MLD Superlight Bivy

I went with the Large to use with my WM Alpinlite 20F. I'm 5'9", 185lb. There's plenty of space for a 20" wide Medium Exped, and it's just about perfect for a 25" wide large Xtherm, but it's too tight in the foot for a 26" wide LW Exped.

I have the L and have borrowed a friend's M.

I was fine in both, with a reg. XLite and a 20 deg EE quilt, but prefer the L. (my friend regrets going with the M).

So yeah, L is the safer bet.

Thoughts on silnylon vs. cuben fiber bottom?

Well, i ordered a sil-nylon, and got a CF bottom. I'm not complaining!

In fact I've slept in 3 different MDL super light bivies in the past year. The first had a sil-nylon bottom. It was fine, but I was in the southwest. And I've had good weather on my other trips, so hard to say.

When I borrowed my friend's with the CF I though, ooooh, I sort of wished I had order mine w/the CF instead of the Sil (and then got lucky). Best I can tell the CF has held up fine.

The CF is nice. Is it worth the money? Depends on your budget.

MLDs Super Light Bivy is a very well made Bivy as you would expect. For me the large was too tight through the hips. I'm 6'3" and 185# and tried the long wide. MLDs Bivy starts tapering at the shoulders and is a straight line to the foot. I use a 25" pad and a 20* FF mummy. This Bivy compressed the down through the middle third and I had to unzip to reach the bottom of my bag. There are a couple of other companies that don't start tapering the girth until near the feet (Borah Gear and ZPacks) and this works much better for me. I have a CF bottom that has worked well but I am careful. Save an ounce or two, but it does cost!

I have no experience with MLD bivy or any bivy with a CF floor. But CF will be more likely to get a hole and leak. It is very easy to puncture or abrade.

I have several pieces of CF gear and… in MY experience, anything CF that touches the ground when in use is very likely to get a hole in it and leak… I have CF kilt, CF day pack, and CF stuff sacks… all have come into contact with the ground and all have leaks.. and got leaks the first time I used them! Some people will say their CF whatever does not leak… but have they actually tried it in water????

My CF Hexamid does not leak… but it is not used touching the ground.

billy

Good point, but definitely different weights if cuben. Still no issue with the MLD 0.74 stuff concerning holes.

I put a puncture hole and two abraded holes in my zPacks day pack first time I had it out… Cuben 1.43 :(

Billy

Wow. That sucks,

By the way, your new avatar is showing…..;)

Ha… new avatar is not showing on my machine !

BTW… also put a hole in my 1.0 Cuben kilt first time I sat on someething… and have since discovered my 1.0 Cuben roll top stuff sacks have abrasions that make them leak… presumable from them being on granite when stuffing my sleeping bag…

I would got go with a Cuben bottom on a bivy unless I planned to have a ground cloth under it to protect it…

I have a BD Bivy that I have used on at least a dozen 7 to 10 day trips that has a silnylon bottom and no leaks… I lay it directly on the ground… often very gravely ground above tree line…

Billy

I find silnylon much more slippery than cuben. A lot of pads will slide inside a sil floored bivy, and you'll wake up at the lowest point if your site is anything but level. That can put strain on the upper material, and just be uncomfortable. Put some silnet on the inside of the bivy or use a less slippery pad (eg TAR XTherm) to mitigate the problem.

Yea… I found the same slippery issue with silnylon so I used some silnet silicone seam sealer to run a few beads perpendicular to the axis of the bivy on the inside side of the silnylon and that fixed the slipping problem…

billy

I have had a similar experience as Mark H above. I have a MLD super light bivy in large with a cuben floor and full head net. The first time I used it was in the snow with a regular sized xtherm and a 15* down bag. I had issues with down compression in the hips when laying on my side (woke up frequently with a cold spot). I chalked it up to the high loft bag. But most recently I used it with a large size xlite and a 40* quilt with the same issue (the pad width takes up a lot of girth) in the same spot. I think I would be okay with a regular width pad and a 30* or lighter bag/quilt, but that's disappointing. I'm not super skinny at 6' 180lbs, but I figured I'd be swimming in a large.

I use my SL bivy from April to October. The other six months of the year I switch to an eVent Soul bivy. It's more than 2x the weight, but has far fewer condensation issues when there's snow on the ground. I had the Soul custom sized to be a few inches wider than the large SL bivy, and so far it's been flawless with my 0F bag on top of a LW DownMat.

This is a good primer: http://40yearsofwalking.wordpress.com/2011/07/04/the-bivy-condensation-conundrum/