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 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 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:

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

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 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:

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

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