Bam! Rims blow out this morning

[Mark Hickey]

[email protected] wrote:

>Claire Petersky writes:
>
>>> Can you post a link to a photo of the damage? It could be worn out
>>> sidewalls from braking, or it could be cracking due to hard anodizing.
>
> Photos here: http://www.geocities.com/cpetersky/rims.html
>
>> Sorry the pictures are not ideal. I will put up perhaps better ones
>> later, but I have many pressing demands on me this evening. Thank
>> you for your interest and advice.
>
>That helps, but from what I see, this is not a mere weak (worn) rim
>failure but one of bottoming the rim on the road with a soft tire.
>Since it didn't occur as an explosion while riding (the initial flat)
>I believe it was a chafing failure of the tube running in the damaged
>rim. This is the kind of flaw that causes a bang as you noticed when
>fully inflating the tire as you described.

I'm thinking it was just a typical braking surface failure, but that
the hook bead held the rim long enough to deform it when the sidewall
gave way. I don't see the typical "flat spot" where the rim actually
made contact - it's a very gradual bend. I can't imagine that rim
would be rideable had the damage happened on a ride (I doubt it would
clear the brakes, for example).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[Claire Petersky]

"Frank Miles" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>,
> Claire <[email protected]> wrote:

> It does seem that 3500-4500 is quite low for this to occur.

Indeed. When I said I was replacing the wheel a year ago after about 12K on
the wheel, people were screaming about why did my wheel was in such bad
shape after such a short period of time. Now, everyone's saying, well, what
do you expect in the Pacific Northwet?


--
Warm Regards,

Claire Petersky
Home of the meditative cyclist:
http://home.earthlink.net/~cpetersky/Welcome.htm
Personal page: http://www.geocities.com/cpetersky/

I'm doing the Big Climb for my friend Dena! See:
http://www.active.com/donations/campaign_public.cfm?key=cpetersky

 

[RonSonic]

On Fri, 4 Feb 2005 19:25:32 +0100, "Sandy" <[email protected]> wrote:

><[email protected]> a écrit dans le message de :
>news:[email protected]...
>>
>>> And then -- I had this wheel built and put on about a year ago.
>>
>> Wait a minute! When did this occur? You say "And then..." meaning
>> subsequently, but a year ago? This is less clear as it unfolds.
>
>You lack of mastery of common conversational English is apparent here. The
>meaning of "and then" would be clear to you, were that not an inadequacy on
>your part. Pedantry is not a virtue.

It is when we are trying to resolve a technical issue.

I'm a technician, I fix music electronics for a living, this is exactly the sort
of conversation that one has to have. It's a little more awkward over the 'net
than face to face, but if there are going to be any meaningful answers to her
questions then we must do better than conversational English.

Ron

>> I think there is a present, past, and future tense problem here as well.
>
>You are predicting, describing the past, and commenting on the current
>status of the author's syntax ? You are completely unclear here, in your
>own syntax and grammar. Is your glass house well ventilated by fast moving
>pebbles ?




>> Pleas clarify.
>
>Finally, don't take former politicos too seriously - there IS a time to put
>an "e" on the end of some words, such as "pleasE". But not potato.
>
>Relying on your excellent good humour, and that you remain silent on
>subjects you have inadequately grasped.

 

[[email protected]]

[email protected] wrote:
> Claire Petersky writes:
>
> >> Can you post a link to a photo of the damage? It could be worn
out
> >> sidewalls from braking, or it could be cracking due to hard
anodizing.
>
> Photos here: http://www.geocities.com/cpetersky/rims.html
>
<snip>
>
<some of Jobst snipped>
>
> The reason I suspect this scenario is that the bend in the rim bead
is
> too short and has a severe outward curl to have occurred from tire
> pressure. It looks like a crack induced by a snake bite ding in the
> rim. A pressure failure would separate the bead over a long segment
> without curling the rim edge.
>
> Jobst Brandt
> [email protected]

I think I understand Jobst's reasoning - but might it also be a case of
a machined rim that was imperfect to begin with? (A rim worn by the
brake shoes would fail over a longer portion of the rim.) Wouldn't a
rim that was of marginal thickness at one spot, then machined, also
create a shortened failure zone as shown in the photo?

