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  1. #1
    Charles Ramsey
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    Catastrophic failure in high thread count tires.

    Here is a photo of a tire that ripped after a glass cut. http://share.ovi.com/media/currentre...resident.10361 I had a similar failure in a trek invert 2K tire a 1 cm glass cut it has a 66 threads per inch and the casing did not rip. There is some evidence that the high thread count tires do not have a lower rolling resistance.

  2. #2
    Insane Bicycle Mechanic Jeff Wills's Avatar
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    You say you had a similar failure with a different tire. Could you define the differences in the two situations?
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    If you think a lower thread count tire would have fared better under similar circumstances you're kidding yourself.

    As for rolling resistance, the difference is narrow enough not to really matter because total energy loss to wall flex is so tiny that a small change is meaningless in the scheme of things. This is doubly true off road, where the interaction of tread on the surface robs much more.

    Simple fact is higher pressure tires are more likely to lose air faster, but I don't think anyone is ready to go back to 35psi ballon tires, especially on the road.

    Also, though I know it's probably happened, I don't know of anyone who's ever suffered an injury following a tire failure. Flats and blowouts are a real possibility on bikes, and something that any rider should be able to manage when (not if) they happen. From personal experience, I've suffered lots of flats and blowouts some at high speeds, one at 45+ mph on a descent and not one has ever led to a crash, though I've dinged a rim or two.
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  4. #4
    Senior Member rekmeyata's Avatar
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    Looks like a victim of too low of air pressure tire hitting a curb, but obviously that's just a stupid guess. Anytime you ride a bike the possibility of a flat is there, major cut like that needs to be examined to figure out why and how and what can be done to prevent it. But I seriously doubt a 1 cm piece of glass caused that, I've ran into larger pieces of glass then that with skinny fragile road tires with far less damage then that, and a small 1 cm piece of glass did that to a MTB tire? I doubt it.

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    Quote Originally Posted by rekmeyata View Post
    But I seriously doubt a 1 cm piece of glass caused that, I've ran into larger pieces of glass then that with skinny fragile road tires with far less damage then that, and a small 1 cm piece of glass did that to a MTB tire? I doubt it.
    After 40+ years and more miles than I want to count riding on the streets of NYC, I can tell you that a chunk of glass can cause that kind of cut. Glass is tricky and probably the most important factor is how the tire hits it.

    Dead on, in the center of the tread you can get a small nick, or no damage at all. but the same piece of glass hitting either side can hace a shearing as the tire slides off it or pings it to the side. That causes the type of cut the OP saw.

    But I agree that flats, cuts and tire failures are a fact of life bike riding, and you just have to learn to deal with them.

    I've also had stuff make similar cuts in my auto tire, so better, thicker, heavier tires aren't necessarily bulletproof either. Car, motorcycle, or bike flats are an unavoidable result of riding littered roads on an air-filled chunk of rubber.
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  6. #6
    Senior Member gyozadude's Avatar
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    Sorry for being dense and slow. But am I to take that the OP was inferring that high TPI casings are weaker and more prone to tearing when cut than lower TPI? Or that there was some inference about TPI being more supple and therefore lower in rolling resistance? How are rolling resistance connected to cut-resistance of a tire? Aren't the two orthogonal issues?
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  7. #7
    Senior Member rekmeyata's Avatar
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    Quote Originally Posted by FBinNY View Post
    After 40+ years and more miles than I want to count riding on the streets of NYC, I can tell you that a chunk of glass can cause that kind of cut. Glass is tricky and probably the most important factor is how the tire hits it.

    Dead on, in the center of the tread you can get a small nick, or no damage at all. but the same piece of glass hitting either side can hace a shearing as the tire slides off it or pings it to the side. That causes the type of cut the OP saw.

    But I agree that flats, cuts and tire failures are a fact of life bike riding, and you just have to learn to deal with them.

    I've also had stuff make similar cuts in my auto tire, so better, thicker, heavier tires aren't necessarily bulletproof either. Car, motorcycle, or bike flats are an unavoidable result of riding littered roads on an air-filled chunk of rubber.
    You realize he's talking about 1 CM of glass? That's 3/8th's of an inch that sliced a MTB tire a good 2 inches. I hit a broken beer bottle once that was about 3 inches of glass that cut my MTB tire similar to the OP's cut, but never a 1cm piece of glass. I've been riding my self for more then 40 years both road and off road. But like I said, in a very remote possibility anything is possible I guess. But the damage he shows is consistent with what I've seen tires do after getting chopped by a curb with low PSI in the tire.

