Re: Is my tire bad?

[Phil, Squid-in-Training]

NiteRider wrote:
> Last season, I managed to have two major problems with one tire, an
> IRC Metro/K. The first time was my fault. I apparently hadn't seated
> the new tire properly on the rim and when I was pumping up, a few
> inches of bead came off and the tube blew into pieces, bending the
> rim sidewall. I rebuilt with a Campy Thorr rim, which should be much
> stronger than the factory rim. But on the long, last ride of the
> season, it blew again. Didn't bend the rim, but destroyed another
> tube. (Pain in the neck, too, since this tube had sealant inside and
> basically blasted it all over the place.) I made sure I'd seated the
> bead properly this time.
>
> Is this particular tire bad, or am I just a victim of bad luck?
> There've been no problems at all with the other Metro I have on my
> front wheel, which was bought at the same time. I'd hate to trash a
> tire that's only got a couple of hundred miles on it. But I expect to
> be doing a few more long rides this season and I don't want to risk
> being stranded far from home (yeah, I can carry a tube, pump, and
> levers, but that should be a last resort). Anybody else have problems
> with Metros or IRC tires in general?

If these are wire bead, have you ever folded these tires? I folded a wire
bead road tire incorrectly once, and this made the bead uneven, working its
way off the rim after 0.5 miles and blowing the tube. Unless your sidewall
was already suspect, however, I don't see how a tire blowing off could bend
a rim...
--
Phil, Squid-in-Training

 

[[email protected]]

Phil Lee writes:

>> Last season, I managed to have two major problems with one tire, an
>> IRC Metro/K. The first time was my fault. I apparently hadn't
>> seated the new tire properly on the rim and when I was pumping up,
>> a few inches of bead came off and the tube blew into pieces,
>> bending the rim sidewall. I rebuilt with a Campy Thorr rim, which
>> should be much stronger than the factory rim. But on the long,
>> last ride of the season, it blew again. Didn't bend the rim, but
>> destroyed another tube. (Pain in the neck, too, since this tube
>> had sealant inside and basically blasted it all over the place.) I
>> made sure I'd seated the bead properly this time.

>> Is this particular tire bad, or am I just a victim of bad luck?
>> There've been no problems at all with the other Metro I have on my
>> front wheel, which was bought at the same time. I'd hate to trash
>> a tire that's only got a couple of hundred miles on it. But I
>> expect to be doing a few more long rides this season and I don't
>> want to risk being stranded far from home (yeah, I can carry a
>> tube, pump, and levers, but that should be a last resort). Anybody
>> else have problems with Metros or IRC tires in general?

> If these are wire bead, have you ever folded these tires? I folded
> a wire bead road tire incorrectly once, and this made the bead
> uneven, working its way off the rim after 0.5 miles and blowing the
> tube. Unless your sidewall was already suspect, however, I don't
> see how a tire blowing off could bend a rim...

The best you can do with a wire bead tire is to not fold it but to
coil it as shown:

http://draco.acs.uci.edu/rbfaq/FAQ/8b.23.html

[email protected]

 

[[email protected]]

On Wed, 23 Mar 2005 04:36:06 GMT, NiteRider
<[email protected]> wrote:

>In article <MDZ%[email protected]>, Phil,
>Squid-in-Training <[email protected]> wrote:
>
>> If these are wire bead, have you ever folded these tires? I folded a wire
>> bead road tire incorrectly once, and this made the bead uneven, working its
>> way off the rim after 0.5 miles and blowing the tube. Unless your sidewall
>> was already suspect, however, I don't see how a tire blowing off could bend
>> a rim...
>
>I never folded them. They did come coiled from the store, but that's
>safe. What bent was the edge of the wall. It looked almost like I'd
>gotten big air and landed with zero air pressure, so the flange bent
>outward a couple of mm. I'd send a picture of the failed rim, but this
>isn't a binaries group. I'm not surprised that factory rims (not name
>brand) aren't especially strong. The Thorr didn't bend when the tube
>blew out of that.

