mavic rims don't *all* suck

Discussion in 'Cycling Equipment' started by Dvt, Feb 26, 2004.

  1. Werehatrack

    Werehatrack Guest

    On Sat, 28 Feb 2004 01:41:16 GMT, [email protected] may
    have said:

    >I have a calibrated thumb and forefinger that I pass over the rim in a brake caliper manner feeling
    >the hollow cheeks of the rim. I know how .5mm wall feels.

    I my days of building performance engines, I used to joke about my "eyecrometer"; with experience,
    organic tools can be amazingly accurate.

    --
    My email address is antispammed; pull WEEDS if replying via e-mail.
    Typoes are not a bug, they're a feature.
    Words processed in a facility that contains nuts.
     


  2. Werehatrack

    Werehatrack Guest

    On Sun, 29 Feb 2004 06:07:00 GMT, [email protected] may
    have said:

    >Werehatrack <[email protected]> writes:
    >
    >>>> Have you inspected the flanges on the *inside* for signs of cracks around the rest of the
    >>>> circumference of the wheel? I'm betting that you'll find that you have more than just the two
    >>>> which precipitated the failures.
    >
    >>> I don't see any cracks. The inside of the flanges is pretty gooped up with Velox adhesive, so
    >>> the cracks may be disguised.
    >
    >> That's quite possible. It's probably academic, though, since the rim is obviously going to be out
    >> of service anyway. Even if there were cracks that could have been found, it's unlikely that they
    >> would have been spotted prior to the failure since it's not like you're going to rip a good sew-
    >> up off of the wheel just to inspect the flanges periodically.
    >
    >As far as I could see, this is a clincher rim

    Yes, correct; I must have been half asleep; I missed the "velox" and just saw "adhesive". Still, I
    doubt that the average owner would expect to need to be observant for this specific type of failure.
    And, to make matters worse, would the dark anodizing not tend to make such a crack harder to spot?

    --
    My email address is antispammed; pull WEEDS if replying via e-mail.
    Typoes are not a bug, they're a feature.
    Words processed in a facility that contains nuts.
     
  3. Jim Beam

    Jim Beam Guest

    [email protected] wrote:
    > Werehatrack <[email protected]> writes:
    >
    >
    >>>> Have you inspected the flanges on the *inside* for signs of cracks around the rest of the
    >>>> circumference of the wheel? I'm betting that you'll find that you have more than just the two
    >>>> which precipitated the failures.
    >
    >
    >>>I don't see any cracks. The inside of the flanges is pretty gooped up with Velox adhesive, so the
    >>>cracks may be disguised.
    >
    >
    >
    >>That's quite possible. It's probably academic, though, since the rim is obviously going to be out
    >>of service anyway. Even if there were cracks that could have been found, it's unlikely that they
    >>would have been spotted prior to the failure since it's not like you're going to rip a good sew-up
    >>off of the wheel just to inspect the flanges periodically.
    >
    >
    > As far as I could see, this is a clincher rim and the crack should be detectable on the outside
    > when it first developed. As was mentioned, it grew and failed while parked, so it must have been
    > there before it was parked. In any case, with many years of no anodized rims, such failures did
    > not occur to any of the many bikies in our area. In contrast, with the advent of dark anodized
    > rims, they occurred often.

    you keep making this allegation jobst, but the only "evidence" i've ever seen you present that
    "supports" your "anodizing induced fatigue" theory is dye penetrant testing. all dye penetration
    does is tell you whether there is a crack detectable by that means. it does *NOT* analyze cause.

    you also make the [il]logical jump from the presence of a dye penetrant positive to the complete
    diagnosis of its initiation, propagation & eventual failure. you've never addressed the effects of
    alloy composition, environment or even spoke tension on your analysis - you merely assert that "it
    never used to happen before... so i therefore conclude that... ". that's not complete analysis and
    certainly no causal definition.

    in the case of the above photos, which while they are too unfocused to show conclusive evidence of
    anything, /do/ arguably show some intergranular cracking features. intergranular cracking is /not/
    typical of fatigue, whether it be anodizing induced or not.

    in short, this is probably a complex failure. asserting guesswork pertaining to only one particular
    potential failure element is amateurish. you fail to differentiate between different anodizing
    processes. what you probably are trying to say is that hard anodizing induced cracking, but instead
    you use the term "dark" anodizing, which is too broad a definition and includes cosmetic processing.
    normal anodizing that has been dyed is no worse than clear anodizing - and clear anodizing is not a
    problem as evidenced by the vast quantities of clear anodized ma2's that were sold. failure to
    differentiate between normal protective [and cosmetic] anodizing & hard anodizing merely serves to
    undermine you.