  8. #8
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    Quote Originally Posted by gyozadude View Post
    .... But am I to take that the OP was inferring that high TPI casings are weaker and more prone to tearing when cut than lower TPI? Or that there was some inference about TPI being more supple and therefore lower in rolling resistance? How are rolling resistance connected to cut-resistance of a tire? Aren't the two orthogonal issues?
    othogonal??! Isn't that a kinda big word for a bike forum.

    Like you I inferred that the OP was saying that high thread count tires were more vulnerable to glass cutting. I don't agree with his opinion. But if the thinner more supple walls of high thread count tires were more prone to cutting, and if they also offer lower resistance, then rolling resistance and cut vulnerability wouldn't be orthogonal, since they arise from a common cause.
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  9. #9
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    Quote Originally Posted by rekmeyata View Post
    You realize he's talking about 1 CM of glass? That's 3/8th's of an inch that sliced a MTB tire a good 2 inches. I hit a broken beer bottle once that was about 3 inches of glass that cut my MTB tire similar to the OP's cut, but never a 1cm piece of glass. I've been riding my self for more then 40 years both road and off road. But like I said, in a very remote possibility anything is possible I guess. But the damage he shows is consistent with what I've seen tires do after getting chopped by a curb with low PSI in the tire.
    I agree that a 1cm piece of glass is unlikely to make that kind of cut. It's possible that it broke off from a bigger chunk when the OP hit it and that's what he found. I've also seen longish side cuts made as a tire slipped off or pinged a chunk of glass.

    The real issue isn't how the tire got cut - since stuff happens - but whether we want to accept the premise that high thread count tires are somehow more prone to this kind of cut. I, for one am not.
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  10. #10
    Senior Member gyozadude's Avatar
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    Quote Originally Posted by FBinNY View Post
    othogonal??! Isn't that a kinda big word for a bike forum.
    Is it a big word? Hmmm. Not sure. Just that I thought it was kind of common in discussing issues.

    Quote Originally Posted by FBinNY View Post
    Like you I inferred that the OP was saying that high thread count tires were more vulnerable to glass cutting. I don't agree with his opinion. But if the thinner more supple walls of high thread count tires were more prone to cutting, and if they also offer lower resistance, then rolling resistance and cut vulnerability wouldn't be orthogonal, since they arise from a common cause.
    I was just like you, and thinking however, why folks would buy into the lower rolling resistance of higher TPI when the dominant effect is the tread deformation of both the tread and the sidewall thickness (caused by the rubber stuck to the casing, and not the casing TPI itself). You can have high or low TPI casings. Slap a lot of thick hard rubber on the sidewall that still deforms poorly while riding and you still have high rolling resistance. But have less rubber on the sidewalls and have a round sidewall profile, and the rolling resistance improves. I guess this only has a higher percentage effect on the most narrow of tires. But like you - the actual amount is small relative to the tread. So I wasn't sure why TPI was relevant.

    But I was thinking that common sense would indicate that high TPI (thinner/finer) casings are likely to cut more easily, and also, if under pressure, they would tend to fail more catastrophically.
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  11. #11
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    Rofl. This thread is the biggest piece of BS i've ever read on this forum.

    If you think 66tpi is high, try 120 to 330 tpi for ANY regular 700x23 road tire. That type of failure happens but isn't common. Where do people come up with ridiculous conclusions like this.
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  12. #12
    Senior Member JonathanGennick's Avatar
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    Quote Originally Posted by Charles Ramsey View Post
    There is some evidence that the high thread count tires do not have a lower rolling resistance.
    You reminded me of this article: http://www.cyclingnews.com/features/...f-wheel-energy

    The article suggests that around 60tpi is a good place to be in terms of finding the balance between low rolling resistance and high flat resistance. The article is short on data though, and I wouldn't mind seeing more of the numbers to get a better sense of exactly how much impact TPI has in the overall scheme of things.

  13. #13
    Charles Ramsey
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    I tour and when I don't I keep the bicycle loaded for testing. Under the best circumstances I get 2500 miles out of a rear tire the best ones so far have been the trek invert 2K 1.5 inches wide. After 80000 miles in the last 20 years I've had just about every tire made. all the 1.5 and 1.375 inch tires failed from glass cuts generally when two cuts happened in the same spot. I was doing 30 mph in the mountains in Oregon when I got a 1 CM glass cut I was able to stop the bicycle safely the trek invert 2K did not rip. Glass has the same stiffness as aluminium and the edge of broken glass is one molecule wide. I know high thread count tires rip like fabric when cut it is only recently I got a camera to photograph this other photos will follow. Unless you are racing using high thread count tires is stupid. Trek has stopped making the invert 2K and the Bontrager replacement has thinner thread. If you need thicker tires for thorns the best place to put the rubber is on the tire not the tube.

  14. #14
    Senior Member gyozadude's Avatar
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    Quote Originally Posted by operator View Post
    Rofl. This thread is the biggest piece of BS i've ever read on this forum.

