Puncture proofing

Discussion in 'Cycling Equipment' started by Dieter Britz, May 5, 2004.

  1. Dieter Britz

    Dieter Britz Guest

    I note that I can buy a couple of kinds of plastic strip
    to put in under the tyres, guaranteed to prevent punctures.
    One type is called "Slime" (it's sort of greenish), the other
    "Nix Panne" (meaning no punctures). They look like plastic,
    but I wonder what (supposedly) makes them so strong. Anyone
    know what material they are made of? Where I live, there is
    a fair amount of flint chips on the road, and these needle
    shaped bits even get through Kevlar, so how come... ?
    --
    Dieter Britz, Kemisk Institut, Aarhus Universitet, Danmark.
     
    Tags:


  2. On Wed, 05 May 2004 09:34:14 +0200, Dieter Britz <[email protected]>
    wrote:

    >I note that I can buy a couple of kinds of plastic strip
    >to put in under the tyres, guaranteed to prevent punctures.
    >One type is called "Slime" (it's sort of greenish), the other
    >"Nix Panne" (meaning no punctures). They look like plastic,
    >but I wonder what (supposedly) makes them so strong. Anyone
    >know what material they are made of? Where I live, there is
    >a fair amount of flint chips on the road, and these needle
    >shaped bits even get through Kevlar, so how come... ?


    Dear Dieter,

    Whatever specific tough plastic is used in pliable tire liners, they
    work in two ways.

    First, the solid liners often stop broader sharp-edged debris from
    cutting through--the tire is gashed, but the plastic liner protects
    the inner tube. The liner edges typically feather out, so there's less
    protection at the edges, but the centers of some brands of liners are
    tough enough to stop sharp-edged fragments of rock, glass, and metal.
    They're even tough enough to stop some modest thorns.

    Second, the liners work just like integrated kevlar belts by making
    the tire thicker. Yes, thorns can go through kevlar threads like
    needles through steel wool. And yes, hard thorns can sometimes drive
    through plastic liners (solid material, not threads). But the extra
    thickness may still stop the thorns short of puncturing the inner
    tube--many thorns just aren't long enough to reach through alll that
    material.

    Such liners are quite popular in hot, dry areas of the U.S., where the
    goathead thorn is widespread. Here's a picture of a goathead on a 13mm
    wide dime that shows how short its wicked thorn tips are:

    http://home.comcast.net/~carlfogel/download/Goathead.jpg

    They're long enough to lance through a tire and inner tube, but the
    extra layer of a plastic liner can stop the thorn, deflect it, or
    simply prove too thick.

    Unfortunately, the tire liners add weight, increase rolling
    resistance, and complicate mounting tires.

    Carl Fogel
     
  3. Dieter Britz <[email protected]> wrote:
    [Tyre liners]
    >Where I live, there is
    >a fair amount of flint chips on the road, and these needle
    >shaped bits even get through Kevlar, so how come... ?


    Kevlar is a woven fabric, and so is easily penetrated by long thin
    objects. A tyre liner is solid. However, I suspect much of their
    effectiveness simply comes from increased thickness; an object that isn't
    long enough to be driven all through the tyre and liner will stay stuck in
    the tyre, but not reach the tube...
    --
    David Damerell <[email protected]> Distortion Field!
     
  4. gwhite

    gwhite Guest

    David Damerell <[email protected]> wrote in message news:<+ys*[email protected]>...
    > Dieter Britz <[email protected]> wrote:
    > [Tyre liners]
    > >Where I live, there is
    > >a fair amount of flint chips on the road, and these needle
    > >shaped bits even get through Kevlar, so how come... ?

    >
    > Kevlar is a woven fabric, and so is easily penetrated by long thin
    > objects. A tyre liner is solid. However, I suspect much of their
    > effectiveness simply comes from increased thickness; an object that isn't
    > long enough to be driven all through the tyre and liner will stay stuck in
    > the tyre, but not reach the tube...


    While touring across Nevada, I had a small spine go right through a
    mr. toughy. I don't use them anymore. I just accept my flats and fix
    them. They probably do help for some situations. But they are heavy
    and increase rolling resistance. I didn't care about the weight when
    touring, but I was never clear on if the higher rolling resistance was
    "worth it."
     
  5. gwhite <[email protected]> wrote:
    >David Damerell <[email protected]> wrote:
    >>Kevlar is a woven fabric, and so is easily penetrated by long thin
    >>objects. A tyre liner is solid. However, I suspect much of their
    >>effectiveness simply comes from increased thickness;

    >While touring across Nevada, I had a small spine go right through a
    >mr. toughy. I don't use them anymore.


    I never have used them. These days I flat about once every 1,000 miles,
    which I ride at an average of about 15mph (most of my riding is my
    commute, which I do quickly because that means more time in bed in the
    morning...); so I spend 67 hours riding between each flat. Fixing a flat
    takes me 15 minutes for a rear wheel with an elusive penetrator (I don't
    count the tube-fixing time because I can do that at home while watching TV
    or something), but sometimes I miss a half-hourly train or something, so
    the actual loss in time is probably more like 20 minutes. Hence if a
    puncture-proofing system was 100% effective (which they're not) I would
    still lose time if it slowed me down by 0.5%.
    --
    David Damerell <[email protected]> flcl?
     
  6. Werehatrack

    Werehatrack Guest

    On Wed, 05 May 2004 09:34:14 +0200, Dieter Britz <[email protected]>
    may have said:

    >I note that I can buy a couple of kinds of plastic strip
    >to put in under the tyres, guaranteed to prevent punctures.
    >One type is called "Slime" (it's sort of greenish), the other
    >"Nix Panne" (meaning no punctures). They look like plastic,
    >but I wonder what (supposedly) makes them so strong. Anyone
    >know what material they are made of? Where I live, there is
    >a fair amount of flint chips on the road, and these needle
    >shaped bits even get through Kevlar, so how come... ?


    As others have said, one of their ways of reducing punctures is by
    simply putting more material in the path of the object, so that more
    damage must be done before the tube is actually reached. Some of the
    liners I've seen are made from a plastic that's both stretchy and
    clingy; it seems to engulf and grab the puncturing object rather than
    allowing itself to be cut; sort of a variaion on the Zen "bend with
    the wind" theory. All liners add weight and increase the complexity
    of tire installation. I've used just one pair, and I can't really say
    that they did much, as I don't get a lot of flats in any event. An
    acquaintance used to swear by them until he took a trip to California
    and encountered the infamous goathead weeds. He quickly concluded
    that the best defense in that case was avoidance coupled with a setup
    that permitted the speediest possible patch-and-pump process, which
    made the liners somewhat less productive. He also learned that in
    goathead country, one needs shoes with thick, wide, hard-to-puncture
    soles; while patching a tube, two goatheads speared his foot right
    through the shoe next to the edge of the sole.

    --
    My email address is antispammed; pull WEEDS if replying via e-mail.
    Typoes are not a bug, they're a feature.
    Words processed in a facility that contains nuts.
     
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