snake bit tube?

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

If you've had it happen a couple of times, you know.

First part: Loaded wheel encounters obstacle at speed, deforming the
tire sufficiently that the tread/tube/tube/sidewall sandwich is
pressed against the rim flange hard enough to squeeze the tube layers
to the bursting point.

Second part: Tire rebounds, possibly with tube temporarily adhered to
the inside of the tire.

Third part: Now-punctured tube leaks down quickly from radially
aligned pair of holes. (This can happen immediately or it can occur a
short distance farther along if the adhesion mentioned occurs.)

Fourth part: Rider employs invective of choice and seeks dismount
point.

--
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duhduhduhduh????? the duhduh first puncture happens on impact
and duhduhd second on rebound as tube tears away from first puncture
occurence in time AND space

In article <[email hidden]>,

Werehatrack said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

If you've had it happen a couple of times, you know.

First part: Loaded wheel encounters obstacle at speed, deforming the
tire sufficiently that the tread/tube/tube/sidewall sandwich is
pressed against the rim flange hard enough to squeeze the tube layers
to the bursting point.

Second part: Tire rebounds, possibly with tube temporarily adhered to
the inside of the tire.

Third part: Now-punctured tube leaks down quickly from radially
aligned pair of holes. (This can happen immediately or it can occur a
short distance farther along if the adhesion mentioned occurs.)

Fourth part: Rider employs invective of choice and seeks dismount
point.

Fifth part: Rider patches one of the two hole, mounts the
tube&tire, and attempts to pump the tire.

Sixth part: Rider explores new frontiers of invective.

--
Michael Press

Michael Press said:

In article <[email hidden]>,

Werehatrack said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

If you've had it happen a couple of times, you know.

First part: Loaded wheel encounters obstacle at speed, deforming the
tire sufficiently that the tread/tube/tube/sidewall sandwich is
pressed against the rim flange hard enough to squeeze the tube layers
to the bursting point.

Second part: Tire rebounds, possibly with tube temporarily adhered to
the inside of the tire.

Third part: Now-punctured tube leaks down quickly from radially
aligned pair of holes. (This can happen immediately or it can occur a
short distance farther along if the adhesion mentioned occurs.)

Fourth part: Rider employs invective of choice and seeks dismount
point.

Fifth part: Rider patches one of the two hole, mounts the
tube&tire, and attempts to pump the tire.

Sixth part: Rider explores new frontiers of invective.

And in a significant number of instances, we can add:

Seventh part: Rider patches other hole in tube, and while hurriedly
reinstalling tire, pinches the tube with the tire lever...

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Werehatrack said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

If you've had it happen a couple of times, you know.

First part: Loaded wheel encounters obstacle at speed, deforming the
tire sufficiently that the tread/tube/tube/sidewall sandwich is
pressed against the rim flange hard enough to squeeze the tube layers
to the bursting point.

Second part: Tire rebounds, possibly with tube temporarily adhered to
the inside of the tire.

Third part: Now-punctured tube leaks down quickly from radially
aligned pair of holes. (This can happen immediately or it can occur a
short distance farther along if the adhesion mentioned occurs.)

Fourth part: Rider employs invective of choice and seeks dismount
point.

The obstacle must be higher than the tire. (>25mm for a 700x25 tire)

The obstacle must have an abrupt edge.

Compression of the tire results in an upward force and acceleration.

You must be going fast enough so that the upward acceleration does not
lift the rim above the obstacle before the rim reaches the obstacle.

"Werehatrack" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Michael Press said:

In article <[email hidden]>,

Werehatrack said:

On 12 Apr 2006 11:03:20 -0700, [email hidden] wrote:

>anyone know the mechanics of snake bite? before, after and during?

If you've had it happen a couple of times, you know.

First part: Loaded wheel encounters obstacle at speed, deforming the
tire sufficiently that the tread/tube/tube/sidewall sandwich is
pressed against the rim flange hard enough to squeeze the tube layers
to the bursting point.

Second part: Tire rebounds, possibly with tube temporarily adhered to
the inside of the tire.

Third part: Now-punctured tube leaks down quickly from radially
aligned pair of holes. (This can happen immediately or it can occur a
short distance farther along if the adhesion mentioned occurs.)

Fourth part: Rider employs invective of choice and seeks dismount
point.

Fifth part: Rider patches one of the two hole, mounts the
tube&tire, and attempts to pump the tire.

Sixth part: Rider explores new frontiers of invective.

And in a significant number of instances, we can add:

Seventh part: Rider patches other hole in tube, and while hurriedly
reinstalling tire, pinches the tube with the tire lever...

Let's also throw in 6.5 - Rider realizes he only brought one CO2 cartridge.

Hank Wirtz said:

Let's also throw in 6.5 - Rider realizes he only brought one CO2 cartridge.

Bah! I only bring one Zefal HPX, and it's always enough.

Quoted message said:

and against what?

All odds?

On Wed, 12 Apr 2006 14:10:02 -0700, Dan <[email hidden]>

Quoted message said:

Werehatrack said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

If you've had it happen a couple of times, you know.

