Tyre blowout advice

[roubaixtuesday]

Just suffered the second of these on tour, both rear wheel. Sudden BANG with no apparent immediate cause, tyre still on rim but bead detached from tyre.

First was on the old gatorskins the bike came with, second on a new (~500 miles) vittoria randonneur.

Photo of the second attached.

Never experienced anything like it before, the second suggests more than mere bad luck.

Ask advice and suggestions welcome.

It's a laden tandem.

 

[John the Monkey]

I've had this when one of my brake blocks was slightly over the rim - over time, it wore into a shape that rubbed the tyre, cutting it just above the bead.

 

[roubaixtuesday]

I've had this when one of my brake blocks was slightly over the rim - over time, it wore into a shape that rubbed the tyre, cutting it just above the bead.

Thanks, should have added, disc brakes. Though there is a residual Canti used as a parking brake, which is worth checking...

 

[Ian H]

It's a known thing with tandems and narrower tyres. Higher pressure might help.

 

[roubaixtuesday]

It's a known thing with tandems and narrower tyres. Higher pressure might help.

Thanks. It's never happened to me before in many thousand of miles. Hard to believe it's suddenly happened twice without some cause?

 

[Ian H]

Thanks. It's never happened to me before in many thousand of miles. Hard to believe it's suddenly happened twice without some cause?

It is worth running your fingers round the edges of the rim to check there's nothing sharp.

 

[geocycle]

Are the tyres too wide for the rim at the pressure you need on the loaded tandem??

 

[roubaixtuesday]

Are the tyres too wide for the rim at the pressure you need on the loaded tandem??

No, if anything the tyres more on the narrow side

 

[ebikeerwidnes]

Did have it happen once

Turned out - I think - to be old tyre sealant in the inner tube which had become less fluid and so a pocket of air got trapped and couldn;t move

When I went over a tone and the pressure happened to go exactly on the trapped air - which massively increased the pressure at that point - whereas normally it would be spread out over the whole inner tube

Very weird - and probably doesn;t apply here - but it can happen

all my opinion - but when I cut the tube open there was a pocket at that point


ages ago - sealant has probably improved since - especially as I only put cheap stuff in it!

Oh - and they were ancient tyre which had been stored unused for many years (not my bike!) so were probably degraded

 

[Ming the Merciless]

I’d would check the hook inside the rim as that split looks very much like it would sit against it. Maybe the internal rim hook abraded the tyre? How many miles have the tyres done, how long ago were they fitted?

 

[roubaixtuesday]

I’d would check the hook inside the rim as that split looks very much like it would sit against it. Maybe the internal rim hook abraded the tyre? How many miles have the tyres done, how long ago were they fitted?

This tyre was new a couple of weeks ago. ~500 miles.

The first one to blow came with the 2nd hand bike. Didn't look at all worn - and I got an lbs opinion on that too.

 

[Ajax Bay]

Share the overall load eg 200kg, the internal rim width, the tyre width (nominal) and the pressure you roll, in that tyre Vittoria Randonneur, please.

 

[PedallingNowhereSlowly]

Can't really see any evidence of abrasion in that photo - but still worth checking the rim hook.

I wonder if the tyre is too narrow and consequently you are running pressures too high for tandem load / speed?

Are you running tubes or tubeless? With tubes, the additional friction between the inner tube and the tyre will generate more heat causing a further increase in air pressure.

 

[T4tomo]

I’d would check the hook inside the rim as that split looks very much like it would sit against it. Maybe the internal rim hook abraded the tyre? How many miles have the tyres done, how long ago were they fitted?

If someone has used a metal lever to put a tyre on (or something else entirely) there could be a sharp spot on inside of rim. Did you line up tyre labels to the valve holes, that would give you a clue where to look / feel for anything.

As you have discs I'd be tempted to go up to a higher volume tyre any event - helps for comfort.

There is no sign its from the canti brake rubbing it.

 

[Ajax Bay]

Are you running tubes or tubeless? With tubes, the additional friction between the inner tube and the tyre will generate more heat causing a further increase in air pressure.

Go on then! "More heat"? What, a couple of degrees more? Share a link offering any quantitative analysis please.
And even then I'd point out that any increase in pressure is the percentage increase in degrees Kelvin. So if the pressure was 100psi and the temperature was raised by "friction between the inner tube and the tyre" from (say) 17C to (say) 20C the internal pressure would increase to 101psi.
Blowout cause? I suggest not.