Flints don't puncture bicycle tires?
carl...@comcast.net
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
LSMike
Flints? I wouldn't know whether they are flints, but small pieces of
sharp flat stone have caused the last few p***t**"s I've had.
Sometimes the odd piece of glass too.
Don Whybrow
> 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.
Certainly flints have been in the UK since primitive times, The area
round where I used to live was a well known stone age industrial site
exporting flints around Europe [1]. In fact at the local Rugby [2] club
both teams had to walk the field prior to each game to pick up flints
that had worked their way to the surface, even if you were playing
immediately after anther match.
[1] http://en.wikipedia.org/wiki/Grimes_Graves
[2] For the leftpondians, a superior version of your "football", not to
be confused with football, that you call "soccer".
--
Don Whybrow
Sequi Bonum Non Time
"Lord, please make me the kind of person my dog thinks I am."
Paul Boyd
> Over in rec.bicycles.tech, Jobst Brandt argues that flint flats are
> just a myth:
Really? The last puncture I had was on a newly surfaced Sustrans
cyclepath in Lincolnshire. Two punctures in fact on the same section of
path. Surfaced with small sharp flinty stones, several of which were
sticking out of the tyre.
(For the US readers, Sustrans masquerades as a national cycling
organisation, so really should know better)
--
Paul Boyd
http://www.paul-boyd.co.uk/
peter
> 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."
I've never had a flat from a flint or other sharp stone, but a couple
years ago I had a simple twig go right through the tread of my tire.
It was a cheap Hutchinson that Nashbar had on sale for about $3 - after
several flats culminating in the one above I gave up on this tire even
though it had plenty of rubber left. If a stick can make it through a
tire tread and casing it seems reasonable to me that a properly
oriented sharp rock could as well.
Tim McNamara
should be seasoned with a grain of salt.
I can remember many flat tires from small shards of glass. I really
don't know if these are picked up and work their way through the tread,
through the casing and into the tube to cause the flat or if they just
go straight through. I've heard arguments both ways. Not sure that it
matters.
I've had sharp somethings cut my tires without causing flats. That's
probably not germaine.
I've had thumbtacks, screws, roofing nails, construction staples, box
staples, stationery staples, large shards of glass, sharp pieces of
metal all cause flats. I've ever seen the seed of a puncture vine
except in person, since it doesn't seem to grow here in Minnesota or at
least in the parts I've lived in.
I've had flats from odd little pieces of wire about 1/4" long. Some
call them "Michelin" wires and allege that they come from blown-out
Michelin car tires. I don't know if that's the source. Not sure it
matters. I've also had flats from what are obviously little bits of
brake or derailleur cable, from cutting cables in my workshop and not
sweeping adequately.
I've had pinch flats from running into large rocks, potholes, etc. Once
I pinch flatted in a road race when someone had laid large square metal
poles across the lane in the middle of the race between laps, and I
couldn't see one for all the riders packed in front of me who were
yelling incomprehensibly and jinking around every which way.
I've had a number of flats from valve stems separating from the tube,
almost all of them with Specialized brand tubes. I've had mysterious
flats when my bike has been in my car on hot sunny days, sometimes
not-so-mysteriously resulting in the aforementioned valve stem failure.
I've found small stones imbedded in cuts in the tire tread. The vast
majority were just noticed and removed, and were not associated with
flats. I can't unequivocally recall ever having had a flat that was
definitely caused by a small sharp piece of rick (a.k.a., a "flint").
But then I wouldn't take an oath on pain of death that it had never
happened. I just don't remember ever having it happen for sure. If it
has, it's been a very very small percentage of the flat tires I have had
in the past 40 years.
Andrew F Martin
Sorry, no pictures - but when I was working in Copenhagen I averaged a
flat a ride until I put Tuffy's in. the locals swear by riding lower
pressures, but it didn't seem to help me (Vittoria Rubino Pros).
Simon Proven
Tim McNamara wrote:
> I've found small stones imbedded in cuts in the tire tread. The vast
> majority were just noticed and removed, and were not associated with
> flats. I can't unequivocally recall ever having had a flat that was
> definitely caused by a small sharp piece of rick (a.k.a., a "flint").
> But then I wouldn't take an oath on pain of death that it had never
> happened. I just don't remember ever having it happen for sure. If it
> has, it's been a very very small percentage of the flat tires I have had
> in the past 40 years.
I tend to find lots of small stones in the tyre tread; when I'm out on
a group
and someone's got a puncture I amuse myself by picking them out their
tread (as well as the one that cause the puncture) while they repair
the
tube. I find 2-3 embedded when I do that, typically. They're not
flints,
IME because they're too light in colour, and are probably cherts.
My touring bike has 11,500 miles behind it, and has had /one/ puncture,
and IIRC (it was 2004 that it happened) it was a chert. It was right
by
the front door when I noticed it, having just got home. Convenient.
Other punctures since 1998:
- folding bike, drill bit through bottom of tread and out of sidewall
- folding bike, small nail in bottom of tread
- racer, tread puncture, small fragment of glass
- racer, puncture due to poor rim tape supplied with bike, at spoke
hole
- tourer, aforementioned chert
- audax bike, no punctures
I think those bikes have about 16K miles and 5 punctures, so about
3.2K miles per puncture. The tourer with the TT2000 tyres seems to
be the best, the audax bike's not done enough miles yet to know.
Simon
peter
> I've had flats from odd little pieces of wire about 1/4" long. Some
> call them "Michelin" wires and allege that they come from blown-out
> Michelin car tires. I don't know if that's the source.
They're not specific to any particular tire brand anymore, but were
originally given the name "Michelin thorn" back when steel-belted
radial car tires were relatively rare and Michelin was the brand most
associated with that technology.
Sue White
>
>Primitive superstitions about flints still flourish in the UK and
>Denmark, so I'm asking for your views on the matter, somewhat like a
I live in Reading, which is a very good area for flints.
You can pick up Stone Age flint tools in the fields round here.
You can also pick small sharp chips of flint out of your punctured
tyres, a few times a year depending on your mileage.
Of course there are millions of small sharp flint chips on our roads and
bridleways, and it's only a tiny antisocial minority that stick into
your tyres. Most often the back tyre: your front wheel disturbs a chip
that was lying flat on the ground, and your rear one rolls onto it while
its pointy end is still sticking up.
--
Sue ]:(:)
Andrew F Martin
Strange - when I lived in Maidenhead, Berkshire - I never got a flat
from flints. Actually - I can't remember getting any flats at all
while there.
jobst....@stanfordalumni.org
>> 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.)
> Sorry, no pictures - but when I was working in Copenhagen I averaged
> a flat a ride until I put Tuffy's in. the locals swear by riding
> lower pressures, but it didn't seem to help me (Vittoria Rubino
> Pros).