First part: Loaded wheel encounters obstacle at speed, deforming the
tire sufficiently that the tread/tube/tube/sidewall sandwich is
pressed against the rim flange hard enough to squeeze the tube layers
to the bursting point.

Second part: Tire rebounds, possibly with tube temporarily adhered to
the inside of the tire.

Third part: Now-punctured tube leaks down quickly from radially
aligned pair of holes. (This can happen immediately or it can occur a
short distance farther along if the adhesion mentioned occurs.)

Fourth part: Rider employs invective of choice and seeks dismount
point.

The obstacle must be higher than the tire. (>25mm for a 700x25 tire)

Not always. See below.

Quoted message said:

The obstacle must have an abrupt edge.

A curb, even one with a shoulder radius of 3 inches, will do. If the
tire pressure is a bit low, the snakebit conditions can be met by
coming off the curb on to a flat paved surface. If the wheel has a
significant downward acceleration component, particularly if there's a
small rock (or some such) that compresses the tire more on one side
than the other, the conditions are distressingly easy to encounter.
Upward acceleration isn't the only way to compress the sandwich.

Quoted message said:

Compression of the tire results in an upward force and acceleration.

Or one with a horizontal vector element as well, in the case of a
curb.

Quoted message said:

You must be going fast enough so that the upward acceleration does not
lift the rim above the obstacle before the rim reaches the obstacle.

That's what the "sufficiently" was about. If the speed and/or loading
isn't sufficient to produce the described result, then the snakebite
is avoided. How fast is fast enough? How much load is enough? What
kind of obstacle is enough? These questions can be answered with an
infinite number of solutions, but the bottom line is that you'll know
you've found one when it happens.

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Mechanically, the rim is cutting the tube where the tube contacts the
edge of the rim's sidwalls. The tire is briefly flattened against the
rim by an obstacle (like a frozen squirrel). The sidewalls of the rim
are using the inside of the tire and the outer surface of the tube as a
cutting board to cut the inner surface of the tube. This is much the
same way that you can cut a pancake bite with the blunt side of your
fork.

Often, snakebite is easier to achieve because of an undetected small
puncture that has allowed the tire pressure to drop significantly. This
makes it easier for the frozen squirrel to flatten the tire against the
rim.

-Mike

Quoted message said:

but do the two holes hole at the same time or at different times

It is rare for a snakebite to produce just one hole. Both are formed
at the same time, or not at all. How could they form later?

Quoted message said:

and against what?

It's a high-pressure pinch; the component that is "softest" is the
tube, and it gets squeezed between the tire sidewall and the tire
tread.
--
Typoes are a feature, not a bug.
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On 12 Apr 2006 15:26:59 -0700, "Mike Reed" <[email hidden]>

Quoted message said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Mechanically, the rim is cutting the tube where the tube contacts the
edge of the rim's sidwalls. The tire is briefly flattened against the
rim by an obstacle (like a frozen squirrel). The sidewalls of the rim
are using the inside of the tire and the outer surface of the tube as a
cutting board to cut the inner surface of the tube. This is much the
same way that you can cut a pancake bite with the blunt side of your
fork.

Often, snakebite is easier to achieve because of an undetected small
puncture that has allowed the tire pressure to drop significantly. This
makes it easier for the frozen squirrel to flatten the tire against the
rim.

Quibble: The tire bead is still between the rim flange and the tube.
The snakebit portion of the tube is never directly in contact with the
rim.
--
Typoes are a feature, not a bug.
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Werehatrack said:

Quoted message said:

but do the two holes hole at the same time or at different times

It is rare for a snakebite to produce just one hole. Both are formed
at the same time, or not at all. How could they form later?

It happens. Many times when I used to ride urban, I'd do a jump, case it on
a curb/stair, and ride gingerly for 30 seconds or so afterwards, at which
time the tube finally fails and begins hissing.

Quoted message said:

Quoted message said:

and against what?

It's a high-pressure pinch; the component that is "softest" is the
tube, and it gets squeezed between the tire sidewall and the tire
tread.

Roots on the MTB trail: pinch-flat friendly. Sharp stairs: not your friend.

--
Phil, Squid-in-Training

Mike Reed said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Mechanically, the rim is cutting the tube where the tube contacts the
edge of the rim's sidwalls. The tire is briefly flattened against the
rim by an obstacle (like a frozen squirrel). The sidewalls of the rim
are using the inside of the tire and the outer surface of the tube as
a cutting board to cut the inner surface of the tube. This is much the
same way that you can cut a pancake bite with the blunt side of your
fork.

Often, snakebite is easier to achieve because of an undetected small
puncture that has allowed the tire pressure to drop significantly.
This makes it easier for the frozen squirrel to flatten the tire
against the rim.

-Mike

Are your roads bordered by frozen squirrels?
--
Phil, Squid-in-Training

Mike Reed said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Quoted message said:

Mechanically, the rim is cutting the tube where the tube contacts
the edge of the rim's sidewalls. The tire is briefly flattened
against the rim by an obstacle (like a frozen squirrel). The
sidewalls of the rim are using the inside of the tire and the outer
surface of the tube as a cutting board to cut the inner surface of
the tube. This is much the same way that you can cut a pancake bite
with the blunt side of your fork.

