Just like the title says, do Foss tubes leak? My 36Foss tube has had a slow leak since new and I am wondering is anyone else having the same problem.
If I inflate to 50psi it will be at 25-35psi in about 24 hours
I think the material is just more porous than normal butyl tubes. I had the same problem with latex tubes.
Anyway, it’s no big deal- the pressure doesn’t go down significantly on a single ride, but you may need to top up the pressure every few days.
try a dab of waterd down sealent.
The heavy 36" tube that came equipped on my Nimbus Impulse (discontinued) never leaked. 65 psi from day one until the day I sold it. The FOSS tube in my second 36er does tend to work it’s way back down to 45 psi (I guess it just feels more comfortable there 
) over a couple weeks time. Like Ken said, nothing drastic but keep your pump handy. Guess that’s the price you pay for 30% savings in rotational weight. Worth it? I think so. Still, a pain in the ass when your wife takes off running up the street, you mount up, feel the squish, and look down to say “legs, it’s going to be a tough day”.
anyone use co2 to fill them? MBA (mountain bike action) did a test with CO2 vs air and the co2 has bigger partials and says at a higher pressure longer
I have had 2 leak… 1 was faulty where the valve joined the tube… the other was a straight forward puncture but I could never get the Foss patches to seal properly 
Interesting. My question would be how many of those cartridges would be needed to pump up a 36 x 2.125 tire (or whatever size they are. Probably a lot! Even a 24 x 3" MUni tire is probably equivalent to the volume of 3 road bike tires.
So I would also like to know if people have experience using those. Sounds wasteful though. Not to mention litter-prone. I see them along the trails. I prefer a little micro-pump in my Camelbak. Same pump for about 10 years, still works, and will, eventually, fill that 36" tire. 
Can you site this? It flies in the face of everything that I’ve read, for example. Now it may not be true for Foss tubes.
Since a while I only use 20" Foss tubes as I like them better than butyl, at 70 PSI.
The word is not leak. But everything indicates it’s not vulcanized, opposite to what specs tell or suggest. Whatever it is, it just porous.
But from 50 to 35 in 24h sounds like… you do have leak (or bad or dirty valve because of not using valve caps).
My first one leaked, then the valve broke off, so I only use my replacement Foss as a back up for my tubless.
I strongly recommend going tubeless on a 36er, it’s lighter and safer (less blowout risks).
It can be a pain to set up, a used tire is easier, if you struggle with it or don’t want to foll with it, have you LBS do it for you.
And the CO2 thing is silliness, a good tube will leak, all tubes leak, a tubless set up will hold the best due to the liquid sealant. @ Wes, you need to check your spelling, “particles vs partials”, I believe you are talking about molecules??
You may have to add air every 24-48 hours (I did), but certainly not in the same day/ride, so you may have a patchable leak or a bad tube.
Go tubeless, then use the Foss as back up, you’ll be happier that way.
That reminds me to the manual (page 3)…
Funny, on my hunt to 20" latex, that noone wants to produce, even while having virtually zero startup costs, I ended at Foss.
But the word latex reminded me to Pariba, who did a not so good copy of a super pink tire I saw very long ago (rodin?): the valve would heat up the rubber and melt it! Having seen that to more than a couple bicyclists that were about to start a timetrial; I now always keep it in mind when inflating this odd tubes.
Well, apparently the foss tube really is somewhat self sealing, I decided to take apart my tire and found a hole in the tube and a thorn thru the tire. The last 4or 5 months It had leaked faster than when I first installed it, I guess now I know why. At least I know I shouldnt have to worry about getting a flat when out on a ride anymore
Ben, I assume you have a write-up of how to go tubeless on the 36, can you point me to it? I would like to give it a try. Thanks
Here ya go. Was checking it out recently, as I’m mulling it over myself.