Cycling UK Forum

I was sitting on the sofa and heard bang and hissing noise which made me jump out of my skin! I felt my tires and one was a bit softer than I'd expected, but not flat. Spent ages looking round the room with my Mum for the source of the bang. Anyway later went to cycle somewhere and realised the tyre was indeed the source of the noise. When I came to take it off next day it still had some air in.

I had pumped it up a few days before after it being pretty low pressure, maybe too low, and used on occasional local trips. Maybe I'd had it too low and it had managed to slip between the bead and rim and got pinched?

Also, we have underfloor heating in that room so possibly I'd pumped it up when the floor was cold, to around the max 85 psi, and then the floor had heated it up and caused the pressure to rise.

Anyway in the shop I mentioned the explosion and they recommended checking the tyre and rim which I did, can only see some external looking damage near the tyre bead, not sure if that was even near the hole.

Anyone recognise that kind of hole? I just want to avoid it happening again in that way. Never had this issue before with that wheel and tyre.

It could be a pinch flat, on the other hand if the tyre was damaged like that before it could be that there is something on the tyre, maybe one of the wore beads which has stuck into the tube. I'd dismiss the heating, 30 degrees rise in temperature would only give around a 10% rise in pressure (engineering approximation)

From the pictures it looks like the wire bead is separating from the tyre sidewall. If so, a possible cause is brake blocks being set too high. Under braking they can rub against the tyre and wear through. The puncture when it comes can be explosive.

Ask me how I know

OK thanks for the ideas! I hadn't thought of the brake blocks, will check them when I get home. I guess will need a new tyre which is a pain but can't be helped. May have an intact one in the garage

That rim tape has a big hole for a Schrader valve; for a Presta valve you need a small hole, otherwise the tube can chafe on the metal edge.

The tyre damage is either from a brake block rubbing, or abrasion from ( eg) a corroded rim, this latter is called either a flange split or a rim split; search the forum for either and it will come up.
A really clear photo might be enough to differentiate the cause of the tyre failure.

actually looks like the tyre has suffered some chafing, IME this usually due to riding with insufficient air.

as above,that rim looks to be drilled for woods/schrader. If you want to use presta in that rim,you really need a spacer of some kind. If you ride on a tyre that is underinflated, not only does it knacker the tyre pdq, but it also causes the rim to pull hard on the valve stem, because otherwise the tyre will be turning on the rim. The valve stem usually sits at a jaunty angle if this has been happening. Needless to say but this can seriously damage the tube.

Mr Tom wrote: ↑15 Dec 2023, 11:40am I was sitting on the sofa and heard bang and hissing noise which made me jump out of my skin! ...

I once had the same thing: pumping up a tyre on my commuter a bit too hard, and then putting it in the hall against the radiator in winter. I was watching the telly, and it sounded like a gunshot going off.

Over the years I have had to use spokes of all lengths when there were breakages with assorted old wheels, some of pretty basic quality: I just used them rather than throw them away. Long spokes would occasionally protrude against the rim tape, but a patch of inner tube seemed to mean there was no trouble.

I think the others have addressed your particular issue, though.