Oops! That's another piece of myth and lore. That lower tire
pressure (and we're talking about -20% or so) is a visualization that
assumes a tire casing and tread of extreme flexibility by which the
tire casing could form an umbrella of a few mm diameter around a sharp
object. That is about as valid as the tire wiping gesture:
http://www.sheldonbrown.com/brandt/wiping.html
Jobst Brandt
jobst....@stanfordalumni.org
I beg to differ. I introduced the term "Michelin wire" in this forum
when it was just one group rec.bicycle, and i was describing that type
of puncture. As you say, it was at a time when steel belted tires
were primarily Michelin, the tire that was developed primarily as a
rubber tired railway wheel before its other benefits were accepted by
the auto industry. The Paris metro still runs pneumatic rubber tires.
Jobst Brandt
Werehatrack
>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
May the gods of perversity visit him for that one. The mere fact that
it has not happened to him is not proof that it does not occur.
If I had been prescient enough to find it for him back in 1976, I
possibly could have brought him the stone that poked a hole in the
tire of my '67 VW Van on a road in Montana, but he thoughtlessly
failed to let me know that he wanted it. The road was freshly graded
and gravelled, and I was so certain that there must have been
something other than a rock involved that I spent the better part of
half an hour searching the road for the offending object. The search
was fruitless, of course; under the assumption that a rock couldn't do
the deed, I looked for anything else...but rocks were the only
possible cause. The majority of the rocks were 35 to 70mm in size,
and they were freshly crushed rather than rounded river rock. Sharp
edges abounded, but I ignored them. Finally, I gave up the quest for
the puncture's cause, mounted the spare, and carefully made my way
back to civilization to get the sanctified tire cursed again.
The guy at the tire store knew just which road section was involved.
He'd had several flats to fix that day due to that road and another
which had received similar treatment by the DOT.
Perhaps more to the point, however, in a conversation I had years ago
with one of the engineers at Armstrong (are they still in business?)
he noted that stone-induced holes are exceedingly rare on car tires
now that steel belts are the norm under the tread, and even in those
cases where they still occur, they seldom leave a rock in the breach.
Sometimes, that's because the stone causes a rupture rather than a
puncture; the stone never actually penetrates the surface, but deforms
it so severely that it tears from the inside. When that occurs, the
cords on the inside show a burst pattern rather than a cut. Tire
punctures due to an outright cut from a rock do occur, though, but the
rock is seldom still in the cut when the tire is removed; such rocks
are almost never shaped regularly enough, with a small enough
cross-section with nearly parallel sides, that they get trapped by the
tire material. They poke a hole and get blown back out.
>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.
The Loch Ness Monster, on the other hand, is a known hoax, while the
stone-cut tire is not.
>Any pictures of flints in tires and tubes would be interesting, even
>though they must be obvious fakes.
I suspect that it's just such a matter-of-course occurrence in such
areas that they don't bother taking pictures. To them, I'm sure that
it would be like making photo documentation of dryer lint; why bother?
(Nessie, on the other hand, is a subject whose photo is worth real
money; I can just imagine the melee that would ensue should that
mythical beast surface before a crowd of Scots with cameras in hand.)
>(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.)
And I live in an area where the odd rock is more often a shard of
oyster shell, with less probability of puncturing a tire than the far
more common (on the road, at any rate) shards of broken glass and
plastic remaining from the most recent auto collisions. Still, for
me, the puncturing object is still in the tire only about half the
time with street flats, and less than that when off-road.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
carl...@comcast.net
Dear Jobst,
Why wouldn't sharp objects be less likely to penetrate tough materials
like tires if the resistance is lowered to 60-90 psi instead of 90-120
psi?
There is, after all, a lower limit of pressure below which the sharp
object will not penetrate the tire.
Incidentally, what we call "tire savers" in the US are often called
"flint catchers" in the UK, where riders appear to be unaware of your
theory. (You can google the archives for the quaint phrase, which
appeared in posts to which you replied.)
Cheers,
Carl Fogel
Dennis P. Harris
carl...@comcast.net wrote:
> 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.
>
i have indeed had flats from little chips of flint while touring,
but never since i switched to touring on a fat tire bike with
inverse tread tires.
around here, the bad rocks on several trails are the tilted shale
veins that cross the trails. they are constantly breaking off
new brittle edges that can shred a kevlar knobby like a razor
blade. volunteers haul prybars and sledge hammers up there every
spring to get rid of the new blades that poke up through the fill
gravel.
Fred
of tar covered in fine crushed stone. Sometimes some of the stone is
flint.
I got a flat and when I stopped the tiny piece of flint was still
sticking in the tire.
Think of it this way: The Indians used flint for arrowheads and it
worked OK.
jobst....@stanfordalumni.org
>>> Sorry, no pictures - but when I was working in Copenhagen I
>>> averaged a flat a ride until I put Tuffy's in. the locals swear
>>> by riding lower pressures, but it didn't seem to help me (Vittoria
>>> Rubino Pros).
>> Oops! That's another piece of myth and lore. That lower tire
>> pressure (and we're talking about -20% or so) is a visualization
>> that assumes a tire casing and tread of extreme flexibility by
>> which the tire casing could form an umbrella of a few mm diameter
>> around a sharp object. That is about as valid as the tire wiping
>> gesture:
http://www.sheldonbrown.com/brandt/wiping.html
> Why wouldn't sharp objects be less likely to penetrate tough
> materials like tires if the resistance is lowered to 60-90 psi
> instead of 90-120 psi?
As I mentioned above. For this scenario to succeed, the tire would
need enough flexibility to allow a dimple several mm in diameter to be
supported on a thorn or sharp (knife like) object not more than 2mm in
length. Tires are not that flexible. Try that manually and you'll
see that even at 30psi there is enough pressure to puncture through to
the air chamber.
> There is, after all, a lower limit of pressure below which the sharp
> object will not penetrate the tire.
Describe that for an average tire. Just try that with any of yours.
> Incidentally, what we call "tire savers" in the US are often called
> "flint catchers" in the UK, where riders appear to be unaware of your
> theory. (You can Google the archives for the quaint phrase, which
> appeared in posts to which you replied.)
Tire savers are those things that do no good except that, when roads
are moist, cover the rider and bicycle with road debris, much like the
back of automobile vans. I haven't seen one used in years.
Jobst Brandt
carl...@comcast.net
Dear Werehatrack,
Yes, my impression is that flats from what the UK crowd and the Danes
call flints are so common that they'll be amused by this thread.
I don't doubt that Jobst's tires are unsullied by such thoughtless
rock chips, but his habit of denying the existence of anything outside
his experience grows tiresome. Right now, he's evading the issue in
several posts, with red herring quibbles about who first used the term
"Michelin wire" and blather about how terrible I am to ride where I
live and take pictures that don't support his theories about
goatheads.