Claire- you still haven't said what brand and model of rim we're
seeing.

Jeff

 

[Luke]

In article <[email protected]>, Mike
Jacoubowsky/Chain Reaction Bicycles <[email protected]> wrote:

> Also, many newer rims now have wear indicators
> built into them... basically, little carved-out spots which indicate, when
> the rim is worn down to the bottom of them, that it's time to replace.

I've not seen these. Would you please post a link or specify a model.

Thanks
luke

 

[Lou Holtman]

Luke wrote:
> In article <[email protected]>, Mike
> Jacoubowsky/Chain Reaction Bicycles <[email protected]> wrote:
>
>
>> Also, many newer rims now have wear indicators
>>built into them... basically, little carved-out spots which indicate, when
>>the rim is worn down to the bottom of them, that it's time to replace.
>
>
> I've not seen these. Would you please post a link or specify a model.
>
> Thanks
> luke


For instance the DT Swiss XR 4.1 rim has wear indicators.

Lou
--
Posted by news://news.nb.nu

 

[Mark Hickey]

"Claire Petersky" <[email protected]> wrote:

>"Frank Miles" <[email protected]> wrote in message
>news:[email protected]...
>> In article <[email protected]>,
>> Claire <[email protected]> wrote:
>
>> It does seem that 3500-4500 is quite low for this to occur.
>
>Indeed. When I said I was replacing the wheel a year ago after about 12K on
>the wheel, people were screaming about why did my wheel was in such bad
>shape after such a short period of time. Now, everyone's saying, well, what
>do you expect in the Pacific Northwet?

It's all relative. If you are wearing out road bike rims in Arizona
(hot and VERY dry for those of you not fortunate enough to have
visited) in 12K miles something would be wrong indeed. Doing the same
while riding in hilly, wet, sloppy terrain would be very normal.

My guess is that those doing the "screaming" had a reference point of
the former scenario, and didn't realize you were living in the latter.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[jim beam]

Claire wrote:
> Yesterday, I got out the bike to ride to work, and the rear tire was
> flat. Not having much spare time, I took the bus instead of dealing
> with it.
>
> This morning, I made sure I had the time. I pulled off the wheel and
> then the tire and tube, and then did the morning meditation of feeling
> for what might be poking through the tire. I pulled out various tiny
> pieces of glass, gravel, and wire, but nothing seemed to have
> penetrated all the way through. I did a more cursory review of the
> tube, and didn't find anything obvious.
>
> Since at this point I was running low on time, I decided to set the
> tube aside for later repair and grab another tube. I put the new tube
> and tire on, and pumped it up. I had just reached the rated pressure of
> 105 when I heard bam!. I thought, "oh ****, I didn't have the tube
> seated properly". I found another yet another tube to put on the bike,
> but upon examination, became clear that the rims had blown out in two
> places.
>
> Do you think that the rim blew out with the initial "bam!", and I just
> didn't notice it? I was in such a tizzy about being increasingly late
> for work, it's certainly possible. And was the initial flat because
> there was something wrong with the rims in the first place?
>
> And then -- I had this wheel built and put on about a year ago. So,
> although there was some wear on the rims, it wasn't a deep groove.
> There's probably only about 3500 - 4000 miles on the wheel. Was this
> blow-out a fault of the wheel builder? I'm going to call him this
> morning and have a talk with him, anyway.
>
> I'm sure glad, if the rims were going to blow out, they did so in my
> hands in the garage, as opposed to while I was screaming down Kamber
> Road at 45 mph in this morning's pouring rain. I'm also glad that the
> ride I'm leading this weekend is a tandem ride, and I'm not dependent
> on this bike as a ride leader.
>
> Warm Regards,
>
>
> Claire Petersky
> Home of the meditative cyclist:
> http://home.earthlink.net/~cpetersky/Welcome.htm
> Personal page: http://www.geocities.com/cpetersky/
>
> I'm doing the Big Climb for my friend Dena! See:
> http://www.active.com/donations/campaign_public.cfm?key=cpetersky
>

claire, it just looks like rim wear. not much a builder could have done
to cause this problem. consider ceramic rims next time. they /are/
designed for this situation.

also, with larger tires, the inflation presure needs to be lower than
smaller ones. there's a table on the mavic web site for instance
showing inflation pressure vs. tire size.