Dear NiteRider,

Feel free to email a picture in an attachment to me for
hosting: [email protected]

There are also free hosting sites:

http://www.theimagehosting.com/

Carl Fogel

 

[[email protected]]

On Tue, 22 Mar 2005 22:50:37 -0700, [email protected]
wrote:

>On Wed, 23 Mar 2005 04:36:06 GMT, NiteRider
><[email protected]> wrote:
>
>>In article <MDZ%[email protected]>, Phil,
>>Squid-in-Training <[email protected]> wrote:
>>
>>> If these are wire bead, have you ever folded these tires? I folded a wire
>>> bead road tire incorrectly once, and this made the bead uneven, working its
>>> way off the rim after 0.5 miles and blowing the tube. Unless your sidewall
>>> was already suspect, however, I don't see how a tire blowing off could bend
>>> a rim...
>>
>>I never folded them. They did come coiled from the store, but that's
>>safe. What bent was the edge of the wall. It looked almost like I'd
>>gotten big air and landed with zero air pressure, so the flange bent
>>outward a couple of mm. I'd send a picture of the failed rim, but this
>>isn't a binaries group. I'm not surprised that factory rims (not name
>>brand) aren't especially strong. The Thorr didn't bend when the tube
>>blew out of that.
>
>Dear NiteRider,
>
>Feel free to email a picture in an attachment to me for
>hosting: [email protected]
>
>There are also free hosting sites:
>
>http://www.theimagehosting.com/
>
>Carl Fogel

Er, [email protected].

Dyslexically,

Carl Fogel

 

[Phil, Squid-in-Training]

[email protected] wrote:
> On Tue, 22 Mar 2005 22:50:37 -0700, [email protected]
> wrote:
>
>> On Wed, 23 Mar 2005 04:36:06 GMT, NiteRider
>> <[email protected]> wrote:
>>
>>> In article <MDZ%[email protected]>, Phil,
>>> Squid-in-Training <[email protected]> wrote:
>>>
>>>> If these are wire bead, have you ever folded these tires? I
>>>> folded a wire bead road tire incorrectly once, and this made the
>>>> bead uneven, working its way off the rim after 0.5 miles and
>>>> blowing the tube. Unless your sidewall was already suspect,
>>>> however, I don't see how a tire blowing off could bend a rim...
>>>
>>> I never folded them. They did come coiled from the store, but that's
>>> safe. What bent was the edge of the wall. It looked almost like I'd
>>> gotten big air and landed with zero air pressure, so the flange bent
>>> outward a couple of mm. I'd send a picture of the failed rim, but
>>> this isn't a binaries group. I'm not surprised that factory rims
>>> (not name brand) aren't especially strong. The Thorr didn't bend
>>> when the tube blew out of that.
>>
>> Dear NiteRider,
>>
>> Feel free to email a picture in an attachment to me for
>> hosting: [email protected]
>>
>> There are also free hosting sites:
>>
>> http://www.theimagehosting.com/
>>
>> Carl Fogel
>
> Er, [email protected].
>
> Dyslexically,
>
> Carl Fogel

Where's Sorni? He should have jumped all over this one by now... maybe he
has to wait till tomorrow's slow morning?
--
Phil, Squid-in-Training

 

[[email protected]]

On Thu, 24 Mar 2005 00:32:47 GMT, NiteRider
<[email protected]> wrote:

>In article <[email protected]>,
><[email protected]> wrote:
>
>> >I never folded them. They did come coiled from the store, but that's
>> >safe. What bent was the edge of the wall. It looked almost like I'd
>> >gotten big air and landed with zero air pressure, so the flange bent
>> >outward a couple of mm. I'd send a picture of the failed rim, but this
>> >isn't a binaries group. I'm not surprised that factory rims (not name
>> >brand) aren't especially strong. The Thorr didn't bend when the tube
>> >blew out of that.
>>
>> Dear NiteRider,
>>
>> Feel free to email a picture in an attachment to me for
>> hosting: [email protected]
>
>I had a friend email it to you. I considered hammering the rim back
>since this wheel has a disk brake, but then I noticed the crack on the
>inside of the rim, visible in the third picture.
>
>> There are also free hosting sites:
>>
>> http://www.theimagehosting.com/
>
>Doesn't work. Looks like Yahoo bought them out and shut it down.