What's actually interesting is how the stone-chip flats seem to be
much more common in England and Denmark. I wondered if it was just
some local road-building custom, but a post in this thread mentions
that the rugby teams in one area search the grass for flints before
games, which suggests that the evil little things are part of the
general landscape.
For what it's worth, here's the shortest and sharpest (sorry, can't
resist it) comment that I've found in the archives about the
supposedly non-existent flints:
Andrew Muzi of yellowjersey.org in Wisconsin wrote skeptically about
the danger of checking for sharp objects inside flat tires:
"Myth. Having run my fingers inside literally many thousands of
tires, often with nicely mounted glass shards, staples, wire, nails
and evey imaginable penetrating object, I cannot recall ever having
cut my finger while wiping the inside of a tire."
David Damerell of the UK replied:
"I have once, on a flint. However, I don't think it's worth buggering
about with cotton balls to prevent one trivial injury in many years of
riding."
http://groups.google.com/group/rec.bicycles.tech/msg/64c1101610ba1d6e
As a sidelight, a friend of mine startled me recently by casually
mentioning that he expects two or three flat tires per year just
driving his car. He started ticking off flats in the last year in his
car, his wife's car, his parents' car, and rental cars, all just
driving around paved streets all over the western US. The tires were
new, not worn out.
After I decided that my friend wasn't joking, I told him that he
certainly won't be borrowing my car. Tthis seemed like a more
practical approach than the Jobstian tactic of telling him that he was
mistaken.
Around here, we actually have a phrase to describe a certain
personality: "He'd argue with a flat tire."
Cheers,
Carl Fogel
doug....@gmail.com
carl...@comcast.net wrote:
> Yes, my impression is that flats from what the UK crowd and the Danes
> call flints are so common that they'll be amused by this thread.
>
> I don't doubt that Jobst's tires are unsullied by such thoughtless
> rock chips, but his habit of denying the existence of anything outside
> his experience grows tiresome.
Dear Carl,
This may be true, but right now you want to bust him so bad it is
interfering with your judgement. Calm down and regroup -- if you are
correct, he will soon will afford you another opportunity.
Cheers,
Doug
Doug
carl...@comcast.net
[snip]
>> Why wouldn't sharp objects be less likely to penetrate tough
>> materials like tires if the resistance is lowered to 60-90 psi
>> instead of 90-120 psi?
>
>As I mentioned above. For this scenario to succeed, the tire would
>need enough flexibility to allow a dimple several mm in diameter to be
>supported on a thorn or sharp (knife like) object not more than 2mm in
>length. Tires are not that flexible. Try that manually and you'll
>see that even at 30psi there is enough pressure to puncture through to
>the air chamber.
>
>> There is, after all, a lower limit of pressure below which the sharp
>> object will not penetrate the tire.
>
>Describe that for an average tire. Just try that with any of yours.
[snip]
Dear Jobst,
Okay, let's try it with an average tire, one of mine.
Here's about 4mm of small nail sticking up in a vise, with its twin
brother lying beside it and spoke ruler. The nail point, considerably
enlarged, appears to be less than half a millimeter wide:
http://server5.theimagehosting.com/image.php?img=325a_30psi_setup.jpg
or http://tinyurl.com/whahk
Here's a 700c x 26 tire inflated to 30 psi and about to test your
theory, again considerably enlarged:
http://server5.theimagehosting.com/image.php?img=326a_30psi_and_nail.jpg
or http://tinyurl.com/y6g36w
And here's the result:
http://server5.theimagehosting.com/image.php?img=327a_30psi_no_puncture.jpg
or http://tinyurl.com/y74wc8
As you can see, the tire is holding pressure, having flattened out and
tented over the nail point quite flexibly--no puncture, not even a
mark on the tread.
Experience suggests that this is not the result of running over a
small nail point at normal touring tire pressures.
Obviously, the sharper the object, the lower the crucial pressure. And
equally obviously, the lower the pressure, the less the likelihood of
a puncture.
Feel free to do more testing on your own to confirm this.
But you can save time by pondering how Indian fakirs lie on beds of
nails.
I hear it has something to do with keeping the pressure below the
crucial level by spreading out the body weight over enough nails,
which allows the skin to tent and dimple over the the nail points
instead of puncturing (like certain theories).
Cheers,
Carl Fogel
carl...@comcast.net
Dear Doug,
Right now, I'm waiting for the predictable explanations that my
pictures of a nail failing to penetrate a tire at 30 psi are mistaken,
since they fail to confirm Jobst's latest theory:
http://groups.google.com/group/rec.bicycles.tech/msg/6955c93a5f6a06a0
Cheers,
Carl Fogel
Robin Hubert
In many thousands of miles on limestone trails, on 25-28mm road
clinchers (performance type), I have never had a flint puncture.
Robin Hubert
jobst....@stanfordalumni.org
>>> Why wouldn't sharp objects be less likely to penetrate tough
>>> materials like tires if the resistance is lowered to 60-90 psi
>>> instead of 90-120 psi?
>> As I mentioned above. For this scenario to succeed, the tire would
>> need enough flexibility to allow a dimple several mm in diameter to
>> be supported on a thorn or sharp (knife like) object not more than
>> 2mm in length. Tires are not that flexible. Try that manually and
>> you'll see that even at 30psi there is enough pressure to puncture
>> through to the air chamber.
>>> There is, after all, a lower limit of pressure below which the
>>> sharp object will not penetrate the tire.
>> Describe that for an average tire. Just try that with any of yours.
> [snip]
> Okay, let's try it with an average tire, one of mine.
> Here's about 4mm of small nail sticking up in a vise, with its twin
> brother lying beside it and spoke ruler. The nail point,
> considerably enlarged, appears to be less than half a millimeter
> wide:
> Here's a 700c x 26 tire inflated to 30 psi and about to test your
> theory, again considerably enlarged:
> And here's the result:
> As you can see, the tire is holding pressure, having flattened out
> and tented over the nail point quite flexibly--no puncture, not even
> a mark on the tread.
Now try that with a goathead or a sharp sliver of glass. Dull nails
don't do much for the experiment at hand.
> Experience suggests that this is not the result of running over a
> small nail point at normal touring tire pressures.
A small nail doesn't stick up out of the ground a few millimeters, it
gets flipped up by the front tire and pierces the back tire. Even a
thumbtack should do for this experiment but we're taking cherts and
thorns as I recall.
> Obviously, the sharper the object, the lower the crucial pressure.
> And equally obviously, the lower the pressure, the less the
> likelihood of a puncture.
> Feel free to do more testing on your own to confirm this.
> But you can save time by pondering how Indian fakirs lie on beds of
> nails.
> I hear it has something to do with keeping the pressure below the
> crucial level by spreading out the body weight over enough nails,
> which allows the skin to tent and dimple over the the nail points
> instead of puncturing (like certain theories).
The effect applies here where we have only one (almost) sharp object.
