Foss Tubes

What do you do if you get a flat while riding?

I move my furniture in. :sunglasses:

Did you check your tyre on the inside? Maybe something sharp is stuck there. When I get a flat and remove the tube, I mark the valve hole on the tyre. I also mark which way the tube was put in (mark the valve or something). That way when you find the puncture in the tube, you can locate where on the tyre the puncture happened by laying the tube over the wheel with the valve where the valve hole is. I found a tiny piece of glass in my tyre that way. When I got that puncture, I didn’t notice until the next time I was going for a ride.

Edit: I didnt read good enough. I thoght the puncture was on the outside of your tube.

Well, with a FOSS tube, you apparently patch it and still end up walking home :frowning: So maybe a 29er isn’t such a bad idea!


If it goes with a bang then you’re probably right. I was thinking about running over a thorn which is big enough to defeat the magic self-healing Fossness but small enough that the tube is still intact. For such occasions I carry some Foss patches and a pump.

I like the idea of using a 29er tube since they’re cheap and easy to come by. I just wonder whether they can be patched, or if they are stretched enough that any puncture would allow them to tear beyond the point of repair.

Maybe the point is moot since 36er punctures seem to be pretty rare. I’ve had two so far. The first time was a mysterious needle thorn thing. I patched with a Foss patch (at home) and all was well. Then a while later that tube went silently into the night. I went to go ride one morning and the tyre was flat, with a small hole by the valve. It had been fine the night before. No bangs or dramatic noises. I replaced it with another Foss tube for the above reasons but am considering a 29er tube next time.

Put your spare 29er tube in. Then when you get home you can try patching it with your normal, non-proprietary patches.

Gonna try a 29er tube this weekend. Is it just, stretch it over the rim, pump it up to be circular, leave overnight, then fit it inside a tyre the normal way? Or is there more (or less) to it?

That’s what I’m leary of. Are they reliable if you just slap one in and ride? Thinking about side of the road repairs here…

Put it on like a regular tube.

Leave one bead of the tire on the rim, put your valve stem in, and working from the valve stem down stretch the tube onto the rim.

It’ll hang over the rim bead but that’s okay. Now make sure it’s not twisted anywhere. Go around the whole tube and make sure it’s flat on the rim.

Now put some air in it until it just starts to get some shape. Go around the wheel and make sure it’s as far into the rim as it can go.

Now you should be able to work the other bead onto the rim. Once on, put a little more air in. Now walk the tire around pushing it into the rim to make sure the beads don’t stick up.

Now because I’m crazy, I’ll deflate all the way again and then re inflate to riding pressure. This is one last step to eliminate twists in the tube. I do this with all tubes. On the road you can skip this part.

It’s really not any different then a regular tube, you just want to be careful and make sure beads are pushed in, and you don’t pinch the tube.

Do not use tire levers no matter how bad you want to.

Thanks, that’s reassuring since it’s how I would fit any tube anyway. So it sounds like it’s not too much hassle. I’m going to give it a go if/when my current Foss tube bites the dust.

You’ve never used a TA/Qu-Ax rim combo have you :roll_eyes:

I’ll see about trying it soon, you may it sound like pre-stretching isn’t even necessary which sounds a bit strange, but I suppose that’s good!

No I don’t prestretch the tube since imo it doesn’t accomplish anything. I pulled a 29er tube out of my 36 after a year and it was still pretty much a 29er tube. It still needed stretched and all that.

Regarding the TA on the Qu Ax rim, I have not messed with one but I have put Gatorskins on CR18s with velox rim tape (read: very tight) and it just took some time.

Tire levers with a 29er tube is asking for trouble unless you are VERY careful. As a rule I think it’s good practice to never use them.

That’s good advice but also can’t be applied to any 36" rim I’ve had. My current setup (Nimbus rim with the holes, Nimbus tire) almost requires a crowbar to get the tire back on. That might be the reason I haven’t tried the 29" tube thing. Plus I like having a FOSS product on a unicycle. :slight_smile:

My point exactly with the TA/Qu-Ax combo. It ends up about 4 inches off the rim when you get to the last bit. I have worked it on with fingers before but it took me a LONG time and I REALLY worked at it.

Plus, is a stretched 29er really much more fragile than a FOSS? I managed those fine with levers, the trick is just not to stick it in your tube like an idiot :smiley:

Shouldn’t be more fragile. If you inflate one out of tire, you’ll be surprised by how much it stretches.

I’m with Killian on this one; however, there is a bead jack that is made for installing tires.

I used a 29er tube in a TA, on a Quax rim, and never needed a lever to install the tire. I did use clamps to keep the beads together in the “well” of the rim on the opposite side. Without that I might have needed the “bead jack,” but really it is a last resort.

It’s not more fragile, but since you’re stretching the tube on it is very easy to pinch it.

I’d suggest trying soapy water on the bead if you didn’t already.

I’d do whatever I had to do to not use levers. I hate those things.

I’ve been riding Foss in the KH36 for a couple of weeks now and there are two things I wonder about:

It looses air pretty quickly, something like 100 kPa per week (1 bar drop). Did I somehow inflict a minor puncture on the tube while installing or is the valve (I’m riding the UDC Schrader valve edition) really that shitty?

There is a lot of clearance between the valve and the rim, because it’s skinny and doesn’t have threads on the outside to put one of those circular nuts on it that are used to keep the valve from disappearing inside the rim on low pressures.
I’m wondering, how do I keep the rim from filling with water and dirt. Small amounts of water can evaporate, but as far as I can tell dirt stays in the rim till I dismantle the wheel to get it out.

  1. it’s not the valve, it’s the rubber itself that it’s seeping through. If you’ve ever owned a road bike (high pressure, low volume) you are familiar with tubes being porous and having the fill them regularly. The foss tubes are more porous than the basic 36er tube, probably due to the material, and them being thinner.

  2. It looks like you have a rim designed for the old 36er tube that used a HUGE hole for the valve stem. I have one wheel with that and use the old “commuter” tube. has something similar and, but I would contact them directly to see if they have something specifically for the older 36er rims to make it compatible with the new tube. It’s not a normal Schrader size.

That makes me wonder, can I reduce that problem by putting a little bit of tyre sealant used in tubeless setups in to seal the pores? I mean the Foss tube weighs a whooping 410g less than the stock tube, even with 20g of sealant it would still be a big win.

I’ll have a look.