Mavic MA-40 - Piece of Crap?
David White
apart, I took it over to my neighbor's for a minor truing. On the way back home
with the wheel, I noted that the MA-40 rim is cracking in several places near
where the sidewalls meet the other part of the rim. It looks like the eyelet is
being pulled toward the hub. This is like the 4th or 5th one of these rims to
do this to me.
In the past, I have taken the failed rims to a big local Mavic dealer and they
have given me replacement rims. I am pretty sure this was one of those
replacements as it has the newer label. The last time I went in, I said, "no
way - no more MA-40's, give me the cheaper MA-2 instead" and they did. I have
yet to encounter this problem with the MA-2, now sadly no longer being made.
I have read in several places that the grey anodizing/hardening of these rims
causes this to happen. It seems to be a well known failure. This wheel was
built in 1997 but has seen little use (when you have 8 bikes, each gets little
milage). There is brake wear on the sidewalls but not very much.
Is this a problem on other rims? Is there an easy way to know which to avoid in
the future? Thanks...
BaCardi
HAHAH!!!! WTF-ever! The MA-40 is a legendary high durability rim. Lots
of people swear by them for their training wheels.
--
daveornee
Sometimes hard annodized rims crack, but sometimes totally non-annodized
rims crack too. I have experience with both. The alloy, extruding, heat
treating, and annodizing all make a difference. Rim finishing such as
maching the sidewalls and working the surface(s) surrounding the eyelets
make a difference as well. I am not an engineer or metalurgist. I have
had good experiences and bad with all manuafacturer's products. Your
dealer has a relationship with his suppliers that provide for some
coverage in case of difficulties or failures. Circumstances, including
time, are what drives how each individual case is handled. I think that
there are three things that I know you can do:
1. Buy rims that fit the application, including riding situations, tire
size/inflation, and rider weight.
2. Use crossed Double Butted spokes that are evenly tensioned.
3. Deal with a dealer that will support your reasonable expectations.
You should understand ahead of time what is and isn't covered, and
for how long.
--
Tim McNamara
> David White wrote:
>
> > I got a flat on my bike's rear yesterday. So today while I had
> > the rear wheel apart, I took it over to my neighbor's for a
> > minor truing. On the way back home with the wheel, I noted that
> > the MA-40 rim is cracking in several places near where the
> > sidewalls meet the other part of the rim. It looks like the
> > eyelet is being pulled toward the hub. This is like the 4th or
> > 5th one of these rims to do this to me.
>
> > In the past, I have taken the failed rims to a big local Mavic
> > dealer and they have given me replacement rims. I am pretty sure
> > this was one of those replacements as it has the newer
> > label. The last time I went in, I said, "no way - no more
> > MA-40's, give me the cheaper MA-2 instead" and they did. I have
> > yet to encounter this problem with the MA-2, now sadly no longer
> > being made.
You have discovered on of the home truths about rims. Anodizing
makes them more prone to cracking in exactly the way you describe.
This has been discussed many times in this newgroup, and thousands of
posts on the subject are available via Google and don't bear
repeating here.
> > I have read in several places that the grey anodizing/hardening
> > of these rims causes this to happen. It seems to be a well known
> > failure. This wheel was built in 1997 but has seen little use
> > (when you have 8 bikes, each gets little milage). There is brake
> > wear on the sidewalls but not very much.
Anodized rims frequently fail by cracking long before they wear out
from braking. This is probably not much of a problem if you're 120
lbs and ride 36 spoke wheels. If you're 215 lbs and ride 32 spoke
wheels, you'll see this problem more often.
> > Is this a problem on other rims? Is there an easy way to know
> > which to avoid in the future? Thanks...
Avoid anodized rims. Well, good luck, there aren't any non-anodized
rims on the (after)market to my knowledge except possibly the Torelli
Master, and reports conflict on that rim.
> HAHAH!!!! WTF-ever! The MA-40 is a legendary high durability
> rim. Lots of people swear by them for their training wheels.
Swear at them, perhaps. The MA-40 was a dog. The MA-2 was a great
rim, the best Mavic ever made for general use. David's post is far
more accurate that your pathetic attempt to ridicule him.
dianne_1234
This is the classic example of the bad effects of hard anodization.
David Ornee's advice is good. And if all else is equal, choose a
non-hard anodized rim.
David Reuteler
: Avoid anodized rims. Well, good luck, there aren't any non-anodized
: rims on the (after)market to my knowledge except possibly the Torelli
: Master, and reports conflict on that rim.
several of the velocity deep-v rims are powder coated. hopefully they
weren't annodized first.
--
david reuteler
reut...@visi.com
Tim McNamara
David Reuteler
: David Reuteler <reut...@visi.com> writes:
:> several of the velocity deep-v rims are powder coated. hopefully
:> they weren't annodized first.
: Well, it would be a waste of money to have done so.
yea, you'd think that would prevent them for doing it. velocity's site
*SEEMS* to explicitly state when a rim is annodized but only list the colour
when it's powdercoated. i know some of the deep-vs are 'cause i use black
deep-v rims. but it looks like at least some of the aerohead and razor rims
may also be powdercoated. the dyad (their touring rim) otoh appears to only
be annodized.
the bontrager maverick has a powdercoat black 32-hole 700c version. they
used to offer the fairlane (its predecessor) in a 36-hole non annodized
plain al but no longer. rivendell still sells them here
http://rivendellbicycles.com/webalog/wheels/18094.html
but their claim that they were made "just for us" is pure bunk. you can/could
buy them at any trek dealer. well, i did anyway. at freewheel in minneapolis
in march of 2002 to be very specific.
