My tube exploded

Ben Kaufman said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road bike with 27x1.25" tire. First time out with
the new tire. Doing laps around the park. I was about 10
miles into the ride when. I'm coming down a small hill and
I start to feel a thump in the rear wheel. I look down and
it appears there is a bulge in the side. The wheel is now
warping and rubbing the brake. I stop and just as I'm about
to get off the bike there is an explosion. It sounds like a
gunshot. The tire is off the rim. I see a straight 2" break
in the tube. All I've got is a flat kit and it's not going
to help this so I remount the tire, (the bead and walls
looked good) and walk her back. Does this sound like a
defective tube or was the tube pinched or twisted on the
install to cause this?

Ben

Dear Ben,

Since the tire was intact, the explosion occurred when the
tube snuck out between the tire and the rim. (It's hard to
imagine a situation in which a tube inside an intact tire
can go bang.)

The thump that you felt was probably the bead working itself
over the rim, the bulge that you saw as you glanced down and
back at the whirling tire. What was rubbing the brake was
probably the bulg of the tire slithering over the rim, not
the rim itself.

Anyway, once the tire bead worked off the rim, about two
inches of the tube was forced out under around 100 psi and
went bang as soon as enough thin rubber was exposed without
any tire to restrain it.

Nothing wrong with the inner tube, no defect.

At this point, the tube had started the tire-removal process
by forcing the bead over the rim and then politely deflated
itself, so by the time that you stopped and got off, the
tire was completely off the rim and the limp tube was trying
to look innocent.

This happens with relatively easy-to-mount, loose-
fitting tires whose beads are not seated all the way
around on both sides of the rim, particularly when they
are highly inflated.

Instead of popping out and seating correctly, the reluctant
section of the bead pulls down deeper into the well of the
rim. The far side of the bead mistakenly thinks that someone
is trying to pry it off the rim.

As the reluctant side of tire works down into the well of
the rim, the far side of the tire is then forced off the rim
by the internal pressure instead of the more traditional
tire lever.

The moral of the story is that you should eyeball the bead
on both sides of a newly inflated tire and fiddle with it,
pushing with your thumbs, deflating, re-inflating, cursing,
or whatever, until the bead pops out all the way around on
both sides.

Or so I've heard . . . loudly.

Carl Fogel

Ben Kaufman said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road bike with 27x1.25" tire. First time out with
the new tire. Doing laps around the park. I was about 10
miles into the ride when. I'm coming down a small hill and
I start to feel a thump in the rear wheel. I look down and
it appears there is a bulge in the side. The wheel is now
warping and rubbing the brake. I stop and just as I'm about
to get off the bike there is an explosion. It sounds like a
gunshot. The tire is off the rim. I see a straight 2" break
in the tube. All I've got is a flat kit and it's not going
to help this so I remount the tire, (the bead and walls
looked good) and walk her back. Does this sound like a
defective tube or was the tube pinched or twisted on the
install to cause this?

Just a guess, but I'd say that the tire was not correctly
seated on the rim, possibly because of the way the tire and
tube were installed. It sounds like the bead of the tire at
the point of failure worked itself up (or was forced up)
past the rim's edge and allowed the tube to protrude. In my
experience, one way that this can happen is if the tube was
completely uninflated when the tire was put on. If there's
just enough air in the tube to make it round before the tire
is slipped onto the rim, it's much less likely that a fold
of it can get trapped under the bead and cause the type of
event you experienced. If the tube is flat, it's possible
for a fold to get hooked under the bead and cause a delayed
failure like yours.

On Sat, 19 Jun 2004 05:37:34 GMT, Werehatrack <[email hidden]>

Quoted message said:

Ben Kaufman spaXm-mXe-anXd-paXy-5000- said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road bike with 27x1.25" tire. First time out
with the new tire. Doing laps around the park. I was about
10 miles into the ride when. I'm coming down a small hill
and I start to feel a thump in the rear wheel. I look down
and it appears there is a bulge in the side. The wheel is
now warping and rubbing the brake. I stop and just as I'm
about to get off the bike there is an explosion. It sounds
like a gunshot. The tire is off the rim. I see a straight
2" break in the tube. All I've got is a flat kit and it's
not going to help this so I remount the tire, (the bead
and walls looked good) and walk her back. Does this sound
like a defective tube or was the tube pinched or twisted
on the install to cause this?