I think you have an incorrect model of the event. The tube never
touches the rim. It is pinched between the sidewall of the flattened
tire the same as it would if the air was let out of the tire when it
is standing upright. That is why a double snake bite is possible.

Quoted message said:

Often, snakebite is easier to achieve because of an undetected small
puncture that has allowed the tire pressure to drop significantly.
This makes it easier for the frozen squirrel to flatten the tire
against the rim.

Most snake bite flats occur with no prior leaks in the tube.

http://www.sheldonbrown.com/brandt/snakebites.html

To compare puncture abilities of various tubes, take cast-off ones
(too many patches) and cut flat pieces from them with shears. Lay the
test piece on a smooth flat surface and strike it with the flat face
of a hammer. You can assess how much harder a blow is required to
penetrate various tubes. The problem with this is that many tubes
that are used, are far smaller in cross section than the tire, so
these tubes are already stretched fairly thin. In that condition they
are even easier to penetrate.

Jobst Brandt

Phil Lee said:

Quoted message said:

Quoted message said:

but do the two holes hole at the same time or at different times

Quoted message said:

Quoted message said:

It is rare for a snakebite to produce just one hole. Both are
formed at the same time, or not at all. How could they form later?

Quoted message said:

It happens. Many times when I used to ride urban, I'd do a jump,
case it on a curb/stair, and ride gingerly for 30 seconds or so
afterward, at which time the tube finally fails and begins hissing.

I think you'll have to explain what you think occurs in the formation
of the hole in your scenario. I am certain that what you experienced
was that the perforated tube was stuck to the inside of the tire (that
doesn't have a hole) and gradually leaked down to a pressure that the
tube separated from the tire and began massively leaking.

As I said, I have had large slits, caused by pot holes, that held for
a hundred yards or more before leaking down. This is the advantage of
not using talcum powder. You get a chance to make a graceful stop on
a fast road descent.

Quoted message said:

Quoted message said:

Quoted message said:

and against what?

Quoted message said:

Quoted message said:

It's a high-pressure pinch; the component that is "softest" is the
tube, and it gets squeezed between the tire sidewall and the tire
tread.

Quoted message said:

Roots on the MTB trail: pinch-flat friendly. Sharp stairs: not your
friend.

Botts dots are good enough to cause snake bites and they are smooth
and broad.

Jobst Brandt

Squid-in-Training said:

Mike Reed said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Mechanically, the rim is cutting the tube where the tube contacts the
edge of the rim's sidwalls. The tire is briefly flattened against the
rim by an obstacle (like a frozen squirrel). The sidewalls of the rim
are using the inside of the tire and the outer surface of the tube as
a cutting board to cut the inner surface of the tube. This is much the
same way that you can cut a pancake bite with the blunt side of your
fork.

Often, snakebite is easier to achieve because of an undetected small
puncture that has allowed the tire pressure to drop significantly.
This makes it easier for the frozen squirrel to flatten the tire
against the rim.

-Mike

Are your roads bordered by frozen squirrels?

I'm told that this has been instituted as a cost-cutting measure in
certain localities. Here, they've been using petrified 'dilloes as
wake-up bumps on the road shoulders for decades.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Just under 50% of Eastern Diamondback Rattlesnake strikes are dry bites.

Ron

Quoted message said:

Mike Reed said:

Quoted message said:

anyone know the mechanics of snake bite? before, after and during?

Quoted message said:

Mechanically, the rim is cutting the tube where the tube contacts
the edge of the rim's sidewalls. The tire is briefly flattened
against the rim by an obstacle (like a frozen squirrel). The
sidewalls of the rim are using the inside of the tire and the outer
surface of the tube as a cutting board to cut the inner surface of
the tube. This is much the same way that you can cut a pancake bite
with the blunt side of your fork.

I think you have an incorrect model of the event. The tube never
touches the rim. It is pinched between the sidewall of the flattened
tire the same as it would if the air was let out of the tire when it
is standing upright. That is why a double snake bite is possible.

Right -- as also pointed out by werehatrack it's the sidewall of the
tire pushed up by the rim. I never thought about the double snakebite
coming from the same side of the rim, but I guess that's pretty common.
I've seen double also coming from each sidewall from my snakebites (I
can tell where they are on the tube).

Quoted message said:

Quoted message said:

Often, snakebite is easier to achieve because of an undetected small
puncture that has allowed the tire pressure to drop significantly.
This makes it easier for the frozen squirrel to flatten the tire
against the rim.

Most snake bite flats occur with no prior leaks in the tube.

http://www.sheldonbrown.com/brandt/snakebites.html

To compare puncture abilities of various tubes, take cast-off ones
(too many patches) and cut flat pieces from them with shears. Lay the
test piece on a smooth flat surface and strike it with the flat face
of a hammer. You can assess how much harder a blow is required to
penetrate various tubes. The problem with this is that many tubes
that are used, are far smaller in cross section than the tire, so
these tubes are already stretched fairly thin. In that condition they
are even easier to penetrate.

Jobst Brandt