Dear NiteRider,

Your 14k rim triptych can be seen here:

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

Anyone surprised by the small size of the file should
remember that the three pictures of the rim are practically
black and white, so the detail is actually good.

The hosting service seems to be working--I just registered,
logged in, and uploaded the same file:

http://server5.theimagehosting.com/image.php?img=rim_nite.jpg

http://www.theimagehosting.com

Carl Fogel

 

[[email protected]]

NiteRider? writes:

> I never folded them. They did come coiled from the store, but
> that's safe. What bent was the edge of the wall. It looked almost
> like I'd gotten big air and landed with zero air pressure, so the
> flange bent outward a couple of mm. I'd send a picture of the
> failed rim, but this isn't a binaries group. I'm not surprised that
> factory rims (not name brand) aren't especially strong. The Thorr
> didn't bend when the tube blew out of that.

http://server5.theimagehosting.com/image.php?img=rim_nite.jpg

I am certain that the damage on the pictured rim did not come from
tire inflation or a faulty tire bead. The damage was most likely
caused by hitting something lying on the road, like a one inch high
block of wood or other such obstacle, even a rock. It most likely was
not an excavation cover plate of step in the pavement, because that
would have damaged both edges of the rim.

Kevlar beads have no significant bending resistance and do not blow
out in this manner when inflated, nor did the wire bead tires tested
for clinch by cutting the wire at a number of places. I wasn't there
but I suspect you noticed the jolt and assumed it was caused by the
blowout. I believe the jolt caused the blowout.

[email protected]

 

[[email protected]]

On Thu, 24 Mar 2005 02:34:50 GMT, NiteRider
<[email protected]> wrote:

>In article <[email protected]>,
><[email protected]> wrote:
>
>> Dear NiteRider,
>>
>> Your 14k rim triptych can be seen here:
>>
>> http://home.comcast.net/~carlfogel/download/rim_nite.jpg
>>
>> Anyone surprised by the small size of the file should
>> remember that the three pictures of the rim are practically
>> black and white, so the detail is actually good.
>>
>> The hosting service seems to be working--I just registered,
>> logged in, and uploaded the same file:
>
>Thanks, Carl. I don't know what's wrong on my end. Every time I click
>on your link for imagehosting.com, I instantly get redirected to
>Yahoo's home page, and I can't find anything about image hosting there.

Dear NiteRider,

You're welcome.

Possibly you need to clean out your browser's cache? Your
header indicates Thoth and OS X, so I have no idea how to
empty the cache, but these links work reliably for me:

http://server5.theimagehosting.com/image.php?img=rim_nite.jpg

http://www.theimagehosting.com

Carl Fogel

 

[[email protected]]

NiteRider? writes:

>> http://server5.theimagehosting.com/image.php?img=rim_nite.jpg

>> I am certain that the damage on the pictured rim did not come from
>> tire inflation or a faulty tire bead. The damage was most likely
>> caused by hitting something lying on the road, like a one inch high
>> block of wood or other such obstacle, even a rock. It most likely
>> was not an excavation cover plate of step in the pavement, because
>> that would have damaged both edges of the rim.

>> Kevlar beads have no significant bending resistance and do not blow
>> out in this manner when inflated, nor did the wire bead tires
>> tested for clinch by cutting the wire at a number of places. I
>> wasn't there but I suspect you noticed the jolt and assumed it was
>> caused by the blowout. I believe the jolt caused the blowout.

