Mavic MA-40 - Piece of Crap? - Page 3

anonymous writes:

>>>> Oh? If all that welding, machining and heat treatment isn't a huge waste. Suckers!!!

>>> Oh and the seam welding and machining is a waste too? Give me a break

That's spelled Rollei. Rolleis take pictures.

>> And what problem did these expensive adjuncts solve? You probably did not ride on rims that were
>> not welded for any reasonable sampling. MA-2 rims and their equals for tubulars were used for
>> about 50 years with no problem. Besides, the alloys used are not heat treatable. We went through
>> that a few years back. Why would you want to heat treat aluminum rims? I think you'll believe
>> anything manufacturers put out as a marketing gimmick. People actually believed Rolf's claim that
>> his wheels, having laterally paired spokes, prevented shimmy.

> HAHAH! Whatever dude! The seam is machined for better braking. Now, you'll NEVER get rims that
> stick at the seam. But according to you its all marketing. Geez! Get a clue!

Your reply may be convincing to those impressed with empty swagger, however, I see no content. On
the other hand, you cannot find the rim joint on the many butt joined rims with filler sleeves that
I have here by scraping your fingernail over the joint. This is an entirely imagined problem created
by advertising based on the work of a bad wheel builder who caused a mismatch and did not correct
it. For this we should pay someone to weld and machine rims?

Jobst Brandt jobst.brandt@stanfordalumni.org

Jim Beam writes:

>>> Getting back to the ma40, all modern rims are made from extruded aluminum. Extruded aluminum,
>>> depending on subsequent heat treatments, will usually have a strongly anisotropic
>>> microstructure. [Just like striped toothpaste coming out of a tube.] Modern alloys are extruded
>>> much closer to their ductility limits than some of the older ones. It's part of what makes them
>>> strong. If one sees cracking following the extruded microstructure of a component, one /has/ to
>>> assume this microstructure plays a significant role in failure. I believe the ma40 was a
>>> somewhat unsuccessful attempt to push Mavic's then-used alloy to its limits but it's failure
>>> paved the way for the "open" rim series with a much superior alloy. The "open" series and their
>>> successors have not been as failure prone, regardless of anodizing.

>> I have a store of MA-2 rims and they are not anodized. They are polished aluminum with a clear
>> lacquer finish that just barely presents an insulating -

> /is/ it laquer? Are you able to remove with the correct solvent?

It is lacquer and the edges of the bead have areas where the lacquer has worn off from handling.
These are unused rims with a mirror like finish. Even if it were anodizing, if thin enough to
conduct and leave a mirror like shiny finish, it would be so thin as to have no effect on crazing.

> As I said, Mavic sold these polished & anodized, but all the silver ones I've ever seen, and I
> /have/ looked since we first discussed this, have definitely been anodized.

How did you determine that. At best, I believe they are clear alodine finish as I pointed out to the
last flood of Mavic apologists and black anodized rim defenders. Clear alodine finish has a
conductive surface. That is why I specify it on many parts I design where electrical conductivity
and dimensional integrity are required.

>> - surface and the rim displays electrical continuity with a flashlight battery on its bead edge.

> What does that prove? Laquer and anodizing are both insulators. If you were trying to say that
> your rims are polished, as is an old Fiamme rim I have, then it will conduct on any surface and
> you should readily see that.

What it proves is that it is not anodizing, something that doesn't rub off and is not readily worn
off by handling. To pursue your claim that it is not lacquer would require rubbing them down with
lacquer thinner or paint remover, something I am not ready to do for your curiosity. I intend to
ride on these rims for a long time to come.

>>> I'm not sure if it's still up, but there was a very illustrative photo that showed the effect of
>>> microstructure on rim failure:

>>> in ASCII: The more common failure:

>> _______________ crack
>>
>>> ______ ______ / \ / \ / \ / \ ___| | ____| |____ crack
>>> | | | |
>>> \ / \ /
>>> \______/---- \______/
>>
>> _______________ crack

>>> Lousy drawing, but this is supposed to show the photo with the two cracks initiating at the
>>> eyelet. This is important because if you look at an anodized rim with a magnifier, [silver 517
>>> being a classic example], you will see cracks in the anodizing *radiating* around the eyelet
>>> where it has been punched through the rim. Straight out of the factory. Again, the anodizing
>>> cracks exactly radiate around the spoke hole.

>> You'll find that these cracks are aligned with extrusion marks and the cracks of interest are
>> those across bridging stresses from edge to edge of the rim, there being significantly less
>> bending stress between spokes.

> I think we're on the same page, but which paragraph? Yes, the cracks that support the "anodizing
> only" hypothesis /do/ share the same axis as extrusion, but there's no definitive causal
> relationship between the two.

