mavic rims don't *all* suck

[Carl Fogel]

Rick Onanian <[email protected]> wrote in message news:<[email protected]>...
> On 29 Feb 2004 17:55:31 -0800, [email protected] (Carl Fogel) wrote:
> >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
>
> Just a few minutes ago, catching up on this thread, I read this message:
> http://groups.google.com/groups?&selm=veO0c.25457%246K.16459%40nwrddc02.gnilink.net
>
> I guess this sarcasm isn't so preposterous after all: Matt O'Toole wrote :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...

Dear Rick,

Actually, it doesn't seem to be very well-informed sarcasm.

Despite what was said in the post that you cite, the anodizing process increases the weight of the
piece being anodized, unless I've badly misunderstood basic chemistry--no aluminum is removed, but a
layer of aluminum is being oxidized, and dye is often being added. The increase in weight is small,
but easily noted when the pieces are weighed.

The difference between U.S. and Japanese anodizing techniques described by the BikePro catalogue may
no longer exist, or there may be even more differences among a wider range of rim makers.

In any case, the use of different preparation steps, different acids, and different dyes may have a
noticeable effect. In the current thread on track glue, John Everett gives a link to a study that
shows that all the glues preferred one kind of anodizing over another, clear versus hard, depending
on the glue manufacturer:

http://www.engr.ukans.edu/~ktl/bicycle/Cusa1.pdf

Something about the different glues works better with different kinds of anodizing--possibly the
dyes, maybe the kind of acid used, perhaps the temperature, voltage, or preparation. The difference
may extend to other things, like corrosion and fatigue problems.

Frankly, I'm baffled by posts claiming that various well-documented anodizing processes don't even
exist, that the different techniques cannot have any effect, and that detailed tables are somehow
utterly mistaken.

As I pointed out elsewhere in this thread, the only other weight table so far mentioned is Damon
Rinard's admirable effort, but its rim section is clearly inferior to the BikePro table.

http://www.sheldonbrown.com/rinard/weights.htm

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

Damon innocently lumped together what are actually three kinds of MA2 rims, for example, and gave
the misleading impression that their weight varies from about 444 to 480 grams, a 10% variation. The
BikePro catalogue breaks the MA2 weights down into the three sub-categories that account for the
variation, spoke eyelets that are 2-piece (464), double-wall (473), or stainless steel (485).

Differences in drilling (32-36-40) and brake-area wear might account for the other differences in
Damon's haphazard sample, as well as his use of two different scales over several years.

Again, I should add that I'd have weighed rims just as trustingly (and not nearly as well) as Damon
did. Does anyone know of a better rim-weight table than the BikePro table, which unfortunately
stopped about ten years ago? Something, perhaps from some magazine devoted to reviewing bicycles?

Carl Fogel

 

[Carl Fogel]

dianne_1234 <[email protected]> wrote in message news:<[email protected]>...
> On 1 Mar 2004 11:03:34 -0800, [email protected] (Carl Fogel) wrote:
>
> >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
>
> Careful -- individual rims vary in weight even with the same finish.
>
> For examples, see http://www.sheldonbrown.com/rinard/weights.htm#clincherrims
>
> Same model rims weighting Matrix ISO-C II 392,398,405,406,411,412,440 Mavic Open 4 CD
> 412,456,456,437,434 Mavic Reflex 422,427,427,439 Mavic Open Pro 405,424,424,437,440,441,445
>
> I'm not sure how many rims bike pro measured, but it would be simple to find one rim heavier than
> another and (erroneously) conclude it was due to different finish.

Dear Dianne,

Just a quick note--I'm looking into anodizing further and am catching faint hints that the weight
may not work at all the way that I thought.

So far, I haven't found anything clear, but it might be that more aluminum is dissolved than is
retained in the hardened oxide layer. Possibly someone who knows more can clear this up.

Carl Fogel

 

[Carl Fogel]

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

Dear Tim,

Here's a link to a brief description of "hard anodizing" that might address the flaking:

http://www.eastwestdye.com/technical_info.html

Voltage and temperature control various aspects of the anodizing process. The "hard anodizing" uses
a lower temperature and greater current (recall the BikePro comments on different U.S. and Japanese
anodizing) and, as a result, penetrates the metal as well as forming an outer layer.

