Flints don't puncture bicycle tires?

[* * Chas]

"Tony Raven" <[email protected]> wrote in message
news:[email protected]...
> * * Chas wrote on 27/10/2006 19:03 +0100:
> >
> > Nope, got it from friend in Manchester.... but I'll spot you a pint
of
> > bitters if you ever get over this way (SF Bay Area).
> >
>
> I used to go there monthly but I've now hung up my Frequent Flyer
card.
> There's some interesting beers in the microbreweries but I wasn't so
> sure about the Pale Ale that one owner was very keen that I tried in a
> Brewpub on 4th in San Rafael on my way back from riding up in the
hills.
>
> --
> Tony
>
There are still a lot of Americans who are "afraid of the dark" and many
microbreweries tailor their output for that market. I've tasted some
brewpub ales that made Bud Light seem like a monster beer! Pale ale to
some means just that!

If you ever get back this way, the Pacific Coast Brewery in Oakland has
consistently good brews on tap. Let me know when you are coming and I'll
sport you one.

http://www.pacificcoastbrewing.com/

Chas.

 

[Tony Raven]

* * Chas wrote on 27/10/2006 20:38 +0100:
>
> Flint as far as I've used the term is usually found as inclusions in
> limestone rocks however, Zippo brand cigarette lighters use a small
> cylindrical metallic? object for creating a spark to light the flame
> that they call "flints".
>

Named after the real flints which when struck with steel will produce a
spark. Flints were used to light the gunpowder fuse for cannons,
muskets and pistols - hence the name flintlocks


--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[* * Chas]