There is a direct relationship between cracking and stress concentrations. These cracks are
initiated by the hard surface crust on the rim. I don't understand where you are trying to direct
this. The only difference between the MA-2 and MA-40 is anodizing. What does all this diversionary
metallurgical jargon have to do with this?

> I guarantee that a "bad" extrusion, unanodized, will fail in axactly the same way as your diagram,
> whereas a "good" extrusion, anodized, will not, or at least, not during a normal component
> lifetime. the "pull-through" cracks at the top & bottom of your diagram are not caused by cracking
> of the anodizing radiating from the spoke hole.

Now you are implying that the failed rims were bad extrusions. Are you proposing that MA-2 rims were
inspected for extrusion quality and if found to be lacking, were relegated to the hard anodizing
tank to be renamed MA-40?

>> That riveting eyelets and sockets causes crazing is not unusual, however, the cracks of
>> interest are those that lie across principal bending planes. These are the ones that propagate
>> into the metal.

> You would expect, but not exclusively, which where my original diagram and the photo that it's
> based on came from.

Your diagram shows longitudinal cracks as does my additional picture. These are not solely extrusion
failures because they did not occur on MA-2 rims.

>> Non anodized rims having no crust do not develop cracks as readily although cracking is possible
>> with cyclic overload. Steady stress great enough to cause cracks would cause immediate failure
>> similarly to spoke failure.

>>> If anodizing were to be the sole cause of cracking, one would therefore expect to see the
>>> cracking exactly axial with the lines of the cracked anodizing, as we see for the crack on the
>>> left. And there would be no variation is this failure mode.

>> Not so. Those cracks are not in line with the principal stress,

> How not so? If the r/h crack in my diagram is not in line with the principal stress, then doesn't
> it argue a secondary cracking mechanism?

So? What explanation consistent with your radial crack theory do you have for this occurrence? I
didn't ignore stress direction. What you choose to ignore is that for the previous 50 years, such
cracks were a rarity and were seen principally on tandems and other overloaded rear wheels.

>> However, there have been star burst failures on rims with sufficiently thick anodizing.

> See above. Yes, you /can/ see failures like that, and yes, that /would/ be anodizing induced.

>>> But on the right, this photo also showed cracking *tangential* to the spoke eyelet - i.e. /not/
>>> following the radial cracks in the anodizing but following inherent flaws in the metal's
>>> extruded microstructure.

>> These all ran along the direction of extrusion, finally breaking across the rim the slender
>> bridge they made of the mid section of the rim. This is one of the inherent disadvantages of
>> extrusions.

> Extrusions are not inherantly flawed. Indeed, the opposite is often true. Flaws come with bad
> processing, bad q.c. and bad material selection.

Are you refuting your earlier claim of orientational structural differences in extrusions. I don't
understand your dodging and weaving and ignoring the mass of failure evidence occurring subsequent
to the advent of anodized rims. A failure that was predicted and subsequently occurred.

>>> One *cannot* therefore solely attribute cracking simply to anodizing, whether it be hard,
>>> silver, black or purple. There don't seem to be any real micrographs on the net showing what
>>> extruded material looks like, but this is a good representation:

http://www.stud.ntnu.no/~fjeldly/forming.html

>>> Just like a piece of wood is easy to split along its grain, so can be a faulty extrusion.

>> Or for that matter a good extrusion.

> Not if properly done.

You seem to be saying that all failures result from extrusion faults when in reality extrusions are
known to have orientation and strong and weak axes, just as the wood you cite.

>>> The ma40 was junk. Just throw it away. No, most modern rims do not have this problem.

>> Oh BS! A modern rim with anodizing presents the same failure.

> Since when? what's a current anodized rim cracking failure rate? how does that compare to the same
> alloy unanodized? That's an entirely unsupported assumption.

It is hard to compare, there being no rims of the kind that failed so readily. Today's rims are
heavier, have a deeper cross section, and have no broad flat inside circumference. Some of the rims
are so massive in the failure region that gratuitous machining is done there. A process patented by
Mavic. This machining coincidentally removes the anodizing that would cause failures although at
spoke penetrations, wall thickness is so massive that no failures have occurred there to my
knowledge.

>> The difference is that manufacturers are cutting back on anodizing thickness.

> Measurements please.

I see, you believe the lower failure rate is due to improving rim extrusions, nothing else.

> Fyi, Mavic & Ambrosio are introducing shot peening and other "kinetic" compressive residual
> stress surface treatments. That should mitigate any last fear you have about premature fatigue in
> modern rims.

Oooh! I'm getting a headache from all these expensive "enhancements" without which a plain polished
320 gm rim survived excellently years ago.

