mavic rims don't *all* suck

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

  1. Carl Fogel

    Carl Fogel Guest

    Tim McNamara <[email protected]> wrote in message news:<[email protected]>...
    > Werehatrack <[email protected]> writes:
    >
    > > On Sat, 28 Feb 2004 00:01:28 +0100, "SMMB" <[email protected]> may have said:
    > >
    > >>Now that's the right failure mode ? Everything fails, somehow, sometime.
    > >
    > > Aluminum rims appear not to have a "right" failure mode
    >
    > The "right" failure mode is one that is predictable and non-catastrophic. Non-anodized and
    > socketed aluminum rims have the right failure mode in that failure is predictable from braking
    > area wear. Anodized rims, introducing new catastrophic failure modes, do not have the "right"
    > failure mode.

    Dear Tim,

    Do you have any pictures of brake-wear failure, catastrophic or otherwise? The post below, for
    example, has pictures may be brake-wear failure. (Confusingly, it's from another of the legion of
    Daves on rec.bicycles.tech).

    [begin post with rim failure picture links]

    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]

    Whatever happened to this rim, it looks catastrophic. It would be nice if someone had close-up
    pictures of a non-anodized rim failing from brake-wear.

    Carl Fogel
     


  2. Mike S.

    Mike S. Guest

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

    Yeah, me too. All I gotta do is go out to my garage...

    > 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.

    Quick question: what's the difference between an eyelet ala Mavic Reflex/OP/etc. and this socket?

    > > 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.

    It matters a great deal.

    How can a sidewall crack if it isn't there? Yes, there's a brake track, but no there's no
    unsupported sidewall like a clincher has. I'd think that you wouldn't see ANY sidewall failures in
    tubulars. Non-anodized clinchers? Probably depends on how light you made them... I'm guessing that
    the lighter you make the clincher, the more likely you are to have a sidewall crack.

    Funny how we haven't been bashing on Campy anodized rims, just Mavics... Interesting that.

    >
    > > 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.

    Me too. No cracks in the last 18 years...

    > > 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]
     
  3. Jobst Brandt

    Jobst Brandt Guest

    Peter Rathman 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.

    I'm amazed at the extremes to which defenders of anodizing go, claiming it has no structural
    hazards. Nowhere does the article mention that these rims are anodized or hard coated with a
    structurally significant thickness. As far as I can determine from the unused ones I have, they are
    at best clear alodine finished.

    The stack of new MA-2 rims I have are conductive to a test lamp when the round sides of the probes
    are slid over the surface. That is how thick and hard the coating is. There are places where the
    test lamp lights without making sliding contact. For practical purposes, this is not a hardcoat that
    can initiate cracks. Personal experience with thousands of miles on these and prior rims have not
    developed cracks.

    I note that rims in this web page have eyelets and sockets, the eyelets are stainless but the
    sockets are not something that is verifiable with a magnet. That also is evident from the different
    colors of the socket and eyelet of the MA-40 shown. Calling these double eyelets is a misnomer that
    causes confusion, because the sockets are not eyelets. For a while, only sockets or cups with
    narrow necks that were rolled to retain them in the rim to replace eyelets. Few of these ever
    reached this area.

    Jobst Brandt [email protected]
     
  4. 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.

    >>> 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.

    > Yeah, me too. All I gotta do is go out to my garage...

    >> 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.

    > Quick question: what's the difference between an eyelet ala Mavic Reflex/OP/etc. and this socket?

    Eyelets are what you have on canvas-top basketball shoes for the laces, sockets are cups that rest
    on the inner and outer bed of the rim and are held in with eyelets or rolled over necks as in the
    pictures at:

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

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

    Today, it is less than 1% tubulars on the road I presume. When anodized rims came on the market it
    was still about 50%-50%.

    >> 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.

    > It matters a great deal.

    > How can a sidewall crack if it isn't there? Yes, there's a brake track, but no there's no
    > unsupported sidewall like a clincher has. I'd think that you wouldn't see ANY sidewall failures in
    > tubulars. Non-anodized clinchers? Probably depends on how light you made them... I'm guessing that
    > the lighter you make the clincher, the more likely you are to have a sidewall crack.

    That may be your impression but the G-40 (Hard anodized) tubular rim cracked just the same,
    right down the middle of the sidewall and ripped out bridges of rim beds... along with their
    spoke sockets.

    > Funny how we haven't been bashing on Campy anodized rims, just Mavics... Interesting that.