While looking into anodizing, I keep getting faint hints that I may be dead wrong about the weight
gain. That is, more aluminum may dissolve into the acid solution than is retained in the formed
oxide layer. But so far, I haven't found anything that says one way or the other whether the pieces
come out of the acid bath lighter or heavier. It may even vary, according to the process and the post-
anodizing steps involving sealers.

Carl Fogel

 

[carlfogel]

Originally posted by Carl Fogel
dianne_1234 <[email protected]> wrote in message news:<[email protected]>...
> On 1 Mar 2004 11:03:34 -0800, [email protected] (Carl Fogel) wrote:
>
> >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
>
> Careful -- individual rims vary in weight even with the same finish.
>
> For examples, see http://www.sheldonbrown.com/rinard/weights.htm#clincherrims
>
> Same model rims weighting Matrix ISO-C II 392,398,405,406,411,412,440 Mavic Open 4 CD
> 412,456,456,437,434 Mavic Reflex 422,427,427,439 Mavic Open Pro 405,424,424,437,440,441,445
>
> I'm not sure how many rims bike pro measured, but it would be simple to find one rim heavier than
> another and (erroneously) conclude it was due to different finish.

Dear Dianne,

Just a quick note--I'm looking into anodizing further and am catching faint hints that the weight
may not work at all the way that I thought.

So far, I haven't found anything clear, but it might be that more aluminum is dissolved than is
retained in the hardened oxide layer. Possibly someone who knows more can clear this up.

Carl Fogel

Follow-up:

The weight change in anodizing may be covered by
the term "coating ratio":

"The coating ratio, i.e., the coulombic efficiency for the formation of porous oxide films on Al, was calculated by the ratio of the weight of oxide formed to the weight of aluminium consumed."

http://www2.umist.ac.uk/corrosion/JCSE/Volume3/Paper3/v3p3.html

This paper gave coating ratio values from 1.42 to 1.17
for different acids and techniques, which I think means
that 142 to 117 pounds of oxide layer formed for every
hundred pounds of original aluminum consumed.

If "consumed" includes original aluminum lost and dissolved
into the acid, then anodizing increases the weight of the
part.

This pdf link claculates the coating ratio as "the coating
weight divided by the differerence in weights of aluminum
sample before anodizing and after the anodic coating was removed":

http://www.metalast.com/technology/Research_PDF/Technical_Reports/Pulsed_Current.pdf

The more extensive coating ratios in this pdf link
range from about 1.5 to 2.4 for a variety of alloys.

Again, this suggests overall weight gain. If I follow
the calculation, a 100 pound alloy piece would be
anodized, 5 pounds of resulting anodization coating
would be removed, and the piece weighed again
might be 97 pounds:

(5 lbs coating removed)
/
(100 lbs pre-anodize - 97 lbs after coating-removal)

= 5/3
= 1.66 coating ratio

Of course, this example probably greatly exaggerates
the actual weight gain, depending on surface area.
Since rims, however, are mostly surface area, they
would tend to show weight gain.

Carl Fogel

 

[Jay Beattie]

"Carl Fogel" <[email protected]> wrote in message
news:[email protected]...
> Rick Onanian <[email protected]> wrote in message
news:<[email protected]>...

<snip>

> > On 29 Feb 2004 17:55:31 -0800, [email protected] (Carl
Fogel)
> As I pointed out elsewhere in this thread, the only other weight table so far mentioned is Damon
> Rinard's admirable effort, but its rim section is clearly inferior to the BikePro table.
>
> http://www.sheldonbrown.com/rinard/weights.htm
>
> http://www.bikepro.com/products/rims/rimtables.html
>
> Damon innocently lumped together what are actually three kinds of MA2 rims, for example, and gave
> the misleading impression that their weight varies from about 444 to 480 grams, a 10% variation.
> The BikePro catalogue breaks the MA2 weights down into the three sub-categories that account for
> the variation, spoke eyelets that are 2-piece (464), double-wall (473), or stainless steel (485).

<snip>

Dear Carl, AFAIK, all the predecessors and permutations of the MA2 (Elan, ModE, Mod3, Mod4, E2, MA2,
G40, MA40) had the same two-piece, spoke socket and stainless steel rivet (eyelet) arrangement. You
could not buy them with just a socket, or just a rivet or in plain steel. The weights stated in the
BikePro catalogue do not correspond to any MA2-like rim I ever saw. -- Jay Beattie.