> Nice hypothesis, but completely wrong. This was the first rim, the
> first time this tire caused a problem for me. That time, I wasn't
> out on the road. I was in my apartment having just finished
> mounting a brand new wire bead Metro on the wheel. The wheel wasn't
> even back on my bike. Pumping it up, it blew at around 50-60psi,
> surprisingly low in my opinion but not inconsistent with a badly
> seated bead. Pretty deafening in a confined space, too.

Well then its worse than I suspected. The rim could not be bent to
that shape with 60psi or even 120psi. If so, you need to explain
where the local force arose that cause this at this point dent and
nowhere else. I can't see your face or whether you are chuckling as
you write this, but the more I read the more I get the feeling of a
put-on (aka troll). Lateral force around the bead is uniform when the
wheel is not loaded, and couldn't possibly cause a local irregularity.
As I said, Kevlar bead tires have no bead stiffness and press on the
rim uniformly. There is no way your tire could cause this anomaly.

> It blew off again months later on the rim I rebuilt the wheel with,
> a Campagnolo Thorr. But this second time was on a ride and there
> was no apparent damage to that rim. That the tire blew off two
> different rims is my source of concern.

That it occurred the second time while riding ought to make you wonder
who bent the rim the first time, there being no damage to the rim
while it was loaded. I am certain that if air pressure were the
culprit then you could repeat the rim damage experiment by inflating a
tire to 120psi, something that folks report fairly often in here. You
might blow the tire off the rim if it isn't properly mounted but even
then it will not bend the rim, or for that matter cause any damage.

[email protected]

 

[Neil Brooks]

NiteRider <[email protected]> wrote:

>In article <[email protected]>,
><[email protected]> wrote:
>
>> NiteRider? writes:
>>
>> > Nice hypothesis, but completely wrong. This was the first rim, the
>> > first time this tire caused a problem for me. That time, I wasn't
>> > out on the road. I was in my apartment having just finished
>> > mounting a brand new wire bead Metro on the wheel. The wheel wasn't
>> > even back on my bike. Pumping it up, it blew at around 50-60psi,
>> > surprisingly low in my opinion but not inconsistent with a badly
>> > seated bead. Pretty deafening in a confined space, too.
>>
>> Well then its worse than I suspected. The rim could not be bent to
>> that shape with 60psi or even 120psi. If so, you need to explain
>> where the local force arose that cause this at this point dent and
>> nowhere else. I can't see your face or whether you are chuckling as
>> you write this, but the more I read the more I get the feeling of a
>> put-on (aka troll). Lateral force around the bead is uniform when the
>> wheel is not loaded, and couldn't possibly cause a local irregularity.
>> As I said, Kevlar bead tires have no bead stiffness and press on the
>> rim uniformly. There is no way your tire could cause this anomaly.
>>
>> > It blew off again months later on the rim I rebuilt the wheel with,
>> > a Campagnolo Thorr. But this second time was on a ride and there
>> > was no apparent damage to that rim. That the tire blew off two
>> > different rims is my source of concern.
>>
>> That it occurred the second time while riding ought to make you wonder
>> who bent the rim the first time, there being no damage to the rim
>> while it was loaded. I am certain that if air pressure were the
>> culprit then you could repeat the rim damage experiment by inflating a
>> tire to 120psi, something that folks report fairly often in here. You
>> might blow the tire off the rim if it isn't properly mounted but even
>> then it will not bend the rim, or for that matter cause any damage.
>
>Okay, I can see now why some people around here have no use for your
>rantings. Jobst Brandt knows everything. And if you contradict him, you
>must be a troll. Enough with you, then. I have no patience to deal with
>a self-important self-described genius. Off to the killfile with you.

It is oft said that a wise man can learn from a fool, but a fool
cannot learn from a wise man.

NiteRider: I leave it to you to decide how and if this little maxim
applies here....