    You can do that. I never used their rims because they cost 50% more than others. Today there are no
    rims of consequence that are not anodized hard enough to cause failures. I've got some Torelli
    Master rims to try but they are silver anodized to the point that there is no telling that they are
    even aluminum other than from their weight.

    >>> 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.

    > Me too. No cracks in the last 18 years...

    So why don't you reveal your secret to those who have failures?

    >>> 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.

    Jobst Brandt [email protected]
     
  5. Mike S.

    Mike S. Guest

    <snip>
    > > Me too. No cracks in the last 18 years...
    >
    > So why don't you reveal your secret to those who have failures?
    >
    That's easy. Pick the right rims.

    Mike
     
  6. A Muzi

    A Muzi Guest

    > Dave 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."

    Jobst:
    > "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."

    Carl Fogel wrote:
    > Seriously, how do you know when to replace a rim?

    I think Jobst is quite serious. When a rim is concaved, that itself indicates both significant
    material loss and deformation outwards at the top from the tire pressure.

    That's as good a point as any to declare it fully depreciated. Unless you want to wait and see if
    there is a car in the intersection when it finally separates.

    I get a good close look at about twenty or thirty rims a day at eye level in a good light when doing
    brake inspection/adjustment this time of year. Jobst is exactly right that a finger will feel the
    concave deformation before it is visible. By the time the rim's visibly concave, a closer look will
    usually show small cracks longitudinally at a few areas of the rim. The cracks will be just below
    the parts that are farthest over the brake shoe.

    Yes, there may be useful life remaining when that phenomenon can be felt but not yet easily seen.
    But you asked when to replace and Jobst gave a good answer - when it just starts to bow outward,
    before cracks are very deep.
    --
    Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
     
  7. Peter

    Peter Guest

    [email protected] wrote:

    > Peter Rathman writes:
    >
    >>>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.
    >
    > I'm amazed at the extremes to which defenders of anodizing go, claiming it has no structural
    > hazards. Nowhere does the article mention that these rims are anodized or hard coated with a
    > structurally significant thickness. As far as I can determine from the unused ones I have, they
    > are at best clear alodine finished.

    I'm amazed that you would accuse someone of making statements they did not make and of holding
    positions that they do not hold. I am not nor have I ever been a "defender of anodizing" nor have I
    ever claimed that it "has no structural hazards". I merely quoted a source that is presumably
    relatively unbiased and usually reasonably accurate about describing bicycle components aince their
    description sounded quite different from Tim's. If the MA2s are not in fact anodized, then you
    should take it up with bikepro.

    My experience has been that both anodized and non-anodized rims can be sufficiently durable for my
    uses. The rims on my most frequently used bike are anodized but they only have about 40k miles on
    them so I can't yet say how durable they may be. I think the rims I used before are not anodized
    (Rigida 13-19) and are also still in good condition with considerably more miles (the hubs and
    spokes have both been replaced).

    Anodizing may well reduce the potential lifetime and if rims are available without it I would prefer
    to buy those but it's not something that I'm particularly concerned about one way or the other.
     
  8. A Muzi

    A Muzi Guest

    [email protected] wrote:

    > 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.

    The rims which are bent outward have deep gouges from years of winter braking in sand and grit.

    Something like this: http://www.yellowjersey.org/photosfromthepast/CONCAVE.JPG

    Although that one hasn't yet deformed - it was replaced for a different reason. It was the only
    thing in the recycling today. I'll keep an eye out for a better (worse) rim.
    --
    Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
     
  9. Dvt

    Dvt Guest

    [email protected] wrote:
    >>>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.

    No connection, just a response to your comments.

    --
    Dave dvt at psu dot edu
     
  10. dvt <[email protected]> wrote:
    >Same question to you: How do you tell when a brake wall is too thin for continued service?

    In the last instance, because of the sneaking realisation that the rim doesn't have five separate
    welds on it.
    --
    David Damerell <[email protected]> Distortion Field!
     
  11. Mike S.

    Mike S. Guest

    <snip> The rims on my most frequently used bike are anodized but they only have about 40k miles on
    them so I can't yet say how durable they may be.

    Uhhh, yeah. 40k miles on a pair of rims and you don't know how durable they are?

    What more do you want? Infinite lifespan?

    Mike
     
  12. Jobst Brandt

    Jobst Brandt Guest

    Mike Shaw writes:

    >> The rims on my most frequently used bike are anodized but they only have about 40k miles on them
    >> so I can't yet say how durable they may be.

    > Uhhh, yeah. 40k miles on a pair of rims and you don't know how durable they are?

    > What more do you want? Infinite lifespan?