Jobst Brandt
wafflycat
<carl...@comcast.net> wrote in message
news:1161892033.0...@h48g2000cwc.googlegroups.com...
> 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."
>
Then he hasn't cycled in Norfolk (UK) during or after the rain when many a
sharp flint (or whatever you want to call them) is washed off the fields on
to the roads. Indeed they do get imbedded not only in cycle tyres but also
in car tyres. I've picked several out of bicycle tyres and car tyres. OTOH,
perhaps it's Jobst who is a figment of the imagination ;-)
Mike Jacoubowsky
> when it was just one group rec.bicycle, and i was describing that type
> of puncture. As you say, it was at a time when steel belted tires
> were primarily Michelin, the tire that was developed primarily as a
> rubber tired railway wheel before its other benefits were accepted by
> the auto industry. The Paris metro still runs pneumatic rubber tires.
There's an implication here that runs counter to the truth. The Paris Metro
originally was entirely steel wheels on steel rails, but a number of lines
were converted starting in 1951. The last line built, #14, was rubber-tired
from the start. For reference,
http://www.ina.fr/voir_revoir/metro/techno.en.html &
http://en.wikipedia.org/wiki/Rubber-tired_metro.
So it's a bit odd to say that the Paris Metro "still" runs pneumatic rubber
tires. It has seen a conversion from steel on steel to pneumatic rubber on
concrete over the years. It has not seen any moves in the other direction.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
<jobst....@stanfordalumni.org> wrote in message
news:4541640e$0$34491$742e...@news.sonic.net...
carl...@comcast.net
Dear Jobst,
Wanna bet against this prediction of the theory that higher pressures
will cause sharp objects to eventually penetrate tires?
If I keep increasing the pressure and the nail height, the nail will
be sharp enough to puncture the tire?
If so, wouldn't the sharp object fail to pentrate at 80% of the lowest
penetration pressure--you know, that 20% reduction figure that you
threw out in order to dismiss it because it disagrees with you.
Or do you want to insist that the testing be done with the sharp
flints, the ones that you originally insisted didn't puncture tires,
but now are arguing will puncture tires just as easily when tire
pressure is reduced 20%?
Apart from vague claims that UK riders are simply fooling themselves
about getting flats from flints, that is where you've ended up, isn't
it?
Let me know if you want me to increase the tire pressure and nail
height until it punctures the tire.
Cheers,
Carl Fogel
Smokey
carl...@comcast.net 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."
>
>
> 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
I live on a gravel road here in central MO and 30+ years ago, before
the advent of steel belted radials (at least around here), flint rock
flats were a big problem for car tires. We would probably average at
least 2-3 per summer, sometimes more. Our mailman, who drove on gravel
all the time, said he would get a least a dozen in that period of
time. Nowadays tires are better and the flint rock flat seems to be a
thing of the past.
Smokey
Tony Raven
>
> Yes, my impression is that flats from what the UK crowd and the Danes
> call flints are so common that they'll be amused by this thread.
>
As one of the UK crowd, they are not that common. I have never suffered
on despite riding on flinty trails although a quick Google.co.uk will
show some people have. My punctures have all been thorns, glass,
various bits of metal and pieces of wood.
Flints tend to be rather large stones with smooth outsides that only
have sharp edges if freshly knapped. Small flint shards tend to be
rather fragile and break very easily.
--
Tony
"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
carl...@comcast.net
wrote:
Dear Smokey,
For the benefit of UK readers (and those colonials who confuse the
two-letter US state and possessions postal codes for Maine (ME), the
Marshall Islands (MH), Maryland (MD), Massachusetts (MA), Minnesota
MN), Mississippi (MS), Missouri (MO), and Montana (MT), "MO" means
Missouri, the birthplace of Mark Twain.
So at least one citizen of the Show-Me state has been shown flat tires
from rock chips.
Sorry for the dreadful manners attributed to Colorado miners:
http://www.sos.mo.gov/archives/history/slogan.asp
A quick calculation shows that my grandfather, born in Ohio in 1889
and then moved as an infant to Leadville, was a bit too young to have
been in the mines at the time--whew!
Cheers,
Carl Fogel
Dave Larrington
> 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.)
I think about half the people who rode the Rural South 300 in 2005 would
venture to disagree. Indeed, most people who do Audax rides in southern
England probably would - 'twas here that a certain model of Continental tyre
acquired the name "Ultra Hamsterskins". With but one exception - that being
a rogue self-tapping screw - I think every rural visit from the P+nct+r+
Fairy in recent memory has been caused by a Very Small Rock. In town, her
Weapon of Choice is glass.
Cue Dave Kahn...
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Hoc ardur vincere docet.
carl...@comcast.net
wrote:
>carl...@comcast.net wrote on 27/10/2006 03:24 +0100:
>>
>> Yes, my impression is that flats from what the UK crowd and the Danes
>> call flints are so common that they'll be amused by this thread.
>>
>
>As one of the UK crowd, they are not that common. I have never suffered
>on despite riding on flinty trails although a quick Google.co.uk will
>show some people have. My punctures have all been thorns, glass,
>various bits of metal and pieces of wood.
>
>Flints tend to be rather large stones with smooth outsides that only
>have sharp edges if freshly knapped. Small flint shards tend to be
>rather fragile and break very easily.
Dear Tony,
Forgive a foreigner's curiosity . . .
My earlier peek in the uk.rec.cycling archives showed a number of
posts mentioning flint flats.
Those posts and the ones in this thread give me the impression that
flint flats occur mostly on paved roads, with Denmark being oddly
prominent in the matter, while you're talking about flinty trails.
Are your flinty trails off-road, unpaved trails through the rocky
countryside, as opposed to paved bicycle paths (or whatever they're
called in the UK) next to roads?
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.)
Curiously, the wretched goathead thorn is mostly a pavement problem in
Colorado, growing almost exclusively in the scraped ground next to
paved roads and bicycle paths.
Dogs on leashes stop and hold their impaled paws up when walked on the
roads around here, but I've never had to pluck thorns out of the paws
of the same dogs when they're running loose in the countryside, away
from the roads.
To return to the UK side of things, could flint-flats be worse in some
parts of the UK? I confess that I have no notion of the geography, but
posters have mentioned flint-flats in Grimes Graves, Lincolshire,
Reading, and Norfolk, while one poster spoke of thousands of miles "on
limestone" (?) without flats. One Berkshire poster suffered flint
flats, while another who had flint-flats elsewhere was flat-free in
Berkshire.
I expect that any thoughts that you have on the matter would be
interesting to the US posters, partly because it's all strange to us
and partly because you can hardly be accused of jumping on the
bandwagon.