<[email protected]> wrote in message
news:[email protected]...
> On 26 Oct 2006 12:47:13 -0700, [email protected] wrote:
>
> >Over in rec.bicycles.tech, Jobst Brandt argues that flint flats are
> >just a myth:
> >
> >"I keep hearing about these mysterious cherts [flints] yet have never
> >seen one on the road or in a tire. I ride many miles of rocky roads
> >here and in Europe and have not had a flat from these mysterious
sharp
> >rocks that don't seem to cut car tires or we could find examples of
> >them embedded in the surface of car tires."
> >
> >http://groups.google.com/group/rec.bicycles.tech/msg/97f538aa81f0f1ed
> >
> >Primitive superstitions about flints still flourish in the UK and
> >Denmark, so I'm asking for your views on the matter, somewhat like a
> >sociologist asking about the Loch Ness monster.
> >
> >Any pictures of flints in tires and tubes would be interesting, even
> >though they must be obvious fakes.
> >
> >(Alas, the nearby sand and gravel pit closed a few years ago, so I'm
no
> >longer able to photograph the flint flats whose existence Jobst
> >denies.)
> >
> >Cheers,
> >
> >Carl Fogel
>
> Prompted by Jobst's shoot-from-the-hip claims elsewhere in this
> thread, I pumped a smooth, worn Kevlar-belt 700x26 tire up from 30 psi
> to 110 psi at 10 psi increments and rolled it over a nail sticking up
> from a vise.
>
> (Pictures below.)
>
> Nothing happened until the tire pressure reached 100 psi.
>
> At that pressure, the nail audibly penetrated into the tread, leaving
> a hole and making a little popping noise--but the tire didn't go flat.
>
> I stopped rolling various sections of the tire over the nail at 100
> psi after only half a dozen popping noises, which showed considerable
> maturity and restraint.
>
> (Try to stop popping after only six bubble-wrap bubbles.)
>
> At 110 psi, ten psi higher, the pop seemed louder when I rolled the
> tire over the nail--but the tire still stubbornly held air.
>
> Suspicious, I took the tire off the rim and looked at the inside of
> the tire and the inner tube.
>
> Aha! No penetration at 100 psi, but a hole all the way through the
> tire at 110 psi, plus a faint little circular scrape and tiny dent on
> the inner tube.
>
> As the pressure increased, the nail dimpled the tire and inner tube
> until it broke through the tread at 100 psi and then through the
> hidden Kevlar belt at 110 psi.
>
> After it broke through, the nail pushed the stretchy inner tube off
> the inside of the tire, and started making a new dimple in the inner
> tube.
>
> Two points are illustrated.
>
> First, tires at lower pressures obviously resist punctures by reducing
> how hard the debris can push against the tire. Lower tire pressures
> have been recommended by Danish riders, whose pavement seems to
> provide a lot of rock chip or flint flats:
>
> http://groups.google.com/group/uk.rec.cycling/msg/5f7c729c68b72204
>
> A drop from 110 psi to 100 psi stopped a short section of an ordinary
> nail, roughly similar to a small rock chip or flint, from penetrating.
>
> Of course, some debris is so sharp and so tall that it will focus
> enough force in a small enough area to penetrate a tire at any
> reasonable pressure. For example, the needle-like tip of a goathead
> thorn will go through the same tire at only ten psi. But my fairly
> sharp nail tip failed to break through the tire until the air pressure
> reached 110 psi over the dimple that the nail made in the tire.
>
> Second, some objects can puncture tires without puncturing the inner
> tube.
>
> A shorter but similarly sharp object that stopped without puncturing
> the tube, such as a rock chip, would still have eventually worn a hole
> in the inner tube and caused a flat.
>
> This unexpected behavior makes an interesting case for the
> often-maligned tire-saver theory that some kinds of embedded debris
> can be removed before they cause a flat. Most debris goes right
> through the tire and tube immediately, so there may be little
> practical use for scraping debris off tires or digging it out of the
> tread, but some kinds of debris must end up behaving like the nail.
>
> Four pictures follow.
>
> Here's the nail sticking up about 6 mm from the vise:
>
> http://server5.theimagehosting.com/image.php?img=334a_110psi_setup.jpg
> or http://tinyurl.com/wrm78
>
> Here's the outside of the tire and the exposed inner tube. Blunt
> toothpicks are stuck in the holes made by the nail at 110 psi on the
> left and 100 psi on the right. A third toothpick points to where the
> inner tube shows a faint mark from the nail that penetrated the tire
> at 110 psi:
>
>
http://server5.theimagehosting.com/image.php?img=331a_110psi_penetrates.
jpg
> or http://tinyurl.com/ssc8k
>
> Here's the inside of the tire. One toothpick is visible where the nail
> penetrated at 110 psi. The second toothpick can't be seen, since the
> 100 psi hole in the tread didn't go all the way through the Kevlar
> belt. The inner tube mark is out-of-focus, but shown by a third
> toothpick:
>
>
http://server5.theimagehosting.com/image.php?img=332a_110psi_penetrates.
jpg
> or http://tinyurl.com/y7bmnx
>
> Here's a slightly better picture of the inner tube mark. It's just a
> very faint circular scraped area around a tiny dent that shows up as a
> black shadowed area, not quite as wide as the end of the blunt
> toothpick:
>
>
http://server5.theimagehosting.com/image.php?img=333a_110psi_mark_on_tub
e.jpg
> or http://tinyurl.com/y2ngj3
>
> For those curious about such simple tests, far more time was spent
> fiddling with the camera and bashing the keyboard than clamping a nail
> in a vise, pumping an old tire up, and imitating an Iron Maiden. The
> actual testing took about fifteen minutes.
>
> It never occurred to me that the inner tube would behave like this,
> which is why I like fooling around with such simple tests--I was
> annoyed when the nail seemed to puncture the tire, but the tire
> refused to go flat.
>
> Cheers,
>
> Carl Fogel

Great stuff.

As far as tire savers or sticker flickers are concerned, I've watched
them clean goatheads off with out getting a puncture. Our contention
was/is that many times, goatheads and glass shards don't puncture when
they get picked up or even on the first rotation of the tire.

I've seen sewups with what I assumed where small glass cuts in the
treads that cut through the casing but didn't penetrate the tube. It
appeared that they got picked up in the soft rubber tread and worked
their way through before coming loose.

I rode Clement Campionato del Mundo and Paris Roubaix sewups throughout
the Southwest for many years. This included Southwestern Colorado - the
Iron Horse Race in Durango and so on. This is prime goathead country. My
friends and I kept our tire pressures under 90 PSI and we had very few
flats.

