Just blew up an inner tube!

[redcard]

Got a puncture last night, so had to replace the inner tube, my first ever time! Well, didn't have to, but it was the easier option.

Anyway, I was blowing the tube up (not in the tyre), the pressure gauge on the pump wasn't moving much from 10 psi so kept going. And going. And going. And BOOM!

An almighty bang, and dust / chalk all over the place.

Anyway, is the pressure gauge only effective when the tube's in the tyre? Or did I just have a loose connection with the pump?

Thankfully I bought 2 tubes, and the second one is in my tyre. I pumped it up to 60ish psi, and am scared to keep going! It only feels a little softer than it did before. Need to grow a pair and get some more air in there.

 

[guitarpete247]

You have no pressure on the tube except from the thin rubber of the tube. In the tyre you have much more pressure as there is not much expansion of rubber of the tyre. Blowing up a tube out of the tyre offers not a great deal more resistance than a kids party balloon so you would expect it to blow whilst showing low pressure.

Yeah put some more air in there your pressure gauge is correct.

 

[fossyant]

LMFAO ! ​

 

[fossyant]

You do one push max on a non fitted tube - I usually just use my mouth. BANG

 

[redcard]

You do one push max on a non fitted tube - I usually just use my mouth. BANG

I bought a new pump as well, and wanted to get an idea how long it would take before doing it on the tyre.

 

[smokeysmoo]

Happened to me once. Fettled bike in the living room, replaced a tube, whacked on track pump, started pumping and BANG!
Blew tyre off rim and big hole in the tube.
Trust me when I say it's freakin' loud when it happens inside!


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[redcard]

Happened to me once. Fettled bike in the living room, replaced a tube, whacked on track pump, started pumping and BANG!
Blew tyre off rim and big hole in the tube.
Trust me when I say it's freakin' loud when it happens inside!


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What was the reading on the pressure gauge when it exploded??

 

[Rob500]

Redcard. Your gauge is probably working ok. As Pete points out, there is nothing to contain the air in a tyre-less tube except the thin rubber of the tube itself.
When the tube is in a tyre, ie a constant volume, pumping more and more air will increase the number of atoms inside the fixed space thus increasing the pressure.

 

[Andy_R]

I would give it another go in exactly the same circumstances, just to make sure

 

[simon.r]

I know you should put a bit of air in the tube before fitting it, to reduce the risk of nipping the tube between tyre and rim, but I never do - just feel it carefully before inflating and after a few strokes of the pump. It's worked for me so far!

 

[simon.r]

Redcard. Your gauge is probably working ok. As Pete points out, there is nothing to contain the air in a tyre-less tube except the thin rubber of the tube itself.
When the tube is in a tyre, ie a constant volume, pumping more and more air will increase the number of atoms inside the fixed space thus increasing the pressure.

Boyle's law? (Vague memories of night-school lessons)

 

[derrick]

That's the funniest thing i have ever read on here.

 

[smokeysmoo]

What was the reading on the pressure gauge when it exploded??

IIRC it got to about 80psi. My pump is fine and it's never happened since. Guess I must have trapped the tube.


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[ianrauk]

A lesson learned...

 

[andrew_s]

What was the reading on the pressure gauge when it exploded??

i had a tube blow at 160psi one time, testing the rim for brake wear. I made a note to put in ear plugs next time, but ended up getting a rim thickness gauge instead (a tenth gauge from a jewellery bits supplier).