Cheers,
Carl Fogel
Michael Press
<1161904014....@e3g2000cwe.googlegroups.com>,
"Simon Proven" <spr...@gmail.com> wrote:
> Tim McNamara wrote:
> > I've found small stones imbedded in cuts in the tire tread. The vast
> > majority were just noticed and removed, and were not associated with
> > flats. I can't unequivocally recall ever having had a flat that was
> > definitely caused by a small sharp piece of rick (a.k.a., a "flint").
> > But then I wouldn't take an oath on pain of death that it had never
> > happened. I just don't remember ever having it happen for sure. If it
> > has, it's been a very very small percentage of the flat tires I have had
> > in the past 40 years.
>
> I tend to find lots of small stones in the tyre tread; when I'm out on
> a group
> and someone's got a puncture I amuse myself by picking them out their
> tread (as well as the one that cause the puncture) while they repair
> the
> tube. I find 2-3 embedded when I do that, typically. They're not
> flints,
> IME because they're too light in colour, and are probably cherts.
Flint and chert are the same except for colour.
"Chert and flint are finely crystallized varieties of
gray to black quartz that occur as nodules or bands in
sedimentary rocks.
A cryptocrystal is a rock whose texture is so finely
crystalline that is, made up of such minute crystals
that its crystalline nature is only vaguely revealed
even in a thin section by transmitted polarized light.
Among the sedimentary rocks, chert and flint are
cryptocrystalline."
The point is that chert (flint) fractures more like
glass than most minerals. The microcrystalline
structure imposes no constraints on the angle of two
fracture planes nor upon the sharpness of the edge
itself.
Chert is technically a sedimentary rock. It forms when
minerals in buried sediment dissolve and then
precipitate out again as tiny crystals.
--
Michael Press
carl...@comcast.net
Dear Dave L.,
An Audax ride in southern England is . . . ?
And just in case Dave K. misses his cue, is he famed for suffering or
avoiding flint-fl--
Er, naming calls, if memory serves.
--suffering or avoiding flint-fl+ts?
Cheers,
Carl Fogel
Peter Clinch
> My earlier peek in the uk.rec.cycling archives showed a number of
> posts mentioning flint flats.
>
> Those posts and the ones in this thread give me the impression that
> flint flats occur mostly on paved roads, with Denmark being oddly
> prominent in the matter, while you're talking about flinty trails.
>
> Are your flinty trails off-road, unpaved trails through the rocky
> countryside, as opposed to paved bicycle paths (or whatever they're
> called in the UK) next to roads?
Flint/chert is a natural glass that tends to crop up most in chalk rocks
and derived soils. Chalks are not used for roadstone, metamorphics
being much more common for that. In fact Britain's biggest quarry is in
Leicestershire (a little to the right of ventral England) because
there's very little suitable road stone in the south east, which happens
to be where a lot of the flint/chert is found.
In the Downs, which are chalk hills in the SE, it wouldn't be
particularly uncommon for an off-road trail to have flint/chert on it,
because there's lots in the local geology. But you won't get them in
formally hard surfaced roads and tracks AFAICT.
> 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.)
As above, not in the UK, where you won't flint in the road stone.
> To return to the UK side of things, could flint-flats be worse in some
> parts of the UK?
Certainly: the Downs have plenty of flint and plenty of off-road trails,
for example.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.c...@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
wafflycat
<carl...@comcast.net> wrote in message
news:7je3k2tsb58aatn31...@4ax.com...
>
> 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. 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.
Alan Braggins
>On 26 Oct 2006 12:47:13 -0700, carl...@comcast.net 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
>
>May the gods of perversity visit him for that one. The mere fact that
>it has not happened to him is not proof that it does not occur.
>>Any pictures of flints in tires and tubes would be interesting, even
>>though they must be obvious fakes.
>
>I suspect that it's just such a matter-of-course occurrence in such
>areas that they don't bother taking pictures. To them, I'm sure that
>it would be like making photo documentation of dryer lint; why bother?
Certainly it's never occured to me to take photos of small sharp rocks
embedded in my tyres, bike or car. Nor to worry about their exact nature
chert, flint or other. And if Jobst is so full of himself that he's going
to declare any evidence that contradicts him an obvious fake in advance
there seems little point in bothering next time I see one.
Michael Press
<hfd3k2lcgirs96aef...@4ax.com>,
carl...@comcast.net wrote:
> For the benefit of UK readers (and those colonials who confuse the
> two-letter US state and possessions postal codes for Maine (ME), the
> Marshall Islands (MH), Maryland (MD), Massachusetts (MA), Minnesota
> MN), Mississippi (MS), Missouri (MO), and Montana (MT), "MO" means
> Missouri, the birthplace of Mark Twain.
Any omission or omissions?
--
Michael Press
Tony Raven
Dear Carl
Let me start by returning your earlier comprehension condescension
toward your Rightpondian bretheren by pointing out that over here a
pavement is what you walk on and a road is what you cycle and drive on
(the notorious pavement cyclist excepted)
I am sure there are examples around of flints puncturing tyres (that's
tires for your benefit Carl) but I've not had the problem despite
cycling on and off road in the regions where I live which have lots of
flints. I've had punctures from some unusual objects including several
times from splinters of wood broken off rotting tree trunks and the ends
of small broken off branches. In the ten years plus I've been on
uk.rec.cycling and other uk cycling groups, I can recall lots of
discussions about punctures but none about your specific topic of flints
as a cause of punctures. So its not exactly at the forefront of every
UK cyclist's thinking, which is what you seem to imply. I must leave
the Danes to speak for themselves but I've not had a flint puncture
cycling on and off road in Denmark either.
Helen of this parish notes that flints embedded in tyres are common in
her locality but strange things happen in Norfolk because local lady
cyclists dance nekkid round their willow trees uttering incantations -
and because it's Norfolk.
Have a nice day
Dave Larrington
> An Audax ride in southern England is . . . ?
A brevet organised under the auspices of Audax UK:
<URL:http://www.audax.uk.net/>
Draw a line on a map of the BRITONS' England from the Bristol Channel in the
south-west to The Wash in the north-east. Most areas to the south-east of
this line will have more than their fair share of flints and similar strewn
about the place by She Who Must Not Be Named.
> And just in case Dave K. misses his cue, is he famed for suffering or
> avoiding flint-fl--
>
> Er, naming calls, if memory serves.
>
> --suffering or avoiding flint-fl+ts?
Suffering from just about every kind of flat, from flints to catastrophic
rim failure...
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
External Transparent Wall Inspection Operative.
Mark Thompson
The only way you can stop the p*ncture fairy now is to sacrifice an inner
tube and smear patches of vulcanising solution to the sides and top of your
front door frame.
wafflycat
"Tony Raven" <ju...@raven-family.com> wrote in message
news:4qe0e6F...@individual.net...
>
> Helen of this parish notes that flints embedded in tyres are common in her
> locality but strange things happen in Norfolk because local lady cyclists
> dance nekkid round their willow trees uttering incantations - and because
> it's Norfolk.