Just a guess, but I'd say that the tire was not correctly
seated on the rim, possibly because of the way the tire and
tube were installed. It sounds like the bead of the tire at
the point of failure worked itself up (or was forced up)
past the rim's edge and allowed the tube to protrude. In my
experience, one way that this can happen is if the tube was
completely uninflated when the tire was put on. If there's
just enough air in the tube to make it round before the
tire is slipped onto the rim, it's much less likely that a
fold of it can get trapped under the bead and cause the
type of event you experienced. If the tube is flat, it's
possible for a fold to get hooked under the bead and cause
a delayed failure like yours.

Thanks. ... bringing it back to the store this morning.
Hopefully he will make good on this. Learned my lesson,
though, I have to make enough room in my pack for a spare
tube. <g>.

Ben

Quoted message said:

Ben Kaufman spaXm-mXe-anXd-paXy-5000- said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road bike with 27x1.25" tire. First time out
with the new tire. Doing laps around the park. I was about
10 miles into the ride when. I'm coming down a small hill
and I start to feel a thump in the rear wheel. I look down
and it appears there is a bulge in the side. The wheel is
now warping and rubbing the brake. I stop and just as I'm
about to get off the bike there is an explosion. It sounds
like a gunshot. The tire is off the rim. I see a straight
2" break in the tube. All I've got is a flat kit and it's
not going to help this so I remount the tire, (the bead
and walls looked good) and walk her back. Does this sound
like a defective tube or was the tube pinched or twisted
on the install to cause this?

Ben

Dear Ben,

Since the tire was intact, the explosion occurred when the
tube snuck out between the tire and the rim. (It's hard to
imagine a situation in which a tube inside an intact tire
can go bang.)

The thump that you felt was probably the bead working
itself over the rim, the bulge that you saw as you glanced
down and back at the whirling tire. What was rubbing the
brake was probably the bulg of the tire slithering over the
rim, not the rim itself.

Anyway, once the tire bead worked off the rim, about two
inches of the tube was forced out under around 100 psi and
went bang as soon as enough thin rubber was exposed without
any tire to restrain it.

Nothing wrong with the inner tube, no defect.

At this point, the tube had started the tire-removal
process by forcing the bead over the rim and then politely
deflated itself, so by the time that you stopped and got
off, the tire was completely off the rim and the limp tube
was trying to look innocent.

This happens with relatively easy-to-mount, loose-fitting
tires whose beads are not seated all the way around on both
sides of the rim, particularly when they are highly
inflated.

Instead of popping out and seating correctly, the reluctant
section of the bead pulls down deeper into the well of the
rim. The far side of the bead mistakenly thinks that
someone is trying to pry it off the rim.

As the reluctant side of tire works down into the well of
the rim, the far side of the tire is then forced off the
rim by the internal pressure instead of the more
traditional tire lever.

The moral of the story is that you should eyeball the bead
on both sides of a newly inflated tire and fiddle with it,
pushing with your thumbs, deflating, re-inflating, cursing,
or whatever, until the bead pops out all the way around on
both sides.

Or so I've heard . . . loudly.

Carl Fogel

Carl,

Thanks for the detailed analysis.

Ben

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

Quoted message said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road

bike

Quoted message said:

with 27x1.25" tire. First time out with the new tire.
Doing laps around

the

Quoted message said:

park. I was about 10 miles into the ride when. I'm coming
down a small

hill and

Quoted message said:

I start to feel a thump in the rear wheel. I look down and
it appears

there is

Quoted message said:

a bulge in the side. The wheel is now warping and rubbing
the brake. I

stop

Quoted message said:

and just as I'm about to get off the bike there is an
explosion. It sounds

like

Quoted message said:

a gunshot. The tire is off the rim. I see a straight 2"
break in the

tube.

Quoted message said:

All I've got is a flat kit and it's not going to help this
so I remount

the

Quoted message said:

tire, (the bead and walls looked good) and walk her back.
Does this sound like a defective tube or was the tube
pinched or twisted

on the

Quoted message said:

install to cause this?

Ben

It sounds more like a failure of the tyre. The tubes job is
to stop the air escaping. It's up to the tyre to maintain
the correct shape. If you had a bulge it was probably caused
by a weakness in the tyre. Folded or pinched tubes can cause
the problem too, but it's difficult to blame a pre-existing
fault in the tube.

Marty

Quoted message said:

Thanks. ... bringing it back to the store this morning.
Hopefully he will

make

Quoted message said:

good on this. Learned my lesson, though, I have to make
enough room in my

pack

Quoted message said:

for a spare tube. <g>.