 

[jim beam]

Mike Latondresse wrote:
> [email protected] wrote in
> news:[email protected]:
>
>
>>Mike Latondresse wrote:
>>
>>>Claire, that is more than the mileage I usually get out of a rim
>>
>>before
>>
>>>it starts to bulge....the Pacific NW rainy season really wears
>>>them away.
>>
>>Moreover, it would be helpful to know what kind of rim it was to
>>begin with. (Syntactically speaking- tell us what kind of rim it
>>is. I'll presume that the rim did not magically morph through
>>years of use. Hmmm... alliteration, too.)
>
>
> It has been a variety of rims over the years from the absolutely
> cheapest Campy ones to Muscova 80 which went last fall. Interestingly
> looking at it all the give in the rim was on one side.
>
>>I have a Sun CR-18 rim that has survived many more miles than
>>that, including several Pacific Northwest winters. However, my
>>winter mileage has dropped lately due to my lack of employment.
>>
>
> I commute just a hair over 40k/day and it was the front wheel on my
> fixie, my only brake however most of the others were on a bike with 2
> brakes.
>
have you tried ceramic? sounds like you're a perfect candidate. i ask
because it would be good to get user data onto this group.

 

[Claire Petersky]

"jim beam" <[email protected]> wrote in message
news:1107619132.ac9b2e72c493bd85fe055875d26ac6ec@teranews...

> also, with larger tires, the inflation presure needs to be lower than
> smaller ones. there's a table on the mavic web site for instance
> showing inflation pressure vs. tire size.

I put in the tire what the tires are rated for. I realize what goes on the
sidewall of tire is a struggle between the engineering department and the
marketing department. These particular tires are rated at 105 psi. The exact
same tire used to be rated at a max of 110 psi, so maybe after a while, the
engineers won.

The mavic website, even after going to their site map, was pretty
unpenatrable, so I couldn't find the matrix you describe.

--
Warm Regards,

Claire Petersky
Home of the meditative cyclist:
http://home.earthlink.net/~cpetersky/Welcome.htm
Personal page: http://www.geocities.com/cpetersky/

I'm doing the Big Climb for my friend Dena! See:
http://www.active.com/donations/campaign_public.cfm?key=cpetersky

 

[Claire Petersky]

<[email protected]> wrote in message
news:[email protected]...

> Claire- you still haven't said what brand and model of rim we're
> seeing.

Mavic MA3 "A high quality and affordable classic rim". I had the tire
pressure, as noted in a previous post, at ~105 with 28 mm tires, below the
max rating of 117 psi as noted on the website (I found the matrix).


--
Warm Regards,

Claire Petersky
Home of the meditative cyclist:
http://home.earthlink.net/~cpetersky/Welcome.htm
Personal page: http://www.geocities.com/cpetersky/

I'm doing the Big Climb for my friend Dena! See:
http://www.active.com/donations/campaign_public.cfm?key=cpetersky

 

[RonSonic]

On Sat, 5 Feb 2005 09:23:26 -0800, "Claire Petersky" <[email protected]>
wrote:

><[email protected]> wrote in message
>news:[email protected]...
>
>> Claire- you still haven't said what brand and model of rim we're
>> seeing.
>
>Mavic MA3 "A high quality and affordable classic rim". I had the tire
>pressure, as noted in a previous post, at ~105 with 28 mm tires, below the
>max rating of 117 psi as noted on the website (I found the matrix).


