Flat sodding tyres

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Dec66

A gentlemanly pootler, these days
Location
West Wickham
In recent weeks I've had three instances of tubes letting go, apropos of nothing. They are pumped to 100psi. The tubes are supposedly able to take that pressure. Evidently they can't.

I'm suspecting I've been sent a crap batch (10 X ITS tubes with long stems from InnerTubeShop.com; I'll be on to them in the morning). One thing I find curious, though; the split always seems to occur at a point just over a hole in the rim where the spoke screws in (not the same one each time I hasten to add). I know this, not only because I can work it out from the position of the split in relation to the valve, but also because when the tube lets go it the escaping air puts a small rip in the rim tape.

Why would they go at that particular point, I wonder?
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
New rim tape first.
 
At 100 psi, you haven't got a lot of room for manoeuvre, regarding heating up of the tyre's, due to direct sunlight ( which is more intense at this time of year). I'd change the rim tape, and then pump the tyre's up to 90 psi tops, at this time of year.
 

KnackeredBike

I do my own stunts
Surely it depends on the tyre, I am on 700x23s and keep them at 125psi (100kg of me) and I have had not so much as a snap or crackle out of them.

But I would concur, one tube is possible defect, two tubes perhaps, three tubes it's your wheel.
 
OP
OP
Dec66

Dec66

A gentlemanly pootler, these days
Location
West Wickham
Surely it depends on the tyre, I am on 700x23s and keep them at 125psi (100kg of me) and I have had not so much as a snap or crackle out of them.

But I would concur, one tube is possible defect, two tubes perhaps, three tubes it's your wheel.
Thing is, I took it all over France and Belgium, 35°C+, 300 miles or so of riding, no problem. I'd reduced the pressure to 90psi on the back as I was carrying panniers.

Blew front and back up to 100psi before going to work this morning, and at some point while I've been working... Pfffffffft.
 

si_c

Guru
Location
Wirral
New rim tape. Don't settle for anything less than Velox, as already mentioned.
 

rrarider

Veteran
Location
Liverpool
The important question is 'What caused the slit in the rim tape in the first place?' It won't have been a puncture in the tube blowing air on to the tape. Are you sure that a spoke hasn't travelled down through the nipple and poked a hole in the tape?
 
OP
OP
Dec66

Dec66

A gentlemanly pootler, these days
Location
West Wickham
The important question is 'What caused the slit in the rim tape in the first place?' It won't have been a puncture in the tube blowing air on to the tape. Are you sure that a spoke hasn't travelled down through the nipple and poked a hole in the tape?
100% certain.
 
OP
OP
Dec66

Dec66

A gentlemanly pootler, these days
Location
West Wickham
Surely it depends on the tyre, I am on 700x23s and keep them at 125psi (100kg of me) and I have had not so much as a snap or crackle out of them.

But I would concur, one tube is possible defect, two tubes perhaps, three tubes it's your wheel.
I'm running 28's which the rim is happy with (they came with 25's and until recently I had 32's on there).
 

rogerzilla

Legendary Member
At 100 psi, you haven't got a lot of room for manoeuvre, regarding heating up of the tyre's, due to direct sunlight ( which is more intense at this time of year). I'd change the rim tape, and then pump the tyre's up to 90 psi tops, at this time of year.
The pressure difference from a nirmal 20 deg C to 50 deg C in the sun is (323/293) - 1 = 10%. The thing is not to buy tyres that are rated for a low max pressure, like Schwalbe Durano. Their max pressure is lower than the MINIMUM pressure of my usual Vredesteins, which will take 185psi if you want them to (track racing?). The Duranos need to be kept to 100psi or lower to avoid blow-offs (and they really do blow off at a smidgen over 110psi) which puts you in pinch flat territory on bad roads with 25c.
 
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