>
> Have a nice day
Didn't use the word 'common' but it does indeed happen. Husband, son & I
have had such punctures happen, but judicious choice of tyre and keeping
tyres well inflated seems to keep punctures down to a manageable level. Last
three punctures when I've been on bike happened within half-an-hour of each
other and were due to broken glass on a dreaded psychlepath farcilitiy in
King's Lynn. The puncture before that was some considerable time ago and was
indeed a shard of flint stuck into the tyre. But I usually go long periods
between punctures: except on dreaded psychlefarcilities. Which is another
reason to keep off farcilities and on the road. The last time the offspring
punctured was flint shard. Just up the road from us is a gravel quarry. At
the entrance to the quarry they have a couple of seriously impressive flint
boulders on display. I have picked out many a flint shard from a tyre or
three where no puncture has been caused - but if left in the tyre, they'd
have possibly worked their way through to the inner tube.
Turning a bit chilly for nekkidniss round the willow tree in the garden
tho-but. ;-)
Derk
> 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 have flats caused by a very small piece of flint at least once a year.
Flint only seems to pierce the Conti tire after a few thousand miles, when
it gets softer and ruptures more easily than when it's new.
Gr, Derk
Dave Larrington
> I think those bikes have about 16K miles and 5 punctures, so about
> 3.2K miles per puncture. The tourer with the TT2000 tyres seems to
> be the best, the audax bike's not done enough miles yet to know.
Though it /did/ come perilously close to suffering one at the lunch break on
the Golden Tints 200 the other week, when Simon mentioned this fact as I was
mending my second small-rock induced p+nct+r+ of the day...
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Badger Badger Badger Badger Badger Badger Badger Badger Badger
Badger Badger Badger Badger Badger Badger Badger Badger Badger
Badger Badger
Mike Jones
> carl...@comcast.net wrote:
>
>> An Audax ride in southern England is . . . ?
>
> A brevet organised under the auspices of Audax UK:
>
> <URL:http://www.audax.uk.net/>
>
> Draw a line on a map of the BRITONS' England from the Bristol Channel in the
erm the Britons call that part Lloegr.
> south-west to The Wash in the north-east. Most areas to the south-east of
> this line will have more than their fair share of flints and similar strewn
> about the place by She Who Must Not Be Named.
http://www.soton.ac.uk/~imw/jpg/ukmap8.jpg
for all your Great Britain geological needs (i.e British Isles with
Ireland left out; probably for political reasons [OK, and Shetland])
Those measures with the names Limestone, or Oolite are potentially flint
bearing, as they were deposited when the land was under water (Or are
you left-pondians still having trouble with Bible v. Science?)
http://geology.about.com/library/bl/maps/n_map_usa48geo.htm
is pretty, but there's no indication of what the colours represent!
But what's wrong with shale eh?
Simon Bennett
> http://www.soton.ac.uk/~imw/jpg/ukmap8.jpg
Why is Cromer singled out for special attantion? Other than London, it seems
to be the only settlement mentioned.
Tony Raven
>
> Didn't use the word 'common' but it does indeed happen.
Are you sure its not paving slab shrapnel?
> Just
> up the road from us is a gravel quarry. At the entrance to the quarry
> they have a couple of seriously impressive flint boulders on display. I
> have picked out many a flint shard from a tyre or three where no
> puncture has been caused - but if left in the tyre, they'd have possibly
> worked their way through to the inner tube.
>
Ah, a fleet of local flint scatters leaving said quarry would explain
your predicament
> Turning a bit chilly for nekkidniss round the willow tree in the garden
> tho-but. ;-)
>
Nearly time though to burn some guy on top of a bonfire to keep you warm
while you dance.
Tony Raven
>
> Suffering from just about every kind of flat, from flints to catastrophic
> rim failure...
>
Indeed I believe he bravely but unknowingly has volunteered to have
everyone else's punctures for them so we can all ride virtually puncture
free
Mike Jones
Dave Larrington
> Dave Larrington wrote on 27/10/2006 10:50 +0100:
>>
>> Suffering from just about every kind of flat, from flints to
>> catastrophic rim failure...
>>
>
> Indeed I believe he bravely but unknowingly has volunteered to have
> everyone else's punctures for them
Except mine.
Bah!
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Give the anarchist a cigarette.
Pete Biggs
> As one of the UK crowd, they are not that common. I have never
> suffered on despite riding on flinty trails although a quick
> Google.co.uk will show some people have. My punctures have all been
> thorns, glass, various bits of metal and pieces of wood.
>
> Flints tend to be rather large stones with smooth outsides that only
> have sharp edges if freshly knapped. Small flint shards tend to be
> rather fragile and break very easily.
I agree they're not common, at least where I cycle most: within 30 mile
radius from north London, mostly on-road. I can remember only one puncture
that was clearly from a flint shard. Both in and out of town, the large
majority of my punctures have been caused by glass, with the occasional
thorn, nail or piece of wire.
~PB
Tim McNamara
carl...@comcast.net wrote:
> Okay, let's try it with an average tire, one of mine.
Do you routinely find it a good thing to ride around on 700 x 26 tires
inflated to 30 psi? This is another one of your absurd, orthogonal red
herrings. The discussion would be furthered by sticking to normal
operating conditions instead of being hindered by your tendency for
whittering on about strange special cases that provide little
information that can be generalized to normal use.
* * Chas
"Mark Thompson"
<pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com> wrote in
message news:Xns9869704862426pl...@130.133.1.4...
In Southwestern US, doors and window frames were/are traditionally
painted turquoise or blue to ward off EEVIILE sprits like goatheads. If
you look at a goathead it's actually the face of the DEVIL!
Put your hand on the radio!
Chas.
Retro Grouch
* * Chas
> Curiously, the wretched goathead thorn is mostly a pavement problem in
> Colorado, growing almost exclusively in the scraped ground next to
> paved roads and bicycle paths.
>
> Dogs on leashes stop and hold their impaled paws up when walked on the
> roads around here, but I've never had to pluck thorns out of the paws
> of the same dogs when they're running loose in the countryside, away
> from the roads.
>
> Carl Fogel
...New Mexico, Arizona, West Texas and Northern Mexico too! They grow in
lawns as well as along side the roads. The I-25 corridor seems to be a
major route in spreading these pests.
Chas.
* * Chas
I'll drink to that. Here a little missive from a friend in the UK:
"In response to your series of dialectical discussions, may I present a
few samples from around the UK. These all say approximately the same
thing and may lend some insight into British regional characteristics
as well.
GEORDIE: "Why, aye. Shall wa gan doon toon fer a cuppla bevies, then?"
BRUMMIE: "Duh yow wont ter coom owt fer a pint er two?"
YORKSHIRE: "Ist'a coming downt' poob, lad? Tha's payin'."