    It's the failure mode that is under discussion here, not the number of miles. An aluminum road rim
    ridden in dry weather with reasonable brake pads will outlast the rider and if that rider chooses to
    ride only in clement weather, the rim will not wear out in a foreseeable time.

    As I have mentioned before in threads on this subject, I wore out a front rim in 2500 miles on the
    road on a tour of the Alps on which every major descent was with rain. Other rims have lasted as
    much as ten times that far.

    Rim failure is not a matter of miles as much as wear conditions and the predictability of a need for
    replacement. We often read here that a component lasted for x-number of years, presumably being used
    or maybe standing in a garage.

    Failure mode. That's what it's about.

    Jobst Brandt [email protected]
     
  13. Carl Fogel

    Carl Fogel Guest

    A Muzi <[email protected]> wrote in message news:<[email protected]>...
    > > Dave 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."
    >
    > Jobst:
    > > "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."
    >
    > Carl Fogel wrote:
    > > Seriously, how do you know when to replace a rim?
    >
    > I think Jobst is quite serious. When a rim is concaved, that itself indicates both significant
    > material loss and deformation outwards at the top from the tire pressure.
    >
    > That's as good a point as any to declare it fully depreciated. Unless you want to wait and see if
    > there is a car in the intersection when it finally separates.
    >
    > I get a good close look at about twenty or thirty rims a day at eye level in a good light when
    > doing brake inspection/adjustment this time of year. Jobst is exactly right that a finger will
    > feel the concave deformation before it is visible. By the time the rim's visibly concave, a closer
    > look will usually show small cracks longitudinally at a few areas of the rim. The cracks will be
    > just below the parts that are farthest over the brake shoe.
    >
    > Yes, there may be useful life remaining when that phenomenon can be felt but not yet easily seen.
    > But you asked when to replace and Jobst gave a good answer - when it just starts to bow outward,
    > before cracks are very deep.

    Dear Andrew,

    Elsewhere in this thread, Jobst has said that worn rims don't actually bow outwards:

    "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."

    (Possibly the idea is that rims should be replaced before they begin crack and bow outward, or else
    that the actual bowing-out occurs almost instantaneously therefore is never observed?)

    I'm sorry, but I didn't follow your description: "The cracks will be just below the parts that are
    farthest over the brake shoe." Where would the cracks appear on the crude diagram below?

    tire
    -------------------
    upper area untouched by brake

    UUUUUUUUUUUUUUUUUUU upper brake track uuuuuuuuuuuuuuuuuuu MMMMMMMMMMMMMMMMMMM middle brake track
    mmmmmmmmmmmmmmmmmmm LLLLLLLLLLLLLLLLLLL lower brake track lllllllllllllllllll lower area
    untouched by brake

    -------------------
    spokes

    Have you noticed whether the cracks tend to be centered over spokes, as Dave wondered?

    Is there a thickness of the rim wall below which you'd consider it worn-out, regardless of
    concavity, thumb-tests, lack of cracks, and so on?

    Jobst has said that he can tell with his thumb when a rim wall is worn to 0.5mm (0.020 inches),
    which I took to be humor, but others insist is serious.

    Dave somehow measured his cracked rim wall at 1.5-1.8mm, or 0.060-0.070 inches.

    It's interesting that what sounds like either the range error or the actual rim-thickness variation
    in Dave's measurement is 50% of the total that Jobst says that he can determine by swiping his thumb
    and finger over two brake surfaces. (Of course, Dave might just have eyeballed things or used a less
    sensitive thumb.)

    The few rims that I looked at, trusty dial calipers in hand, seemed to be very badly designed in
    terms of easy measuring.

    Do the rim makers even mention how thick the walls are? Was I just unlucky in looking at hard-to-
    measure rim-designs, or is the difficulty in measuring why we're literally using rules of thumb? Is
    there even a standard rim-wall thickness? Can you--

    Sorry, better stop before I start asking a busy mechanic to perform double-blind thumb-testing. I
    just get excited when I have someone handy with a stack of rims and a lot of experience. After you
    read Jobst's comment, do worn rims still seem to bow out to you? And where exactly do you see the
    first tiny cracks on the brake surface?

    Thanks,

    Carl Fogel
     
  14. Carl Fogel

    Carl Fogel Guest

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

    [snip]

    > > 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.
    >

    Dear Jobst,

    Well, not exactly. When the same model of rim is offered both anodized and unanodized, the anodized
    rim ends up a bit heavier after its bath in electrified acid:

    "Hard anodizing is said to increase a rim's rigidity between 10 and 20 per cent. Somehow that seems
    a little high, but is certainly adds something to a rim's weight, as the Rim table demonstrates."