 

[Tom Sherman]

Carl Fogel wrote:

> Just a quick note--I'm looking into anodizing further and am catching faint hints that the weight
> may not work at all the way that I thought.
>
> So far, I haven't found anything clear, but it might be that more aluminum is dissolved than is
> retained in the hardened oxide layer. Possibly someone who knows more can clear this up.

Dear Carl,

Just remember that weights/masses will be lower in the US; due to the loss of an "i" as aluminium is
transformed into aluminum.

Tom Sherman - Quad Cities (Illinois Side)

 

[Tim McNamara]

[email protected] (Carl Fogel) writes:

> Frankly, I'm baffled by posts claiming that various well-documented anodizing processes don't
> even exist,

What I said was "I don't know if clear anodizing in fact exists." What I'm seeing in my mind's eye
in reference to this is a clear, shiny and fairly thick coating that I've seen on some rims and
various other bike parts (e.g. late 70's Dura Ace). It looks very different from any other type of
anodizing, which tends to have an opaque matte surface whether it is the same color as the base
metal or not.

> that the different techniques cannot have any effect, and that detailed tables are somehow utterly
> mistaken.

If you're referring to Bike Pro's Web site, then I'll reiterate that Bike Pro's stuff was not all
that accurate, mainly being a repetition of hoary old myths and legends. The example already cited
by someone else in the Bike Pro Web site that anodizing makes rims stiffer is a classic. However,
there was also quite a bit of accurate stuff, and it was an attempt to provide much more information
than most bikies had access to without paying the high proces of a Sutherland's or similar tome.

Detailed tables can easily be mistaken; indeed, the more detailed data presentation is the more
likely it is to be mistaken. There are just more chances for error. Some people like to overwhelm
with detail to camoflage the gaping errors in fundamental assumptions and logic.

 

[carlfogel]

Originally posted by Tim McNamara
[email protected] (Carl Fogel) writes:

> Frankly, I'm baffled by posts claiming that various well-documented anodizing processes don't
> even exist,

What I said was "I don't know if clear anodizing in fact exists." What I'm seeing in my mind's eye
in reference to this is a clear, shiny and fairly thick coating that I've seen on some rims and
various other bike parts (e.g. late 70's Dura Ace). It looks very different from any other type of
anodizing, which tends to have an opaque matte surface whether it is the same color as the base
metal or not.

> that the different techniques cannot have any effect, and that detailed tables are somehow utterly
> mistaken.

If you're referring to Bike Pro's Web site, then I'll reiterate that Bike Pro's stuff was not all
that accurate, mainly being a repetition of hoary old myths and legends. The example already cited
by someone else in the Bike Pro Web site that anodizing makes rims stiffer is a classic. However,
there was also quite a bit of accurate stuff, and it was an attempt to provide much more information
than most bikies had access to without paying the high proces of a Sutherland's or similar tome.

Detailed tables can easily be mistaken; indeed, the more detailed data presentation is the more
likely it is to be mistaken. There are just more chances for error. Some people like to overwhelm
with detail to camoflage the gaping errors in fundamental assumptions and logic.

Dear Tim,

Here's what the BikePro page actually says:

"Hard anodizing is said to increase a rim's rigidity
between 10 and 20 per cent. Somehow that seems
a little high . . ."

This doesn't sound as if they quite endorse it,
does it? And their weight table looks quite
sensible when checked against Damon Rinard's
rim weights.

I haven't looked into the matter yet, since the
original question was whether unanodized and
clear/hard anodized rims weighed exactly the
same, but what effect do you predict hard anodizing
has on a rim's rigidity? Significantly less rigid, a tiny
bit less rigid, no effect at all, a tiny bit more rigid, or
significantly more rigid?

That is, what's your fundamental assumption?

Carl Fogel

 

[Jobst Brandt]

Tim McNamara writes:

> If you're referring to Bike Pro's Web site, then I'll reiterate that Bike Pro's stuff was not all
> that accurate, mainly being a repetition of hoary old myths and legends. The example already cited
> by someone else in the Bike Pro Web site that anodizing makes rims stiffer is a classic. However,
> there was also quite a bit of accurate stuff, and it was an attempt to provide much more
> information than most bikies had access to without paying the high prices of a Sutherland's or
> similar tome.