 

[Jim Smith]

NiteRider <[email protected]> writes:

> In article <[email protected]>,
> <[email protected]> wrote:
>
>> NiteRider? writes:
>>
>> > Nice hypothesis, but completely wrong. This was the first rim, the
>> > first time this tire caused a problem for me. That time, I wasn't
>> > out on the road. I was in my apartment having just finished
>> > mounting a brand new wire bead Metro on the wheel. The wheel wasn't
>> > even back on my bike. Pumping it up, it blew at around 50-60psi,
>> > surprisingly low in my opinion but not inconsistent with a badly
>> > seated bead. Pretty deafening in a confined space, too.
>>
>> Well then its worse than I suspected. The rim could not be bent to
>> that shape with 60psi or even 120psi. If so, you need to explain
>> where the local force arose that cause this at this point dent and
>> nowhere else. I can't see your face or whether you are chuckling as
>> you write this, but the more I read the more I get the feeling of a
>> put-on (aka troll). Lateral force around the bead is uniform when the
>> wheel is not loaded, and couldn't possibly cause a local irregularity.
>> As I said, Kevlar bead tires have no bead stiffness and press on the
>> rim uniformly. There is no way your tire could cause this anomaly.
>>
>> > It blew off again months later on the rim I rebuilt the wheel with,
>> > a Campagnolo Thorr. But this second time was on a ride and there
>> > was no apparent damage to that rim. That the tire blew off two
>> > different rims is my source of concern.
>>
>> That it occurred the second time while riding ought to make you wonder
>> who bent the rim the first time, there being no damage to the rim
>> while it was loaded. I am certain that if air pressure were the
>> culprit then you could repeat the rim damage experiment by inflating a
>> tire to 120psi, something that folks report fairly often in here. You
>> might blow the tire off the rim if it isn't properly mounted but even
>> then it will not bend the rim, or for that matter cause any damage.
>
> Okay, I can see now why some people around here have no use for your
> rantings. Jobst Brandt knows everything. And if you contradict him, you
> must be a troll. Enough with you, then. I have no patience to deal with
> a self-important self-described genius. Off to the killfile with you.

That may be so, but you are still wrong about how your rim got bent.
It just isn't possible for the tire to apply the necessary force.

 

[[email protected]]

doa

 

[Jim Smith]

NiteRider <[email protected]> writes:

> In article <[email protected]>, Jim Smith
> <[email protected]> wrote:
>
>> > Okay, I can see now why some people around here have no use for your
>> > rantings. Jobst Brandt knows everything. And if you contradict him, you
>> > must be a troll. Enough with you, then. I have no patience to deal with
>> > a self-important self-described genius. Off to the killfile with you.
>>
>> That may be so, but you are still wrong about how your rim got bent.
>> It just isn't possible for the tire to apply the necessary force.
>
> Then you tell me how it got bent. Don't you think I would have noticed
> such a dent when I was mounting the tire? Is this all you can do, just
> call me a liar or an idiot? Who knows, maybe there was a weakness in
> this specific rim. You can't rule that out unless you're an omniscient
> god like Brandt. If you're both so sure that it was because of an
> impact with a rock, which I'm absolutely sure there wasn't since I
> wasn't on a ride, why isn't there so much as a scratch on the edge of
> the rim? Even a tire's casing couldn't cushion such an impact so well
> that the anodizing isn't touched. I can show you more closeup pictures
> if you don't believe me. Heck, if you're willing to pay the shipping,
> I'd be happy to ship the rim to you for inspection.

I'm not exactly calling you a liar or an idiot. yet. However, I don't
believe in magic either.

Now aliens, on the other hand...