In the mid 1970's a group of 5 doctors bought top end bikes from us and
rode them from New Mexico to New Orleans. They each had 5 del Mundos. At
the end of their trip they flew back to NM with their bikes. We bought
back their extra del Mundos as they only had 1 flat between the five of
them.

Chas.

 

[Ted Bennett]

Mike Jones <[email protected]> wrote:

> > WALES: "Ah, boyo, do you fancy a pint? Oh, bugger, it's Sunday - they're
> > shut."
> >
> >
> It's all a bit of fun, but on Sunday we now say "Who's round is it?"


No you don't. You say "Whose round is it?"

Ted

--
Ted Bennett

 

[[email protected]]

wafflycat who? writes:

>> I'm really just wondering if the flint-flat is weirdly a pavement
>> problem instead of an off-road phenomenon. (I don't know if the
>> chips are true wild flints, washed onto the pavement as some posts
>> in this thread suggest, or some other rock cracked in some paving
>> process or broken by traffic.)

> Are you using the leftpondian definition of pavement? Over here in
> rightpondia, the pavement is the area at the side of a road that is
> for pedestrians to walk on - usually tarmac or paving slabs.

I assume you have paved roads in that region so I wonder what the
definition of being on that paved road is to not being on its paved
surface. I've seen all sorts of pavement from roman stone roads,
Italian red granite slabs, alpine granite cubes, basalt headstones,
asphalt and concrete, not to mention plank roads.

So what do you call such road surfaces, generically? I always thought
"tarmac" was a cumbersome name specific to John Loudon McAdam's
invention especially when referring to other paving.

> In my bit of the UK I'm in a rural setting. The tarmac roads mostly
> don't have a pavement for pedestrians. It's tarmac road then
> fields/hegerows/trees to the side. It's common that rain will cause
> run-off from the fields, bringing soil, pebbles, flints etc., on to
> the roads. These do cause punctures. I am reminded of a time trial
> my offspring was taking part in. During the event there was heavy
> rain. Cue one exceedingly p!$$ed-off offspring who punctured on the
> way from event HQ to the start. Pulled some nasty sharp flint
> shards from his tyre that day.

What if the road shoulder is striped as a bicycle and pedestrian zone,
but part of the road? I'm unclear on the usage. How do you verbally
distinguish between paved and unpaved roads?

Jobst Brandt

 

[Tony Raven]

[email protected] wrote on 27/10/2006 22:16 +0100:
>
> So what do you call such road surfaces, generically?
>

Metalled. Originally it meant surfaced by broken stone but it how means
mainly a tarmac

>
> What if the road shoulder is striped as a bicycle and pedestrian zone,
> but part of the road? I'm unclear on the usage. How do you verbally
> distinguish between paved and unpaved roads?
>

The pavement or footway is what you would call a sidewalk and is part of
the highway comprising the carriageway and footway. A paved road will
be called a metalled road and an unpaved one a track or an unmade up road.


--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[[email protected]]

Chas who? writes:

>>> Nope, got it from friend in Manchester... but I'll spot you a
>>> pint of bitters if you ever get over this way (SF Bay Area).

>> I used to go there monthly but I've now hung up my Frequent Flyer card..

>> There's some interesting beers in the microbreweries but I wasn't
>> so sure about the Pale Ale that one owner was very keen that I
>> tried in a Brewpub on 4th in San Rafael on my way back from riding
>> up in the hills.

> There are still a lot of Americans who are "afraid of the dark" and
> many microbreweries tailor their output for that market. I've tasted
> some brewpub ales that made Bud Light seem like a monster beer! Pale
> ale to some means just that!

> If you ever get back this way, the Pacific Coast Brewery in Oakland
> has consistently good brews on tap. Let me know when you are coming
> and I'll sport you one.

> http://www.pacificcoastbrewing.com/

As more breweries spring up here, Germany has lost more than half its
"big" breweries in the last ten years. My old haunts in Stuttgart had
four major brands: Stuttgarter Hofbräu, Schwabenbräu, Dinkelacker, and
Wulle. Today there are none. Without the large beer tents of these
Breweries, Oktoberfest in Stuttgart has no face.

