New Inner tube bursts on first inflation !

[Jammyjames]

I just got myself some Schwalbe Big Ben MTB Tyres (27.5 x 2.00 with a min - max PSI of 35 - 70) to replace my stock Kenda knobbly tyres (27.5 x 2.1 Max PSI 50) (K1027 i think). I also got myself some new slime innertubes 27.5 (650b) x 1.90-2.125.

So now as I've fitted the new Schwalbe tyres and slime inner tubes I inflated the first tyre to 60PSI (bare in mind the max is supposedly 70) and the inner tube burst about a meter away from me (i dont recomend this, my ears were ringing for an hour ) so essentially given that the new tyres a slightly different to the old ones i have to know did this happen because the innertube cant take the high PSI (though the instructions for the innertube only say not to exceed the max PSI of the tyre sidewall, or is it something to do with the stock tyres only taking 50PSI but the new tyres have a slimmer profile so it cant take the same Max PSI or something? Or is this just potentially a fault with the inner tube?

TIA

[hamster]

Sounds like:
1. You were just unlucky with the tube, or
2. That the tyre wasn't properly seated on the rim, blew off and the tube then went
3. The tube was pinched between rim and tyre.

[Jammyjames]

Sounds like:
1. You were just unlucky with the tube, or
2. That the tyre wasn't properly seated on the rim, blew off and the tube then went
3. The tube was pinched between rim and tyre.

I cant be 100% certain but im fairly confident it was seated ok, and i dont think the tube was pinched (though it is possible) so I am just going to assume i was unlucky ... itll make me feel better is i am wrong haha

[Marcus Aurelius]

You’d be surprised how big you can get an inner tube to go, before it goes bang. I’d be looking at my rim tape if I were you. If it’s broken around the spoke holes, this will lead to a loud bang.

[Jammyjames]

You’d be surprised how big you can get an inner tube to go, before it goes bang. I’d be looking at my rim tape if I were you. If it’s broken around the spoke holes, this will lead to a loud bang.

I have now used my old standard inner tube and both the front and rear tyres are at 50PSI without an issue so i wouldnt have thought this would be the problem? besides that the bike hasnt even done 20 miles (all miles so far on the road too), so i doubt there would be anny issues on the rim.

[Marcus Aurelius]

You’d be surprised how big you can get an inner tube to go, before it goes bang. I’d be looking at my rim tape if I were you. If it’s broken around the spoke holes, this will lead to a loud bang.

I have now used my old standard inner tube and both the front and rear tyres are at 50PSI without an issue so i wouldnt have thought this would be the problem? besides that the bike hasnt even done 20 miles (all miles so far on the road too), so i doubt there would be anny issues on the rim.

I’ve had this happen on brand new bikes before now. At 50 psi, you may not be getting the tube forced through the holes enough to cause the problem.

[Brucey]

if the bang was that loud the tube probably burst into free air, not into the rim hollow. If the tyre is still intact this means the tube was pinched or the tyre blew off the rim.

So I'd suggest that you check

a) that your rims definitely have hook beads
b) the state of your rim tapes
c) that the tyre is properly seated next time
d) that the tube definitely isn't pinched
e) that your pressure gauge isn't telling you fibs

You should inflate to about 15-20psi and then check the tyre/tube for correct seating, before inflating to any kind of high pressure.

cheers

[peetee]

Tubes do not always inflate evenly and depending on your rim and tyre combo the fit might have been quite slack. As the tube is inflated it could have reset the tyre off-centre radially, laterally or both, not enough to be immediately apparent but enough for the result you had.

[robgul]

My 2p would be that the tube was pinched by the tyre. Whenever I fit a new tube - and I've fitted many hundreds when running an LBS - apart from a visual check of the tyre bead, I inflate the tube to about 30/35 psi and then let it down again before inflation to the required pressure - the chances are that IF it's pinched it will free itself.

That said, slime tubes are the work of Satan - better to use normal tubes and then remove the valve core to add sealant after the tube has been inflated the first time

Rob

[mattsccm]

As above although maybe it had stuck together internally.
Had an old latex tub on a rim that would, as you might expect, lost air over a week. Splashed a drop of tubeless sealant in in case it was a tiny hole. Forgot it for months and found it flat and flattened. Pumped it up. Bang. I guess the latex had stuck the sides together and they didn't separate.
Trapped tubes are dead easy with Challenge open tubulars that sit flat on a rim.

[backnotes]

You’d be surprised how big you can get an inner tube to go, before it goes bang.

This is what CTC Cambridge did for entertainment in the 1930s - an inner tube bursting competition. Taken from this site https://ctccambridge.org.uk/ctccambridg ... #ontheroad. Apologies in advance for this light-hearted diversion from the more serious topic under discussion, but it illustrates the point above!

[pwa]

I would pump the tyres up to the max to test them, then reduce to the preferred pressure. Watch the seating of the tyre as you pump to see if it is rising off the rim.

And do make sure the rim tape is not shifting around, and properly covers spoke heads.