WEST COUNTRY YOKEL: "Be thee be comin' down ter zup a few?"
COCKNEY: "'Ahs abaht cummin' dahn the ol' rub-a-dub an' sinkin' a
couple?"
SLOAN: "Pimms, anyone?"
GLASGOW: "Ah'm gonnae go an' git rat-arsed. Are yez comin'?"
(later on, it's more likely to be: "Are yez lookin' a' me? Ah'll come
doon there an' gi' yez a smack roond the heed!")
WALES: "Ah, boyo, do you fancy a pint? Oh, bugger, it's Sunday - they're
shut."
Chas.
Tony Raven
>
<snip attempt at regional accents>
UR a Hollywood scriptwriter and I claim my five pounds.
* * Chas
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).
Chas.
Michael Press
Peter Clinch <p.j.c...@dundee.ac.uk> wrote:
> Flint/chert is a natural glass that tends to crop up most in chalk rocks
> and derived soils. Chalks are not used for roadstone, metamorphics
> being much more common for that. In fact Britain's biggest quarry is in
> Leicestershire (a little to the right of ventral England) because
> there's very little suitable road stone in the south east, which happens
> to be where a lot of the flint/chert is found.
Flint/chert is not glass. Glass is vitreous. Glass is
not crystalline. Glass is formed from a molten flow.
Flint/chert is micro-crystalline silica. Flint/chert
does not form from a molten flow. It appears to have
more than one path to formation. One path is the
amalgamation of diatom skeletons, themselves made from
silica. Another path is solution and precipitation of
silica in under-sea limestone formations.
The gross mechanical properties of flint/chert arise
from its micro-crystalline structure. It can fracture
at small angles at the fracture planes, with a smooth
fracture plane, and with a thin edge because there is
no large crystal structure to prevent it. The edges are
sharp because silica is hard.
--
Michael Press
Tony Raven
>
> Helen of this parish notes that flints embedded in tyres are common in
> her locality but strange things happen in Norfolk because local lady
> cyclists dance nekkid round their willow trees uttering incantations -
> and because it's Norfolk.
>
I told you they were strange in Norfolk
http://news.bbc.co.uk/1/hi/england/norfolk/6091832.stm
But at least semolina won't puncture your tyres.
Danny Colyer
> My punctures have all been thorns, glass,
> various bits of metal and pieces of wood.
I've just remembered my puncture log. It lists details of my last 74
punctures (I've been keeping it since March 2003).
14 were caused by thorns, 24 by glass, 2 by stones (possibly flints,
possibly not) and one by an object that I found but wasn't able to
identify. The others were caused by objects that were no longer in the
tyre by the time I stopped.
--
Danny Colyer <URL:http://www.colyer.plus.com/danny/>
"He who dares not offend cannot be honest." - Thomas Paine
Simon Proven
I did that. Can't open the door now.
Simon Proven
I did that. Can't open the door now.
Michael Press
<tvWdnW9JALmApN_Y...@comcast.com>,
"* * Chas" <verkt...@aol.spamski.com> wrote:
> "Tony Raven" <ju...@raven-family.com> wrote in message
> news:4qe0e6F...@individual.net...
> > carl...@comcast.net wrote on 27/10/2006 09:19 +0100:
[...]
> I'll drink to that. Here a little missive from a friend in the UK:
>
> "In response to your series of dialectical discussions, may I present a
> few samples from around the UK. These all say approximately the same
> thing and may lend some insight into British regional characteristics
> as well.
[...]
Reminds me of some dialogue form one of John Mortimer's
stories. Rumpole is interviewing trooper Boyne, who is
accused of murder, in the company of Boyne's solicitor.
Rumpole: It says here that you were overheard saying to
the deceased "Ah'm goonnae cut ya."
Solicitor: That is a manner of speaking. Trooper Boynes
is from Glasgow.
Rumpole: Oh, is that to be our defense?
--
Michael Press
Michael Press
Bart Bailey <m...@privacy.net> wrote:
> In Message-ID:<jack-BF55E0.0...@newsclstr02.news.prodigy.com>
> posted on Fri, 27 Oct 2006 08:59:58 GMT, Michael Press wrote: Begin
> >In article
> ><hfd3k2lcgirs96aef...@4ax.com>,
> > carl...@comcast.net wrote:
> >
> >> For the benefit of UK readers (and those colonials who confuse the
> >> two-letter US state and possessions postal codes for Maine (ME), the
> >> Marshall Islands (MH), Maryland (MD), Massachusetts (MA), Minnesota
> >> MN), Mississippi (MS), Missouri (MO), and Montana (MT), "MO" means
> >> Missouri, the birthplace of Mark Twain.
> >
> >Any omission or omissions?
>
> (CA) California, where there are probably more cyclists than all those
> other places combined.
Michigan (MI).
--
Michael Press
Tony Raven
That's how the punctures are stopped ;-)
Ian Smith
> carl...@comcast.net wrote on 27/10/2006 03:24 +0100:
> >
> > Yes, my impression is that flats from what the UK crowd and the Danes
> > call flints are so common that they'll be amused by this thread.
>
> As one of the UK crowd, they are not that common. I have never suffered
> on despite riding on flinty trails although a quick Google.co.uk will
Mine are mostly glass, followed by thorns. However, it's hard to tell
a small shard of glass from a small shard of flint.
My most inconvenient puncture was definitely flint - a flat, viciously
sharp flake about the size of my thumbnail, which sliced the tyre
sidewall and innertube with a big enough hole that I didn't have a
patch suitable. I had to walk home.
> Flints tend to be rather large stones with smooth outsides that only
> have sharp edges if freshly knapped. Small flint shards tend to be
> rather fragile and break very easily.
You get shards on flinty ground tracks which have a lot of horse
traffic. I think the horse-shoes fracture the flints. This sort of
surface is also horrific if you fall off - it takes lots of skin and
bits of flesh of you very easily (I have the scars on one shoulder).
regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|
Ian Smith
On Fri, 27 Oct 2006, Danny Colyer <danny_...@hotmail.com> wrote:
> Tony Raven wrote:
> > My punctures have all been thorns, glass,
> > various bits of metal and pieces of wood.
>
> I've just remembered my puncture log. It lists details of my last 74
> punctures (I've been keeping it since March 2003).
Wow. My puncture log since the start of 2003 would be, errm, five.
Three in the front left, two in the rear wheel. Both the rears
were within the last month, which I interpret as an indication that
the tyre has worn sufficiently that it needs replacement.
None in bikes. None in unicycles. (But I do probably 50 times as much
mileage on the trice than either bikes or unicycle.)
The most recent puncture was a thorn, the previous was glass. One of
the others was glass (I remember because it was quite a big bit and
was a pain to extract from the tyre). I don't recall what the others
were.
Mike Jones
>
> WALES: "Ah, boyo, do you fancy a pint? Oh, bugger, it's Sunday - they're
> shut."
