I just purchased a beautiful expedition-size backpack and I would like to train walking around town with a loaded pack in preparation for an expedition. Although i'd love to play British SAS and carry a 200 lbs pack, I probably don't want to bother too too much... I won't fill it up with the gear I will bring, but I might stuff a 5 lb protein tub in there along with a wool blanket, things like that.

I would like, however, to attach my self-inflating sleeping pad under the pack using the straps that are there. Do you think there might be a problem doing this?

I assume I should unroll and inflate the pad once in a while, but... how often is that? I'm wish to train with this pack setup all winter... and several times per week... which is why I'd like to avoid the unroll/inflate/deflate/repack sequence as much as possible.

Any tips appreciated! <img src="/images/graemlins/smile.gif" alt="" />

I've got my Thermarest stored rolled-up, with a nylon buckle strap around it. Not cinched up super tight.

Is your inflating pad for training for additional weight, or just to take up space where the pad would usually be?

You could buy a cheap non-inflating foam pad and use that in its place for training or walking around with the pack loaded like it might be.

Hi Ced!

As it will be the pad that I'm going to take on this expedition... this is the real deal... <img src="/images/graemlins/laugh.gif" alt="" />

It's like to see how it feels hiking with this large pad. I'll try to find a pic or two.

I believe that thermorest recommends storing for long periods in the inflated condition rather than rolled up tight. I have a pair of thermorests with the valve open behind the living room couch, leaning against the wall. They cannot be seen without really looking for them. I have a pair of cheaper (and thicker & heavier!) Coleman self inflatables from Sam's Club. The instructions that came with them recommend inflating prior to use, then rolling them down and inflating again to restore loft. That seems to help with those mattresses.

I would think that if you are in a training program, that leaving them rolled for a couple of months shouldn't cause any permanent issues.

When we went training with the Scouts for Philmont, I packed my pack about 70% with what I was going to bring on the real trip and made up the rest of my desired training weight with water bottles. Easy to adjust prior to leaving on a practice hike and if you find out you bit off more than you can chew, it is easy to shed those pounds so that you can make it back before anyone starts getting worried.

It would be worthwhile to carry the thermorest a few times to get the feel of it. They have a tendency to stick out farther to each side than you expect. But you don't need to carry it everytime. Make up the weight with something else.

Something to consider. I had a new internal frame pack for my trip. The top of the pack had a detachable fanny pack as the cover. The thermorest went under that fanny pack. Found out the hard way on the trail that the rain cover for the pack was spread wide at the top by the thermorest. With the wind in the right direction, the rain collected and puddled in the bottom of the rain cover. Wet sleeping bag. I thought the rain cover would eliminate the need for using a garbage bag for waterproofing around the sleeping bag. Needed just a couple more inches of material to each side of the rain cover. I would recommend trying out any rain cover you might use with the thermorest attached to your pack prior to making your trip.

Is there a reason for this? I always store mine rolled-up pretty tight. <img src="/images/graemlins/confused.gif" alt="" />

Storing them in the inflated state helps them retain the shape, and keeps the foam inside from becoming permanently compressed.

It's almost like loft in sleeping bags though somewhat less finicky.

REI's self-inflating mats should be stored inflated as well. I keep mine behind the door in the spare room.

Living full time in a motorhome presents some special storage problems for a lot of things, including our thermarest pads, which live full time in a pod on top of our towed vehicle. We haven't noticed a problem yet, and sometimes they might to almost a year (sad, I know) without being used...

Thermarest suggests for long term storage it should be unrolled and slightly inflated.
Otherwise the ends get creases that reduce the durability over time.
I stopped using T-Rests because sooner or later they leak.
I now use a Mtn Hardwear pad. It is a bit more bulky but the same weight and cannot fail.

My experience has been that it takes longer to self inflate, and the loft is reduced from original. Not necessarily an issue. The non-thermorest mattresses that I have seem to regain most of their loft through repeated inflations and rerolls over a 30 min period. Just a pain to have to do. It is easy for me to store the thermorests inflated since they are so thin as opposed to the others that are much thicker. When I leave the bigger ones inflated, they do reinflate much quicker to fuller loft when I roll them right before the trip.

You can always blow air into the mattress through the valve to help regain loft, but that has several potential problems for the gear freak. Adding moisture from your breath over quite a few years can make the insides a little funky. I'm sure there are some A.T. through hikers that will bemoan the extra ounce of moisture added to the weight of the mattress from breath. The second is that in extreme cases of reduced loft, the mattress then becomes as much an air mattress as a foam pad, with some of the heat transfer issues. Is this really a problem? The latest and greatest thermorests have a diamond cut pattern in the foam to reduce weight, increasing the air vs foam volume of the mattress. (Isn't it amazing how the more air in a thermorest the greater the price??) Personally, I'm not sure either of these two issues are that important.

I suppose that with really old mattresses, you could develop weak spots at the creases where the edges crinkle.

I really haven't had a problem with any of these potential issues since I don't use them that often, they are relatively new (less than 10 years old), and I do store them inflated as much as possible.

I wouldn't worry too much about it. After all, the thermarest come tightly rolled up from the factory, and who knows how long it's been sitting around like that. However, if you haven't noticed, it takes forever to self inflate after keeping it compresesed for a while, if it ever self inflates. I notice it takes 10X longer to inflate if i kept it rolled up for a long period, as opposed to a overnight. I don't think it causes any permanent damage though. I follow the manufactureres recommendations and keep it inflated with the valve open, that allows any moisture from my breath to dry out inside too.

Also, the backpacker models with the die cut foam are even more suceptible to this. The one I have is halfway between an air matress and thremarest, because it will never fully inflate on it's own.

As has been mentioned, the recommended long term storage is inflated. Mine are under the spare bed in the guest room.

One thing you asked about, carrying it under your pack using the straps on the pack, might be something to reconsider. If it were a closed cell foam pad, that's probably fine, but, for an inflatable, I wouldn't want that on the bottom. Imagine setting down your inflatable pad on something like a rock, with perhaps a sharp point, and then put your 40 pound pack on top of that? Could be a bad scenario. The Thermarests are great, and I have a Thermarest 4 that's perfect for hiking, but, if you puncture them, good luck making a field repair. That's why on "rough" trips, the old standby is a roll of closed cell foam, or a folded waffle style pad.