 

[Phil, Squid-in-Training]

NiteRider wrote:
> In article <[email protected]>, Jim Smith
> <[email protected]> wrote:
>
>>> Okay, I can see now why some people around here have no use for your
>>> rantings. Jobst Brandt knows everything. And if you contradict him,
>>> you must be a troll. Enough with you, then. I have no patience to
>>> deal with a self-important self-described genius. Off to the
>>> killfile with you.
>>
>> That may be so, but you are still wrong about how your rim got bent.
>> It just isn't possible for the tire to apply the necessary force.
>
> Then you tell me how it got bent. Don't you think I would have noticed
> such a dent when I was mounting the tire? Is this all you can do, just
> call me a liar or an idiot? Who knows, maybe there was a weakness in
> this specific rim. You can't rule that out unless you're an omniscient
> god like Brandt. If you're both so sure that it was because of an
> impact with a rock, which I'm absolutely sure there wasn't since I
> wasn't on a ride, why isn't there so much as a scratch on the edge of
> the rim? Even a tire's casing couldn't cushion such an impact so well
> that the anodizing isn't touched. I can show you more closeup pictures
> if you don't believe me. Heck, if you're willing to pay the shipping,
> I'd be happy to ship the rim to you for inspection.

One of the first things to check would be if the sidewall was really thin at
that point, by machining or otherwise.
--
Phil, Squid-in-Training

 

[jim beam]

NiteRider wrote:
> In article <[email protected]>, Jim Smith
> <[email protected]> wrote:
>
>
>>>Okay, I can see now why some people around here have no use for your
>>>rantings. Jobst Brandt knows everything. And if you contradict him, you
>>>must be a troll. Enough with you, then. I have no patience to deal with
>>>a self-important self-described genius. Off to the killfile with you.
>>
>>That may be so, but you are still wrong about how your rim got bent.
>>It just isn't possible for the tire to apply the necessary force.
>
>
> Then you tell me how it got bent. Don't you think I would have noticed
> such a dent when I was mounting the tire? Is this all you can do, just
> call me a liar or an idiot? Who knows, maybe there was a weakness in
> this specific rim. You can't rule that out unless you're an omniscient
> god like Brandt. If you're both so sure that it was because of an
> impact with a rock, which I'm absolutely sure there wasn't since I
> wasn't on a ride, why isn't there so much as a scratch on the edge of
> the rim? Even a tire's casing couldn't cushion such an impact so well
> that the anodizing isn't touched. I can show you more closeup pictures
> if you don't believe me. Heck, if you're willing to pay the shipping,
> I'd be happy to ship the rim to you for inspection.

relax guy.

the no-name rim bent because it was weak/defective - as evidenced by
having the same tire blowing out again, it did not bend the better
quality campy rim. the tire blew because it's got a bead defect. it's
unfortunate coincidence you got the first two in the same place at the
same time. please note however, that regardless of the pressure rating
on the tire sidewall, the wider the tire, the lower the pressure the rim
can take. you don't state the tire width in your original post, but
check out mavic's web site for a table that shows this relationship.

best, safest thing to do is discard those tires. you don't want that
same experience with the front blowing out on a descent.

regarding "garage" blowouts, i've had almost identical experience with
cheapo kenda tires & some other no-name brand, i forget which. just
thrown them as far away as possible. and cut the bead before hand so
noone else can salvage them. these days i stick with "known" tire
brands like michelin, hutchinson, continental, etc. [my hutchinsons
have been /fantastic/ for winter puncture resistance btw.]

the rim in jobst's image clearly shows a crack - probably an extrusion
defect. if your bent rim shows a similar feature, consider yourself
lucky it didn't happen while you were trying to emergency brake on a
hill. use this as a positive learning experience about cheap tires &
cheap rims.

 

[Phil, Squid-in-Training]

NiteRider wrote:
> In article <%[email protected]>, Phil,
> Squid-in-Training <[email protected]> wrote:
>
>> One of the first things to check would be if the sidewall was really
>> thin at that point, by machining or otherwise.
>
> Thank you! Finally somebody who doesn't just say, "You're an idiot and
> it can't possibly happen." Especially since none of these
> self-annointed "experts" are structural engineers.
>
> As I wrote, there may possibly be a manufacturing defect in this rim
> that weakened it at that point, but I don't have the tools to detect
> such a defect, such as a micrometer. All I can say definitively is
> that the rim wasn't bent like that when I mounted the tire but clearly
> displayed the damage after the tube blew inside my apartment.