Today Stuttgarter Hofbräu is brewed in Munich.

Jobst Brandt

 

[Mike Jones]

Ted Bennett wrote:
> Mike Jones <[email protected]> wrote:
>
>>> WALES: "Ah, boyo, do you fancy a pint? Oh, bugger, it's Sunday - they're
>>> shut."
>>>
>>>
>> It's all a bit of fun, but on Sunday we now say "Who's round is it?"
>
>
> No you don't. You say "Whose round is it?"
>
> Ted
>
Cheers!

 

[John Forrest Tomlinson]

Two comments:

1 -- I've learned some new words in this thread!
2 -- Some people have said they never get flats from X or Y cause, but
I wonder how they can be of that. Sometimes I can't tell what caused
a flat and I presume that is the case for other people as well.
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

 

[Michael Press]

In article <[email protected]>,
Mike Jones <[email protected]> wrote:

> Michael Press wrote:

[...]

> Thank you.
> But still it cuts! (apologies to Galileo)
>
> Basically any path strewn with flint shards, glass (and I contend shale)
> or screws, nails, thumbnails aka tacks, or thorns is PF land.

You imply that I argue about the frequency of tire
punctures from flint. I propose that you find where I
do so.

--
Michael Press

 

[Johnny Sunset aka Tom Sherman]

John Forrest Tomlinson wrote:
> Two comments:
>
> 1 -- I've learned some new words in this thread!
> 2 -- Some people have said they never get flats from X or Y cause, but
> I wonder how they can be of that. Sometimes I can't tell what caused
> a flat and I presume that is the case for other people as well.

ALL my bicycle tire flats are caused by a reduction in air pressure in
the inner tube.

--
Tom Sherman - Here, not there.

 

[Earl Bollinger]

<[email protected]> wrote in message
news:[email protected]...
> Over in rec.bicycles.tech, Jobst Brandt argues that flint flats are
> just a myth:
>
> "I keep hearing about these mysterious cherts [flints] yet have never
> seen one on the road or in a tire. I ride many miles of rocky roads
> here and in Europe and have not had a flat from these mysterious sharp
> rocks that don't seem to cut car tires or we could find examples of
> them embedded in the surface of car tires."
>
> http://groups.google.com/group/rec.bicycles.tech/msg/97f538aa81f0f1ed
>
> Primitive superstitions about flints still flourish in the UK and
> Denmark, so I'm asking for your views on the matter, somewhat like a
> sociologist asking about the Loch Ness monster.
>
> Any pictures of flints in tires and tubes would be interesting, even
> though they must be obvious fakes.
>
> (Alas, the nearby sand and gravel pit closed a few years ago, so I'm no
> longer able to photograph the flint flats whose existence Jobst
> denies.)
>
> Cheers,
>
> Carl Fogel
>

In what way is a small sharp piece of flint different from a small piece of
glass?
If a small piece of a broken beer bottle can work its way into a tire and
cause a flat, why can't a small piece of a flint do the same thing?
I have had small sharp bits of gravel, damage a tire enough to cause a weak
spot in the casing so that the tire tube blows out later.
So I can see where a small sharp something can get in a bike tire and work
its way through the tire and casing to puncture the tube.

 

[[email protected]]

On Fri, 27 Oct 2006 21:26:22 -0500, "Earl Bollinger"
<[email protected]> wrote:

><[email protected]> wrote in message
>news:[email protected]...
>> Over in rec.bicycles.tech, Jobst Brandt argues that flint flats are
>> just a myth:
>>
>> "I keep hearing about these mysterious cherts [flints] yet have never
>> seen one on the road or in a tire. I ride many miles of rocky roads
>> here and in Europe and have not had a flat from these mysterious sharp
>> rocks that don't seem to cut car tires or we could find examples of
>> them embedded in the surface of car tires."
>>
>> http://groups.google.com/group/rec.bicycles.tech/msg/97f538aa81f0f1ed
>>
>> Primitive superstitions about flints still flourish in the UK and
>> Denmark, so I'm asking for your views on the matter, somewhat like a
>> sociologist asking about the Loch Ness monster.
>>
>> Any pictures of flints in tires and tubes would be interesting, even
>> though they must be obvious fakes.
>>
>> (Alas, the nearby sand and gravel pit closed a few years ago, so I'm no
>> longer able to photograph the flint flats whose existence Jobst
>> denies.)
>>
>> Cheers,
>>
>> Carl Fogel
>>
>
>In what way is a small sharp piece of flint different from a small piece of
>glass?
>If a small piece of a broken beer bottle can work its way into a tire and
>cause a flat, why can't a small piece of a flint do the same thing?
>I have had small sharp bits of gravel, damage a tire enough to cause a weak
>spot in the casing so that the tire tube blows out later.
>So I can see where a small sharp something can get in a bike tire and work
>its way through the tire and casing to puncture the tube.

Dear Earl,

Much the same thoughts occurred to me when I removed nasty little
green-Slime-covered rock chips from my flat tires, but read that
flint-flats were myth and lore.

Obviously, my tongue-in-cheek style needs improvement.

As penance, here's a earlier post with some older pictures, provoked
by the familiar flints-don't-cause-flats claim:

http://groups.google.com/group/rec.bicycles.tech/msg/a4a0b6cb9a83e15e

Fogel Labs has since replaced its $15 WalMart USB camera with a modern
marvel, but is still looking for a competent photographer. Here's one
of the nitwit's more embarrassing recent shots:

http://server5.theimagehosting.com/image.php?img=314hawkb.jpg
or http://tinyurl.com/ygfaf7

A magnificent prairie hawk flew across the road as I climbed up the
side of the dam, did some swooping, and then perched on a convenient
nearby stake, so I stopped and took several pictures of it, most of
which showed the hawk nicely.

The picture above captures the breathtaking wild beauty of another
stake, neatly centered. (The part of the hawk that went over the fence
last is just visible on the extreme left, sitting on a different
stake.)

Cheers,

Carl Fogel

 

[Michael Press]

In article
<[email protected]>,
"* * Chas" <[email protected]> wrote:

> "Don Whybrow" <[email protected]> wrote in message
> news:[email protected]...
> > * * Chas wrote:
> > >
> > > Nope, got it from friend in Manchester.... but I'll spot you a pint
> of
> > > bitters if you ever get over this way (SF Bay Area).
> >
> > That would a) put you under the table & b) taste terrible [1]
> >
> > On the subject of language differences and to bring this back onto
> topic
> > for a moment I was wondering if what we have here is a geological
> equal
> > to the pavement issue. I.e. over here in Rightpondia, the term "flint"
> > refers to a specific type of stone and over there in Leftpondia it is
> a
> > generic term. Of course I could be spouting drivel and we are all
> > talking about the same stuff.
> >
> >
> > [1] http://en.wikipedia.org/wiki/Bitters
> >
> > --
> > Don Whybrow
> >
> > Sequi Bonum Non Time
> >
> > Wit levels low. Attempting to compensate.
>
> Choke! Gag! I stand or lay down corrected. Many of the brew pups in the
> states refer to "bitter" versus "bitter".
>
> Flint as far as I've used the term is usually found as inclusions in
> limestone rocks however, Zippo brand cigarette lighters use a small
> cylindrical metallic? object for creating a spark to light the flame
> that they call "flints".

Have not been made from flint for a long time. Some
kind of pyrophoric metal. Reportedly iron and cerium.

--
Michael Press

 

[[email protected]]

On 26 Oct 2006 12:47:13 -0700, [email protected] wrote:

>Over in rec.bicycles.tech, Jobst Brandt argues that flint flats are
>just a myth:
>
>"I keep hearing about these mysterious cherts [flints] yet have never
>seen one on the road or in a tire. I ride many miles of rocky roads
>here and in Europe and have not had a flat from these mysterious sharp
>rocks that don't seem to cut car tires or we could find examples of
>them embedded in the surface of car tires."
>
>http://groups.google.com/group/rec.bicycles.tech/msg/97f538aa81f0f1ed
>
>Primitive superstitions about flints still flourish in the UK and
>Denmark, so I'm asking for your views on the matter, somewhat like a
>sociologist asking about the Loch Ness monster.
>
>Any pictures of flints in tires and tubes would be interesting, even
>though they must be obvious fakes.
>
>(Alas, the nearby sand and gravel pit closed a few years ago, so I'm no
>longer able to photograph the flint flats whose existence Jobst
>denies.)
>
>Cheers,
>
>Carl Fogel

Come to think of it . . .

