Ramshackle

An enigma. We on the couch watching TV. The bike was on a floor rack and hadn't been ridden in two days. Suddenly a loud hiss and the back tire instantly deflates. The tube has never been patched. I'm guessing it's the rubber seal by the valve, but not sure. I can't think of what else it would be.

Trevtassie

Pixies. They need some rubber for their moonshot slingshot. They'll wait until you bin the old tube and then pounce...

Moe Zhoost

Perhaps you will discover the cause when you dismount the tire. Let us know what you find.

rosefarts

You are correct in your description of a sudden flat tire. Good job.

I don't know why people are offering suggestions, you clearly didn't pose a question.

ramzilla

We walk around in a circle and suppose but the secret lies in the middle and knows.

canklecat

Check around the valve for cuts -- hold the tube under water and check where the bubbles come out. If it's around the valve stem, check the rim for burrs. Especially with Presta valves if you use the retainer nuts. I do -- makes it easier to inflate a tube from scratch, especially with push-on chucks like that on my floor pump (my mini-pumps have threaded chucks).

Recently I forgot to loosen the Presta valve retainer nut after inflating the tube. A few days later it leaked through a nick around the valve stem. Sure nuff, burr around the rim valve stem hole. And I made it worse by overtightening the valve retainer nut. I deburred the rim and reminded myself to loosen the nut after inflating, if I can't force myself to do without the retainer nuts completely.

On the plus side, I'm doing my part to keep my LBS in business during this carumbavirus pandemic (they're limiting the shop to 2 customers at a time, and I wore my mask and tried to avoid touching stuff I didn't plan to actually buy). Had to visit a couplafew days ago so they could pull a jammed crown race for me (they have the proper fancypants Park tool, which I can't justify buying). And they never charge me enough for service favors, so my conscience compels me to buy tubes and stuff I won't need for years. I usually patch tubes until there's more patch than tube, but I don't try to fix tubes with cuts near the valve stem.

Maelochs

I have had mystery blow-outs .... sounds like a gun going off .... great to liven up a quiet evening ......

Ramshackle

Trevtassie, if you lived in Hawaii you would know it was the Menehune not pixies that did ii. A burr around the valve hole (it was a presta) sounds plausible, but why suddenly with no movement did it pop. My hunch is that the glue on the flap holding the valve in place gave out. I had a similar sudden deflation happen while I was riding on another bike. It was the valve flap. Both were Specialized tubes.

308jerry

Apparently we have different types of guns......

skidder

Over-inflation? I've had it happen twice, both times when I inflated a tire in the PM for a ride the next morning. I overinflated 70psi tires to about 85psi and they went 'BOOM' without warning a few hours later. First time I thought it was a faulty tire, next time I got a little more inquisitive and noticed the displaced tire; the tire bead gets pushed out over the rim where the tube was able to force its way out, and the tube pops along a seam in that area. Solution: pay attention to the psi rating on the tire sidewall and don't exceed it!!

BlazingPedals

If i were to hazard a guess as to why it went flat, I'd say it was due to all the air escaping. You could probably resolve the enigma by investigating what may have caused it.