Actually anodizing make the rim measurably stiffer since the exterior skin has a far higher modulus
of elasticity than aluminum. The problem is as soon as its tensile and compressive strength is
exceeded by any significant load, the stiffness is mostly gone leaving a crazed hard skin that
initiates the cracks under discussion here.

I can only repeat the example of a scab on you knee that stiffens the skin but breaks as soon as the
knee is significantly bent, blood being the indicator. That is the most palpable example of material
mismatch similar to aluminum and anodizing that comes to mind readily.

Jobst Brandt [email protected]

 

[carlfogel]

Originally posted by Jobst Brandt
Tim McNamara writes:

> If you're referring to Bike Pro's Web site, then I'll reiterate that Bike Pro's stuff was not all
> that accurate, mainly being a repetition of hoary old myths and legends. The example already cited
> by someone else in the Bike Pro Web site that anodizing makes rims stiffer is a classic. However,
> there was also quite a bit of accurate stuff, and it was an attempt to provide much more
> information than most bikies had access to without paying the high prices of a Sutherland's or
> similar tome.

Actually anodizing makes the rim measurably stiffer since the exterior skin has a far higher modulus
of elasticity than aluminum. The problem is as soon as its tensile and compressive strength is
exceeded by any significant load, the stiffness is mostly gone leaving a crazed hard skin that
initiates the cracks under discussion here.

I can only repeat the example of a scab on your knee that stiffens the skin but breaks as soon as the
knee is significantly bent, blood being the indicator. That is the most palpable example of material
mismatch similar to aluminum and anodizing that comes to mind readily.

Jobst Brandt [email protected]

Dear Jobst,

That's an awfully nice job of clearing up the
question of rigidity and hard anodizing.

Thanks,

Carl Fogel

 

[Dave Lehnen]

Tom Sherman wrote:
> Carl Fogel wrote:
>
>> <something more or less serious>
>
>
> Dear Carl,
>
> Just remember that weights/masses will be lower in the US; due to the loss of an "i" as aluminium
> is transformed into aluminum.
>
> Tom Sherman - Quad Cities (Illinois Side)
>

Misleading. In the U.S., aluminum is converted to aluminum oxide, for a letter gain of 5/8 or 62.5%,
while in the British Empire, aluminium is converted to aluminium oxide, for a gain of
5/9 or only 55.6%, not counting blanks. Conversion to corundum rather than aluminum oxide further
complicates matters.

Dave Lehnen

 

[Jim Beam]

[email protected] wrote:
> Tim McNamara writes:
>
>
>>If you're referring to Bike Pro's Web site, then I'll reiterate that Bike Pro's stuff was not all
>>that accurate, mainly being a repetition of hoary old myths and legends. The example already cited
>>by someone else in the Bike Pro Web site that anodizing makes rims stiffer is a classic. However,
>>there was also quite a bit of accurate stuff, and it was an attempt to provide much more
>>information than most bikies had access to without paying the high prices of a Sutherland's or
>>similar tome.
>
>
> Actually anodizing make the rim measurably stiffer since the exterior skin has a far higher
> modulus of elasticity than aluminum.

really? it makes the /surface/ harder, obviously, but anodizing increases bulk modulus???
data please!

> The problem is as soon as its tensile and compressive strength is exceeded by any significant
> load, the stiffness is mostly gone leaving a crazed hard skin that initiates the cracks under
> discussion here.
>
> I can only repeat the example of a scab on you knee that stiffens the skin but breaks as soon as
> the knee is significantly bent, blood being the indicator. That is the most palpable example of
> material mismatch similar to aluminum and anodizing that comes to mind readily.
>
> Jobst Brandt [email protected]

 

[Carl Fogel]

Dave Lehnen <[email protected]> wrote in message news:<[email protected]>...
> Tom Sherman wrote:
> > Carl Fogel wrote:
> >
> >> <something more or less serious>
> >
> >
> > Dear Carl,
> >
> > Just remember that weights/masses will be lower in the US; due to the loss of an "i" as
> > aluminium is transformed into aluminum.
> >
> > Tom Sherman - Quad Cities (Illinois Side)
> >
>
>
> Misleading. In the U.S., aluminum is converted to aluminum oxide, for a letter gain of 5/8 or
> 62.5%, while in the British Empire, aluminium is converted to aluminium oxide, for a gain of
> 5/9 or only 55.6%, not counting blanks. Conversion to corundum rather than aluminum oxide further
> complicates matters.
>
> Dave Lehnen

Dear Tom and Dave,

Luckily, it all comes out in the wash. We adjust by using smaller, non-Imperial gallons of acid in
our U.S. anodizing tanks.

