Thus CW Spake

Hi all,

Last night my boyfriend and I were sitting in the living room and it was totally quiet. All of a sudden, we heard a pop and then air rapidly being pushed out of - you guessed it - one of our bike tires. I went to check them out and one back tire was totally flat. Before riding to work a few days ago my boyfriend's tires were really low on air so we pumped them up to about 110 psi, and his tires have a max 120 psi. I suppose my gauge could be off on my pump and we could have really overinflated but I've never had a problem with it before, and the gauge read properly this morning when i was leaving.

I know how to change the flat and all, but I'm wondering - does anyone have any other suggestions about what might have happened?

dabac

A creeping rim tape can do that, check position of where it punctured.

DiabloScott

Well you heard a "pop" and not a "bang" so you didn't have an explosion, you had a puncture. That means you didn't have a casing tear and the tube didn't blow out. Somehow, something got to your tube and somehow the effect was delayed and somehow it did the damage when the bike was not moving.

The puncture could be a very small thorn or piece of wire or burr on the rim - check the inside of the tire in the location of the tube failure.

The delay effect could be caused by a change in temperature maybe... just a guess.

Usually an uncovered spoke head would cause an immediate failure, so I think that's an unlikely cause but easy to check for.

Mentor58

I'd second looking at the tube, see where it let go. I'm going to make a friendly bet that it's on the inside (rim) part of the tube. Almost everytime thats happened to me it's been a rim tape issue. If it's the rubber band type that some rims have, that can slip over a bit, over time time the tube develops a weak area where it's forced into the exposed spoke hole, and then it finally lets go. Cheap rim tape (or using something like electrical tape rather than rim tape) can also cause that, it starts to sag under the pressure.

I think that some good troubleshooting will help prevent this from happening in the future. I HIGHLY doubt that you overinflated the tire by that much. Even if the gauge isn't dead spot on (and I don't know how accurate they are), it takes a LOT more than the max pressure rating to actually cause things to blow. (assuming that everything is solid mechanically). (now I've got an overwhelming urge to actually try and cause a tube to blow by over inflating it with a hand pump).

Hope this helps

M58

DannoXYZ 

Yeah, the max-pressure rating on a tyre is common set at 1/2 of what it really takes to stretch and blow a tyre off the rim. Most likely it's a tube-mounting issue. Mark the valve-stem position on the tyre and inspect the hole in the tube. Most likely the tyre is perfectly fine with no holes in it. The tube most likely squeezed out somewhere either on the rim-strip side or through the gap between the tyre and tube.

This is by far the most common 99% of the problems out there. When mounting a tyre, DO NOT immediately pump it up. Inspect the gap between the tyre and rim first. Pull the tyre sideways so you can look down this gap, you should not see any tube showing. Move over a little and pull the tyre sideways again until you've inspect the entire side. Then pull it over to the opposite side and inspect the other side of the tyre. Only when you've confirmed both sides of the tyre isn't pinching the tube, only then would you pump it up.

Thus CW Spake

Well, I guess it was more of a bang than a pop...it was really loud. I've checked around the office with other riders and they suggested the rim tape thing as well, so I'll check that. Thanks for the help!

Al1943

+1
DannoXYZ's got it right. Velox rim tape is also an excellent idea.

Closed Office

I usually pump up my tires just a bit and then check to make sure they are evenly seated.
They have a line just above the edge of the rim to help out with that. The most common
place for a problem is by the valve stem because of the thicker rubber where it joins the
tube. This sometimes holds the tire bead from seating evenly there.

It took 3 or 4 of those delayed reaction pops before I was impressed enough to start doing
that. If the bead is seated a bit higher along the rim somewhere, the tube just slowly starts
to push it even higher until it bubbles out from under the tire and it really does make a loud
noise when it blows. Also you usually wind up with a long hole, about 3 inches, instead of
a tiny puncture.

cyclodan

Often when a tire gets very low this will allow the tube to get trapped between the tire and rim. Now when you bring it up to full pressure and even tho' it looks like the tire is seated evenly, it will start to creep out and ...BAM! I have seen this type blowout damage the wire bead of the tire, bend single wall rims or break a thumb of a guy who just happened to be holding one when it went.

StephenH

I've had two blowouts on 20" unicycle tires where the tire popped off the rim on one side and let the tube blow out. Both times, there was no visible damage to the tire, and the tire was still in place after the event. There was a pencil-sized or bigger hole in the tube that was pretty obvious. These both happened while riding, but not while doing anything special either, so still somewhat mysterious. And yes, they made a pretty good "BLAM" when that happened.