Ben

It's also possible that the tire/tube were installed
correctly, but overinflated. Some older rims didn't have
much of a "hook" on the inside, made to capture the tire
bead. Without this hook, it's virtually impossible to center
the tire (and keep it centered) so perfectly that it can't
blow off the rim, even though the tire is rated for that
much pressure.

So, what happens is you get a younger mechanic (OK, any
mechanic under... hmm... ok, we won't even go there!) who
isn't experienced with older rims, assumes that the rated
pressure on the sidewall is the way to go, and inflates to
that pressure. In my experience, most older 27" rims are
risky at pressures above 70psi. Not all, but most. There
are exceptions, and these are easy to spot by their
pronounced hooks.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

On Sun, 20 Jun 2004 05:31:39 GMT, "Mike Jacoubowsky" <[email hidden]>

Quoted message said:

Quoted message said:

Thanks. ... bringing it back to the store this morning.
Hopefully he will

make

Quoted message said:

good on this. Learned my lesson, though, I have to make
enough room in my

pack

Quoted message said:

for a spare tube. <g>.

Ben

It's also possible that the tire/tube were installed
correctly, but overinflated. Some older rims didn't have
much of a "hook" on the inside, made to capture the tire
bead. Without this hook, it's virtually impossible to
center the tire (and keep it centered) so perfectly that it
can't blow off the rim, even though the tire is rated for
that much pressure.

So, what happens is you get a younger mechanic (OK, any
mechanic under... hmm... ok, we won't even go there!) who
isn't experienced with older rims, assumes that the rated
pressure on the sidewall is the way to go, and inflates to
that pressure. In my experience, most older 27" rims are
risky at pressures above 70psi. Not all, but most. There
are exceptions, and these are easy to spot by their
pronounced hooks.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

This is a rim that has handled these pressures in the past
but that is a good point. If memory serves me correct, the
original tires were rated around 85. (this is a bicycle I
bought in 1980 or so but never started riding it regularly
until 2 years ago).

I brought it back to the shop, he looked the tire over and
put another tube in. He carefully inflated/adjusted it and
showed me spots where, despite adjustment, the tire was
higher on the rim. However, I saw the same thing on the
front tire, which has been doing well at 90 psi for close to
2000 miles. So since I'm a light guy I am going to use the
tire at 80 psi for a while. I am also going to control my
downhill speed (which can reach 40+) just coasting in
sections of Harriman State park (NY)..

Come to think of it, that day it blew, I was able to get
that tire back on the rim, using a tool, without too much
hassle. The previous tire (another brand) was very
difficult to get on the rim... maybe that's a better/safer
fit for this rim?

Ben

Marty Wallace said:

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

Quoted message said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road

bike

Quoted message said:

with 27x1.25" tire. First time out with the new tire.
Doing laps around

the

Quoted message said:

park. I was about 10 miles into the ride when. I'm coming
down a small

hill and

Quoted message said:

I start to feel a thump in the rear wheel. I look down
and it appears

there is

Quoted message said:

a bulge in the side. The wheel is now warping and rubbing
the brake. I

stop

Quoted message said:

and just as I'm about to get off the bike there is an
explosion. It sounds

like

Quoted message said:

a gunshot. The tire is off the rim. I see a straight 2"
break in the

tube.

Quoted message said:

All I've got is a flat kit and it's not going to help
this so I remount

the

Quoted message said:

tire, (the bead and walls looked good) and walk her back.
Does this sound like a defective tube or was the tube
pinched or twisted

on the

Quoted message said:

install to cause this?

Ben

It sounds more like a failure of the tyre. The tubes job is
to stop the air escaping. It's up to the tyre to maintain
the correct shape. If you had a bulge it was probably
caused by a weakness in the tyre. Folded or pinched tubes
can cause the problem too, but it's difficult to blame a
pre-existing fault in the tube.

Marty

I was moving at speed when I took a quick look down and saw
the bulge so I can't be sure what it was that I saw.

Ben

Ben Kaufman said:

Mike Jacoubowsky said:

Quoted message said:

Thanks. ... bringing it back to the store this morning.
Hopefully he will

make

Quoted message said:

good on this. Learned my lesson, though, I have to make
enough room in my

pack

Quoted message said:

for a spare tube. <g>.

Ben

It's also possible that the tire/tube were installed
correctly, but overinflated. Some older rims didn't have
much of a "hook" on the inside, made to capture the tire
bead. Without this hook, it's virtually impossible to
center the tire (and keep it centered) so perfectly that
it can't blow off the rim, even though the tire is rated
for that much pressure.