I'm 21 and haven't settled into my air of superiority yet

On a serious note, you should be able to use your fingers to roughly gauge
the thickness of the rim at that point, even though it's blown out and
cracked. Check to see if other parts of the rim feel thin, too.
--
Phil, Squid-in-Training

 

[[email protected]]

NiteRider? writes:

>>>> http://server5.theimagehosting.com/image.php?img=rim_nite.jpg

>>>> I am certain that the damage on the pictured rim did not come
>>>> from tire inflation or a faulty tire bead. The damage was most
>>>> likely caused by hitting something lying on the road, like a one
>>>> inch high block of wood or other such obstacle, even a rock. It
>>>> most likely was not an excavation cover plate of step in the
>>>> pavement, because that would have damaged both edges of the rim.

>>>> Kevlar beads have no significant bending resistance and do not
>>>> blow out in this manner when inflated, nor did the wire bead
>>>> tires tested for clinch by cutting the wire at a number of
>>>> places. I wasn't there but I suspect you noticed the jolt and
>>>> assumed it was caused by the blowout. I believe the jolt caused
>>>> the blowout.

>>> Nice hypothesis, but completely wrong. This was the first rim,
>>> the first time this tire caused a problem for me. That time, I
>>> wasn't out on the road. I was in my apartment having just
>>> finished mounting a brand new wire bead Metro on the wheel. The
>>> wheel wasn't even back on my bike. Pumping it up, it blew at
>>> around 50-60psi, surprisingly low in my opinion but not
>>> inconsistent with a badly seated bead. Pretty deafening in a
>>> confined space, too.

>> Well then its worse than I suspected. The rim could not be bent to
>> that shape with 60psi or even 120psi. If so, you need to explain
>> where the local force arose that cause this at this point dent and
>> nowhere else. I can't see your face or whether you are chuckling
>> as you write this, but the more I read the more I get the feeling
>> of a put-on (aka troll). Lateral force around the bead is uniform
>> when the wheel is not loaded, and couldn't possibly cause a local
>> irregularity. As I said, Kevlar bead tires have no bead stiffness
>> and press on the rim uniformly. There is no way your tire could
>> cause this anomaly.

>>> It blew off again months later on the rim I rebuilt the wheel
>>> with, a Campagnolo Thorr. But this second time was on a ride and
>>> there was no apparent damage to that rim. That the tire blew off
>>> two different rims is my source of concern.

>> That it occurred the second time while riding ought to make you
>> wonder who bent the rim the first time, there being no damage to
>> the rim while it was loaded. I am certain that if air pressure
>> were the culprit then you could repeat the rim damage experiment by
>> inflating a tire to 120psi, something that folks report fairly
>> often in here. You might blow the tire off the rim if it isn't
>> properly mounted but even then it will not bend the rim, or for
>> that matter cause any damage.

As others have mentioned. the curled lip of the rim cannot have gotten
that way from air pressure, especially when not in use. You are
drawing the conclusion that only a non-observant rider could do this.
No one put that proposition forward in response to your questions.

That there is a crack inside the sidewall of the rim is not proof of
anything other than that the force that curled the rim was strong
enough to produce such a curl, one that no one here has ever seen
without external mechanical interventions, aka witting an obstacle.

As I said, if it was caused by tire inflation then how come there was
no damage on the second occurrence? There is no way a tire can cause
this damage regardless of how poorly it is made. At worst it wold not
stay on the rim, but damaging the rim is not a result of that. The
curl is so rounded that a tire wold locally detach before it got to
that state. There being no holding force left in the rim once it
angles out 30 degrees or so would make further rim deformation an
impossibility.