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

    The rim table itself is at:

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

    The first rim in the table, for example, goes from 409 grams with clear anodizing to 413 grams with
    hard anodizing. Presumably, the unanodized original would have been a svelte 400-405 grams.

    Carl Fogel
     
  15. Dvt

    Dvt Guest

    Carl Fogel wrote:
    > I'm sorry, but I didn't follow your description: "The cracks will be just below the parts that are
    > farthest over the brake shoe." Where would the cracks appear on the crude diagram below?
    >
    > tire
    > -------------------
    > upper area untouched by brake
    >
    > UUUUUUUUUUUUUUUUUUU upper brake track uuuuuuuuuuuuuuuuuuu MMMMMMMMMMMMMMMMMMM middle brake track
    > mmmmmmmmmmmmmmmmmmm LLLLLLLLLLLLLLLLLLL lower brake track lllllllllllllllllll lower area untouched
    > by brake
    >
    > -------------------
    > spokes

    Based on my sample of one rim, the wall on both sides of the crack have brake wear. I think the
    crack might correlate more closely to the location on the inside of the rim wall. My ascii art
    attempt at a cross section of the rim:

    D <- hook for the bead
    |
    |
    | <- crack goes right at the interface from straight to curved
    \
    |\ <- I show this transition as a straight line, but it's curved \ \ ------ <- outer wall of
    |"box" section
    |
    |
    \ \ \ ------------- <- spoke bed

    The straight section with the bead hook is a cantilever that is stiffly supported at the base. It
    stands to reason that the base would be the point of highest stress and thus the most likely point
    of failure.

    > Dave somehow measured his cracked rim wall at 1.5-1.8mm, or 0.060-0.070 inches.

    I used a caliper. I goofed on the initial measurement, allowing the caliper to slip down over the
    curved section and overestimating the remaining wall thickness. If I'm a bit less cavalier with the
    calipers, I get 1.1-1.3 mm. I don't think that changes any of the conclusions.

    The sections of rim that *didn't* fail are noticeably concave to the thumb. I hope to get a photo
    just like Andy's to show the curvature. I would still like to know how to tell if a rim's wall is
    too thin, preferably without removing the tire. The calibrated thumb trick is beyond my feeble end-
    user capacity.

    --
    Dave dvt at psu dot edu
     
  16. Matt O'Toole

    Matt O'Toole Guest

    Carl Fogel wrote:

    > Well, not exactly. When the same model of rim is offered both anodized and unanodized, the
    > anodized rim ends up a bit heavier after its bath in electrified acid:
    >
    > "Hard anodizing is said to increase a rim's rigidity between 10 and 20 per cent. Somehow that
    > seems a little high, but is certainly adds something to a rim's weight, as the Rim table
    > demonstrates."
    >
    > http://www.bikepro.com/products/rims/rimover.html
    >
    > The rim table itself is at:
    >
    > http://www.bikepro.com/products/rims/rimtables.html
    >
    > The first rim in the table, for example, goes from 409 grams with clear anodizing to 413 grams
    > with hard anodizing. Presumably, the unanodized original would have been a svelte 400-405 grams.

    First, I wouldn't take Bike Pro as the ultimate authority on anything. It may be useful as a general
    reference for ID'ing old parts, etc. But the stuff you just quoted is just plain ridiculous. Gee,
    which type of anodizing adds more rigidity, Japanese or French? Maybe Italian, where they age the
    rims in the wine cellar, alongside the salamis, and tubular tires...

    I don't know how much anodizing affects weight. But those weight differences could easily be due to
    normal production tolerances. When making extruded parts like rims, the dies wear. Early production
    is thinner in cross section and lighter, becoming fatter and heavier over a production run.
    Eventually the dies are replaced, and the process starts all over.

    Now, why the anodized rims would weigh more than the unanodized ones -- maybe the unanodized ones
    (from which the weights were taken) were from an earlier, lighter batch. Maybe this is on purpose
    -- to leave you the impression that anodizing "adds something." Or maybe it's all just typical
    brochure bullshit.

    Matt O.
     
  17. carlfogel

    carlfogel New Member

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    Dear Matt,

    They weighed each rim on their own scales and
    found, as expected, that more anodization meant
    more weight. Perhaps my understanding of
    chemistry is wrong?