Carl Fogel

 

[James Thomson]

"Jay Beattie" <[email protected]> wrote:

> AFAIK, all the predecessors and permutations of the MA2 (Elan, ModE, Mod3, Mod4, E2, MA2, G40,
> MA40) had the same two-piece, spoke socket and stainless steel rivet (eyelet) arrangement. You
> could not buy them with just a socket, or just a rivet or in plain steel.

Single-eyelet MA2s have been available on the British market in the past. I don't remember any
difference in labelling between the single eyelet model and the more common double eyelet version,
but I don't have an example on hand to compare.

James Thomson

 

[Tim McNamara]

carlfogel <[email protected]> writes:

> Here's what the BikePro page actually says:
>
> "Hard anodizing is said to increase a rim's rigidity between 10 and 20 per cent. Somehow that
> seems a little high . . ."
>
> This doesn't sound as if they quite endorse it, does it?

That they mention it at all, and the choice of phrasing, carries an endorsement of the concept.

> I haven't looked into the matter yet, since the original question was whether unanodized and
> clear/hard anodized rims weighed exactly the same, but what effect do you predict hard anodizing
> has on a rim's rigidity? Significantly less rigid, a tiny bit less rigid, no effect at all, a tiny
> bit more rigid, or significantly more rigid?

Since the anodized layer is brittle, I think it adds no rigidity whatsoever. However, as the saying
goes, one measurement is worth a thousand opinions. Find an MA2 and an MA40, and measure it.

 

[Tim McNamara]

[email protected] writes:

> Tim McNamara writes:
>
>> If you're referring to Bike Pro's Web site, then I'll reiterate that Bike Pro's stuff was not all
>> that accurate, mainly being a repetition of hoary old myths and legends. The example already
>> cited by someone else in the Bike Pro Web site that anodizing makes rims stiffer is a classic.
>> However, there was also quite a bit of accurate stuff, and it was an attempt to provide much more
>> information than most bikies had access to without paying the high prices of a Sutherland's or
>> similar tome.
>
> Actually anodizing make the rim measurably stiffer since the exterior skin has a far higher
> modulus of elasticity than aluminum. The problem is as soon as its tensile and compressive
> strength is exceeded by any significant load, the stiffness is mostly gone leaving a crazed hard
> skin that initiates the cracks under discussion here.

Interesting. Thanks.

 

[Jobst Brandt]

Tim McNamara writes:

>> Here's what the BikePro page actually says:

>> "Hard anodizing is said to increase a rim's rigidity between 10 and 20 per cent. Somehow that
>> seems a little high . . ."

>> This doesn't sound as if they quite endorse it, does it?

> That they mention it at all, and the choice of phrasing, carries an endorsement of the concept.

>> I haven't looked into the matter yet, since the original question was whether unanodized and
>> clear/hard anodized rims weighed exactly the same, but what effect do you predict hard anodizing
>> has on a rim's rigidity? Significantly less rigid, a tiny bit less rigid, no effect at all, a
>> tiny bit more rigid, or significantly more rigid?

> Since the anodized layer is brittle, I think it adds no rigidity whatsoever. However, as the
> saying goes, one measurement is worth a thousand opinions. Find an MA2 and an MA40, and
> measure it.

The way rigidity is measured is, for instance, how much a beam bends per unit of loading. That says
nothing about at how much load. Therefore, using a suitably light test load, an anodized part will
register less deflection than it had before anodizing. However, a bicycle rim will crack that
coating the first time it is loaded in use after which all increased rigidity is effectively gone.

These are "lies of the second kind" where what was said is true but the message delivered is
entirely false. Anodizing always increases rigidity but not for loads for which the original cross
section was designed. Therefore, there is no increase in functional rigidity.

We should recognize such distortions of facts, now that political campaigning is swinging into
expensive action.

