained, as the VB does not breathe--and since that moisture didn't have the chance to evaporate then it won't have had to opportunity to take your heat with it, meaning you'll have a warmer night's sleep. Edit: If you were to put the VB on the outside of your sleeping bag, not only would moisture would still move from your skin to the sleeping bag (transferring heat), but the

Some words of caution, though: You'll need to to dry yourself off before putting on any dry clothes... otherwise all of that moisture you've accumulated overnight is going to get pushed into your layers, reducing their insulating/breathable properties by a fair amount. Even then, you may want to only put on a base layer and then do some high-intensity hiking/movement to get the last bit of moisture off your skin and out of your clothing system before putting on the rest of your insulation. This could easily be achieved on the hike back to your hitching spot, for example.

Personally I'm not a huge fan of vapor barriers... but they certainly have their uses and I will use them when I have to.

Tldr: Vapor barriers work the same way (and for the same reasons) as wearing plastic bags under your sock, although vapor barrier-specific clothing does exist for those who can afford it.