>
>
Pubs in Wales, as in England are now open .. well whatever the local
licensing law is, but *could* (in theory) be all day.
The last referendum on Sunday drinking had Dwyfor vote for boozin' in
1989 after more than a century:
http://www.heretication.info/_enjoyment.html
refers if you aren't invited down the pub.
Mind you *shopping* on the Sabbath is limited to 8 hours at the most!
(again both E&W, dunno 'bout Scotland).
Mike Jones
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.
Don Whybrow
>
> 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.
Don Whybrow
>
> I told you they were strange in Norfolk
> http://news.bbc.co.uk/1/hi/england/norfolk/6091832.stm
>
> But at least semolina won't puncture your tyres.
It would be a bugger to ride through though.
--
Don Whybrow
Sequi Bonum Non Time
"To communicate with Mars, converse with spirits, To report the
behaviour of the sea monster, Describe the horoscope, haruspicate or
scry, Observe disease in signatures." (T.S.Eliot)
carl...@comcast.net
Dear Tim,
Er, you're "whittering."
Jobst is the one who specified 30 psi, not me. Look at the posts that
you snipped.
So please blame Jobst for the absurd, orthogonal red herrings
concerning 30 psi, not me.
Then please see the post that I'm about to make in this thread about
that nail, which fails to puncture that tire at 100 psi, but punctures
it at 110 psi--without puncturing the inner tube.
Cheers,
Carl Fogel
Tony Raven
>
> 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.
* * Chas
"Don Whybrow" <d...@fwhybrow.wanadoo.co.uk> wrote in message
news:4qf46rF...@individual.net...
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".
Chas.
carl...@comcast.net
>Dave Larrington wrote:
>> carl...@comcast.net wrote:
>>
>>> An Audax ride in southern England is . . . ?
>>
>> A brevet organised under the auspices of Audax UK:
>>
>> <URL:http://www.audax.uk.net/>
>>
>It's some kind of endurance test for the lycra-clad.
>
>> Draw a line on a map of the BRITONS' England from the Bristol Channel in the
>erm the Britons call that part Lloegr.
>
>> south-west to The Wash in the north-east. Most areas to the south-east of
>> this line will have more than their fair share of flints and similar strewn
>> about the place by She Who Must Not Be Named.
>
>
>
>http://www.soton.ac.uk/~imw/jpg/ukmap8.jpg
>for all your Great Britain geological needs (i.e British Isles with
>Ireland left out; probably for political reasons [OK, and Shetland])
>
>Those measures with the names Limestone, or Oolite are potentially flint
>bearing, as they were deposited when the land was under water (Or are
>you left-pondians still having trouble with Bible v. Science?)
>
>
>http://geology.about.com/library/bl/maps/n_map_usa48geo.htm
>is pretty, but there's no indication of what the colours represent!
>
>But what's wrong with shale eh?
Dear Mike and Dave,
Thanks, Mike's geological map shows Dave's line from the Bristol
Channel to the Wash nicely:
http://www.soton.ac.uk/~imw/jpg/ukmap8.jpg
Cheers,
Carl Fogel
* * Chas
> Tony Raven wrote on 27/10/2006 10:05 +0100:
> >
> > Helen of this parish notes that flints embedded in tyres are common
in
> > her locality but strange things happen in Norfolk because local lady
> > cyclists dance nekkid round their willow trees uttering
incantations -
> > and because it's Norfolk.
> >
>
> I told you they were strange in Norfolk
> http://news.bbc.co.uk/1/hi/england/norfolk/6091832.stm
>
> But at least semolina won't puncture your tyres.
>
> --
> Tony
But what of semolina pilchard.....
Chas.
carl...@comcast.net
>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_tube.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
Don Whybrow
> "Don Whybrow" <d...@fwhybrow.wanadoo.co.uk> wrote in message
> news:4qf46rF...@individual.net...
>
>>
>
> 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.
>>
>
> 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".
Ah! That is that theory down the drain then, it is the same stuff.
--
Don Whybrow
Sequi Bonum Non Time
The media finally figured out that their "paying customers" (i.e.
advertisers) don't WANT an intelligent, thoughtful audience. And they
no longer have one." (Rich Tietjens)
Don Whybrow
>
> Mind you *shopping* on the Sabbath is limited to 8 hours at the most!
> (again both E&W, dunno 'bout Scotland).
If you are in an area dominated by the Wee Free [1] you could find all
sorts of curtailments. Particularly in the Outer Hebrides.
[1] http://en.wikipedia.org/wiki/Free_Church_of_Scotland
--
Don Whybrow
Sequi Bonum Non Time
Question _your own_ authority.
* * Chas
> * * 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
>
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
>
> 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
* * Chas
<carl...@comcast.net> wrote in message
news:uho4k2hkv8ijh43bm...@4ax.com...
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
> > 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
jobst....@stanfordalumni.org
>> 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
>
> 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.
jobst....@stanfordalumni.org
>>> 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
John Forrest Tomlinson
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
Mike Jones <ad...@127.0.0.1> 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.
Johnny Sunset aka Tom Sherman
Fred wrote:
> In our area they like to use chip seal on the roads. That's a layer
> of tar covered in fine crushed stone....
Tar, not asphalt!?
Earl Bollinger
news:1161892033.0...@h48g2000cwc.googlegroups.com...
> 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.
carl...@comcast.net
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
<Bqednfe6t6CI_d_Y...@comcast.com>,
Have not been made from flint for a long time. Some
kind of pyrophoric metal. Reportedly iron and cerium.
--
Michael Press
Dennis P. Harris
Chas" <verkt...@aol.spamski.com> wrote:
> These all say approximately the same
> thing and may lend some insight into British regional characteristics
> as well.
ABERDEEN:
"Ach, lad, that's grand, ye should buy me a wee dram to
celebrate!"
carl...@comcast.net
>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
Ben C
[snip]
> 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.
Surely the main reason is the much thicker casings and treads of car
tyres?
A car tyre with a radius of 92mm has a casing tension at 30psi of about
four times that of a 10mm radius bicycle tyre at 60psi.
There's masses of steel wire in there. And then they have a thick tread
with deep rainwater grooves (about 4mm deep on newish tyres) because
cars are so dangerous and therefore need so much grip.
I'm interested by this theory that you get fewer punctures with softer
tyres. The "umbrella" theory makes sense, but on the other hand, the
harder tyre has a smaller contact patch, so you have a higher chance of
missing the flint/goathead/fairy in the first place.
It also seems that you're quite likely to pick up the shard after
"tenting over it", for it to work its way in later.
* * Chas
<jobst....@stanfordalumni.org> wrote in message
news:45427b2d$0$34556$742e...@news.sonic.net...
Chas who? writes:
> http://www.pacificcoastbrewing.com/
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
>
> 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