Are you sure you aren't a government spin doctor who also interprets political blunders as advances
these days. I see your sig seems to refer to government. Your apologist style makes me wonder in
whose employ you are writing this stuff.

Jobst Brandt jobst.brandt@stanfordalumni.org

Tim McNamara wrote:
> BaCardi <usenet-forum@cyclingforums.com> writes:
>
>
>>Jobst Brandt wrote:
>> > anonymous writes:
>> >
>> > >> Oh? If all that welding, machining and heat treatment isn't a huge waste. Suckers!!!
>> >
>> > > Oh and the seam welding and machining is a waste too? Give me a break
>> >
>> > And what problem did these expensive adjuncts solve? You probably did not ride on rims that
>> > were not welded for any reasonable sampling. MA-2 rims and their equals for tubulars were used
>> > for about 50 years with no problem. Besides, the alloys used are not heat treatable. We went
>> > through that a few years back. Why would you want to heat treat aluminum rims? I think you'll
>> > believe anything manufacturers put out as a marketing gimmick. People actually believed Rolf's
>> > claim that his wheels, having laterally paired spokes, prevented shimmy. Jobst Brandt
>> > jobst.brandt@stanfordalumni.org
>>
>>HAHAH! Whatever dude! The seam is machined for better braking. Now, you'll NEVER get rims that
>>stick at the seam. But according to you its all marketing. Geez! Get a clue!
>
>
> The anonymous Christmas troll reveals himself for what he is.
>
> The one in need of the clue is yourself, rumdude. Why are rims machined? Because anodized
> sidewalls provide miserable and dangerous wet weather braking characteristics.

sorry to interrupt the trivialities, but do you have personal experience of anodized sidewalls? i
have "cd" rim coatings on both my road bikes, and my experience is that their wet weather braking
remains strong, constant & reliable because they don't grit up the pads as badly as standard rims.
and when pads are gritted up, braking sucks.

and before you ask, yes, i've tried plain, cd and ceramic. my experience is that ceramic are best
in the wet.

> A few high-level pro racer crashes that caused injury pointed this out very early in the game,

really? who?

> and pro mechanics started taking sandpaper to the braking surfaces. But that made the rims look
> ****ty, and customers complained after their expensive rims started to look bad. Anodized rims
> also tend to cause brake squeal and eat brake pads for lunch,

i've never suffered pad squeal on my road bikes, regardless of rim coating. ever. and the pads last
just great. see above.

> which didn't sit well with the manufacturers of dual pivot brakes.
>
> One of Mavic's owners is a metal finishing company specializing in anodizing (hello!) and the
> company had to do something or start losing market share. They weren't going to stop anodizing, so
> Plan B was to machine the sidewalls. This solved the bad braking, squealing and early pad death-
> but at the cost of thin areas on the rims that wore through quicker.

i find that claim hard to believe. can you substantiate it? and in what way is that worse than an
unmachined braking surface habitually locking up at the rim join - like my cxp14 does?

>
> So, basically for fashion- because red and green and black and whatever rims look cooler than
> polished silver ones, we all get to buy inferior products that will crack and fail on us, and cost
> twice as much. Cool! So, Rum-pot-stiltskin, have yourself a merry little Christmas and if you're
> really good, Santa will bring you a pair of MA-2s. If you've been bad, MA-40s.

are you absolutely /certain/ your ma2's are not anodized?

jb

Jim Beam writes:

>> The one in need of the clue is yourself, rumdude. Why are rims machined? Because anodized
>> sidewalls provide miserable and dangerous wet weather braking characteristics.

> Sorry to interrupt the trivialities, but do you have personal experience of anodized sidewalls? I
> have "CD" rim coatings on both my road bikes, and my experience is that their wet weather braking
> remains strong, constant & reliable because they don't grit up the pads as badly as standard rims.
> And when pads are gritted up, braking sucks.

I have enough experience with them to know they do not work well when wet or dry. When wet, before
the water layer is "burned off" brakes are poor and don't get better until the sidewalls are fairly
dry. Then braking is also poor because the pads overheat as they do in dry conditions anyway.

As I mentioned previously in these threads, I discovered that wet rims don't brake worth a damn
until they are dried off from descending in snow with snow on the inner circumference of the rim.
While braking, minimal power is dissipated in the rim and gradually melts the snow. Moderate braking
to which we are accustomed in rain only begins when all the snow on the rim has melted and the rim
partially dries.

The reason for using ceramic rims for wet riding is so that grit in wet conditions won't eat rims as
fast and the higher surface temperatures keep rims drier. Dry braking, unless with special pads, is
poorer than bare aluminum for lack of a heat sink and dissipater.

