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Why Blowouts Happen ?

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  • 11-10-2018 11:08pm
    #1
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭


    Cycling last Sunday on a smooth section of road and got a blowout. Big tear in sidewall and rapidly deflated. Tyre was less than 3 months old, in good condition and hadn't seen a lot of mileage.

    Can't fathom whether it was a bad tire or if I unwittingly hit something. Its only the second time in years of cycling this has happened to me (slow puncture lots)

    Ideas ?

    Interested in hearing other peoples blowout stories.


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    #2
    saccades
    Registered Users Posts: 1,256 ✭✭✭saccades


    Brake pads badly adjusted ( or mudguards) and rubbing.

    Snagging something in the shed.

    Too high a pressure once for me, racing down a hill in summer the back popped off the rim.

    Hard to get enough spit in summer to be able to seat the bead with a regular pump. Only time UST let me down


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    #3
    smacl
    Moderators, Society & Culture Moderators Posts: 15,722 Mod ✭✭✭✭smacl


    One and only for me was having the sidewall sliced by a piece of flint passing a gravel drive way, which was a bit ironic having done a good bit of gravel riding with no issues. Tyre boot got me home but I binned the tyre and replaced it. Whats's the orange gunk at the cut?


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    #4
    elfy4eva
    Registered Users Posts: 1,204 ✭✭✭elfy4eva


    harringtonp wrote: »
    Cycling last Sunday on a smooth section of road and got a blowout. Big tear in sidewall and rapidly deflated. Tyre was less than 3 months old, in good condition and hadn't seen a lot of mileage.

    Can't fathom whether it was a bad tire or if I unwittingly hit something. Its only the second time in years of cycling this has happened to me (slow puncture lots)

    Ideas ?

    Interested in hearing other peoples blowout stories.

    U replace the tube recently? Possible pinching?


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    #5
    bingobars
    Registered Users Posts: 156 ✭✭bingobars


    Riding under deflated tires wears the sidewalls and each and every time you put the bead back on the rim too. Brakes pad run potentially as mentioned. Debris obviously and defective tire is more of a long shot I find


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    #6
    Kissy Lips
    Closed Accounts Posts: 297 ✭✭Kissy Lips


    How much do you weigh and what PSI was the tyre at?


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    #7
    07Lapierre
    Registered Users Posts: 8,219 ✭✭✭07Lapierre


    Looks like a damaged tyre possibly due to riding over a sharp object. Maybe a stone or glass.


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    #8
    Miklos
    Registered Users Posts: 985 ✭✭✭Miklos


    I had a blowout this morning and the bike was just sitting in the hall, bizarre! About to get out of bed and all of a sudden I hear all the air bursting out of the tyre.


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    #9
    Crocked
    Registered Users Posts: 543 ✭✭✭Crocked


    Miklos wrote: »
    I had a blowout this morning and the bike was just sitting in the hall, bizarre! About to get out of bed and all of a sudden I hear all the air bursting out of the tyre.

    Had that happen me a few years ago. I had the bike leaning against a radiator so think the air heating up in the tube was too much, then KABOOM, frightened the ****e out of me


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    #10
    seamus
    Registered Users Posts: 68,317 ✭✭✭✭seamus


    A blow out sidewall specifically means some kind of trauma. The weave runs vertically in the sidewall, so it should should only pop where something has cut that weave laterally.

    Examples tend to be as above - rubbing brake pads, jagged edges on the rim, or unlucky encounters with a kerb/wall/stone. As bingobars says too, if you ride underinflated tyres routinely, this will wear down the sidewall quicker.

    When I first got back into cycling though I bought an MTB and some big ass tyres, then proceeded to pump them up to their rated max of 60psi or something. The tyre was too wide for the rim and the rim cut into the sidewall and failed. Like other stories here I was elsewhere in the house several hours after pumping them up before I heard them fail. Wrecked 3 tyres (no I didn't learn after the first two).

    The very specific triangle shape in the OP, I'd also go with some kind of glass or stone shard. Probably a tiny pinhole in the tyre, which then tore out and downwards.