So, what happens is you get a younger mechanic (OK, any
mechanic under... hmm... ok, we won't even go there!) who
isn't experienced with older rims, assumes that the rated
pressure on the sidewall is the way to go, and inflates to
that pressure. In my experience, most older 27" rims are
risky at pressures above 70psi. Not all, but most. There
are exceptions, and these are easy to spot by their
pronounced hooks.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

This is a rim that has handled these pressures in the past
but that is a good point. If memory serves me correct, the
original tires were rated around 85. (this is a bicycle I
bought in 1980 or so but never started riding it regularly
until 2 years ago).

I brought it back to the shop, he looked the tire over and
put another tube in. He carefully inflated/adjusted it and
showed me spots where, despite adjustment, the tire was
higher on the rim. However, I saw the same thing on the
front tire, which has been doing well at 90 psi for close
to 2000 miles. So since I'm a light guy I am going to use
the tire at 80 psi for a while. I am also going to control
my downhill speed (which can reach 40+) just coasting in
sections of Harriman State park (NY)..

Come to think of it, that day it blew, I was able to get
that tire back on the rim, using a tool, without too much
hassle. The previous tire (another brand) was very
difficult to get on the rim... maybe that's a better/safer
fit for this rim?

Ben

Dear Ben,

This problem is more common on the rear wheel, which has
more of your weight on it.

With no rider sitting on the bike and the wheel turning, the
tire bead is unlikely to creep further into the well of the
rim on one side and off the rim on the opposite side.

(Unless, of course, you have a really bad fitting tire and
a free hand with an air compressor. Turn your back
trustingly on such a freshly mounted tire to do something
else and bang!)

Usually, it takes some riding for your weight and the normal
rolling bulge in the tire to push and wiggle the bead a
little deeper on one side and to allow the air pressure to
work it off on the other side.

The rear tire simply has more weight on it to encourage this
Houdini-like squirming with each spin, and no front-fork
springiness to lessen normal impacts. Besides, we tend to
absorb shock better with our hands and bendable elbows than
we do with the seats of our pants.

So front tires survive more often because they may never
work free, work free more slowly, and are literally under
our noses, where we're likely to notice the odd bulge as the
tire starts creeping off the rim.

Carl Fogel

You don't honestly believe that do you? It is these kind of
coverups that make my blood boil.

Recent evidence has come to light showing that you were just
another innocent the victim of a CIA plot to overthrow a
democratically elected central american leader.

Yes, it is true.

The plan was to capture Bigfoot, and, using the latest
concoction of psychadelic drugs developed by Timothy Leary
in the 60s, program Bigfoot to parachute into the central
american country, and kill the leader on one of his hunting
excursions. As usual the plan failed miserably. They
couldn't catch Bigfoot. When the specially trained CIA
hunter took his only shot at Bigfoot with dart gun, some
cyclist wizzing by blocked the dart. Alerted by the
explosion of said cyclist's tire, Bigfoot escaped and the
CIA plot was foiled.

That must have been the reason for your blowout.

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

Quoted message said:

Quoted message said:

Ben Kaufman spaXm-mXe-anXd-paXy-5000- said:

I just had the rear tire and tube replaced. 24 year old
Panasonic road

bike

Quoted message said:

Quoted message said:

Quoted message said:

with 27x1.25" tire. First time out with the new tire.
Doing laps around

the

Quoted message said:

Quoted message said:

Quoted message said:

park. I was about 10 miles into the ride when. I'm
coming down a small

hill and

Quoted message said:

Quoted message said:

Quoted message said:

I start to feel a thump in the rear wheel. I look down
and it appears

there is

Quoted message said:

Quoted message said:

Quoted message said:

a bulge in the side. The wheel is now warping and
rubbing the brake.

I stop

Quoted message said:

Quoted message said:

Quoted message said:

and just as I'm about to get off the bike there is an
explosion. It

sounds like

Quoted message said:

Quoted message said:

Quoted message said:

a gunshot. The tire is off the rim. I see a straight 2"
break in the

tube.

Quoted message said:

Quoted message said:

Quoted message said:

All I've got is a flat kit and it's not going to help
this so I remount

the

Quoted message said:

Quoted message said:

Quoted message said:

tire, (the bead and walls looked good) and walk her
back. Does this sound like a defective tube or was the
tube pinched or twisted

on the

Quoted message said:

Quoted message said:

Quoted message said:

install to cause this?

Ben

Dear Ben,

Since the tire was intact, the explosion occurred when
the tube snuck out between the tire and the rim. (It's
hard to imagine a situation in which a tube inside an
intact tire can go bang.)