> And before you ask, yes, I've tried plain, CD and ceramic. my experience is that ceramic are best
> in the wet.

But we weren't talking about ceramic rims.

>> A few high-level pro racer crashes that caused injury pointed this out very early in the game,

> really? who?

>> And pro mechanics started taking sandpaper to the braking surfaces. But that made the rims look
>> ****ty, and customers complained after their expensive rims started to look bad. Anodized rims
>> also tend to cause brake squeal and eat brake pads for lunch, -

> I've never suffered pad squeal on my road bikes, regardless of rim coating. Ever. And the pads
> last just great. See above.

So what does that have to do with welded and machined rims?

>> - which didn't sit well with the manufacturers of dual pivot brakes.

>> One of Mavic's owners is a metal finishing company specializing in anodizing (hello!) and the
>> company had to do something or start losing market share. They weren't going to stop anodizing,
>> so Plan B was to machine the sidewalls. This solved the bad braking, squealing and early pad death-
>> but at the cost of thin areas on the rims that wore through quicker.

> I find that claim hard to believe. Can you substantiate it? And in what way is that worse than an
> unmachined braking surface habitually locking up at the rim join - like my CXP14 does?

Why do you put up with that. Firstly, the rims do not lock up. That's a blatant exaggeration.
Secondly, they guy who built the wheels failed to fix that if it is a large misalignment. You
must have wondered what sort of manufacturing error could cause such a step. Extrusions can be
made to excellent dimensions and so can the mating insert. I have only seen slight steps caused
by crashes or as happened recently, a motorcyclist knocked the bicycle over and rode over the
rear wheel. That Taco was repaired so you can't see it anymore. It was a wow so large the wheel
would not turn through the brake bridge, quite aside from the chainstays. There is no joint
mismatch on that rim now.

>> So, basically for fashion- because red and green and black and whatever rims look cooler than
>> polished silver ones, we all get to buy inferior products that will crack and fail on us, and
>> cost twice as much. Cool! So, Rum-pot-stiltskin, have yourself a merry little Christmas and if
>> you're really good, Santa will bring you a pair of MA-2s. If you've been bad, MA-40s.

> Are you absolutely /certain/ your MA2's are not anodized?

Oh get off it. If it's that hard to see, then it doesn't matter what sort of surface finish it has
because it is invisibly thin. Such a thin coating cannot have a crazing effect on the substrate.
Classically aircraft hydraulic fittings have transparent red, green, yellow, and blue anodizing that
is too thin to have any effect other than visual identification.

Jobst Brandt jobst.brandt@stanfordalumni.org

Richard Ney <rtn@pobox.com> writes:

>>>> ...A modern rim with anodizing presents the same failure. The difference is that manufacturers
>>>> are cutting back on anodizing thickness.

>>> Or perhaps, having learned that there is a problem, they are at last attempting to engineer for
>>> an acceptable result with anodizing? This still begs the question of why to bother with
>>> anodization in this application at all, of course.

>> Currently black is beautiful, be that rims tires or SUV's (with blackened windows). You see even
>> Avocet knuckled under and blackened their great IRC made tires and claims to have has an
>> immediate jump in sales, although I doubt it.

> Did they also make the tread thinner? I got only 1500 miles out of the last two rear (folding)
> Road tires.

I think there may have been a change in tread compound but I don't know. I am no longer involved in
their developments as you can imagine by the carbon 12 promotion.

Jobst Brandt jobst.brandt@stanfordalumni.org

jobst.brandt@stanfordalumni.org writes:

>>> Currently black is beautiful, be that rims tires or SUV's (with blackened windows). You see even
>>> Avocet knuckled under and blackened their great IRC made tires and claims to have has an
>>> immediate jump in sales, although I doubt it.
>
>> Did they also make the tread thinner? I got only 1500 miles out of the last two rear (folding)
>> Road tires.
>
> I think there may have been a change in tread compound but I don't know. I am no longer involved
> in their developments as you can imagine by the carbon 12 promotion.

So, do you still use Avocet tires?

I have a wire-bead 25mm Road on the rear now. I'm interested to see if I get the same low mileage. I
care less about the marketing and more about the functioanlity. They can call it Carbon 12 or
whatever, but if the tires aren't lasting, I'll find something else.

jim beam <uce@ftc.gov> writes:

>> sorry to interrupt the trivialities, but do you have personal
> experience of anodized sidewalls? i have "cd" rim coatings on both my road bikes, and my
> experience is that their wet weather braking remains strong, constant & reliable because they
> don't grit up the pads as badly as standard rims. and when pads are gritted up, braking sucks.