Well it is certainly a classic rim and generally considered about as reliable as
such a thing has ever been.

Even his Jobst approves of them.

Ron

 

[Phil, Squid-in-Training]

"RonSonic" <[email protected]> wrote in message
news:[email protected]...
> On Sat, 5 Feb 2005 09:23:26 -0800, "Claire Petersky"
> <[email protected]>
> wrote:
>
>><[email protected]> wrote in message
>>news:[email protected]...
>>
>>> Claire- you still haven't said what brand and model of rim we're
>>> seeing.
>>
>>Mavic MA3 "A high quality and affordable classic rim". I had the tire
>>pressure, as noted in a previous post, at ~105 with 28 mm tires, below the
>>max rating of 117 psi as noted on the website (I found the matrix).
>
>
> Well it is certainly a classic rim and generally considered about as
> reliable as
> such a thing has ever been.
>
> Even his Jobst approves of them.


MA2s, actually.

--
Phil, Squid-in-Training

 

[Phil, Squid-in-Training]

"Luke" <[email protected]> wrote in message
news:050220050527203588%[email protected]...
> In article <[email protected]>, Mike
> Jacoubowsky/Chain Reaction Bicycles <[email protected]> wrote:
>
>> Also, many newer rims now have wear indicators
>> built into them... basically, little carved-out spots which indicate,
>> when
>> the rim is worn down to the bottom of them, that it's time to replace.
>
> I've not seen these. Would you please post a link or specify a model.

http://alexrims.com/rims/ma_crostm11.htm

--
Phil, Squid-in-Training

 

[Mike Latondresse]

jim beam <[email protected]> wrote in
news:1107620546.3f7e84a65b5e5273f90ec0e0076baee6@teranews:

>> I commute just a hair over 40k/day and it was the front wheel on
>> my fixie, my only brake however most of the others were on a bike
>> with 2 brakes.
>>
> have you tried ceramic? sounds like you're a perfect candidate.
> i ask because it would be good to get user data onto this group.
>
>
No a little too expensive for me. I either buy the cheapest rim I can
find or recycle reasonable old ones I can scrounge, like the 3
Moscovas I have ready to go.

 

[[email protected]]

Phil Lee writes:

>>> Also, many newer rims now have wear indicators built into
>>> them... basically, little carved-out spots which indicate, when
>>> the rim is worn down to the bottom of them, that it's time to
>>> replace.

>> I've not seen these. Would you please post a link or specify a
>> model.

> http://alexrims.com/rims/ma_crostm11.htm

That isn't a road rim is it? At that width and weight I don't see
what market they are playing to. The description also sounds like
second hand work. These people don't know the difference between an
eyelet and a socket retained by an eyelet. It wouldn't be hard to
include a spoke socket location in a web picture or for that matter a
cross section drawing as was common in the days of yore when people
were still able to understand a B&W 2-D picture.

This rim seems to have all the maladies of modern times, welding,
machining and anodizing.

Jobst Brandt
[email protected]

 

[[email protected]]

Mark Hickey writes:

>>>> Can you post a link to a photo of the damage? It could be worn
>>>> out sidewalls from braking, or it could be cracking due to hard
>>>> anodizing.

Photos here: http://www.geocities.com/cpetersky/rims.html

>>> Sorry the pictures are not ideal. I will put up perhaps better
>>> ones later, but I have many pressing demands on me this
>>> evening. Thank you for your interest and advice.

>> That helps, but from what I see, this is not a mere weak (worn) rim
>> failure but one of bottoming the rim on the road with a soft tire.
>> Since it didn't occur as an explosion while riding (the initial
>> flat) I believe it was a chafing failure of the tube running in the
>> damaged rim. This is the kind of flaw that causes a bang as you
>> noticed when fully inflating the tire as you described.

> I'm thinking it was just a typical braking surface failure, but that
> the hook bead held the rim long enough to deform it when the
> sidewall gave way. I don't see the typical "flat spot" where the
> rim actually made contact - it's a very gradual bend. I can't
> imagine that rim would be ridable had the damage happened on a ride
> (I doubt it would clear the brakes, for example).