The thump that you felt was probably the bead working
itself over the rim, the bulge that you saw as you
glanced down and back at the whirling tire. What was
rubbing the brake was probably the bulg of the tire
slithering over the rim, not the rim itself.

Anyway, once the tire bead worked off the rim, about two
inches of the tube was forced out under around 100 psi
and went bang as soon as enough thin rubber was exposed
without any tire to restrain it.

Nothing wrong with the inner tube, no defect.

At this point, the tube had started the tire-removal
process by forcing the bead over the rim and then
politely deflated itself, so by the time that you stopped
and got off, the tire was completely off the rim and the
limp tube was trying to look innocent.

This happens with relatively easy-to-mount, loose-fitting
tires whose beads are not seated all the way around on
both sides of the rim, particularly when they are highly
inflated.

Instead of popping out and seating correctly, the
reluctant section of the bead pulls down deeper into the
well of the rim. The far side of the bead mistakenly
thinks that someone is trying to pry it off the rim.

As the reluctant side of tire works down into the well of
the rim, the far side of the tire is then forced off the
rim by the internal pressure instead of the more
traditional tire lever.

The moral of the story is that you should eyeball the
bead on both sides of a newly inflated tire and fiddle
with it, pushing with your thumbs, deflating, re-
inflating, cursing, or whatever, until the bead pops out
all the way around on both sides.

Or so I've heard . . . loudly.

Carl Fogel

Carl,

Thanks for the detailed analysis.

Ben

Blair Maynard said:

You don't honestly believe that do you? It is these kind
of coverups that make my blood boil.

If you put this BELOW that to which you're replying, the
masses would be gratified.

Bill "mass spokesperson" S.

"S o r n i" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Blair Maynard said:

You don't honestly believe that do you? It is these kind
of coverups that make my blood boil.

If you put this BELOW that to which you're replying, the
masses would be gratified.

Not only would we be gratified, I would have posted it to
AHBOU in the blink of an eye. But if you have to reformat it
to make the joke apparent then it's no longer authentic and
that would be a travesty of what AHBOU stands for.
--
"The threads in your trousers are probably quite
stable dimensionally but you can deform the trousers
quite happily."
- David Martin in uk.rec.cycling

Ben Kaufman said:

Mike Jacoubowsky said:

Quoted message said:

Thanks. ... bringing it back to the store this morning.
Hopefully he will

make

Quoted message said:

good on this. Learned my lesson, though, I have to make
enough room in my

pack

Quoted message said:

for a spare tube. <g>.

Ben

It's also possible that the tire/tube were installed
correctly, but overinflated. Some older rims didn't have
much of a "hook" on the inside, made to capture the tire
bead. Without this hook, it's virtually impossible to
center the tire (and keep it centered) so perfectly that
it can't blow off the rim, even though the tire is rated
for that much pressure.

So, what happens is you get a younger mechanic (OK, any
mechanic under... hmm... ok, we won't even go there!) who
isn't experienced with older rims, assumes that the rated
pressure on the sidewall is the way to go, and inflates to
that pressure. In my experience, most older 27" rims are
risky at pressures above 70psi. Not all, but most. There
are exceptions, and these are easy to spot by their
pronounced hooks.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

This is a rim that has handled these pressures in the past
but that is a good point. If memory serves me correct, the
original tires were rated around 85. (this is a bicycle I
bought in 1980 or so but never started riding it regularly
until 2 years ago).

I brought it back to the shop, he looked the tire over and
put another tube in. He carefully inflated/adjusted it and
showed me spots where, despite adjustment, the tire was
higher on the rim. However, I saw the same thing on the
front tire, which has been doing well at 90 psi for close
to 2000 miles. So since I'm a light guy I am going to use
the tire at 80 psi for a while. I am also going to control
my downhill speed (which can reach 40+) just coasting in
sections of Harriman State park (NY)..

Come to think of it, that day it blew, I was able to get
that tire back on the rim, using a tool, without too much
hassle. The previous tire (another brand) was very
difficult to get on the rim... maybe that's a better/safer
fit for this rim?

Ben

Follow up:

The tube/tire has held with lower pressure - 75 psi - but I
noticed that there is a spot where it is riding up on both
sides of the rim. Maybe it is just a really cheap tire -
Kenda - so I decided not to gamble and mail ordered some
more of the previous tire that I was using and was happy
with - Performance GT 2 Kevlar. It's bad enough to worry
about the crazy cagers getting me, I shouldn't have to worry
about another blow out.

In the mean time, I'm keeping the speed down in the those
down hills.

Ben