Tyre blowout advice

[PedallingNowhereSlowly]

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.

Does it take you a great deal of practice, or does it come naturally to you?

We've had some cold mornings and warm afternoons. So we could be talking about a significant difference in ambient temperature, plus the the addition of heat generated from friction. As we are talking about a tandem, we have larger forces at play acting on the tyre and potentially higher speeds.

The maximum recommended tyre pressures printed on the side of the tyre are the inflation pressures that assume normal use. I would expect there's plenty of safety margin manufactured into the tyre - but my experiences of riding around on a fully loaded tandem and being able to maintain 30 mph for long stints on flat or being able to accelerate quickly up a climb in order to go from being on the tail end of large group to the front of a large group on club rides suggest to me it is a possible corner case, if the tyre was inflated to the max indicated pressure on a cold day. Especially given that the rim width/tyre/width/nominal pressure/load have not yet been disclosed.

 

[MichaelW2]

If the tyre is undersized, get a wider one.
Make sure it fits the rim without needing too much encouragement with tyre levers. Just enough.
Check rim for any sharp edges.

 

[Dogtrousers]

There does seem to be a dark line running around the tyre in line with the rightmost extremity of the split. It could be just a manufacturing feature but maybe not.

Is it possible that there's something rubbing in this area? I have no idea what. We know it's not brake blocks because there aren't any.

Another idea might be to spin the wheel and see if it's slightly out of true. Maybe a slight buckle in the wheel is bringing that bit of the tyre into contact with the mystery rubbing thing (that may not exist).

Or maybe that's a load of codswallop and it's something else.

 

[Ajax Bay]

Does it take you a great deal of practice, or does it come naturally to you?

Natural enthusiasm for understanding if there's science behind any assertion which seems unlikely (tubes create a significant temperature rise cf tubeless) - isn't life one happy long practice?
And by the way, because I failed to say so in March,

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.

I encouraged you to offer a link to help us/me understand how much heat (metric = rise in tyre temperature) might be thus created (fail).

We've had some cold mornings and warm afternoons. So we could be talking about a significant difference in ambient temperature, plus the the addition of heat generated from friction. As we are talking about a tandem, we have larger forces at play acting on the tyre and potentially higher speeds.

Of course pressure in a hot (environmentally created) tyre, inflated in the cold of early morning (say 7C) will be higher (but not by much (see Prof Kelvin) - maybe an extra 10% if your warm afternoon goes to 35C)).
What do you mean by "heat generated by friction" - the tyre rolling on the road surface? This is the same for tubed and tubeless clinchers.
Heavy rim braking (not applicable here) will actually have a greater effect on tyre temperature - but you know that better than most as those 30mph tandem dashes have to be slowed somehow, or were your brakes drum or disc?

The tyres do look narrow for tandem use and I wouldn't be surprised if they need to be up near their specced max to cope with 200kg. I'm not getting at your actual pressure above max hypothesis, just the tubes v tubeless increased friction and heat wheeze.

https://www.bicyclerollingresistance.com/tour-reviews/vittoria-randonneur-2015
In 37-622 variety, the max pressure spec is 70psi. The review additionally says: "37-622 Randonneur - width on 17C rim is only 33 mm. The Randonneur is a very small tire for its size, most 37-622 rated tires come in closer to 35 mm."

 

[PedallingNowhereSlowly]

I wasn't refering to your 'Natural enthusiasm for understanding'. I was referring to the attitude you present. I note I'm not the only person who has had the misfortune of contending with it and irrespective of whether you think someone is correct or incorrect, it is possible to be considerably more constructive than you appear to be.

I'm sure you can use a search engine as well as I can. There are papers around on coefficients of friction in bicycle tyres and there are papers comparing tubed and tubeless tyres in respect to their efficiency, rolling resistance and friction. You can find these yourself. I'm not doing that for you.

The evidence I've perused suggests that there is more friction generated in a tubed setup. I thus hypothesized, in a marginal situation, the very modest increase in pressure could be significant and push the tyrewall beyond it's safe limits.

Of course, I've not tested that hypothesis. I'm not a professor in thermodynamics with a penchant for bicycle tyres.

And as for 'tandem dashes' ... what I can tell you is an emergency stop on a tandem travelling at 30 mph whilst loaded up with two riders and a family shop because a moton pulls out dead ahead of you makes for a very interesting moment or two.

 

[roubaixtuesday]

We've just sourced a new 32mm Randonneur - best a tour of the bike shops of towns of provence could provide and the largest that will fit within the mudguards.