I'd have to ask if you've ridden a bike, Jim, given these comments. Or at least if you've ridden a
bike in the rain. And, yah, I've ridden anodized, polished, "ceramic", steel, machined/welded/etc.
Steel rims suck in the rain (unless you use leather brake pads), anodized rims suck in the rain and
so-called "ceramic" rims too. Of course, the latter is differentiated just for marketing hype for
since aluminum oxide- the product formed by anodizing- *is* a ceramic.

> and before you ask, yes, i've tried plain, cd and ceramic. my experience is that ceramic are best
> in the wet.
>
> > A few high-level pro racer crashes that caused injury pointed this out very early in the game,
>
> really? who?

Stephen Roche in the Giro (IIRC; might have been a Classic), for one; he was one of a number of pro
riders who wre vocally critical of the braking characteristics of anodized rims in the wet.

> > and pro mechanics started taking sandpaper to the braking surfaces. But that made the rims look
> > ****ty, and customers complained after their expensive rims started to look bad. Anodized rims
> > also tend to cause brake squeal and eat brake pads for lunch,
>
> i've never suffered pad squeal on my road bikes, regardless of rim coating. ever. and the pads
> last just great. see above.

See above what? Anodizing creates an insulating interface with the brake pads, which means the rim
doesn't absorb heat well and the pad material suffers as a result. It's not the rim that grits up
brake pads, that's dependent on the qualities of the brake pad. Pads with channels and such in the
contact surface are more apt to retain grit and to scour the rims with it; pad material also makes a
difference.

> > which didn't sit well with the manufacturers of dual pivot brakes. One of Mavic's owners is a
> > metal finishing company specializing in anodizing (hello!) and the company had to do something
> > or start losing market share. They weren't going to stop anodizing, so Plan B was to machine the
> > sidewalls. This solved the bad braking, squealing and early pad death- but at the cost of thin
> > areas on the rims that wore through quicker.
>
> i find that claim hard to believe. can you substantiate it? and in what way is that worse than an
> unmachined braking surface habitually locking up at the rim join - like my cxp14 does?

Been discussed many times. Do some trivial research on Google. If you're too dim to be able to sort
out a bump at the rim joint, then I feel sorry for you. It's trivially easy to fix.

> > So, basically for fashion- because red and green and black and whatever rims look cooler than
> > polished silver ones, we all get to buy inferior products that will crack and fail on us, and
> > cost twice as much. Cool! So, Rum-pot-stiltskin, have yourself a merry little Christmas and if
> > you're really good, Santa will bring you a pair of MA-2s. If you've been bad, MA-40s.
>
> are you absolutely /certain/ your ma2's are not anodized?

My continuity tester is reasonably reliable.

jobst.brandt@stanfordalumni.org wrote:
> Jim Beam writes:
>
>
>>>>Getting back to the ma40, all modern rims are made from extruded aluminum. Extruded aluminum,
>>>>depending on subsequent heat treatments, will usually have a strongly anisotropic
>>>>microstructure. [Just like striped toothpaste coming out of a tube.] Modern alloys are extruded
>>>>much closer to their ductility limits than some of the older ones. It's part of what makes them
>>>>strong. If one sees cracking following the extruded microstructure of a component, one /has/ to
>>>>assume this microstructure plays a significant role in failure. I believe the ma40 was a
>>>>somewhat unsuccessful attempt to push Mavic's then-used alloy to its limits but it's failure
>>>>paved the way for the "open" rim series with a much superior alloy. The "open" series and their
>>>>successors have not been as failure prone, regardless of anodizing.
>
>
>>>I have a store of MA-2 rims and they are not anodized. They are polished aluminum with a clear
>>>lacquer finish that just barely presents an insulating -
>
>
>>/is/ it laquer? Are you able to remove with the correct solvent?
>
>
> It is lacquer and the edges of the bead have areas where the lacquer has worn off from handling.
> These are unused rims with a mirror like finish. Even if it were anodizing, if thin enough to
> conduct and leave a mirror like shiny finish, it would be so thin as to have no effect on crazing.
>
>
>>As I said, Mavic sold these polished & anodized, but all the silver ones I've ever seen, and I
>>/have/ looked since we first discussed this, have definitely been anodized.
>
>
> How did you determine that.

experience. just like telling ti from ni or al from mg.

At best, I believe they are clear alodine
> finish as I pointed out to the last flood of Mavic apologists and black anodized rim defenders.
> Clear alodine finish has a conductive surface. That is why I specify it on many parts I design
> where electrical conductivity and dimensional integrity are required.
>
>
>>>- surface and the rim displays electrical continuity with a flashlight battery on its bead edge.
>
>
>>What does that prove? Laquer and anodizing are both insulators. If you were trying to say that
>>your rims are polished, as is an old Fiamme rim I have, then it will conduct on any surface and
>>you should readily see that.
>
>
> What it proves is that it is not anodizing, something that doesn't rub off and is not readily worn
> off by handling. To pursue your claim that it is not lacquer would require rubbing them down with
> lacquer thinner or paint remover, something I am not ready to do for your curiosity. I intend to
> ride on these rims for a long time to come.

i destroyed a perfectly good headset for you...