Jobst Brandt [email protected]

 

[Dianne_1234]

On Wed, 03 Mar 2004 16:29:09 GMT, jim beam <[email protected]> wrote:

>[email protected] wrote:
>> Actually anodizing make the rim measurably stiffer since the exterior skin has a far higher
>> modulus of elasticity than aluminum.
>
>really? it makes the /surface/ harder, obviously, but anodizing increases bulk modulus???
>data please!

Aluminum 6061-T6; 6061-T651: Modulus of Elasticity 69 GPa
http://www.matweb.com/search/SpecificMaterial.asp?bassnum=MA6016

Sapco 99.7% Aluminum Oxide: Modulus of Elasticity 380 GPa
http://www.matweb.com/search/SpecificMaterial.asp?bassnum=CSAP01

I don't know if "Sapco 99.7% Aluminum Oxide" is similar to hard ano or not. I just searched for
"aluminum oxide" at matweb and picked a likely looking link.

 

[Jim Beam]

[email protected] wrote:
> Tim McNamara writes:
>
>
>>>Here's what the BikePro page actually says:
>
>
>>>"Hard anodizing is said to increase a rim's rigidity between 10 and 20 per cent. Somehow that
>>>seems a little high . . ."
>
>
>>>This doesn't sound as if they quite endorse it, does it?
>
>
>>That they mention it at all, and the choice of phrasing, carries an endorsement of the concept.
>
>
>>>I haven't looked into the matter yet, since the original question was whether unanodized and
>>>clear/hard anodized rims weighed exactly the same, but what effect do you predict hard anodizing
>>>has on a rim's rigidity? Significantly less rigid, a tiny bit less rigid, no effect at all, a
>>>tiny bit more rigid, or significantly more rigid?
>
>
>>Since the anodized layer is brittle, I think it adds no rigidity whatsoever. However, as the
>>saying goes, one measurement is worth a thousand opinions. Find an MA2 and an MA40, and
>>measure it.
>
>
> The way rigidity is measured is, for instance, how much a beam bends per unit of loading. That
> says nothing about at how much load. Therefore, using a suitably light test load, an anodized part
> will register less deflection than it had before anodizing. However, a bicycle rim will crack that
> coating the first time it is loaded in use after which all increased rigidity is effectively gone.

???? does it increase rigidity or doesn't it? surface hardness is not rigidity.

and how do we reconcile the above with this little nugget?

"Subject: 8.18 Anodized vs. Non-anodized Rims From: Jobst Brandt <[email protected]> Date: Mon, 20
Apr 1998 15:31:32 PDT

Dark anodized rims were introduced a few years ago as a fashionable alternative to shiny metal
finish, possibly as a response to non metallic composites. Some of these rims were touted as HARD
anodized implying greater strength. Hard anodizing of aluminum, in contrast to cosmetic anodizing,
produces a porous ceramic oxide that forms in the surface of the metal, as much as 1/1000 inch
thick, about half below the original surface and half above. It is not thick enough to affect the
strength of the rim but because it is so rigid, acts like a thin coat of paint on a rubber band. The
paint will crack as the rubber stretches before any load is carried by the rubber. Similarly,
anodizing cracks before the aluminum carries any significant load.

<snip this long quote>

Anodizing is not heat treatment and has no effect on the structural properties of the aluminum."

from: http://groups.google.com/groups?selm=7d8lp4%24fni%244%40hplms2.hpl.hp.com&oe=UTF-
8&output=gplain

>
> These are "lies of the second kind" where what was said is true but the message delivered is
> entirely false. Anodizing always increases rigidity but not for loads for which the original cross
> section was designed. Therefore, there is no increase in functional rigidity.

what???

you need to explain this one.

>
> We should recognize such distortions of facts, now that political campaigning is swinging into
> expensive action.
>
> Jobst Brandt [email protected]

 

[James Thomson]

"Carl Fogel" <[email protected]> wrote:

[snip]

> The BikePro catalogue breaks the MA2 weights down into the three sub-categories that account for
> the variation, spoke eyelets that are 2-piece (464), double-wall (473), or stainless steel (485).

Having looked more closely at the table, it seems to me that the eyelets are all "2-piece, double-
wall, stainless steel" (the same description used in the MA2 review), and the weight differences
correspond to the three available drillings (32h, 36h, 40h).

James Thomson