The reduced penetration that accompanies lower tire pressures must be
part of the reason why car tires at 25-35 psi don't suffer from the
flint and rock chip problems mentioned by many posters in this thread,
who probably run 60-120 psi in their bicycle tires.

CF

 

[* * Chas]

<[email protected]> wrote in message
news:[email protected]...
Chas who? writes:

>>> Nope, got it from friend in Manchester... but I'll spot you a
>>> pint of bitters if you ever get over this way (SF Bay Area).

>> I used to go there monthly but I've now hung up my Frequent Flyer
card.

>> There's some interesting beers in the microbreweries but I wasn't
>> so sure about the Pale Ale that one owner was very keen that I
>> tried in a Brewpub on 4th in San Rafael on my way back from riding
>> up in the hills.

> There are still a lot of Americans who are "afraid of the dark" and
> many microbreweries tailor their output for that market. I've tasted
> some brewpub ales that made Bud Light seem like a monster beer! Pale
> ale to some means just that!

> If you ever get back this way, the Pacific Coast Brewery in Oakland
> has consistently good brews on tap. Let me know when you are coming
> and I'll sport you one.

> http://www.pacificcoastbrewing.com/

As more breweries spring up here, Germany has lost more than half its
"big" breweries in the last ten years. My old haunts in Stuttgart had
four major brands: Stuttgarter Hofbräu, Schwabenbräu, Dinkelacker, and
Wulle. Today there are none. Without the large beer tents of these
Breweries, Oktoberfest in Stuttgart has no face.

Today Stuttgarter Hofbräu is brewed in Munich.

Jobst Brandt

Das Biertrinken ist ja gut.

I don't recall ever having any beer from Stuttgart but I found an empty
bier bottle inside the door panel of a Porsche that I was working on
once... Owner kept complaining of a rattle in the door.

My first exposure to great German beer was at the Hofbrauhaus in Munich
in 1965. Muenchen is one of my favorite European cities. Unfortunately I
have yet to make it to Oktoberfest in Germany.

There are only a few good breweries of German style beers (non ales)
that I know of in the US. Gordon Biersch makes a few good ones as well
as Sudwerk up in Davis, CA. Penn Brewery in Pittsburgh, PA makes some
great German style beers and there are still a few good small breweries
in Wisconsin like Leinenkugels but many of them have been bought up by
the big companies.

Chas.

 

[Tony Raven]

Johnny Sunset aka Tom Sherman wrote on 28/10/2006 00:54 +0100:
>
> ALL my bicycle tire flats are caused by a reduction in air pressure in
> the inner tube.
>

Mine aren't* ;-)

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

* Hint: UST

 

[Tony Raven]

Michael Press wrote on 28/10/2006 04:32 +0100:
>
> Have not been made from flint for a long time. Some
> kind of pyrophoric metal. Reportedly iron and cerium.
>

Indeed it is a material called ferrocerium (70% cerium, 30% iron)
developed by Baron Carl Auer Freiherr von Welsbach in 1903. It also has
a role reversal. The original flints struck off small pieces of hot
steel which burnt in the air to create the spark. However in a lighter
the steel strikes off small pieces of ferrocerium which burn up in the
air instead.