    As for their weights, I suspect that they're as
    accurate possible. They did an awful lot of weighing,
    as you can see if you browse their site and look at
    their detailed explanations. Here's their comment,
    which agrees with your point about early runs being
    typically lighter, since the extrusion dies wear and
    chug out slightly thicker forms:

    "We've used a Mitutoyo digital micrometer accurate to the 1000th of a millimeter for the measurements of the rim. We noticed that our measurements to the thousandth of a millimeter are at variance from the manufacturers specifications. In our weights, we've used only production models not prototypes, and have also noticed that the weights are sometimes grossly out of what manufacturers specify they will be. So the question becomes why are the physical characteristics so far out of design spec? The answer has to do with the basic process of extrusion. Remember at the top of the overview we described how aluminum was squeezed through a steel die in "plastic" state, to make long pieces aluminum with the same cross section as the rim? The steel die has a limited useful life before it becomes worn out. At the beginning of the die's use, it has sharp edges that capably shape the aluminum to tolerance in the designer's shape. With each bit of aluminum that is pushed through the die a small amount of the steel shaping surface is worn or abraded permanently away, with the effect of changing the die's shape slightly, as well as its specification tolerances. "

    "After a certain amount of aluminum has been extruded through the die, the figure we are told is between 20, 000 and 40, 000 lineal feet, the nice crisp edges of the die which form the extrusion's shape become worn, to the point where it becomes "washed out" and has to be replaced. Therefore the early aluminum extrusions represent fully the designer's intention, and the later ones, from the same die, make the extrusion with thicker or wider dimensions. The later extrusions when cut into rim pieces are necessarily heavier. We call this phenomena "extrusion wall thickness deviation" and have found that some rims with the same drilling can weigh up to 8 or 9 per cent more, though they appear to have the same shape."

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

    As they commented, they found a fairly consistent pattern of slightkly increasedi weight when the same rim model was given the hard anodizing treatment.

    Elsewhere, they give extensive tire weights with this comment:

    "As always the published weights are from actual production tires, accurate to the 1/2 gram. "
    http://www.bikepro.com/products/tires/tireover.html

    It's not all that tricky to weigh such things with ridiculous precison, given an electronic scale, which the store probably had even back then.

    Frankly, I can't see what's ridiculous about BikePro's explanation of the different anodization techniques that were in use at the time. It seems quite clear and interesting. I'd be just as interested if Chalo Colina took a few moments to explain different welding processes, Tom Sherman detailed some pavement differences, or Phil Holman talked about weird aircraft metal problems.

    Carl Fogel


    Carl Fogel
     
  18. Mike S.

    Mike S. Guest

    <snip>
    > "After a certain amount of aluminum has been extruded through the die, the figure we are told is
    > between 20, 000 and 40, 000 lineal feet, the nice crisp edges of the die which form the
    > extrusion's shape become worn, to the point where it becomes "washed out" and has to be replaced.
    > Therefore the early aluminum extrusions represent fully the designer's intention, and the later
    > ones, from the same die, make the extrusion with thicker or wider dimensions. The later extrusions
    > when cut into rim pieces are necessarily heavier. We call this phenomena "extrusion wall thickness
    > deviation" and have found that some rims with the same drilling can weigh up to 8 or 9 per cent
    > more, though they appear to have the same shape."

    See! Told ya all ya gotta do is pick the right rim...

    Just get one from the latter part of the die used to make the rim's lifespan.

    Mike
     
  19. Tim McNamara

    Tim McNamara Guest

    Peter <[email protected]> writes:

    > 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."

    FWIW, BikrPro was not all that accurate in their analysis of bike components. Their catalog was rife
    with errors, myths and urban legends in lieu of real facts.

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

    Anodizing is not applied to the metal as a coating, and hence it doesn't flake off like this.
    Anodizing is a chemical conversion of the surface of the metal. Nothing I've seen in the reading
    I've been able to do indicates that anything like "clear" anodizing exists (but perhaps I've just
    missed it). The Alodine process seems to be able to produce a clear finish, but that is an
    applied coating.
     
  20. Tim McNamara

    Tim McNamara Guest

    carlfogel <[email protected]> writes:

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

    Spend some time reading through the BikePro Web site and you'll find that they are not a reliable
    source of technical information. Their catalog was ground-breakingly informative, oh, about 10 years
    ago, but contained much myth, lore and legend.

    > 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.

    As I commented to the other person to cite the BikePro Web site, I have not found anything in the
    available literature on the Internet to indicate that clear anodizing is even possible. Clear
    coatings seem to be just that- applied coatings. Anodizing is not an applied coating but a
    conversion of the metal itself into a ceramic. Applied coatings seem not to provoke the same
    problems as anodizing- for example, we have not seen numerous reports of cracked powder coated rims
    in this newsgroup or other media sources.
     
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