    >
    > Jobst Brandt [email protected]
     
  4. Mike S.

    Mike S. Guest

    <[email protected]> wrote in message
    news:[email protected]...
    > Werehatrack <[email protected]> writes:
    >
    > >>> Have you inspected the flanges on the *inside* for signs of cracks around the rest of the
    > >>> circumference of the wheel? I'm betting that you'll find that you have more than just the two
    > >>> which precipitated the failures.
    >
    > >> I don't see any cracks. The inside of the flanges is pretty gooped up with Velox adhesive, so
    > >> the cracks may be disguised.
    >
    > > That's quite possible. It's probably academic, though, since the rim is obviously going to be
    > > out of service anyway. Even if there were cracks that could have been found, it's unlikely that
    > > they would have been spotted prior to the failure since it's not like you're going to rip a good
    > > sew-up off of the wheel just to inspect the flanges periodically.
    >
    > As far as I could see, this is a clincher rim and the crack should be detectable on the outside
    > when it first developed. As was mentioned, it grew and failed while parked, so it must have been
    > there before it was parked. In any case, with many years of no anodized rims, such failures did
    > not occur to any of the many bikies in our area. In contrast, with the advent of dark anodized
    > rims, they occurred often.
    >
    > Jobst Brandt [email protected]

    Hey Jobst,

    How many of those rims that never failed were actually clinchers? Yah, I know you love MA2s,
    but the rest?

    What were the percentage of people riding tubulars vs. clinchers?

    Ya think that maybe, just maybe, that some sidewall failures may have something to do with about a
    cm of unsupported metal being stressed by holding together a clincher inflated to 110psi+?

    Next question: what weight were those clincher rims that never failed? 400g, 500g?

    Just curious... since I haven't been studying stuff like this for as long as you have.

    Mike
     
  5. Carl Fogel

    Carl Fogel Guest

    [email protected] wrote in message news:<[email protected]>...
    > Carl Fogel writes:
    >
    > >> The whole point of this thread is that no matter how thick the sidewalls, rims no longer last
    > >> until the wear limit is reached -- they crack first.
    >
    > > Dear Matt,
    >
    > > You may need to explain what you mean. (Try to be patient with everyone who jumps on you.)
    >
    > > Are you saying that you expect anodized rims to crack elsewhere before the rims fail because of
    > > brake wear? (Cracks, for example, around spoke holes, or cracks around the rim not related to
    > > brake-worn areas. Are there such cracks in these pictures?)
    >
    > > Or do you expect anodized rims to crack in the brake area before normal brake wear should ruin
    > > them? (Anodizing is usually removed from brake areas, either by the machining process or else by
    > > normal brake wear, but it might somehow still be involved.)
    >
    > The rim in question was not worn thin, certainly not thin enough to fail from the experience I
    > have with observing anodized rim failures at local bicycle shops and among the riders with whom I
    > have ridden. The cross section of the failed subject rim is evident from the separation photos
    > that show at least 1mm thickness.
    >
    > > Despite its title, this thread has no point. Dave just asked us all to look at pictures of his
    > > failed rim and to try to figure out why it failed. Is the culprit anodization, brake wear, a
    > > combination of the two, or something else?
    >
    > He also made the claim in contrast to other postings that these rims do not fail in a dange4ous
    > manner. That is the bone of contention. I brought that up and there is apparently no argument with
    > my contention that this is as dangerous a failure as one can encounter. To visualize the danger
    > one must either ride in traffic or descend mountain roads that border precipices.
    >
    > > Personally, I think that an awful lot of questions need to be asked about Dave's sons. The
    > > sudden failure of metal objects, including anvils, is often noticed when children appear.
    >
    > Is this an attempt at humor or are you insinuating that Dave is blind to hazards?
    >
    > Jobst Brandt [email protected]

    Dear Jobst,

    I have a hideous suspicion that I just accidentally posted a list of potential questions as a reply
    to your post.

    I was working through the questions in another window, eliminating most of them as foolish and the
    rest as ill-natured, when the original vanished in a manner that suggests that it escaped into the
    newsgroup.

