Flat...cause?

[Tin Pot]

Scene:

Racing, downhill with power, ~60kph, B road, hard bend, under tree cover...rear suddenly goes soft. Didn’t crash

Context:
Changed rear tyre the night before to Continental Grand Prix 4000S II (folding)
Inner tube was not changed
Tyre temperature likely high due to weather and effort
About 90mins into the bike race

Stopped about 400m later and the rear was soft to squeeze but not completely flat.

Unfortunately I disposed of the inner tube, even then knowing I’d be curious.

1. Is it possible the tyre peeled back briefly during the turn?
I don’t know why, but that’s what it felt like. As it was a folding tyre it was more supple than the rigid.

2. Could the temperature, unlikely I suppose, have caused the nothing-special conti tube to lose pressure?

3. Is the age of the inner the likely cause?
Can’t remember but probably at least 18 months old, ridden outside only in a half dozen races, on the turbo ~3hrs per week for the last six months

4. Was it just a regular flat and I should stop analysing that which can never be truly known?


Cheers,

TP

 

[Jody]

1. The tyre would feel like it peeled back but would have just folded over slightly due to the low pressure. If it peeled back you would have probably had a pinch puncture and known about it when you were eating some gravel.

2. No

3. Doubtful

4. More than likely.

Just be glad you have your teeth and keep spinning.

 

[DRM]

Any chance your rim tape has slipped, letting the tube rub on a spoke hole, I’ve had this before, and was a bit of a head scratcher till I looked at the hole in the tube with relation to it’s position on the rim

 

[Tin Pot]

Any chance your rim tape has slipped, letting the tube rub on a spoke hole, I’ve had this before, and was a bit of a head scratcher till I looked at the hole in the tube with relation to it’s position on the rim

No rim tape needed on Bullet 80s

Nice idea though

 

[ColinJ]

5. You had damaged the tube when putting the new tyre on?

 

[Tim Hall]

You cut it on occam's razor.

(That's 4 on your list)

 

[Ajax Bay]

"Flat...cause?"

Unfortunately I disposed of the inner tube, even then knowing I’d be curious.

This is a case of asking the question after the tube has been chucked (presumably at home after returning from the OP's race) (as in 'horse' and 'bolted').
If the cause of a puncture is not clear (obvious tyre penetration or damage), then without examining the inner tube, then a rider is unlikely to discover the cause.
Surely you'd want to take the tube home to patch it, anyway?

 

[Tin Pot]

Not really, it was hot as fark, I had a tent to pack and I had just DNFd a half Iron I’d been training six months for.

All the stuff I didnt truly need went in the bin. I knew I was throwing away the evidence.

At the moment, given I’ve never had a flat in a race, I’m not exactly singing the praises of the GP4000S II.

 

[Ajax Bay]

I had just DNFd a half Iron I’d been training six months for.

Hard luck: that's a bummer.
My daughter has GP4000s on for her 70.3 this weekend (Calgary!). My GP4000 on the rear has happily done 5000k+ and (inspecting it yesterday) has one small shallow slit (2mm) on the tread and that's it; and the wear dimples are still indented. I think that you have to accept that sh!t happens, sometimes. Choice of tyre can reduce the risk and the rating for protection for 4000s is very good (best in class?) given how low their rolling resistance is.

 

[Tin Pot]

Hard luck: that's a bummer.
My daughter has GP4000s on for her 70.3 this weekend (Calgary!). My GP4000 on the rear has happily done 5000k+ and (inspecting it yesterday) has one small shallow slit (2mm) on the tread and that's it; and the wear dimples are still indented. I think that you have to accept that sh!t happens, sometimes. Choice of tyre can reduce the risk and the rating for protection for 4000s is very good (best in class?) given how low their rolling resistance is.

Yeah, I know you’re right. These are the tyres of preference for the vast majority of iron distance triathletes.

It’s just the non-objective part of me blaming the tyre. In reality I suspect it was the way the tyre was changed, ie me. Which I should have done the week before the race, not the night before

 

[T4tomo]

Yes never piss with anything night before and important ride. Do it in advance and give it a test when it doesn't matter.

 

[davidphilips]

The puncture fairies have made a surprise visit, annoying and cause may never be known as per usual perhaps just your turn for a visit.