It was and it did through the reason for the flat in the first place.
Pressure was low enough that the snake bite occurred and not high
enough to cause a blowout. The rest of the air escaped overnight
through the minimal perforation.

As I mentioned, the bend is too short and the bead curl inexplicable
from anything but a bottoming impact of the tire. That the rim has a
crack is secondary to this incident. It only made bead deformation
easier. This also explains why the flat was only detected the next
day. It was a marginal snakebite that was apparently not diagnosed
when inspecting the tube with the leak.

Snake bites are unambiguously detectable by tire casing cord imprints
surrounding the puncture in tube rubber. Grazing incidence light and,
if need be, magnification will show 45 degree cord impressions in the
tube. Do it!

Jobst Brandt
[email protected]

 

[Tim McNamara]

RonSonic <[email protected]> writes:

> On Sat, 5 Feb 2005 09:23:26 -0800, "Claire Petersky"
> <[email protected]>
> wrote:
>
>><[email protected]> wrote in message
>>news:[email protected]...
>>
>>> Claire- you still haven't said what brand and model of rim we're
>>> seeing.
>>
>>Mavic MA3 "A high quality and affordable classic rim". I had the
>>tire pressure, as noted in a previous post, at ~105 with 28 mm
>>tires, below the max rating of 117 psi as noted on the website (I
>>found the matrix).

That's the "max" pressure rating for those rims? In a world where 120
psi is pretty much normal, that's odd. But the Mavic is very, very
good at placing the blame for the failures of their products onto
others. They have many aplogists in these newsgroups who volunteer to
help them with that, which is nice I guess.

> Well it is certainly a classic rim and generally considered about as
> reliable as such a thing has ever been.
>
> Even his Jobst approves of them.

Yes, his actual quote IIRC was "they are dogs." I guess that could be
construed as a good thing, if you like dogs. Perhaps you were
thinking of MA2s, which Jobst does speak very highly about.

 

[jim beam]

Mike Latondresse wrote:
> jim beam <[email protected]> wrote in
> news:1107620546.3f7e84a65b5e5273f90ec0e0076baee6@teranews:
>
>
>>>I commute just a hair over 40k/day and it was the front wheel on
>>>my fixie, my only brake however most of the others were on a bike
>>>with 2 brakes.
>>>
>>
>>have you tried ceramic? sounds like you're a perfect candidate.
>>i ask because it would be good to get user data onto this group.
>>
>>
>
> No a little too expensive for me. I either buy the cheapest rim I can
> find or recycle reasonable old ones I can scrounge, like the 3
> Moscovas I have ready to go.
>
even if ceramics last [say] 3 times as long?

 

[jim beam]

Claire Petersky wrote:
> "jim beam" <[email protected]> wrote in message
> news:1107619132.ac9b2e72c493bd85fe055875d26ac6ec@teranews...
>
>
>>also, with larger tires, the inflation presure needs to be lower than
>>smaller ones. there's a table on the mavic web site for instance
>>showing inflation pressure vs. tire size.
>
>
> I put in the tire what the tires are rated for. I realize what goes on the
> sidewall of tire is a struggle between the engineering department and the
> marketing department. These particular tires are rated at 105 psi. The exact
> same tire used to be rated at a max of 110 psi, so maybe after a while, the
> engineers won.

ok, but the tire's rating has nothing to do with the rim rating, the
component that failed.

>
> The mavic website, even after going to their site map, was pretty
> unpenatrable, so I couldn't find the matrix you describe.
>
for the mavic ma3:
TIRE SIZE MAXIMUM PRESSURE
mm bars psi
19 10.00 146.00
23 9.50 138.00
25 9.00 131.00
28 8.00 117.00

from:
http://www.mavic.com/servlet/srt/mavic/road-prod_fiche?product.id=55&lg=uk

can't see what your rims are so they may have a different rating, but
you can see the correlation with max pressure vs. tire size.