>
>
>>>>I'm not sure if it's still up, but there was a very illustrative photo that showed the effect of
>>>>microstructure on rim failure:
>
>
>>>>in ASCII: The more common failure:
>
>
>>> _______________ crack
>>>
>>>
>>>> ______ ______ / \ / \ / \ / \ ___| | ____| |____ crack
>>>> | | | |
>>>> \ / \ /
>>>> \______/---- \______/
>>>
>>> _______________ crack
>
>
>>>>Lousy drawing, but this is supposed to show the photo with the two cracks initiating at the
>>>>eyelet. This is important because if you look at an anodized rim with a magnifier, [silver 517
>>>>being a classic example], you will see cracks in the anodizing *radiating* around the eyelet
>>>>where it has been punched through the rim. Straight out of the factory. Again, the anodizing
>>>>cracks exactly radiate around the spoke hole.
>
>
>>>You'll find that these cracks are aligned with extrusion marks and the cracks of interest are
>>>those across bridging stresses from edge to edge of the rim, there being significantly less
>>>bending stress between spokes.
>
>
>>I think we're on the same page, but which paragraph? Yes, the cracks that support the "anodizing
>>only" hypothesis /do/ share the same axis as extrusion, but there's no definitive causal
>>relationship between the two.
>
>
> There is a direct relationship between cracking and stress concentrations.

er, i know that.

> These cracks are initiated by the hard surface crust on the rim. I don't understand where you are
> trying to direct this. The only difference between the MA-2 and MA-40 is anodizing. What does all
> this diversionary metallurgical jargon have to do with this?

that /some/ cracks are initated this way, but not all.

>
>
>>I guarantee that a "bad" extrusion, unanodized, will fail in axactly the same way as your diagram,
>>whereas a "good" extrusion, anodized, will not, or at least, not during a normal component
>>lifetime. the "pull-through" cracks at the top & bottom of your diagram are not caused by cracking
>>of the anodizing radiating from the spoke hole.
>
>
> Now you are implying that the failed rims were bad extrusions. Are you proposing that MA-2 rims
> were inspected for extrusion quality and if found to be lacking, were relegated to the hard
> anodizing tank to be renamed MA-40?

are you denying bad extrusions exist?

>
>
>>>That riveting eyelets and sockets causes crazing is not unusual, however, the cracks of
>>>interest are those that lie across principal bending planes. These are the ones that propagate
>>>into the metal.
>
>
>>You would expect, but not exclusively, which where my original diagram and the photo that it's
>>based on came from.
>
>
> Your diagram shows longitudinal cracks as does my additional picture. These are not solely
> extrusion failures because they did not occur on MA-2 rims.

have you done the metallography? you can't say that.

>
>
>>>Non anodized rims having no crust do not develop cracks as readily although cracking is possible
>>>with cyclic overload. Steady stress great enough to cause cracks would cause immediate failure
>>>similarly to spoke failure.
>
>
>>>>If anodizing were to be the sole cause of cracking, one would therefore expect to see the
>>>>cracking exactly axial with the lines of the cracked anodizing, as we see for the crack on the
>>>>left. And there would be no variation is this failure mode.
>
>
>>>Not so. Those cracks are not in line with the principal stress,
>
>
>>How not so? If the r/h crack in my diagram is not in line with the principal stress, then doesn't
>>it argue a secondary cracking mechanism?
>
>
> So? What explanation consistent with your radial crack theory do you have for this occurrence?

whose radial crack theory? you're the one saying they initiate all cracking, not me!

> I didn't ignore stress direction.

but you're ignoring anodizing crack orientation and the attendant stress concentrations.

> What you choose to ignore is that for the previous 50 years, such cracks were a rarity and were
> seen principally on tandems and other overloaded rear wheels.

when did 6061's & their like start being used in bikes? are you trying to say change of material has
had no influence?

