Cycling UK Forum

Hi - as the title says, the sleep mat isn't inflating on it's own but will be blown up by mouth... Will a replacement valve sort this out?
Thanks in advance

Is this a new mat?
The 'self inflating' aspect of Thermarests is a bit of an exageration, they always need a few breaths of air to fully inflate them, unless you are able to leave it out in the sun with the valve open for quite a while, and even then once the air inside cools down the mat will go down and need a couple of puffs to bring it back up.

is it new? been in its sack for some time? then maybe will need a bit of help. I think they need to be stored fully inflated?

Just bought it second hand and I suspect it was stored closed and rolled up.

Literally nothing is going in from deflated when valve is opened. First time I did it by mouth, there was a noticeable crumple noise as if the air pockets had become a bit stuck.

But it went up and stayed up no problem.

I've left it stored open for 2 days but still not getting any self inflation.

The most recent one I have ( Neoair I think ) doesn't have any foam in it at all so wont do anything unless air is pumped in. I did have a play at bodging something with my bike pump and a cork to help as I didnt like the idea of trying to blow it up myself or of the dampness inside it going moldy. They do sell a small battery pump, and the mat and the pump are still smaller / lighter etc than some of the mats I have, but keep the full length and depth.

My old mats I store unrolled and with the valve open, not sure if it helps with the foam or not, or if the foam will eventually disintegrate, but liek sleeping bags it seemed to make sense and my oldest Thermorest a 3/4 length one from the 90s is still going strong ( if not a little patched ), but is just a little too thin for my aging bones.

The Pro versions have a very much cut about foam core, in the interests of lightness, and the strength of the expansion isn't that much even when new. If it's been used for a fair period inflating by mouth, combined with being stored rolled, I'm not that surprised it struggles.
Older, heavier, mats with unperforated foam did much better, and were warmer too.

I'd look at bodging some sort of pump, probably using a drybag/stuff sack/poly bag with a suitable bit of tubing in the corner, similar to those you can get for the Neoair. There's a fair volume in a sleeping mat, so a bike pump bodge would be a bit tedious, especially if it's a mini-pump rather than full size.

The Thermarest battery pump is just a fan rather than an actual pump, so it gives very little pressure and may struggle to overcome any internal stickiness like the foam core is doing.

andrew_s wrote:The Pro versions have a very much cut about foam core, in the interests of lightness, and the strength of the expansion isn't that much even when new. If it's been used for a fair period inflating by mouth, combined with being stored rolled, I'm not that surprised it struggles.
Older, heavier, mats with unperforated foam did much better, and were warmer too.

I'd look at bodging some sort of pump, probably using a drybag/stuff sack/poly bag with a suitable bit of tubing in the corner, similar to those you can get for the Neoair. There's a fair volume in a sleeping mat, so a bike pump bodge would be a bit tedious, especially if it's a mini-pump rather than full size.

The Thermarest battery pump is just a fan rather than an actual pump, so it gives very little pressure and may struggle to overcome any internal stickiness like the foam core is doing.

Thanks - I think I can live with it, bearing in mind it cost very little.

I am a bit concerned about the moisture content I will be adding by blowing it up.

And thanks for that link.

whizzzz wrote:The most recent one I have ( Neoair I think ) doesn't have any foam in it at all so wont do anything unless air is pumped in. I did have a play at bodging something with my bike pump and a cork to help as I didnt like the idea of trying to blow it up myself or of the dampness inside it going moldy. They do sell a small battery pump, and the mat and the pump are still smaller / lighter etc than some of the mats I have, but keep the full length and depth.

I have the same Neoair and although it is a bit of a pain to blow up by mouth the fact it packs up so much smaller than the self inflating mats is its obvious advantage. I looked at the battery pump but in practice its a simple 10 blows, leave it do something else and another 10 and you're there. Still not 100% decided if its more comfortable than the other type of matt although people swear by it.

Sooper8 wrote:

andrew_s wrote:The Pro versions have a very much cut about foam core, in the interests of lightness, and the strength of the expansion isn't that much even when new. If it's been used for a fair period inflating by mouth, combined with being stored rolled, I'm not that surprised it struggles.
Older, heavier, mats with unperforated foam did much better, and were warmer too.

