zandoval 

Was airing up a wheel set that had been hanging on my garage wall for a few years. The wheel set was protected form the elements except for Texas Heat. Half way through airing at about 28PSI-2BAR they went POP!. On closer exam the tubes and tires were good except at the area below the Presta stem. Is this Common?

genejockey 

I haven't seen anything like that, but it occurs to me that this is the area most exposed to the air, so, maybe oxygen?

cyclezen

Well Butyl tubes do go thru a heat vulcanization process, which bonds the tube ends together and also bonds the valve assembly to the tubing.
My guess is that the heat vulcanization may make the rubber more brittle in that area. The valve stem is contained in a thicker piece of rubber, which bonds to the tubing.
So if too much heat is applied, it may harden the rubber a bit more than the overall tube - and could cause that area to fail sooner than the rest of the tube.
Note in your pic that one failure outlines the underlying valve stem rubber foundation...
...not a materials engineer, but know that 'cold' vulcanization' makes for a more durable rubber - over heat vulcanized...
a material engineer would likely provide a more complete picture of all this...
Don;t think this is a common problem, but I have had older tubes which just 'tore' in a similar fashion.
What brand/model are the tubes?
Ride On
Yuri

pdlamb

I'd guess mechanical failure. After sitting for a few years, you had basically zero pressure in the tube, so nothing to hold it firmly in place. Push the pump head onto the stem, you could have had the bead detach from the rim just below the stem and a bit of the tube get in there. When you then pressurized the tube, the part that was pinched between tire and rim popped the tire off the rim, and instant BAM! resulted.

Iride01 

What internal size rims? That can be a easy place to damage a tube when installing a tire, especially on narrow rims. Though the tube looks more cracked than what I'd expect. What do the other rubber parts look like? Was the bike near something that produced ozone during it's storage time, like a motor?

I've heard that can be hard on rubber. But I'm not where I can go check right now. I put some old tubes and tires near a shop air compressor I have, but so far I don't see any issue. But then again, I don't use the compressor as much as I once did. So it's not running a lot.

spelger

isn't the inside of the tube filled with air? Unless co2 filled.

genejockey 

A point, but the fact that it deteriorated around the hole through the rim is suggestive.

Moe Zhoost

Deterioration of the tube was probably not the cause. I'd say you had a tire bead seating issue, given that all pressure was lost in storage. This allowed the tube to expand under the bead and pop. I've never found age or storage conditions to affect butyl tubes, having used some that were decades old relics.

zandoval 

Could have been water rot. These were old well used tubes and tires. I suspect that every time we air up our tires we get a small amount of moisture into the tube. It is bound to build up over time. The wheel set was hanging off the wall for years with he stems at the lowest point. Moisture could have collected at the bottom of the tube where the stem is at and slowly rotted out the tube. Just thinking...

Kinda like having to bleed the moisture outta the bottom of a compressor tank...

The tubes were KENDA 27 1-1/4. Never had trouble with these tubes before so it must have been the conditions of storage.

spelger

i know some on BF like to argue for the sake of arguing* but...i think it is very unlikely to be caused by oxygen. i run plain old air in my tubes @ ~90psi. that is about 6 times the air in my tubes vs the air in the...air. that means about 6 times the oxygen swimming around in the tube. if oxygen caused this on the outside i would think that our tubes would have burst into flames long ago. some of my tubes are many years old.

*say it ain't so

genejockey 

Okay, but you have to realize that if oxygen DOES react with the butyl rubber, the oxygen would be depleted by the reaction, whereas the oxygen outside the tube is continuously replenished. But it doesn't have to be oxygen. We know that if you leave tubes out in the garage, even where it's relatively dark, they break down over time. If part of that is exposure to SOME COMPONENT OF air, then the are closest to the valve may be more exposed than elsewhere.

I dunno. It's an hypothesis, and not one I give enough of a **** to investigate.

spelger

everything breaks down over time but i'd rather ride than think about how long.

i see you are from the bay area. i used to live in Mountain View in what was an old hotel. then later moved to San Jose. i remember riding on some roads over there. some big hill up to La Honda or along Sand Hill. Isn't sand hill near the linear accelerator?

genejockey 

Yes, the big hill is Old La Honda. Goes from Portola Valley up to the top of the ridge of the Santa Cruz Mountains. You take Sand Hill West from Palo Alto to get to it, and the main entrance to SLAC (Stanford Linear Accelerator Center) is off Sand Hill.

cyclezen

Yes, definitely, that one with the 'star' blowout... I've done that... LOL! the tire bead wasn't properly seated all the way around, I was doing the tube swap in the evening and lighting was low (always have an excuse handy, v- important !!! LOL !) But mine blew when I had it up to pressure - 80 psi - had walked away to get something... BLAM ! LOL!
But the one with the 'age' crack under the valve - old rubber giving way...
Some tubes just seem to age and crack faster than others... I don;t buy Conti tubes anymore. Schwalbe, on the other hand seem to be bulletproof at almost the same weight...
Ride On
Yuri

VegasTriker

One of the tricks I learned working in a bike shop and replacing many tubes was to always push the valve in toward the tire and then pull it back out just before inflating the tube. This made sure the tire bead was properly seated adjacent to the valve. This was just the type of problem that was meant to avoid.

BlazingPedals

While everyone is theorizing bad rubber, the ragged hole indicates explosive decompression, which is impossible if the tube is fully within the tire. What you have here is the results of a pinched tube, and in the most likely place for it to happen. The reinforced part of the tube got caught under the bead the last time the tire was mounted.

ThermionicScott 

I don't think rubber actually rots from that. The "rot" that we see on the sidewalls of car tires is from ozone and UV rays, neither of which bike tubes should experience.

That would be my guess. Same wheels as these overbaked tires? https://www.bikeforums.net/classic-v...gum-walls.html

Maybe, but if the tires were able to completely deflate during their long storage, the beads could come unmounted, and the tubes could find new paths out when the tires get pumped up again. Whenever I have a bike tire go completely flat from storage, I go through the procedure of first adding a few psi and working my way around the rim to check against a trapped tube before airing it up to full pressure, just like when mounting the tire for the first time.

Steel Charlie

the very comment that I was going to make. NEVER tighten that nut - - it is only to prevent the stem from being pushed into the tire when inflating. It is NOT meant to hold anything in place.