>
>
>>>However, there have been star burst failures on rims with sufficiently thick anodizing.
>
>
>>See above. Yes, you /can/ see failures like that, and yes, that /would/ be anodizing induced.
>
>
>>>>But on the right, this photo also showed cracking *tangential* to the spoke eyelet - i.e. /not/
>>>>following the radial cracks in the anodizing but following inherent flaws in the metal's
>>>>extruded microstructure.
>
>
>>>These all ran along the direction of extrusion, finally breaking across the rim the slender
>>>bridge they made of the mid section of the rim. This is one of the inherent disadvantages of
>>>extrusions.
>
>
>>Extrusions are not inherantly flawed. Indeed, the opposite is often true. Flaws come with bad
>>processing, bad q.c. and bad material selection.
>
>
> Are you refuting your earlier claim of orientational structural differences in extrusions.

so what does "This is one of the inherent disadvantages of extrusions." mean exactly? i'm telling
you extrusions are /not/ all inherantly flawed!

> I don't understand your dodging and weaving and ignoring the mass of failure evidence occurring
> subsequent to the advent of anodized rims. A failure that was predicted and subsequently occurred.
>
>
>>>>One *cannot* therefore solely attribute cracking simply to anodizing, whether it be hard,
>>>>silver, black or purple. There don't seem to be any real micrographs on the net showing what
>>>>extruded material looks like, but this is a good representation:
>
>
> http://www.stud.ntnu.no/~fjeldly/forming.html
>
>
>>>>Just like a piece of wood is easy to split along its grain, so can be a faulty extrusion.
>
>
>>>Or for that matter a good extrusion.
>
>
>>Not if properly done.
>
>
> You seem to be saying that all failures result from extrusion faults

read what i said - that not /all/ cracking failures are solely the fault of anodizing, which is what
you've stated here on this forum countless times. /some/ of the failures are extrusion defects. and
that's it! simple! and it's wrong for you to pillory an entire industry based on that incorrect
assumption.

> when in reality extrusions are known to have orientation and strong and weak axes, just as the
> wood you cite.

anisotropy. that's a big plus in a rim extrusion, provided it doesn't go too far.

>
>
>>>>The ma40 was junk. Just throw it away. No, most modern rims do not have this problem.
>
>
>>>Oh BS! A modern rim with anodizing presents the same failure.
>
>
>>Since when? what's a current anodized rim cracking failure rate? how does that compare to the same
>>alloy unanodized? That's an entirely unsupported assumption.
>
>
> It is hard to compare, there being no rims of the kind that failed so readily. Today's rims are
> heavier, have a deeper cross section, and have no broad flat inside circumference. Some of the
> rims are so massive in the failure region that gratuitous machining is done there. A process
> patented by Mavic. This machining coincidentally removes the anodizing that would cause failures
> although at spoke penetrations, wall thickness is so massive that no failures have occurred there
> to my knowledge.

interesting to see you admit these non-cracking rims are still anodized at the spoke holes.

>
>
>>>The difference is that manufacturers are cutting back on anodizing thickness.
>
>
>>Measurements please.
>
>
> I see, you believe the lower failure rate is due to improving rim extrusions, nothing else.

q.c, processing and alloy enhancement, yes!

>
>
>>Fyi, Mavic & Ambrosio are introducing shot peening and other "kinetic" compressive residual
>>stress surface treatments. That should mitigate any last fear you have about premature fatigue in
>>modern rims.
>
>
> Oooh! I'm getting a headache from all these expensive "enhancements" without which a plain
> polished 320 gm rim survived excellently years ago.

luddite.

>
> Are you sure you aren't a government spin doctor who also interprets political blunders as
> advances these days. I see your sig seems to refer to government. Your apologist style makes me
> wonder in whose employ you are writing this stuff.
>
> Jobst Brandt jobst.brandt@stanfordalumni.org

> Been discussed many times. Do some trivial research on Google. If you're too dim to be able to
> sort out a bump at the rim joint, then I feel sorry for you. It's trivially easy to fix.

I'll be honest. I spent 30 minutes trying to find what you're referring to on Google Groups, and I
can't find it. Do you have a reference? My Rhyno Lite has this problem.

--
Phil, Squid-in-Training

Richard Ney writes:

>>>> Currently black is beautiful, be that rims tires or SUV's (with blackened windows). You see
>>>> even Avocet knuckled under and blackened their great IRC made tires and claims to have has an
>>>> immediate jump in sales, although I doubt it.

>>> Did they also make the tread thinner? I got only 1500 miles out of the last two rear (folding)
>>> Road tires.

>> I think there may have been a change in tread compound but I don't know. I am no longer involved
>> in their developments as you can imagine by the carbon 12 promotion.

> So, do you still use Avocet tires?

I have a stash of yellow bare walled Road model tires. These went more than 2500 miles for mu trip
in the alps this summer and subsequent riding here in the local mountains. They did not last as long
as the best ones I had that lasted close to 3000 miles but that's good enough for me.

> I have a wire-bead 25mm Road on the rear now. I'm interested to see if I get the same low mileage.
> I care less about the marketing and more about the functionality. They can call it Carbon 12 or
> whatever, but if the tires aren't lasting, I'll find something else.

