I’ve smashed a couple of rims beyond repair hitting grated storm drains and ripped valve stems out of inner tubes while riding on dirt with very little air in the tires, but never had a pinch flat in over sixty years of riding. Has anyone here ever had one or know someone who has and what were the circumstances? I don’t doubt they happen. You can’t read an article or view a You Tube video on cyclocross tires without pinch flats being mentioned. But even my cross friends admit they have never had a pinch flat, although they talk about prevention a lot.

I went online to make sure I knew what a pinch flat is. Turns out there are two different types. One, which I think is one most talked about, is when the tire compresses to the point that the inner tube is crushed between the tire sidewalls as the wheel strikes a hard edges like a pothole or curb. It produces two symmetric holes on opposite sides of the tube. Those seem like they could happen to anyone, at anytime, on any bike. The other is when the tire bead comes away from the rim on one side causing the tube to rupture. I’m not sure what would cause the second type, perhaps cornering with very under inflated tires like cyclocross racers seem to favor.

I've never seem symmetric holes on opposite sides of the tube, rather "snake bite" two slits about 1/2" apart.

scott s.
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Saw my first ever snake bite pinch flat during a Wednesday night group ride -- two symmetrical splits where the tube pinched between the bead and rim on both sides. I'd heard about it many times but never saw it before.

Fellow on a nice road bike with fairly skinny 700x25 or so tires hit a rough bit of pavement and flatted the rear. Inflation was probably a bit low for his weight (pretty big fellow, a bit overweight but mostly just a big guy) -- front had only 40 psi, no telling for sure what the rear had been. After borrowing a replacement tube and pumping it up to the max of around 120 psi he remarked it felt much harsher but he'd get accustomed to it. Probably will handle better too -- it must have felt splashy on turns at only 40 psi or so.

Reminds me of why I now prefer fatter 700x40 or so tires that can be safely ridden at 40-60 psi. I've bombed across some pretty harsh sharp edged pavement this year (unavoidable due to road construction/destruction in places I must scoot across quickly to be safe), as well as some pretty rough gravel, dirt and grassy levees. No problems with the cyclocross tires on my mountain bike or all terrain chevron tread tires on the hybrid. But they're not really underinflated for my weight (160 lbs).

'Snakebites' are my most common flats. Usually caused by hitting camouflaged rocks or pot holes. They're not from each side of the rim punching through the tube, they're from one side bottoming out and in the process 'folding' the tube over on itself and then punching through both sides of the fold.

The last one I got occurred right on the rim's seam, and broke the seam on that side.

Blowouts where the tube is caught under the bead and eventually forces the bead off the rim (with a loud bang as the tube inflates like a balloon and pops) -- this isn't usually called a "pinch flat".

Since pinch flats are small slits, the air comes out with a hiss over a few seconds time.

I keep my tires inflated correctly. I've still had two pinch flats over the last 10 years.

One from hitting a cast iron water valve housing in the road, with a pothole in front. It was a sharp 90 degree edge. I wasn't watching the road, and hit it hard.

The other was a small rock that I hit in a high speed corner. This pinched on one side of the rim.

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Yeah, pinch flats are less common than having something sharp cut the tire.

Sometimes, there's only one slit instead of two. And I've seen it take a few seconds after the hit to start hissing, the damage must be not quite all the way through the tube at first, but pops open from the inflation stress.

Yep, had 2 pinchflats. Couple little holes next to one another like a snakebite. Sucks, happens, oh well.

Incorrect. Pinch flats are caused by an under inflated tire. Such as in mt biking. Both side of the rim bottom out against a sharp edged rock or such. The rim on each side hits against the hard object and pinching both sides of the tube. Fact.

Two years ago on RAGBRAI (10K plus riders) there was a very rough railroad crossing about 5 miles into the first day ride. About 30 yards past the tracks were 5-6 cyclists changing tires from their new pinch flats. There were probably people changing tires all day.

I had 2 or 3 snakebite flats in a month. After that I started checking tire pressure more regularly...

had one on a brand new front tire. Went to the shop, took it around the block, hit a pot hole and thought nothing of it.

an hour later was at home riding, and front was going down. Took back to shop, pinch flat

In virtually all of my pinch flats, the tires were inflated to the max recommended pressure. If you hit a bad enough obstacle, the tire will bottom out regardless. That's because air is compressible. How wide are your rims vs how far apart your 'fang holes' are? I have narrow road rims, but 6mm spacing for the holes is still too narrow for your explanation.

I've had one pinch flat, and that was from running over a large stick that I didn't see. Damaged the tire sidewalls too.

Seen ....screwdriver snake bites, from prying the tire on..

My wife was the Queen of snake bites. It must have had something to do with her rims, when I switched from 23's to 25's on her bike, no more pinch flats.

You are looking at a deflated tube. Think about when it is inflated. The tube is stretched. Correct?

2-3x stretch? No. Are you disbelieving that there would be 2 layers of tube under each side of the rim, or do you believe that every obstacle that you might hit is so perfectly level and square that it hits both sides simultaneously to within the thickness of a tube, but only punches a hole in one layer?

Please check your facts. Jobst Brandt comes to mind. The pinch flats are not caused by the tube folding itself over inside the tire. The inner tube is filled with air. The rim hits something hard, pinches the tube, air loss. 1-4 spots, I've had them all. That's why I run tubeless now, no pinch flats.

The perfect explanation is that the tube( 6mm apart) hits something hard, rim punches through 1 side of the tube in 2 spots. I can't believe one has to explain how a pinnch flat happens? Or the tube gets pinched by both sides of the rim on each side, yes? Ie the snakebite.

I used to get pinch flats on my mountain bike from thorns puncturing the tube, causing a slow leak that lower the pressure enough to cause a pinch. Then I switched to tubeless, thorns don't cause slow leaks anymore and I don't get pinch flats anymore.

I used to get snake-bite pinch flats on my old road bike when I ran 700x23mm tires. Since switching to 700x32s I haven't had that type. And I haven't had them on my other two bikes 26x1.75 and 700x32.

However, I have had single-pinch flats after installing tubes, either new or patched. I've had this on all my bikes, but not often, except for the 700x23 tires, and most recently when I bought new Continental Tour IIs. They say 700x32, but are more like 28s and VERY STIFF. These flats come from the tube being folded or twisted before inflation. I usually pump up to 20 psi and release all the air, then to 40 and release all the air, then 60 and release and then full inflation. I don't know if it helps, but that's what I do.

The tubeless police are out in force today...

I've had one snakebike flat, when I was off the road and hit a hard object hidden by grass. It didn't feel like a fully inflated tire hitting something hard, so maybe my tire was low.

Only flat I've ever had on a puncture resistant tire.

Festinating replies, thank you all for the education on pinch flats. I’m thinking a few of those unexplained flats I‘ve experienced over the years may well have been pinch flats unbeknown to me.

I've had several snakebite flats.

I've had a couple of pinch flats, the first when my rear tire was just a little bit low, hadn't added air to it for a while but meant to before my ride. My negligence cost me a few minutes for a roadside repair. The second one just a couple weeks ago happened when I was riding gravel, heading down into a little gully in the road toward a bridge over a creek, hit something hard with my front tire and heard a pssh pssh pssh pssh and knew I was in for a flat. That one gave me not one but two different pinch flats for a total of four holes in the tire. That one I called my wife for a SAG since the sun was going down fast and I didn't want to navigate the rest of the gravel in the dark. I can't wait for daylight savings time.