    If you think 66tpi is high, try 120 to 330 tpi for ANY regular 700x23 road tire. That type of failure happens but isn't common. Where do people come up with ridiculous conclusions like this.
    Pressure is isotropic and measured in units of Force per Unit Area. A narrow tire holds pressure more easily because it has LESS surface area to fail. It's the same reason why 1/4 inch tubing in copper or steel with relatively thin walls can withstand 5000 psi. But take a 1m diameter pressure vessel and sched 80 steel and it's still only marginally safe for recurring operating loads for around 3000 psi.

    Which is why I suggested the two are orthogonal issues. I think higher TPI means thinner thread and with the right layering and casing design will make for light and low rolling resistance tires. But it doesn't necessarily mean more tearing on wider tires. The key is the casing weave and materials. I'm skeptical as to why the two need to be related. But I suspect they are related primarily because manufacturers cut corners in casing fabric weave at higher TPI and this is what results in tearing on fatter tires more than anything else.
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  15. #15
    Senior Member Chombi's Avatar
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    Maybe people should also just age their tires so that they don't pick up so much junk from the roads. Question is, do the newer tire tread and sidewall compounds age like the old tubulars did 20 years ago, or is there so much synthetic rubber material in them that they don't "firm up" like the older more natural rubber/latex based tires did.

    Chombi

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    Quote Originally Posted by Chombi View Post
    Maybe people should also just age their tires so that they don't pick up so much junk from the roads. Question is, do the newer tire tread and sidewall compounds age like the old tubulars did 20 years ago, or is there so much synthetic rubber material in them that they don't "firm up" like the older more natural rubber/latex based tires did.

    Chombi
    I remember the earnest discussions about aged tires from back when I got my first tubular-equipped racing bike in 1965. It probably didn't do anything good for the tires then either. For examples of what happens to aged natural rubber, look at Campy brake lever hoods from the '60s or '70s, unless they've all disintegrated by now.

  17. #17
    Senior Member rekmeyata's Avatar
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    Quote Originally Posted by Trakhak View Post
    I remember the earnest discussions about aged tires from back when I got my first tubular-equipped racing bike in 1965. It probably didn't do anything good for the tires then either. For examples of what happens to aged natural rubber, look at Campy brake lever hoods from the '60s or '70s, unless they've all disintegrated by now.
    I know I had a set of tubulars I bought in 76 and those dry rotted in about 15 years never being mounted. But then I bought a 84 Fuji with the original tires still mounted this last year and they were fine and perfectly rideable with no signs of aging and was stored since purchase in the attic. But about 10 years ago I bought a 88 Miyata with original tires as well and they were severely aged to the point that the tube blew threw the sidewall at 65psi, and it was stored in the garage. When I asked this on another forum a few months back a poster said that if the tires are stored near any electrical motors the ozone created by those motors will destroy the tire. Not sure if that's true or not, but it sounded plausible.

  18. #18
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    Quote Originally Posted by Chombi View Post
    Maybe people should also just age their tires so that they don't pick up so much junk from the roads. Question is, do the newer tire tread and sidewall compounds age like the old tubulars did 20 years ago, or is there so much synthetic rubber material in them that they don't "firm up" like the older more natural rubber/latex based tires did.

    Chombi
    My experience is with 700 x 35c tires and 26 by 1.95 tires over the past 7 years. I have become rather disenchanted with what I am seeing in the tires I have bought. Recently I had to throw out a pair of Continental Town and Country tires that had less than 500 miles on them. The bike sat over last winter out back in the unheated shed. I noticed cracks in the tires. If I bent the casing the cracks opened and showed that the tread was separating from the casing. The year prior I had a set of Continental Travel Contact, 700 x 35c, crack around the circumference of the tire. Middle of the tread where the clam shell mold joint would be.
    I had a set of Bontrager tires develop weather cracks in the sidewalls in less than a year.

    I am running a set of Bontrager Race Lite Hard Case tires on my Trek and they are wearing like iron, showing no cracks and have had no punctures in 2500 miles with them.

    I doubt that you would find any natural rubber in a bicycle tire anymore. The thing about aging and "firming up" depends on how the tires were cured. When tires are first molded the rubber will exhibit a certain tensile strength and elongation. As it sits the tensile strength will go up a bit while the elongation goes down. But that usually reaches a final state within a few days after the tire was cured in the mold.

    I look where the tires were manufactured. I get the gut feeling that there rubber compounding technology is not that great. The rubber industry has also had to change some of the chemicals used in the rubber. They had to get away from stabilizers that are based on one or more heavy metals. The old "lamp black" had to be changed. Most of the old "oil blacks" were shown to be carcinogenics. They also had to change some of the plasticizers used to soften the rubber.

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