    If there is such a previous post, probably unsigned, consider it a glimpse into raw workings of an
    unbalanced mind and ignore it as you would the mutterings of Tourette's syndrome.

    Ruefully,

    Carl Fogel
     
  6. Carl Fogel

    Carl Fogel Guest

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

    [snip]

    >
    > I don't remember if my RM20s were anodized or not. I had the sidewalls blow out from being too
    > thin. Appx a 6" section of brake track pulled away from the rest of the rim. I could tell that
    > they were on their last legs 'cause the brake track was concave.
    >
    > Being a broke college student, I figured I'd ride them till they broke anyway.
    >
    > Mike

    Dear Mike,

    My 1994 Pedal Pusher BikePro catalogue has a two-page rim table and lists Araya RM-20 rims in 24"
    and 26" with oodles of details (eighteen columns).

    Two kinds of surface treatment are listed for the Araya RM-20 rims, Anodized (silver, clear) and
    Hard Anodized (gray and other colors).

    "Hard anodizing is the same electrical process performed at a higher voltage in a different acid
    bath. It delivers a thickening of the hardened surface layer to a greater depth in the metal's
    surface. Hard anodizing is said to increase a rim's rigidity between 10 and 20 per cent. Somehow
    that seems a little high, but it certainly adds something to a rim's weight, as the Rim Table
    demonstrates."

    The table lists the 36-hole Araya RM-20 26" rim as weighing 509 grams after clear-silver anodizing,
    533 grams after gray-hard anodizing. Oxidation is fattening.

    About fifty rims are listed in the table on two small-print pages, and there are eight three-column
    pages of detailed comments on the manufacturing process, with pictures of each rim's cross-section,
    label, and spoke-bed.

    Interestingly, the detail on the Mavic Open SUP CD hard anodized finish lists this step (there's
    lots more):

    "The Open SUP uses a two-piece, double wall stainless steel eyelet to equalize spoke nipple stress
    and help prevent spoke nipple pull-through failure. Both eyelet pieces are stamped from sheet
    stainless steel, the upper eyelet piece is cup shaped, while the lower eyelet piece takes the form
    of a hollow rivet. The upper piece, having an oval flange, is inserted into the spoke hole from the
    interior, or tire side. Because of the heigh between the cross-tie and spoke bed walls, the upper
    steel eyelet cup is taller than occurs on many other double wall eyelets.. The lower piece is set
    into the upper cup piece, with the lower piece protruding through the spoke bed wall. Force is
    applied to the top of the lower piece so a mandrel can flare the lower piece into a smooth round
    blossom that now holds both eyelet pieces firmly within the outer walls of the cross-tie and spoke
    bed walls. The spoke bed wall on the Maciv Open SUP showed no post machining distortion from this
    peening process."

    This sounds as if Mavic squashed the eyelets of Dave's SUP into place on the rim harder than most
    manufacturers after anodizing, but BikePro noticed no obvious damage in the way of cracks or
    distortion.

    If anyone has questions about rims that might be in the 1994 catalogue, I'll be glad to look them
    up. Unfortunately, they're in such tiny print and hide behind so many pink background overlays that
    scanning hasn't produced useful pictures.

    Carl Fogel
     
  7. Carl Fogel

    Carl Fogel Guest

    [email protected] wrote in message news:<[email protected]>...
    > Carl Fogel writes:
    >
    > >> The whole point of this thread is that no matter how thick the sidewalls, rims no longer last
    > >> until the wear limit is reached -- they crack first.
    >
    > > Dear Matt,
    >
    > > You may need to explain what you mean. (Try to be patient with everyone who jumps on you.)
    >
    > > Are you saying that you expect anodized rims to crack elsewhere before the rims fail because of
    > > brake wear? (Cracks, for example, around spoke holes, or cracks around the rim not related to
    > > brake-worn areas. Are there such cracks in these pictures?)
    >
    > > Or do you expect anodized rims to crack in the brake area before normal brake wear should ruin
    > > them? (Anodizing is usually removed from brake areas, either by the machining process or else by
    > > normal brake wear, but it might somehow still be involved.)
    >
    > The rim in question was not worn thin, certainly not thin enough to fail from the experience I
    > have with observing anodized rim failures at local bicycle shops and among the riders with whom I
    > have ridden. The cross section of the failed subject rim is evident from the separation photos
    > that show at least 1mm thickness.
    >
    > > Despite its title, this thread has no point. Dave just asked us all to look at pictures of his
    > > failed rim and to try to figure out why it failed. Is the culprit anodization, brake wear, a
    > > combination of the two, or something else?
    >
    > He also made the claim in contrast to other postings that these rims do not fail in a dange4ous
    > manner. That is the bone of contention. I brought that up and there is apparently no argument with
    > my contention that this is as dangerous a failure as one can encounter. To visualize the danger
    > one must either ride in traffic or descend mountain roads that border precipices.
    >
    > > Personally, I think that an awful lot of questions need to be asked about Dave's sons. The
    > > sudden failure of metal objects, including anvils, is often noticed when children appear.
    >
    > Is this an attempt at humor or are you insinuating that Dave is blind to hazards?
    >
    > Jobst Brandt [email protected]

