this post was submitted on 11 Oct 2023

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So, what actually caused this flat? (lemmy.ca)

submitted 10 months ago by [email protected] to c/[email protected]

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Last month, for the first time in thousands of KM, I got a flat tire.

It was fixed (replaced tube) and I've happily ridden another 400km since.

But I ride at nearly max pressure for the tires, because I assume this was caused by a pinch flat. At the time this flat happened, I was not running low pressure, but lower pressure than I am now (50psi vs 60psi, perhaps), and it happened on a very low speed ride on a smooth trail... no hard hits.

This was a new tube that I installed about 350km earlier, so maybe "user error."

But can someone tell me what might have actually been the cause of that type of flat?

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[–] [email protected] 22 points 10 months ago

... vampire

[–] [email protected] 18 points 10 months ago* (last edited 10 months ago) (2 children)

Looks like you didn’t seat the tube properly before fully inflating.

I’ve had this happen a bunch of times. Inflate the tube, put in in the tire and over the rim, go once around the tire pinching the base of the tire to make sure the tube is sitting deep inside and inflate the rest of the way

But you putting 350 km on it may mean I’m full of shit

[–] [email protected] 7 points 10 months ago

Looks like you didn’t seat the tube properly before fully inflating.

That's what I think, too.

But you putting 350 km on it may mean I’m full of shit

There's the caveat... how could I have gone so long without this happening sooner?

[–] [email protected] 2 points 10 months ago* (last edited 10 months ago)

Since the holes are aligned in the direction of travel not across it like pinch flats usually are, this gets my most probably theory vote too. 50psi is probably doable with a heavy tube. When I’ve done this personally it usually doesn’t blow during inflation until like 90-100psi. And sometimes it will even hold overnight at that pressure until you go ride on it.

So I imagine at half that you might be able to ride on it until wear issues pop it, which is what it looks like here.

[–] [email protected] 6 points 10 months ago (1 children)

Do you have a cat?

[–] [email protected] 7 points 10 months ago

Several. But nowhere near this bike!

[–] [email protected] 6 points 10 months ago (1 children)

Heavy duty construction staple?

[–] [email protected] 3 points 10 months ago

No. Nothing punctured the tire at all. Only the tube was damaged, which is why I'm thinking pinch flat/installation error.

[–] [email protected] 5 points 10 months ago* (last edited 10 months ago) (1 children)

That definitely looks like a pinch flat. Did you do some hard cornering that could have folded it over? Or maybe a jump?

Edit: after looking at it again, I wonder if it's a defective tire. Take it back to the bike shop and ask for a refund.

[–] [email protected] 1 points 10 months ago (1 children)

Defective TIRE? I've had those tires on two bikes, maybe 1500km of riding before that flat. The tubes were "new" (350km-ish).

[–] [email protected] 1 points 10 months ago (1 children)

Did I say tire? I meant inner tube. It almost looks like the rubber separated.

[–] [email protected] 1 points 10 months ago (1 children)

Could be. I've never had this happen, and these were Schwalbe tubes (I've only ever had no-name tubes before. LOL).

[–] [email protected] 1 points 10 months ago* (last edited 10 months ago) (1 children)

This is a good excuse to just go tubeless. The only drawback is that they'll go flat faster from lack of use. Just ride often, or be ready to pump them up before you go riding.

Edit: okay, that's not the "only" drawback, but I've been really happy with my tubeless setup. It's probably not a great idea if you live in California, or other areas with dry dirt and lots of stickers, but it's perfect for the PNW, the South, and other wet areas.

[–] [email protected] 2 points 10 months ago (1 children)

I've got tubeless tires on my e-scooter(s), and it's nice. But I'm not ready to invest in new wheels, new tires, etc. considering I've been perfectly happy with my tube/tires for many thousands of KM.

Not to say that tubeless isn't in my future, eventually. I'm just not ready to go there any time soon 😄

[–] [email protected] 1 points 10 months ago

Oh, yeah if you'd need new wheels then it's probably not worth it. I just got a new bike a few months ago (Cannondale Habit 4), and it came tubeless ready, so I had the shop set me up tubeless. It's pretty rad because I can lower the tire pressure pretty low for slippery stuff and not worry about pinching a tube. It's also a little lighter, although that doesn't matter much considering what a FS mountain bike weighs these days. Welp, good luck avoiding flats in the future! I still say that looks like it might be a tube defect. If you have the time then it might be worth taking it back to where you bought it and asking for a replacement.

[–] [email protected] 1 points 10 months ago

Spider gunna bite. You're lucky it mistook your bike for food and didn't bite you!