Question about Foss tube failure on NightFox

I went to go ride yesterday and found my tire completely flat. When I took it apart I found this (see pics).
The rim strip puckered down and caused “blisters” on the Foss tube - one of them so bad it blew out. Does this mean that my NightFox was built with the wrong rim strip?
Can I just add another strip (or rim tape) over the top and try to patch the tire?




It looks like it has Foss Pox! Eww. Or a bad case of whiteheads.

I get the impression you are running some high pressure? In any case, another strip (or a single, thicker one) should definitely help. As for repairing the tube, I guess that depends on how bad the damage is.

I have no connection to the Foss innertubes, even though they have the best looking valve stems in all of tubedom. I don’t even know why they are called Foss, but would love to find out someday!

If you’re going to add a second strip, you might want to also replace the original since it’s pretty stretched already.

I’ve always wondered this but been too shy to ask, considering that you’re practically unicycling aristocracy. Now I know. :smiley:

I think the old-school cloth-based rim strips may be better in this regard than the rubber types. Perhaps try one of those. In recent times, a couple of wraps of filament (strapping) tape or “Gorilla” tape seems to be a popular option.

Yes, I believe your tube can be successfully patched. (There is a Foss-specific patch kit available.)

Good luck!

I’ve never seen a rim tape do that (At least not to that extent). Sort of making me want to pull my tyre off and see how my Foss is looking! :astonished:

You could probably patch the tube, but yeah, I’d look at getting a stronger rim strip (Or even just gorilla taping all round your rim as though you’re going tubeless). Foss tubes usually have their own special rim strip to avoid this sort of thing, but I didn’t get one with mine.

I’ve been running 65 PSI - the tire says 35-65.

I went through and found that easily 10 of these “blisters” on the tube look very scary. I guess I could put 10 patches on … but seems excessive. I looked at the “heat method” with the lighter - but I don’t know if that’ll work with the blisters the same way it works with straight punctures.

Definitely tape next time - no more strips! This plastic strip is a ticking time bomb as far as I’m concerned. It came this way from UDC and it has very low miles - pretty new in fact. I never knew to check it or that it was even a concern - until now!

Tubes are $38 plus shipping! Ouch! Kind of got bent over on that one… what’re ya gonna do? :frowning:

Assuming you’re running the Nightrider tire, I’d back off the pressure to 55. The handling will not suffer, you will feel a little more cushion in the ride, and your Foss tube will last longer.

My Foss tube did something similar to this on my Coker, when I tried running my new Nightrider at the maximum 65 PSI. I ran a strip of Gorrilia tape for a liner, and put a 29" tube in; haven’t looked back. Not to disparage the Foss tube, I just decided working with more locally available supplies was easier.


First, get rid of the Foss tube. Those things are three kinds of problem in search of a solution.

Second, with a real tube, that level of deformation probably isn’t going to cause flats, but the best way to smooth it out would be to add a strip of nylon strapping tape over the spoke holes (and under the rim strip).

Time to show my ignorance. After 6 months reading the forum I still am not sure how a Foss tube is different from a regular tube and why it is considered (apparently by many) desirable.
I had also been impressed that in addition to John Foss’s skill and experience in the unicycle world he had also created and manufactured some kind of innovative tube. Apparently I was wrong and I have had to reduce my esteem for Mr Foss a notch. I still wish I was going to be home for his Oct invite(if I knew how this is where a smiley face would be).

Basically the Foss tube is much lighter than the standard 36" tube, it’s similar weight to a 29" tube.

The problem with the Foss tube is it has much more plasticity than a regular tube, as in once it assumes a shape, it doesn’t just shrink back to it’s old smaller rounder self afterward. I think this helps it feel better at lower pressure than a stretched 29" tube but is no advantage at the higher pressures most people are riding, and makes it more prone to this type of blowout when the rim-strip stretches over time.

EDIT: If you use a rim strip that doesn’t stretch at all (fibre tape, cloth tape, duct tape etc.) you don’t have any of the rim-strip blow out problems with the Foss tube.

Foss tubes are also (supposedly) self-healing to an extent. If you get a nail stuck in one, it should sort of squish up against the nail and stop air leaking, though I haven’t tested it (Well, not that I know of - I haven’t had a flat since I put it in… maybe there’s like 10 things stuck in it and it’s doing its job properly? :smiley: )

So yeah. Super lightweight, puncture-resistant inner tube, sounds desireable to me! But they’re apparently very fragile as seen in this post, they’re also double the price of a regular 36" tube (which are already expensive to begin with!) Which is why many people go for stretching a 29er tube into a 36er tyre instead. There’s also been problems I’ve seen online where the valve section of the tube has blown out of the rim (basically similar to when a normal tube splits thanks to a sharp valve hole edge).

My experience is limited to 6 months and 3 unicycles. Is the difference in weight actually noticeable? If I’m pedaling the weight of me and a unicycle, 170 lbs or so total, I would not think a pound or two would be noticable?

I noticed the difference immediately on the 36er. Remember, the weight is all at the rim of your wheel, moving quickly, which is really where you feel it most, especially on a wheel as big as a 36". I’ve never tried stretching a 29er tube though so I’ll reserve judgement on that.

Whether or not its worth the huge cost and potentially disastrous fragility is a different story :smiley:

Thanks for the comments.

I really like the feel of the 36" wheel. The NightFox frame is a little funky and at times I wish I’d purchased a more conventional 36er - perhaps someday.

Anyway, I don’t want to change the feel since it’s easily my favorite uni. I ordered two replacement Foss tubes. Just the price of a lesson (hopefully) learned. I’ll ditch this strip in favor of rim tape and run no more than 50 PSI.

Another one of the reasons I didn’t consider the switch to a “normal” tube is that I didn’t want to drill the rim out - lest I want to go back.

Perhaps I’ll play some bic lighter tricks with this one just to learn about that process too - might as well get as much knowledge out of this experience as I can …

I have a similar wheel to yours. Stealth 2 rim, Nightrider tyre, Foss tube and the same blue plastic rim strip. It’s three months old and I’ve been running it at 60 PSI the whole time.

I opened it up today after reading this thread and found that my rim strip was deforming into the rim holes similar to yours. It hadn’t progressed quite as far though - the rim strip was still usable and the tube hadn’t deformed or punctured yet.

I also noticed that there were a significant number of metal filings (presumably from drilling the holes) trapped under the rim strip, and the edges of the holes were really sharp.

I smoothed the edges of all the holes with some sandpaper, vacuumed all the dust and filings out, and added a layer of fibreglass-reinforced strapping tape under the rim strip. Since it doesn’t stretch it should stop the rim strip sagging into the holes (as long as I sanded them smooth enough that the tape doesn’t get cut).

Anyway, I’m glad I decided to be paranoid and take a look…