I'd look at bodging some sort of pump, probably using a drybag/stuff sack/poly bag with a suitable bit of tubing in the corner, similar to those you can get for the Neoair. There's a fair volume in a sleeping mat, so a bike pump bodge would be a bit tedious, especially if it's a mini-pump rather than full size.

The Thermarest battery pump is just a fan rather than an actual pump, so it gives very little pressure and may struggle to overcome any internal stickiness like the foam core is doing.

Thanks - I think I can live with it, bearing in mind it cost very little.

I am a bit concerned about the moisture content I will be adding by blowing it up.

And thanks for that link.

well store it inflated with the valve open for any moisture to evaporate as I do?

mercalia wrote:well store it inflated with the valve open for any moisture to evaporate as I do?

I wouldn't put too much faith in evaporation.
If you consider the amount of air in a mat, the size on the hole in the valve, and the air movement in and out of a mat that's sitting in a corner, you won't lose much moisture. It will mostly just condense on the shell and foam core, and evaporate again, remaining inside the mat the whole time.

Moisture... I've heard various horror stories about this over the years, but in the quarter-century plus I've been using some sort of T-Rest, pretty much always with extra inflation because I like a firm mat, it's never been an issue (and I've never come across a first-hand case of it for anyone else either). I suppose mould isn't really that interested in growing on plastic foam if all it's got to work with is a teensy bit of damp and nothing much in the way of food, but whatever the reason the incidence of problems seems to mainly stop at rumour.

Pete.

ossie wrote:

whizzzz wrote:The most recent one I have ( Neoair I think ) doesn't have any foam in it at all so wont do anything unless air is pumped in. I did have a play at bodging something with my bike pump and a cork to help as I didnt like the idea of trying to blow it up myself or of the dampness inside it going moldy. They do sell a small battery pump, and the mat and the pump are still smaller / lighter etc than some of the mats I have, but keep the full length and depth.

I have the same Neoair and although it is a bit of a pain to blow up by mouth the fact it packs up so much smaller than the self inflating mats is its obvious advantage. I looked at the battery pump but in practice its a simple 10 blows, leave it do something else and another 10 and you're there. Still not 100% decided if its more comfortable than the other type of matt although people swear by it.

I do have the pump and use it sometimes but it isn't very quick so I often use my lungs for the job. I roll off a hard mat so I don't need much air in there to get it to my preferred inflation level. TBH the moisture warning is, I think, to cover their backs - i've never seen any indication of fluid in the mat and worst case scenario I could actually replace the mat, OMG - someone willing to spend money!

A self inflating mat always sounds good, I've had a couple but TBH I find the NeoAir far more comfortable - it's size and weight are a bonus. It's also easier to pack - I was always fighting the SIMs when it came time to break camp! An SIM that doesn't is - well just a heavy and bulky air mattress!

foxyrider wrote:I do have the pump and use it sometimes

I think the reason for the pump is to make it impossible to over inflate the mattress. I had an early Neoair about 8 years ago which was delicate, suffered badly from seam punctures/leaks and I remember nearly passing out when trying to blow it up after a hot and hard day's ride. I ditched that and used a series of lightweight Pro 4 and the Evolite mats. Both of those failed after only a short time. Possibly over inflation or leaving in a hot tent (same effect), although I took great pains not to stress the Evolite. Last year I bought a Neoair Trekker, deliberately a slightly more robust model, and a pump to go with it. I hope that this will be more durable.

tatanab wrote:I remember nearly passing out when trying to blow it up after a hot and hard day's ride.

That's because you were trying to blow it up too fast. If you stick with your normal breathing rate, you'll have no problem with faintness.

Apparently it's that you breathe out more CO2 than your body is creating, and that changes the Ph of the blood, which reduces the transfer of O2 from the blood to the brain (respiratory alkalosis). If you are in a hurry, you could try increasing your normal breathing rate by going for a run round the campsite, and then blowing the mat up before you've stopped puffing .

I've made things easy by using... wind!
A "pumpsack" can be made at home in various ways (like a thick poly bag), or bought ready made.

I use the Thermarest one and it works well, during the trip it doubles as drybag for clothes or other stuff, and during the night can be stuffed with the spare clothes to make a pillow.
Of course, one could blow the mat by breath, depending on the mat (down-filled ones are sensitive in that respect) this may not be good or take some time; since one has to carry drybags to organize the stuff, may as well carry a sack that can pump up the sleeping mat

http://www.outdoorgearlab.com/Sleeping- ... -Pump-Sack