I still think they are the best around but I would be happier with a tire that wasn't black. The
black covers information that I want to see, such as casing aging and side cord cuts.

Jobst Brandt jobst.brandt@stanfordalumni.org

> A Muzi wrote:
> > BaCardi wrote:
> > > Oh and the seam welding and machining is a waste too? Give me a break
> > Well, if it isn't wasteful why do they cost more, weigh more and last not as long?

BaCardi unfortunately wrote:
> Obviously, you haven't been in the game with your eyes open long enough to know about the
> differences between the old seam rims of yesterday and the machined seamed rims of today. So, I'll
> lay it out for you so you can stop deceiving your customers that the old rims are better than new.
>
> 1) Buy a oldie rim with a seam that you can actually feel when you run your fingers across the
> seam.
> 2) Buy a new rim with the seam welded and machined flat.
> 3) Now, when you brake with the old rim, you feel a thud, thud, thud every time the wheel goes
> around to hit the brake pad. Compare that to the smoothness of a rim with a flat and
> machined rim.
>
> You and Jobst are totally WRONG on this one. And it doesn't take a freaking "I got a Stanford
> degree" to see that.

The seam's a red herring.

I have been building wheels for a good long while. It's trivially simple to press an errant plug
seam straight when building a wheel. Not doing so is simple indolence. In fact, I have Fiammes (red
& yelllow, strada & pista) which run dead smooth but were slightly stepped when I built them twenty,
twenty-five, thirty years ago. My Super Champions were all uniform as received and haven't moved in
that time. But even when left askew, such seams smooth from braking in a short while.

Those rims weigh between 290 and 360g. The braking surface life is extremely long compared to modern
cut-side rims. Some have been badly bashed , straightened and rebuilt giving good service yet. What
do your rims weigh? How long do they wear? Can you unbend a flat spot and rebuild without a crack?

You wouldn't spout such crap if you knew anything about wheelbuilding or if you had weighed the
various rims, or if you had ridden bicycles much, or if you had noted the large differences in
longevity between plugged and welded rims.

In another happier post today, I alluded to the occasionally offbeat pontifications from theory here
on r.b.t. You very nicely exhibit how they can wander far from actual bicycles and bicycling.

Degree? Jobst is an educated man. I am a 10th grade dropout. Our experiences and conclusions are the
same on this. It's so blatantly obvious to any and all cyclists who have even casually observed
these trends through the years.
--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

BaCardi wrote:

> A Muzi without taking the time to thingk wrote:
> > BaCardi wrote:
> > > Oh and the seam welding and machining is a waste too? Give me a break
> > Well, if it isn't wasteful why do they cost more, weigh more and last not as long?
> > --
> > Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
>
>
>
>
> Obviously, you haven't been in the game with your eyes open long enough to know about the
> differences between the old seam rims of yesterday and the machined seamed rims of today. So, I'll
> lay it out for you so you can stop deceiving your customers that the old rims are better than new.
>
> 1) Buy a oldie rim with a seam that you can actually feel when you run your fingers across the
> seam.
> 2) Buy a new rim with the seam welded and machined flat.
> 3) Now, when you brake with the old rim, you feel a thud, thud, thud every time the wheel goes
> around to hit the brake pad. Compare that to the smoothness of a rim with a flat and
> machined rim.
>
> You and Jobst are totally WRONG on this one. And it doesn't take a freaking "I got a Stanford
> degree" to see that.

IME the brake pad soon smooths off the join - and I'd hardly describe it as a "thud". This issue
with machined rims is that the wall thickness varies, because it's impossible to keep the rim
running *perfectly* true during the machining process. With an unmachined rim the wall thickness is
constant as originally extruded.

Chalo wrote:

> Sun rims are, to the best of my knowledge, nearly all available in polished bare aluminum, most
> with eyelets too.

Their silver ones - I have Rhyno Lites [1] on the touring bike - have a very thin anodising (as do
many silver rims) which is rubbed off by the brakes after only a couple of hundred miles. I doubt
this thin anodising is particularly harmful to the rim, and it does protect against spots caused by
road salt.

Black anodising - the stuff that looks like paint - is much thicker and harder. There isn't really
any justification for it unless you really must have black wheels.

[1] actually about 1" wide...you should see the non-lite version!

Total BS! The brake pad should not have to smooth out any join of an oldie rim. And some rims are worse than others. Welded and machined rims may be a little heavier, but they are machined smooth. Don't have to have a Stanford degree wedged up your crack to figure that one out. And don't need to a kissing ass LBS owner to see that either. But keep on justifying your stupid arguments, fool.

Bacardi is a loon, don't feed him...

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"