There is something else afoot here and it is not apparent without more
information especially because the question was formatted in such a
mechanically contradictory manner. In other posts it appears that
this is not the first rim, wheel or tire you have ridden and that many
years have passed with much experience. In that event I wonder why
you need to ask and then reject assessments that you get.

I don't think further pictures will make any difference in what people
on this end of the inquiry can offer.

[email protected]

 

[[email protected]]

On Fri, 25 Mar 2005 16:22:15 GMT, NiteRider
<[email protected]> wrote:

>In article <1111725186.d619ca0428f1215011e3c92046f7cf1d@teranews>, jim
>beam <[email protected]> wrote:
>
>> the no-name rim bent because it was weak/defective - as evidenced by
>> having the same tire blowing out again, it did not bend the better
>> quality campy rim. the tire blew because it's got a bead defect. it's
>> unfortunate coincidence you got the first two in the same place at the
>> same time.
>
>You're right. Now that I think about it, the bead did work off on the
>left (non-drivetrain) side in both blowouts. It can't be coincidence
>and both rims can't be bad.
>
>> please note however, that regardless of the pressure rating
>> on the tire sidewall, the wider the tire, the lower the pressure the rim
>> can take. you don't state the tire width in your original post, but
>> check out mavic's web site for a table that shows this relationship.
>
>I can't find the table on Mavic's confusing website, unless it's in the
>"technical manual" available to registered users only. The tire was the
>widest Metro I could get, 26x2.0, which I liked to run at 80psi.
>
>> best, safest thing to do is discard those tires. you don't want that
>> same experience with the front blowing out on a descent.
>>
>> regarding "garage" blowouts, i've had almost identical experience with
>> cheapo kenda tires & some other no-name brand, i forget which. just
>> thrown them as far away as possible. and cut the bead before hand so
>> noone else can salvage them. these days i stick with "known" tire
>> brands like michelin, hutchinson, continental, etc. [my hutchinsons
>> have been /fantastic/ for winter puncture resistance btw.]
>
>That's why I asked here. People have said they've had no problems with
>IRC tires, so it must be just this one tire that has a problem.

Dear NiteRider,

The secret login and password for this site:

http://www.tech-mavic.com/

is mavic-com and dealer.

Security is dreadfully important, so please don't tell
anyone else.

Carl Fogel

 

[[email protected]]

NiteRider Stingray Bowlander Huh? writes from cover of darkness:

>> The secret login and password for this site:

http://www.tech-mavic.com/

>> is mavic-com and dealer.

>> Security is dreadfully important, so please don't tell anyone else.

> Thanks. Took a while, but I found the file. Mavic only recommends
> 60-odd psi max for a 2.0 tire, eh? That's pretty low.

That pressure limit is not for rim protection but rather to prevent
tire blow-off. Blow-off force is proportional to tire pressure times
inside rim width per unit length around the rim and you'll see by this
rule it corresponds to the pressure given for narrower rims, the bead
retaining force being the same for small and large tires.

[email protected]

 

[jim beam]

NiteRider wrote:
> In article <[email protected]>,
> <[email protected]> wrote:
>
>
>>Dear NiteRider,
>>
>>The secret login and password for this site:
>>
>>http://www.tech-mavic.com/
>>
>>is mavic-com and dealer.
>>
>>Security is dreadfully important, so please don't tell
>>anyone else.
>
>
> Thanks. Took a while, but I found the file. Mavic only recommends
> 60-odd psi max for a 2.0 tire, eh? That's pretty low.

jobst is right regarding pressure comparison. 80psi for a 2.0 is too high.

note however that pressure /does/ exert a "separation" load between the
rim beads, in the orientation that the rim is weakest, its extrusion
axis. mavic's pressure limits may not be exactly applicable to all
other rims, but if you follow them, you'll be in a safer ballpark than
where you are presently. if high pressure/lower rolling resistance is
important, consider skinnier tires.