    Dear Jobst,

    Elsewhere in this thread, Dave wrote:

    "The braking surface is definitely concave. The braking surface *did* show significant wear. I don't
    know if it was excessive. How thin does a wall need to be in good aluminum? I don't know how thick
    the wall was when the rim was new, so I can't comment on the change in thicknes. I could measure the
    remaining wall thickness."

    Dave also wrote:

    "These sidewalls are ~1.5-1.8 mm thick at the crack."

    "How do you know when to replace a rim? Concavity in the brake wall? Do you measure the wall
    thickness? Based on your earlier post, I don't think you wait until they crack."

    Your answer to this question seemed about as serious as my suspicions concerning Dave's sons:

    "I have a calibrated thumb and forefinger that I pass over the rim in a brake caliper manner feeling
    the hollow cheeks of the rim."

    Seriously, how do you know when to replace a rim? I seem to recall reading elsewhere on
    rec.bicycles.tech about worn rims bending outward, but pictures like the ones mentioned in the post
    below make me wonder how effective that is:

    [start post]

    From: un smowler <[email protected]> To: [email protected] Subject: Worn Out Rims Date: Tue,
    11 Nov 2003 18:53:25 -0800 (PST)

    Carl: I've been reading some of the RBT threads for lunchtime diversion recently. I was surprised
    that folks with much more cycling experience than mine had never seen worn out rims before. Attached
    are photos of a completely depreciated Mavic 221 rim. Its life was just over 2 seasons of mountain
    biking in southern Maine. For me a season is 6-7 months, 2 to 3 rides/week, 2-3 hours/ride. It's
    about typical rim life for me, only the failure mode is unusual. Usually I replace rims when they've
    gotten a major ding, which becomes easier and easier to do as the rim wears. This one somehow never
    got that abuse. It failed while I was trying to seat a studded tire, at about 60 psi. As an outcome,
    I have gotten a bit quicker to replace rims when they start to flare out, and keep ear protectors
    handy by the floor pump!

    Feel free to quote me when you post the pics. Dave D

    Dear Dave,

    Here are your pictures of the failed rim:

    http://home.comcast.net/~carlfogel/download/rim.jpg
    http://home.comcast.net/~carlfogel/download/rimdetail.jpg

    Thanks!

    Carl Fogel

    [end post]

    Jobst, do you (or anyone else) have any close-up pictures of brake-wear failures on unanodized rims
    that could be put up for comparison with Dave's rim pictures? The ones of the Mavic 221, although
    dramatic, aren't nearly detailed enough to show the edges where things tore.

    (I'd also like to know if unsmowler has any small children. I can't tell for sure, but some of the
    damage looks like tooth-marks.)

    Carl Fogel
     
  8. Carl Fogel wrote:

    > Your answer to this question seemed about as serious as my suspicions concerning Dave's sons:
    >
    > "I have a calibrated thumb and forefinger that I pass over the rim in a brake caliper manner
    > feeling the hollow cheeks of the rim."
    >
    > Seriously, how do you know when to replace a rim?

    I think he *was* being serious. With experience, I suspect one can judge this sort of thing to
    sufficient accuracy. Those of us without such experience must presumably resort to calipers.

