Something very odd happened to me this weekend.
I was out of the house the entire weekend and when I returned I’ve noticed that my 36" wheel was flat out of air - so I assumed this is probably my first puncture.
I spent two hours looking for the damn hole in the FOSS tube but couldn’t find it.
I wanted to try and reproduce the problem, so I returned everything back to its place and inflated the tube back to normal.
I did some freemounts on the wheel, but nothing happened… until suddenly when I was not on the wheel there was a sudden burst of air which came straight from the valve and even threw away its cap.
I could only imagine what would have happened if this was in the middle of a ride
Anyway, it seems like the valve has some sort of fault.
Did you ever encounter such issue?
Is it possible to fix it - or I need to replace the entire tube?
It is possible to remove the central part of a Schraeder valve and replace it - or at least it was 35 years ago when I last did so. Ask at your local bike shop.
If a sudden burst of air blew off your valve cap it sounds like it may be the valve core rather than the connection between the valve and the tube. I hope so.
Sorry, I’ve been down this road with the Foss tubes, valve cores don’t loosen and pop out. The valve is broken. I posted pics somewhere, even sent the pics to UDC USA, but what can be done??
I’ll eat my unicycle if it’s not a bad tube as I suggested, yes, even my flat seat
Frankly, I’m very suprised there are not more Foss tube failures. Furthermore, the rapidity at which the tubes deflate would make me very nervous in a high speed blow out situation…if I rode one that is
So, Mr “One4All”, what did you find when you twisted the valve? Can you pull the valve assembly out of the tube? I’d get teh retailer to replace it at their cost, this is a “known” weakness.
From my experience, Foss tubes suck. Way too thin for my taste, and I ripped the valve off of mine as well after I already trashed it tryng to fix a hole in it.
Valve cores are removable, they thread in like a bolt, so they shouldn’t go anywhere.
Can’t you inflate the tube and see where it’s leaking? If it’s leaking too fast to inflate, the puncture is too big to fix.
Well, I couldn’t pull it out - though I didn’t try to pull it too hard except for twisting the small screw (“release”/ “close” modes) and I did managed to inflate the tube without any leaks.
I tested it for about two hours and saw nothing wrong with it.
It was only when I got it all back together in place - fully inflated and free-mounted a few times.
Luckily, the sudden blow out of air occurred while I was off the uni (without applying any pressure on it).
Otherwise, it could have ended in a brutal fall, not to mention high speed riding as you said yourself.
I think that I would turn to FOSS support, if such exist and if you guys also indicate that this is a known issue (bug?).
I will update you as soon as I’ll get any response.
The tube will hold air as long as the valve stays stuck in the tube, so sitting still it will appear fine, the problem is when you start riding it will wiggle free.
The blue aluminum valve shaft is attached to the flattened portion of the inserted base (which retains the valve in the tube) by four small “threads” of aluminum. These threads are underdesigned, so over time as the valve pushes against the rim hole, those threads will break, then the valve will pull free.
Be careful with this tube if you already had a sudden loss of air, you could have a dangerous blow out at speed!
Go tubeless, it’s da bomb, lighter weight, safer, lasts as long as the tire, all you need to do is add sealant every so often.
@Nurse Ben, I checked with a very well known LBS about modifying my wheel to tubeless and they found all sorts of reasons why it’s impossible - starting from the type of wheel and the rim that should be replaced, etc.
Other than that someone had told me that the puncture self repair fluid may endanger my stability during the ride.
And if that wasn’t enough I was told that if my problem was the valve, then it would still be using one - so the same point of failure exists in tubeless also.
Don’t get me wrong, I’d like very much to go tubeless and if I needed a reason I probably found one
But could you please point me to any “DIY” tutorial regarding this? and if possible could you kindly comment on the above raised issues?
I appreciate your time put into this for helping a newbie
They have no idea what they are saying, the amount of “reserve” fluid is so small and spreads out so thinly during riding that this comment makes no sense. If anything, a blowout if waaaaay more likely with a tube, so tubeless is far safer, which is why cars and motorcycles are tubeless.
Also, the tubeless sealant protects against leaks, so it is more flatproof than a tubed tire.
Uhhh, is that that same well known LBS talking? All bikes have valves, so the “risk” of valve failure is more or less the same for all bikes, as well as all motorized vehicles. A screw in tubeless valve is going to the most secure and leak proof valve you can get, which is why high end cars/trucks and most motorcyles use this type of valve.
I’m a bike mechanic, been working on bikes and related “toys” since I was a teen, and for your LBS to say that making your 36er tubeless is “impossibe”, well, I’d say that your LBS sucks.
You really need to try a different LBS.
The DIY stuff is all over the net, so do some reading and watch some videos.
The essential point that you should take away from going tubeless on a bike is that most cars/trucks and motorcyles are tubeless WITHOUT a sealant, so adding a sealant makes going tubeless much easier because you can seal the small imperfections that come from using rims and tires that are not designed for tubeless.
The 36er is a non standard rim, so you will not find a turnkey “kit” for making it tubeless, which means you will be using a tubeless valve and rim tape or a ghetto tubeless. Tubeless valves are very simple, just a threaded valve that is inserted from the inside of the rim, a gasket seals against the inside rim surface/tape, and a nut and washer threaded on the outside of the rim keep it sealed.
The tape is applied to the inner rim surface to cover over any holes to include spoke holes, seams, breather holes from manufacturing, etc… Depending on the rim you have, you may have to tape all the way into the rim “hook”, esp if there are obvious breather holes. If the tape is not enough to seal these holes, the sealant will more often than not be enough to complete the sealing. Worse case scenario, the tape does not seal the rim, then you move to a “ghetto” tubeless.
A ghetto tubeless uses a “filleted” rubber tube to line the inside of the rim, rim hook, and over the outside edge of the rim. You use the existing valve of the tube, no tape is needed, seating and sealing the tire is the same as for the taped rim. Once your tire is sealed, you can trim back the tube at the edge of the tire for a cleaner look.
For a ghetto tubeless, you may be able to use a 29er tube, but having never tried this with a 36er it is on you to try it and see if the tube will stretch without tearing. A welterweight Maxxis tube is about the thickest 29er tube you can get.
In theory, it’s pretty easy. If you don’t have an air compressor, you need to find a place that has one. Make sure that your tire will seat WITHOUT fluid in it first. I wasted a lot of fluid trying to get my beads to seat when I didn’t have a chance.
What I do, is inflate my tire with a tube in it, to 70 psi to make sure my beads are well seated. Then I slowly remove the valve core to deflate it. Next I pop one bead and remove the tube carefully, making sure the other bead remains seated. Then I carefully install my valve, add my fluid, and inflate. With a little luck and patience, it’ll work.
Edit: Beat me to it Ben.
On ghetto tubeless: Tons of people have used 29er tubes in 36ers so I have a hard time believing you’d teare the rubber but YMMV. I suspect that a ghetto setup, being thicker, would be easier to seat the beads on. That’s just speculation though.
Yes, you need to get a decent dry seat before adding fluid BECAUSE the tire will need to be deflated in order to add fluid. This will also tell you about how good of a seal you have before wasting too much time and sealant.
Fuid is generally added through the valve, esp if there is a risk of the tire unseating; Killian…
Some tires are more difficult to seat than others, esp the wire bead tires; all 36er tires are wire bead
A used tire will be easier to seat because it’s already been broken into the correct shape.
A warmed tire and rim will seat better together.
Using a little warm soapy water can help with seating and sealing.
