I had that happen to me- but after a few weeks of riding. The valve hole on the 36" rim (nimbus 2) on my KH is oversized for the Foss valve. The description of the Foss tube says it has a valve washer but this wasn’t the case with my tube (unless you count the integrated minimal reinforcement around the valve stem).
This likely was the cause of my tube’s failure at 60 psi road riding.
I tried heat repair but was unsuccessful. From years of bike riding the puncture at the valve is as good as impossible to patch.
I brought this to UDC US’s attention and they honored the warranty sending a new replacement tube.
This has been installed over a year now but I made a tight fitting washer around the valve stem and too big valve hole to reinforce this weak point. I used a piece of strong Dacron fabric but a ring of old inner tube might also work. Maybe two layers even.
Thank you for the reminder. I’m about to put a Foss in my road 29". I’ll be checking valve hole size and likely reinforcing.
I hope your local UDC is as good as UDC US. Edit: I see you are in the US- I read MuniTasmania’s post and was still thinking other countries.
That’s good input, paxuni, thanks very much. I read and followed the Foss installation instructions as well as I could, but they didn’t say anything about maximum hole diameter for the inlet valve nozzle. I’ve never really paid much attention to this particular detail. Is there a standard size for the inlet valve hole? I haven’t heard back yet from UDC (US) regarding whether or not they’ll replace it, but in any case, I’ll pay close attention to this detail in the future. Perhaps adding a close-fitting flat washer to the nozzle would prevent this from happening. Would be cheap insurance.
cheers
Well, the good news is that UDC says they are sending me a new tube to replace the failed one. Thanks very much, UDC.
Interestingly, the person on the phone advised during the conversation to run my tire pressure at 45 psi, and that higher than that was risking a blowout. This was news to me. Can anyone shed any light on this? I’m running a Nightrider tire, on the UDC website listing for this tire it says it’s rated to 65 psi. I have been running it at about 55 for quite a while (with the rubber tube). Is the Foss tube the weak link? (I was running 51.5 when it blew out yesterday.)
thanks.
I’ve been running 55-60psi in the same FOSS tube (KH 36er) for years with no ill effects. I don’t know if rider weight has any bearing on the tube life, but uneven, bumpy terrain, especially if you take it offroad, could lead to premature tube failure or leaks. Also not sure if the FOSS tube is inherently weaker than the much heavier rubber tubes, but so far I haven’t seen any evidence in this regard.
Yep, its the tube IMO. Foss tubes have proven to be finicky, and UDC is probably trying to cut down on warranty claims :). I don’t care for someone telling you to run under a certain psi, when a tube should be perfectly capable of handling the pressure.
Also note that the tube must be installed with the seam (also called “junction”) in front of the stem, in the direction of travel. Installing it the opposite way can cause failure. And they also warn against inflating the tube outside of the tire. which can permanently deform the tube causing premature failure. I assume they mean full or excessive inflation, not just a little bit to make the tube easier to install, and so it won’t get twisted inside the tire.
It may have something more to do with bikes, in that when you do hard braking from high speed, if the seam was behind the stem there could be more force pulling at the seam. May not be the reason but it’s possible.
That is very unfortunate what happened to you LanceB. I will lean on the side of defective unit (in mass production there is no 100% success rate).
My experience with FOSS tube is pretty good. Running one on my 29er at 58 PSI on the road and 25 PSI on the trails and no problem to report. I went also to a FOSS tube on my 26 and just my first flat two weeks ago (like any other tube).
I am confident that the nice folks at UDC will process it under warranty.
Yes, they are sending me a new one, no hassles (thanks UDC!). I will report back after installing the new one (paying particular attention to the air valve area).
Good to know you are running higher air pressures without problems. I usually run about 55 on the road, but I’ll give 45 a try and see how it feels.
Make certain that the rim strip fits correctly, doesn’t shift, and fully covers the spoke holes. You should also run your hand along the inside of the tire to make sure there is nothing sticking through, like a thorn that had broken off and is only now on the inside. And try to follow the installation instructions in the FOSS installation guide.
I’ve been running a FOSS tube in a Vee Rubber Off-road 36" tire on a Stealth 2 Dominator rim for a couple of years now without incident (knock wood). I’ve always said I’d replace it with a real rubber tube if it ever fails only because my 36er has a Schlumpf geared hub which adds a little extra hassle when changing tires and tubes. That 36er is really set-up for road riding only so I typically run higher (between 45-50 psi) pressures. It does hold pressure fairly well but I do need to add some air from time to time especially in those winter months when I might not ride for a couple of weeks.
I’ve also been running a FOSS tube in my KH29 for a few months riding MUni with moderate drops. The tire is a Hans Dampf and the rim is 47mm wide with the lightening holes. I know it is not “recommended” to run the FOSS tube with the holes but I’m a rebel. My 29er by far the lightest unicycle in my quiver. I love it!
I run the tire pressure with the FOSS tube between 60-65 psi and never had a problem. I think my tube failed when the LBS replaced a few broken spokes for me and didn’t check if the tube was in the tire correctly when they put it back together. I am glad to have a FOSS tube back in the tire after riding a little while with the back-up rubber tube. I would give the FOSS tube another chance Lance. The first one was probably defective.
I received the replacement Foss tube today. I’ll put it in and give it another try on Saturday. Not wanting to have a repeat of the first go-round, I bought a pack of plastic washers that fit around the valve nozzle. I’m hoping it will reinforce the area where the tube meets the valve hole in the rim. (I don’t know if that was really a factor or not, but I’m just hoping for a little “insurance.”) I’ll take a picture and post it when I install the tube.
Good luck with the new tube LanceB. I have the stock rim that came with the Nimbus 29"Road uni. It is the Dominator rim that someone else noted that they never had a problem with either. The rim may be a factor in supporting the reliability of the FOSS tube.
Yep it will expand to fit the hans with no problem.
If you suddenly want to go back down in size to a big apple 2.0 or similar, you will find the tube is now too big. I spent the winter with a kink in my tube so it would fit in my big apple to avoid trashing my hans with grit.
Im back to using the tube with the hans again and have had no problem but i would recommend against changing to smaller tyre sizes with foss tubes. Mine run at 40 on the coker and 18-20 on my 29er so blow outs are less likely…
As for defects, my valve stem on my 29er is slightly loose and can rotate unless held while removing the valve cap. It doesn’t lose any air but its still slightly worrying.