    --
    Benjamin Lewis

    "Love is a snowmobile racing across the tundra and then suddenly it flips over, pinning you
    underneath. At night, the ice weasels come." --Matt Groening
     
  9. Jobst Brandt

    Jobst Brandt Guest

    jim beam snipes intoxicatedly:

    >>> That's quite possible. It's probably academic, though, since the rim is obviously going to be
    >>> out of service anyway. Even if there were cracks that could have been found, it's unlikely that
    >>> they would have been spotted prior to the failure since it's not like you're going to rip a good
    >>> sew-up off of the wheel just to inspect the flanges periodically.

    >> As far as I could see, this is a clincher rim and the crack should be detectable on the outside
    >> when it first developed. As was mentioned, it grew and failed while parked, so it must have been
    >> there before it was parked. In any case, with many years of no anodized rims, such failures did
    >> not occur to any of the many bikies in our area. In contrast, with the advent of dark anodized
    >> rims, they occurred often.

    > you keep making this allegation jobst, but the only "evidence" i've ever seen you present that
    > "supports" your "anodizing induced fatigue" theory is dye penetrant testing. all dye penetration
    > does is tell you whether there is a crack detectable by that means. it does *NOT* analyze cause.

    What are you talking about. I have never mentioned dye penetration. What's more, you ignore that
    cracked rims were brought to us primarily on the day Mavic offered the MA-40, a version of rim that
    not anodized precursor (MA-2) is still performing well with no cracks and no fear of cracking. You
    may not have ridden bicycles in the days before anodized rims and the greater durability claimed for
    them. Those of us who recall that day also remember how cracked rims were everywhere after that.
    Reducing the anodizing thickness has ameliorated that a little.

    > you also make the [il]logical jump from the presence of a dye penetrant positive to the complete
    > diagnosis of its initiation, propagation & eventual failure. you've never addressed the effects of
    > alloy composition, environment or even spoke tension on your analysis - you merely assert that "it
    > never used to happen before... so i therefore conclude that... ". that's not complete analysis and
    > certainly no causal definition.

    OK, so why do we have, as you seem to imply, poorer alloys today than in the 1950's when none of
    these failures occurred even though average roads were rougher in those days? So you are claiming
    that rims crack not because they are anodized but rather that they are made of less suitable
    alloys... even though the MA-2 and MA-40 were the same extrusion to begin with.

    > in the case of the above photos, which while they are too unfocused to show conclusive evidence of
    > anything, /do/ arguably show some intergranular cracking features.

    You're dodging. With experience in rims, you could readily make an accurate assessment of this
    failure, knowing that such events were unknown before anodizing. Besides, claiming that it couldn't
    be caused by anodizing because it was worn off, as some have opined, misses the point that the crack
    opens in tension, inside the profile, not from the outside (brake surface) that failed last in
    forced rupture.

    > intergranular cracking is /not/ typical of fatigue, whether it be anodizing induced or not.

    OH? You also don't recall the days of failed parts on older cars where axles often broke to expose
    intergranular failure from which mechanics of the day were led to say, "your axle was too old, it
    crystallized" which they went on to show by the surface of the fracture. Forced ruptures are smeared
    and fine in texture, fatigue failures are rough and crystalline in aluminum used here.

    > in short, this is probably a complex failure. asserting guesswork pertaining to only one
    > particular potential failure element is amateurish. you fail to differentiate between different
    > anodizing processes. what you probably are trying to say is that hard anodizing induced cracking,
    > but instead you use the term "dark" anodizing, which is too broad a definition and includes
    > cosmetic processing. normal anodizing that has been dyed is no worse than clear anodizing - and
    > clear anodizing is not a problem as evidenced by the vast quantities of clear anodized ma2's that
    > were sold. failure to differentiate between normal protective [and cosmetic] anodizing & hard
    > anodizing merely serves to undermine you.

    Scraping a knife over either kind of anodizing without penetrating force, you will find a hard crust
    that resists scratching. You can also inspect such surfaces under grazing incidence light and see
    cracks in both hard anodizing and cosmetic anodizing. Your method of attacking straw men does not do
    much convincing for those who are aware of these techniques of argumentation. I haven't seen you
    point out why these rims crack other than saying that it isn't anodizing.

    When are you going to find the shift key on your KBD? Your modernist lower case writing is
    tedious to read.

    Jobst Brandt [email protected]
     
  10. Jobst Brandt

    Jobst Brandt Guest

    Mike Shaw writes:

    >> As far as I could see, this is a clincher rim and the crack should be detectable on the outside
    >> when it first developed. As was mentioned, it grew and failed while parked, so it must have been
    >> there before it was parked. In any case, with many years of no anodized rims, such failures did
    >> not occur to any of the many bikies in our area. In contrast, with the advent of dark anodized
    >> rims, they occurred often.