In the meantime have been running a pirelli sport folding (our emergency backup). No sign of any damage to that.

Total load ca 200kg.

Have been running ~85 psi in the Randonneur, just above nominal.

A very close inspection of the bead revealed nothing untoward.

 

[Ajax Bay]

Vittoria Randonneur
700 x 32c (Wire Bead)
Pressure max 75psi
Randonneur Tech, Double Shielding
Black Reflex
Graphene Plus
32-622
28" / 700 x 32c
Mount on Hooked Type Rims
Part Number: 8022530006859

So 85psi plus any increase through the day in the warmth of Provence is maybe pushing it. What time of day did it blow?
The height limitation from the mudguard forces your 32mm width choice and the load forces those high pressures (to avoid bottoming/snake bites).
I think you have to go for road tyres which will have a higher max pressure.
For example I have a pair of GP5000s 32-622 waiting, and their max is 100psi. In a constructive spirit

 

[roubaixtuesday]

Vittoria Randonneur
700 x 32c (Wire Bead)
Pressure max 75psi
Randonneur Tech, Double Shielding
Black Reflex
Graphene Plus
32-622
28" / 700 x 32c
Mount on Hooked Type Rims
Part Number: 8022530006859

So 85psi plus any increase through the day in the warmth of Provence is maybe pushing it. What time of day did it blow?
The height limitation from the mudguard forces your 32mm width choice and the load forces those high pressures (to avoid bottoming/snake bites).
I think you have to go for road tyres which will have a higher max pressure.
For example I have a pair of GP5000s waiting, and their max is 100psi. In a constructive spirit

Thanks!

The Gatorskin I think was also 100psi and that blew too.

Advice on the best possible tyre would be appreciated.

We've done many thousands of miles previously (on different rims) with various tyres with no such problems.

 

[craigwend]

https://www.cyclechat.net/threads/tandem-tyres.296001/

Unusual as you've not had problems before and plenty of experience

Though it could just be 2 unrelated issues - problem is us humans don't like this and try to solve it...

 

[Ajax Bay]

From that thread

Got Panracer pasala on my tandem trike front wheel. Not a high mileage, but have been on the tandem for well over 25 years now.

https://www.bicyclerollingresistance.com/tour-reviews/panaracer-pasela-pt
Looks to be available in 32s and max said to be 90psi.
SJS Cycles: https://www.sjscycles.co.uk/tyres/700-x-23-23622-panaracer-pasela-tour-guard-tyre-all-black-700-622/

 

[roubaixtuesday]

From that thread

https://www.bicyclerollingresistance.com/tour-reviews/panaracer-pasela-pt
Looks to be available in 32s and max said to be 90psi.
SJS Cycles: https://www.sjscycles.co.uk/tyres/700-x-23-23622-panaracer-pasela-tour-guard-tyre-all-black-700-622/

Problem is, we're in France, shortly Italy, and moving on daily, so sourcing a specific tyre tyre is a challenge. Plus, we also blew a gatorskin at 100psi (I think, memory is fading...)

Nice tomorrow, will pop into a bike shop or two if possible...

 

[albion]

At that weight the tyres have less chance of surviving a puncture or slow puncture .

And sadly newer tyres do seem less robust at preventing this type of thing. Also, tyre defects exaggerate under higher loads.

 

[gbb]

Did it go off like a gunshot ?

Had an old tyre go once, i swear if it had been a busy street, most people would have hit the floor

Frightened the living **** out of me.

 

[Dogtrousers]

Did it go off like a gunshot ?

Had an old tyre go once, i swear if it had been a busy street, most people would have hit the floor

Frightened the living **** out of me.

I remember one morning sitting at a cafe at the start of an audax, looking very chic and stylish sipping my espresso when a tyre exploded - for no reason I understand - on a bike parked right behind me.

I didn't look so chic and stylish with espresso all down my jersey.

 

[HobbesOnTour]

Problem is, we're in France, shortly Italy, and moving on daily, so sourcing a specific tyre tyre is a challenge. Plus, we also blew a gatorskin at 100psi (I think, memory is fading...)

Nice tomorrow, will pop into a bike shop or two if possible...

I have nothing to offer in relation to your tyre woes, other than to wish you well and suggest it's all part of the adventure.

My amateur suggestion would be to sacrifice the mudguards in favour of a wider tyre.

As for being on the move, one option may be to look on Amazon with a view to a purchase being delivered further on down the road either to a campground/hotel or one of the Amazon pick-up points. Just make sure that you pay attention to the delivery time/date.

Best of luck!