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    #11
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭harringtonp


    smacl wrote: »
    One and only for me was having the sidewall sliced by a piece of flint passing a gravel drive way, which was a bit ironic having done a good bit of gravel riding with no issues. Tyre boot got me home but I binned the tyre and replaced it. Whats's the orange gunk at the cut?

    Was messing around with a tire plug while waiting for a spare wheel

    How did you know it was flint, did you see it stuck in the tire or hear it ? It could have been something on the road in my case too but there were no signs.


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    #12
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭harringtonp


    elfy4eva wrote: »
    U replace the tube recently? Possible pinching?

    There was no tube in it :D


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    #13
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭harringtonp


    Kissy Lips wrote: »
    How much do you weigh and what PSI was the tyre at?

    80kg, 80PSI. Tubeless though


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    #14
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭harringtonp


    07Lapierre wrote: »
    Looks like a damaged tyre possibly due to riding over a sharp object. Maybe a stone or glass.

    I'm wondering can things like this have happened on previous spins and it takes a few 100 km before it finally gives... I was rolling smooth when it actually went


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    #15
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 48,492 CMod ✭✭✭✭magicbastarder


    Crocked wrote: »
    Had that happen me a few years ago. I had the bike leaning against a radiator so think the air heating up in the tube was too much, then KABOOM, frightened the ****e out of me
    i doubt that the radiator would make much of a difference - they wouldn't heat the tyres up that much i guess? you'd need a 30C change in temp to make a 10% difference in pressure, IIRC


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    #16
    smacl
    Moderators, Society & Culture Moderators Posts: 15,722 Mod ✭✭✭✭smacl


    harringtonp wrote: »
    Was messing around with a tire plug while waiting for a spare wheel

    How did you know it was flint, did you see it stuck in the tire or hear it ? It could have been something on the road in my case too but there were no signs.

    Passing a driveway on a narrow road that had a lot of flint in the gravel. Mostly smooth except for some crushed shards by the road edge, only noticed the bits of flint while stopped to fix the tyre. Schwalbe marathon supreme, which is puncture resistant on the rolling surface but not the sidewall. As Seamus said, the upward V shape of the cut suggests a nick on the sidewall near the running edge that ripped upwards.


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    #17
    smacl
    Moderators, Society & Culture Moderators Posts: 15,722 Mod ✭✭✭✭smacl


    harringtonp wrote: »
    80kg, 80PSI. Tubeless though

    The tyres I was running when this happened were 32c also at @80psi and I was ~86kg at the time. Lower pressure could mean more bulge in the sidewalls and a slightly increased chance of this type of thing happening. Bit of a pain with tubeless I'd imagine. Did you have a spare tube and boot?


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    #18
    07Lapierre
    Registered Users Posts: 8,219 ✭✭✭07Lapierre


    harringtonp wrote: »
    I'm wondering can things like this have happened on previous spins and it takes a few 100 km before it finally gives... I was rolling smooth when it actually went

    Yes that's quite possible. It also explains "Phantom" blowouts when bikes are in the house at the time of the blow out. The heat from a radiator also helps.


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    #19
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭harringtonp


    smacl wrote: »
    The tyres I was running when this happened were 32c also at @80psi and I was ~86kg at the time. Lower pressure could mean more bulge in the sidewalls and a slightly increased chance of this type of thing happening. Bit of a pain with tubeless I'd imagine. Did you have a spare tube and boot?

    Spare tube but no boot. Hole was too big to put a tube in


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    #20
    8valve
    Registered Users Posts: 976 ✭✭✭8valve


    the secret is in the name, blowout.

    It blows out, due to some form of damage to the tyre; the weakness in the tyre eventually fails due to the high pressure of air from within, forcing the weak spot to split and rapidly deflate.


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    #21
    Wishbone Ash
    Registered Users Posts: 24,960 ✭✭✭✭Wishbone Ash


    I've had a few over the years. One was while in the middle of a group on the outside during a club ride - not a pleasant experience when so close to others. Another one was in the middle of the night in a hotel room in London. I put it down to leaving the bike beside a radiator. The others were while riding solo at night, thankfully never while descending.