    > Hey Jobst,

    > How many of those rims that never failed were actually clinchers? Yah, I know you love MA2s, but
    > the rest?

    I haven't thrown many rims away other than the ones I inspected at the local bicycle shops,
    Wheelsmith, Palo Alto Bicycles, Bicycle Outfitter and some others. Therefore I have a stack of about
    40 rims, among them some tubulars that I can inspect and not find sidewall cracking. At best there
    are some that had short in-line cracks at the eyelets that ceased to grow because the steel socket
    inside took up the load and served until the rim was retired either for worn brake faces or dents.
    Along with anodizing, un-socketed rims are and additional hazard.

    > What were the percentage of people riding tubulars vs. clinchers?

    What does it matter other than more red herrings. This gets tiresome. How about explaining in plain
    English what causes these failures in contrast to rims that were not anodized instead of attacking
    any and all analyses of what we see.

    > Ya think that maybe, just maybe, that some sidewall failures may have something to do with about a
    > cm of unsupported metal being stressed by holding together a clincher inflated to 110psi+?

    No! I do that all the time.

    > Next question: what weight were those clincher rims that never failed? 400g, 500g?

    Exactly the same as the anodized version that failed. I guess you haven't been reading any of this
    over the last 10 years.

    > Just curious... since I haven't been studying stuff like this for as long as you have.

    You might Google into the reams of discourse prompted by anodizing enthusiasts like you.

    Jobst Brandt [email protected]
     
  11. Jobst Brandt

    Jobst Brandt Guest

    Carl Fogel writes:

    > Jobst, do you (or anyone else) have any close-up pictures of brake-wear failures on unanodized
    > rims that could be put up for comparison with Dave's rim pictures? The ones of the Mavic 221,
    > although dramatic, aren't nearly detailed enough to show the edges where things tore.

    I don't have any among all the worn and dented rims in my collection, none of which are anodized.
    The claim that rims bend outwards when they wear thin, in my experience, is an incorrect assessment.
    These rims have been worn hollow and to casual observance appear to be flared out. My worn out rims
    looked that way too but were in fact unchanged when measured internally.

    Jobst Brandt [email protected]
     
  12. Jobst Brandt

    Jobst Brandt Guest

    Benjamin Lewis writes:

    >> Your answer to this question seemed about as serious as my suspicions concerning Dave's sons:

    >> "I have a calibrated thumb and forefinger that I pass over the rim in a brake caliper manner
    >> feeling the hollow cheeks of the rim."

    >> Seriously, how do you know when to replace a rim?

    > I think he *was* being serious. With experience, I suspect one can judge this sort of thing to
    > sufficient accuracy. Those of us without such experience must presumably resort to calipers.

    Since the bead crown of the rim does not wear with reasonably adjusted brakes, measuring with
    calipers and knowing that the original wall thickness was 1.5mm, the resulting wall can be
    assessed within reason. As I said, this can also be done by wiping thumb and forefinger across the
    brake track.

    Jobst Brandt [email protected]
     
  13. Jim Beam

    Jim Beam Guest

    [email protected] wrote: <snip>
    > What are you talking about. I have never mentioned dye penetration. What's more, you ignore that
    > cracked rims were brought to us primarily on the day Mavic offered the MA-40, a version of rim
    > that not anodized precursor (MA-2) is still performing well with no cracks and no fear of
    > cracking. You may not have ridden bicycles in the days before anodized rims and the greater
    > durability claimed for them. Those of us who recall that day also remember how cracked rims were
    > everywhere after that. Reducing the anodizing thickness has ameliorated that a little.

    "I have never mentioned dye penetration." well, it's certainly what you were referring to here:

    http://groups.google.com/groups?selm=9%25x_a.11466%24dk4.433979%40typhoon.sonic.net&oe=UTF-
    8&output=gplain

    either you have done dye penetrant testing for cracks in rims or you haven't. which is it?

    in addition, you assert that the ma2 is not anodized. it most definitely was available in clear
    anodized. i have one. in fact, i've even taken the trouble to specifically look for ma2's since we
    first started this little love-fest, and guess what? only 1 of the 30-odd silver ma2's i have
    inspected has been unanodized, [and that had corrosion issues]. so, while you may be the guy that
    managed to stockpile the last of the small number of unanodized ma2's that were ever imported, the
    poor unsuspecting masses have had to put up with clear anodized ma2's, so kindly adjust your
    rhetoric. and if you still don't believe me, take a look at the old mavic catalog for confirmation
    of the silver anodized ma2's existence.