--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[Tony Raven]

[email protected] wrote on 28/10/2006 06:43 +0100:
>
> Come to think of it . . .
>
> The reduced penetration that accompanies lower tire pressures must be
> part of the reason why car tires at 25-35 psi don't suffer from the
> flint and rock chip problems mentioned by many posters in this thread,
> who probably run 60-120 psi in their bicycle tires.
>

Or maybe its because they are made of much thicker rubber and have a
steel belt under the treads.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

 

[Earl Bollinger]

<[email protected]> wrote in message
news:[email protected]...
> On Fri, 27 Oct 2006 21:26:22 -0500, "Earl Bollinger"
> <[email protected]> wrote:
>
>><[email protected]> wrote in message
>>news:[email protected]...
>>> Over in rec.bicycles.tech, Jobst Brandt argues that flint flats are
>>> just a myth:
>>>
>>> "I keep hearing about these mysterious cherts [flints] yet have never
>>> seen one on the road or in a tire. I ride many miles of rocky roads
>>> here and in Europe and have not had a flat from these mysterious sharp
>>> rocks that don't seem to cut car tires or we could find examples of
>>> them embedded in the surface of car tires."
>>>
>>> http://groups.google.com/group/rec.bicycles.tech/msg/97f538aa81f0f1ed
>>>
>>> Primitive superstitions about flints still flourish in the UK and
>>> Denmark, so I'm asking for your views on the matter, somewhat like a
>>> sociologist asking about the Loch Ness monster.
>>>
>>> Any pictures of flints in tires and tubes would be interesting, even
>>> though they must be obvious fakes.
>>>
>>> (Alas, the nearby sand and gravel pit closed a few years ago, so I'm no
>>> longer able to photograph the flint flats whose existence Jobst
>>> denies.)
>>>
>>> Cheers,
>>>
>>> Carl Fogel
>>>
>>
>>In what way is a small sharp piece of flint different from a small piece
>>of
>>glass?
>>If a small piece of a broken beer bottle can work its way into a tire and
>>cause a flat, why can't a small piece of a flint do the same thing?
>>I have had small sharp bits of gravel, damage a tire enough to cause a
>>weak
>>spot in the casing so that the tire tube blows out later.
>>So I can see where a small sharp something can get in a bike tire and work
>>its way through the tire and casing to puncture the tube.
>
> Dear Earl,
>
> Much the same thoughts occurred to me when I removed nasty little
> green-Slime-covered rock chips from my flat tires, but read that
> flint-flats were myth and lore.
>
> Obviously, my tongue-in-cheek style needs improvement.
>
> As penance, here's a earlier post with some older pictures, provoked
> by the familiar flints-don't-cause-flats claim:
>
> http://groups.google.com/group/rec.bicycles.tech/msg/a4a0b6cb9a83e15e
>
> Fogel Labs has since replaced its $15 WalMart USB camera with a modern
> marvel, but is still looking for a competent photographer. Here's one
> of the nitwit's more embarrassing recent shots:
>
> http://server5.theimagehosting.com/image.php?img=314hawkb.jpg
> or http://tinyurl.com/ygfaf7
>
> A magnificent prairie hawk flew across the road as I climbed up the
> side of the dam, did some swooping, and then perched on a convenient
> nearby stake, so I stopped and took several pictures of it, most of
> which showed the hawk nicely.
>
> The picture above captures the breathtaking wild beauty of another
> stake, neatly centered. (The part of the hawk that went over the fence
> last is just visible on the extreme left, sitting on a different
> stake.)
>
> Cheers,
>
> Carl Fogel

Thanks,

I got to thinking about it some more.
Now I have had a delayed blow out effect. That is where some sort of a
semi-sharp short object manages to punch through the outer tire casing and
damage the plies underneath, but not enough to puncture the tube outright.
It blew out quite spectacularly at work later in my quiet office almost
giving me a heart attack. That was on a cheap brand tire, so I figured the
cheaper tire with its cheaper low thread count casing probably made it
susceptable to such things.
Anyway I wonder if certain tires like the cheaper ones would be more
susceptable to small semi-sharp objects embedded in Chip Seal roads etc.
Heck I think older worn down good tires might even be susceptable too. The
way they do the chip seal roads with the big heavy machines mashing down the
gravel so well, I don't see much happening there as the sharp edges on the
gravel seems to get knocked off or flattened out. But if there are cracks in
the pavement and a sharp rock gets stuck in there just right, it could cause
a tire to get damaged enough to blow out or go flat.