    Incidentally, our road captain had a blow out during a club ride a few weeks ago (Conti GP4000 tyre). In the minutes prior to it happening, a few of us had remarked on a noise coming from his back wheel. In hindsight, it appears that the tyre had bulged for a while before blowing out and the noise was it rubbing on something.


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    #22
    harringtonp
    Registered Users Posts: 2,563 ✭✭✭harringtonp


    Sent a photo into mantel of the tire asking if they were aware of any other problems with the batch and even though I hadn't asked for a replacement I got a reply saying they would send a new one out.


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    #23
    Type 17
    Registered Users Posts: 2,730 ✭✭✭Type 17


    The max pressure marked on every tyre is indicative of the width and quality of the tyre (and it's width - narrower tyres can take more pressure and vice-versa) - better quality tyres have better-quality bead (wire or kevlar-type plastic), which stretches less at a given pressure.

    What this means is that while better quality tyres have a higher pressure limit, every tyre has a limit of pressure, and if exceeded, the bead will stretch enough to lose grip on the crotch (grooved edge) of the rim and the edge of the tyre will pop off.

    I used to pump tyres right to the marked limit, if it was 85PSI or less, but once or twice, in the summer, the tyre blew off about 30 mins later, because the bike was in direct sunshine. Now, I leave tyres at least 10% below the limit, especially in the summer...


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    #24
    dahat
    Registered Users Posts: 16,646 ✭✭✭✭dahat


    Are GP4000's really worth the blowout risk?


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    #25
    07Lapierre
    Registered Users Posts: 8,219 ✭✭✭07Lapierre


    dahat wrote: »
    Are GP4000's really worth the blowout risk?

    Yes.


    (Blowouts are caused by other factors. E.g. The tyre is cut by a sharp stone or glass, badly aligned brake pads etc. Tyre brand is irrelevant)


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    #26
    dahat
    Registered Users Posts: 16,646 ✭✭✭✭dahat


    07Lapierre wrote: »
    Yes.


    (Blowouts are caused by other factors. E.g. The tyre is cut by a sharp stone or glass, badly aligned brake pads etc. Tyre brand is irrelevant)

    The GP4000's seem very prone to sidewall failure /blowout type issues, I have arrived at this from posts here plus seeing a few returns in LBS over last 2/3 years.


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    #27
    07Lapierre
    Registered Users Posts: 8,219 ✭✭✭07Lapierre


    dahat wrote: »
    The GP4000's seem very proe to sidewall failure /blowout type issues, I have arrived at this from posts here plus seeing a few returns in LBS over last 2/3 years.

    Maybe, but I've been using them on my 3 bikes for over 10 years now. I won't fit anything else to be honest because I find them brilliant. The only time I had a blowout was due to misaligned brake pads.


    I've used schawble,Victoria and Michelin tyres and for me, continental are the best.


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    #28
    Wishbone Ash
    Registered Users Posts: 24,960 ✭✭✭✭Wishbone Ash


    07Lapierre wrote: »
    .....(Blowouts are caused by other factors. E.g. The tyre is cut by a sharp stone or glass, badly aligned brake pads etc. Tyre brand is irrelevant)
    The blowouts may be caused by other factors but, in my experience, GP4000's sidewalls will fail compared to other brands when subjected to the same trauma. They roll beautifully but I've never had any luck with them despite giving them several chances.


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    #29
    07Lapierre
    Registered Users Posts: 8,219 ✭✭✭07Lapierre


    Wishbone Ash wrote: »
    The blowouts may be caused by other factors but, in my experience, GP4000's sidewalls will fail compared to other brands when subjected to the same trauma. They roll beautifully but I've never had any luck with them despite giving them several chances.

    Fair enough..I don't doubt you. I'm just relaying my experiences with them, which have been 99% positive.


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    #30
    Wishbone Ash
    Registered Users Posts: 24,960 ✭✭✭✭Wishbone Ash


    07Lapierre wrote: »
    Fair enough..I don't doubt you. I'm just relaying my experiences with them, which have been 99% positive.
    I'd love to have confidence in them, and in fairness, many cyclists do as can be seen in our club where they seem to be the tyre of choice.


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