    <snip>
    > OK, so why do we have, as you seem to imply, poorer alloys today than in the 1950's when none of
    > these failures occurred even though average roads were rougher in those days? So you are claiming
    > that rims crack not because they are anodized but rather that they are made of less suitable
    > alloys... even though the MA-2 and MA-40 were the same extrusion to begin with.

    your implication, not mine. modern alloys have much better yield &
    u.t.s. with better weldability. "suitability" depends on the overall objective. if you want a rim
    that is strong enough to deal with ultra-dished wheels and lower spoke counts, than yes,
    modern alloys are better. as a component whose predominant failure mode [outside of sunny
    california] is braking surface wear, i see no problem with having a rim have a higher chance
    of cracking at higher mileage if physical wear predominates and the other primary design
    criteria are better met.

    <snip>
    > You're dodging. With experience in rims, you could readily make an accurate assessment of this
    > failure, knowing that such events were unknown before anodizing. Besides, claiming that it
    > couldn't be caused by anodizing because it was worn off, as some have opined, misses the point
    > that the crack opens in tension, inside the profile, not from the outside (brake surface) that
    > failed last in forced rupture.

    dodging what? those pics are inconclusive. unless you are telling us that you've had an identical
    failure and that it's been properly analyzed by an appropriate specialist, then you can't feed us
    what then amounts to conjecture and guesswork. your assertion that "such events were unknown before
    anodizing" makes absolutely no account of changes in alloy, heat treatment, eyelet design, etc. etc.
    it's just a wildly emotive statement.

    snip>
    > OH? You also don't recall the days of failed parts on older cars where axles often broke to expose
    > intergranular failure from which mechanics of the day were led to say, "your axle was too old, it
    > crystallized" which they went on to show by the surface of the fracture. Forced ruptures are
    > smeared and fine in texture, fatigue failures are rough and crystalline in aluminum used here.

    since when did a hot [or cold] forged carbon steel axle have the same microstructure as an extruded
    alloy rim? what effect does carbon diffusion have on this extruded alloy rim? how about sulfides?
    this is a complete red herring.

    <snip>
    > Scraping a knife over either kind of anodizing without penetrating force, you will find a hard
    > crust that resists scratching. You can also inspect such surfaces under grazing incidence light
    > and see cracks in both hard anodizing and cosmetic anodizing. Your method of attacking straw men
    > does not do much convincing for those who are aware of these techniques of argumentation. I
    > haven't seen you point out why these rims crack other than saying that it isn't anodizing.

    what you are saying jobst, yet again, is that there is only one element in this failure equation,
    anodizing, and i am telling you, yet again, that it's not as simple as that. there are many
    elements, which do include anodizing, but also include alloy composition, heat treatment, hot & cold
    work history, mechanical design and chemical environment. to make a blanket statement essentially
    saying "it's anodizing - end of story" is as accurate as your mechanic saying "your axle was too
    old, it crystallized".
     
  14. Dvt

    Dvt Guest

    [email protected] wrote:
    > He [Dave] also made the claim in contrast to other postings that these rims do not fail in a
    > dange4ous manner.

    I don't think I said that, or anything that resembles that. I *did* say that the rim was probably
    worn enough to be retired, and I probably should have retired it earlier.

    > To visualize the danger one must either ride in traffic or descend mountain roads that border
    > precipices.

    Just did both of those today. Routine. As a matter of fact, remember the snowbank episode I
    mentioned earlier? Good thing for the snowbank. It kept me from falling off one of those precipices.

    Dave dvt at psu dot edu
     
  15. Carl Fogel

    Carl Fogel Guest

    "James Thomson" <[email protected]> wrote in message news:<[email protected]>...
    > "Carl Fogel" <[email protected]> wrote:
    >
    > > My 1994 Pedal Pusher BikePro catalogue has a two-page rim table and lists Araya RM-20 rims in
    > > 24" and 26" with oodles of details (eighteen columns).
    >
    > The BikePro catalogue is still available online. It hasn't been updated in many years, and as a
    > result is one of the best sources of detailed information on older components.
    >
    > http://www.bikepro.com/products/rims/rims.html http://www.bikepro.com/guide.html
    >
    > James Thomson

    Dear James,

    I'll be damned--you're right, there it is. It never occurred to me that they were still online.

