Tube Explosion(s)...

[Smeggbert]

Hello!

Bit of a newbie here, I recently purchased an entry level road bike (DBR Sprint). I took it into the LBS to fit some new tyres, the stock tyres were 28c and I wanted something a bit thinner, so i've gone down to 25c. I purchased two new tubes at the same time, and the shop fitted the new tyres and tubes and carried out a gear and break service because the gears weren't quite indexed correctly.

On the commute home, the rear tyre suddenly went flat, after a mere 2km. I took it back to the shop, and they said that there was nothing that they could do and that it was probably something that I had done on the road (hit a pothole or drain or something - which I assured them, had not happened). Nevertheless, I'm not one for arguing and purchased a new tube and let them fit it whilst I was at work.

I returned to the shop later that day to find out that after 3 hours of fitting, the tube had exploded in the rim.

The LBS have advised me that it is most likely a manufacturing fault with the rim that has caused both explosions. So I took it home and fitted a new tube myself, ensuring that the tube wasn't pinched under the rim, and that the valve was seated correctly. Pumped it up to 40psi, checked that it was all seated correctly, and then pumped up to 90psi. Around, 6 hours later, the tube started hissing loudly, fearing an explosion I let the air out of the valve and removed the tube. I have since been unable to find a hole in the tube anywhere, and it has stayed inflated outside of the tyre overnight.

Any ideas what is caused the two explosions and the third attempted explosion? Should I contact the manufacturer of the bike?

 

[martint235]

Possible the tyre wasn't seated properly.

I rode 70 miles to Whitstable the other week with the Friday Night Ride to the Coast. I was upstairs in the cafe waiting for my breakfast when my rear tube exploded in a seriously loud way. I don't know why but for some reason when I heard the bang I instinctively knew that out of 50 or so bikes it was my tube that had gone.

 

[raindog]

I have since been unable to find a hole in the tube anywhere, and it has stayed inflated outside of the tyre overnight.

If the tube isn't punctured, and it stayed inflated off the bike, that sounds like a valve problem. Are they cheapo tubes you've bought? IMO it's best not to scrimp on tubes - buy good quality.

 

[Smeggbert]

If the tube isn't punctured, and it stayed inflated off the bike, that sounds like a valve problem. Are they cheapo tubes you've bought? IMO it's best not to scrimp on tubes - buy good quality.

The valve doesn't appear to be leaking at all, and it seems well glued in.

They are "Specialised" tubes, around £4.99 each.

 

[raindog]

The valve doesn't appear to be leaking at all, and it seems well glued in.

They are "Specialised" tubes, around £4.99 each.

Bit of a mystery then. Make sure you've got good quality rim tape and that all the spoke holes are properly covered then try again, I guess.

 

[sidevalve]

How do you check the valve ? Try putting it back on the wheel and pumping up to about 60 psi then try dipping the end in an eggcup of water to check for bubbles.
Second out of the tyre the pressures are much lower. I had a tube that would stay up for days on it's own but once under real preassure it just slowly went down to about 10 psi.
Finally what exactly did the LBS mean by a rim fault, if they can't or wont show you then some fancy tale about a manufacturing fault seems a bit of a cop out to me.

 

[Smeggbert]

How do you check the valve ? Try putting it back on the wheel and pumping up to about 60 psi then try dipping the end in an eggcup of water to check for bubbles.
Second out of the tyre the pressures are much lower. I had a tube that would stay up for days on it's own but once under real preassure it just slowly went down to about 10 psi.
Finally what exactly did the LBS mean by a rim fault, if they can't or wont show you then some fancy tale about a manufacturing fault seems a bit of a cop out to me.

I checked it outside the tyre, pumped the tube up a bit and put it into some water, no bubbles. I'll try pumping it up inside the tyre again and check the valve.

I have no idea what the LBS meant by a rim fault, and they most definitely couldn't tell me where the rim fault was. The only thing that I can see is the joint where to sections of the rim were welded, they are not lined up 100% correctly (a couple of mm's at most). But because the tube sits inside the tyre and doesnt actually directly have contact with this section of the rim, I cant see how this has caused the problem.

With regards to rim tape, the tape is a little on the cheap side.. its fairly thick and covers most of the spoke holes 100%, but other holes have little bits showing and I cant manoeuvre the tape to cover all the spoke holes 100%. So it's possible that this is causing the problem.

 

[Smeggbert]

I dont know whether its worth pointing out at this point, that It wasn't just a small bike shop, it was a cycle surgery, a rather large chain of shops.

 

[Dan B]

With regards to rim tape, the tape is a little on the cheap side.. its fairly thick and covers most of the spoke holes 100%, but other holes have little bits showing and I cant manoeuvre the tape to cover all the spoke holes 100%. So it's possible that this is causing the problem.

In your position I would definitely rectify this before looking for any other possible cause. Spoke hole edges are often quite rough and can easily puncture a tube

 

[raindog]

With regards to rim tape, the tape is a little on the cheap side.. its fairly thick and covers most of the spoke holes 100%, but other holes have little bits showing and I cant manoeuvre the tape to cover all the spoke holes 100%. So it's possible that this is causing the problem.

You need really good quality, thick tape for high pressure tyres. I had loads of tube trouble in the past with crap rim tape - I always use this kind now.

 

[Smeggbert]

You need really good quality, thick tape for high pressure tyres. I had loads of tube trouble in the past with crap rim tape - I always use this kind now.

Is there a specific manufacturer that you use? Have you got a link?

 

[raindog]

just google Michelin high pressure rim tape

 

[Smeggbert]

just google Michelin high pressure rim tape

Thanks!

 

[HLaB]

If the tube isn't punctured, and it stayed inflated off the bike, that sounds like a valve problem. Are they cheapo tubes you've bought? IMO it's best not to scrimp on tubes - buy good quality.

Another possibility is a minute p'ture hole which closes once the pressure has fallen to a certain level or on an older tube a leaky patch, sometimes you have to put the tube under water to find them.

 

[beeblemaster]

I had what I thought was a slow puncture on mine, that I couldn't find. It turned out it was the valve, but it was just that the middle section of the valve had come undone slightly (Schwalbe). I didn't realise this but the valve comes apart about half way down, I assume so you can effectively replace the core section of the valve, if you catch my drift. This image may help explain what I mean.

Worth a check.

I just carefully (as to not damage any threads or crush..) nipped it tight with a pair of pliers. Been fine since.