    There's an interesting section on how Japanese and U.S. hard anodizing differs at the very end of:

    http://www.bikepro.com/products/metals/alum.html

    Thanks,

    Carl Fogel
     
  16. Jobst Brandt

    Jobst Brandt Guest

    Dave vt writes:

    >> He [Dave] also made the claim in contrast to other postings that these rims do not fail in a
    >> dangerous manner.

    > I don't think I said that, or anything that resembles that. I *did* say that the rim was probably
    > worn enough to be retired, and I probably should have retired it earlier.

    These lines are from the posting where you said you have no complaints about the longevity of the
    rim and my response to that. I think it "resembles that" especially under the title "mavic rims
    don't *all* suck"

    -----------------------------------------------------------------------
    > This Mavic Open SUP CD rim from 1993 failed after 10's of thousands of miles. It failed in 2003
    > while I was not on the bike. I inflated the tires in the morning, rode to work, then found the rim
    > in this condition when I was ready to ride home at the end of the day. The failure was a crack in
    > the sidewall. I have no complaints, as the rim served a long and useful life.

    That is not what I would find acceptable. How would you feel if you were descending a mountain road
    while the rim fell apart? Make that a right hand turn with opposing traffic or at the entry of a
    hairpin turn over an abyss. The rim shows no excessive wear on the braking surface so it appeared to
    have plenty of life left... but it didn't.
    -----------------------------------------------------------------------

    >> To visualize the danger one must either ride in traffic or descend mountain roads that border
    >> precipices.

    > Just did both of those today. Routine. As a matter of fact, remember the snowbank episode I
    > mentioned earlier? Good thing for the snowbank. It kept me from falling off one of those
    > precipices.

    So was this related to rim-failure? I didn't get the connection.

    Jobst Brandt [email protected]
     
  17. Tim McNamara

    Tim McNamara Guest

    jim beam <[email protected]> writes:

    > in addition, you assert that the ma2 is not anodized. it most definitely was available in clear
    > anodized. i have one. in fact, i've even taken the trouble to specifically look for ma2's since we
    > first started this little love-fest, and guess what? only 1 of the 30-odd silver ma2's i have
    > inspected has been unanodized,

    Hmm. A nice shiny clear anodized layer, would you say? That flakes off with the slightest scraping
    with a razor blade? That's what's on my MA2s. And it's unlike any anodizing I've ever seen.
     
  18. carlfogel

    carlfogel New Member

    Joined:
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    Dear Tim,

    Here's what

    http://www.bikepro.com/products/rims/mavicroad.html

    has to say:

    "The Mavic MA2 is a double wall 700c road racing rim. As stated the series of alloy used for this rim kept secret. The MA2 is a Box shaped extrusion, with the three exterior surfaces, both side walls and the hub facing side of the spoke bed wall high polished to a bright Silver aluminum then Clear anodized to harden and preserve the finish."

    The difference between what BikePro calls clear and
    hard anodizing appears to be a matter of depth. The
    clear anodizing was used on numerous other rims by
    other manufacturers, too.

    Carl Fogel
     
  19. Peter

    Peter Guest

    Tim McNamara wrote:

    > jim beam <[email protected]> writes:
    >
    >
    >>in addition, you assert that the ma2 is not anodized. it most definitely was available in clear
    >>anodized. i have one. in fact, i've even taken the trouble to specifically look for ma2's since we
    >>first started this little love-fest, and guess what? only 1 of the 30-odd silver ma2's i have
    >>inspected has been unanodized,
    >
    >
    > Hmm. A nice shiny clear anodized layer, would you say? That flakes off with the slightest scraping
    > with a razor blade? That's what's on my MA2s. And it's unlike any anodizing I've ever seen.

    From the bikepro.com description: "The MA2 is a Box shaped extrusion, with the three exterior
    surfaces, both side walls and the hub facing side of the spoke bed wall high polished to a bright
    Silver aluminum then Clear anodized to harden and preserve the finish."

    Doesn't sound like a coating that would flake off.
     
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