--
david reuteler
reut...@visi.com
Allan Butler
I have had the same problem on other anodized rims. In the case of my bike
they were the rims that TREK made or had made for several years. They would
crack at the nipples and on the braking surface. It turns out that someone
had decided a light weight rim would work ok and then decided to make it
lighter and lighter and, well you get the idea. There is a point where it
just ain't gonna work. Add to that matter that I am over 200 pounds and
don't slow down on the hills. :-) I have a set of Mavics that replaced that
problem and they are on my second bike now. Just within the last year or so
I had to replace the rear rim as it also broke. But that was after five
years of riding that wheel. Previously I would replace the rims once a
year. And it always seemed to happen the same week of the year on the same
organized ride on the same day of the week +- 1 day!
Try to find a Mavic that is not a light weight rim and give it a try. The
rims I have are anodized on the surface that the spokes penetrate but the
braking surfaces are machined. I don't recall the model number right at
this time.
Al Butler
ka0ies
jobst....@stanfordalumni.org
> I got a flat on my bike's rear yesterday. So today while I had the
> rear wheel apart, I took it over to my neighbor's for a minor
> truing. On the way back home with the wheel, I noted that the MA-40
> rim is cracking in several places near where the sidewalls meet the
> other part of the rim. It looks like the eyelet is being pulled
> toward the hub. This is like the 4th or 5th one of these rims to do
> this to me.
> In the past, I have taken the failed rims to a big local Mavic
> dealer and they have given me replacement rims. I am pretty sure
> this was one of those replacements as it has the newer label. The
> last time I went in, I said, "no way - no more MA-40's, give me the
> cheaper MA-2 instead" and they did. I have yet to encounter this
> problem with the MA-2, now sadly no longer being made.
> I have read in several places that the grey anodizing/hardening of
> these rims causes this to happen. It seems to be a well known
> failure. This wheel was built in 1997 but has seen little use (when
> you have 8 bikes, each gets little mileage). There is brake wear on
> the sidewalls but not very much.
> Is this a problem on other rims? Is there an easy way to know which
> to avoid in the future? Thanks...
That hard anodizing causes cracking is a well understood phenomenon in
aviation and has been thoroughly documented. When the the hard
anodizing fad first came along, about ten years ago, I wrote
extensively about it to no avail. Wrek.bike.tech folk repeated all
the promotional garbage that Mavic and others had written in defense
of these rims. Meanwhile, I took a section of an MA-2 and an MA-40
with the same service life and had them sectioned and polished by the
Alcan materials lab that was available at the time. The MA-40 had
failures as you describe and the cross sections showed a crazed
anodized surface with anodizing cracks propagating into the aluminum.
The MA-2 had none of this.
The worst rim failure of this type I saw had cracked circumferentially
into the hollow chamber leaving the spokes in the inner part and the
tire on the outer part, the two parts being slightly inter meshed and
offset laterally. The rider was able to stop and call for a ride.
Although cosmetic anodizing is far less damaging, it also cracks and
can in cases generate cracking in the structure of the rim. The
defense for this often given is that nearly all rims have some manner
of anodizing. Well that's not good, no matter who says so.
Jobst Brandt
jobst....@stanfordalumni.org
jobst....@stanfordalumni.org
>>> Avoid anodized rims. Well, good luck, there aren't any
>>> non-anodized rims on the (after)market to my knowledge except
>>> possibly the Torelli Master, and reports conflict on that rim.
>> several of the velocity deep-v rims are powder coated. hopefully
>> they weren't anodized first.
> Well, it would be a waste of money to have done so.
Oh? If all that welding, machining and heat treatment isn't a huge
waste. The MA-2 had none of these features nor did the many Fiamme or
Super Champion rims we rode before Mavic "invented" all these
processes. The MA-2 was still on the market at half the price of the
"New" rims and the public jumped on the more expensive ones.
Suckers!!!
Jobst Brandt
jobst....@stanfordalumni.org
Qui si parla Campagnolo
home
with the wheel, I noted that the MA-40 rim is cracking in several places near
Not uncommon with this hard anodized, eyeleted rim.
david-<< Is this a problem on other rims? Is there an easy way to know which to
avoid in
the future? >><BR><BR>
Don't use eyeleted hard anodized rims. Hard anodizing is marketing, nothing
else.
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Qui si parla Campagnolo
rims on the (after)market to my knowledge except possibly the Torelli
Few of the Velocity rims are 'hard anodized', the problem. Many Mavic rims are
not either, like the OpenPro, CXP-22/33 in black or silver. Many Torelli rims
are not hard anodized as well.
jim beam
yes, anodizing can be a factor in fatigue and therefore rim cracking,
but like all failure analysis, we need to examine the whole picture and
not focus on only one possible element. and it's not sensible to
hearken back to the "old days" of unanodized rims as if some despotic
modern satan is forcing us to eat our own children. for the most part,
modern rim alloys are not as corrosion resistant as their older brethren
and for them, anodizing is an important part of protecting them from the
elements. for the record, the much fabled ma2 rim /was/ sold in silver
anodized form. the old mavic catalogs list silver anodized as well as
"bright" among the available options. the ma2 i own is definitely
anodized, as have been all the ma2's i've seen at swap meets over the years.
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'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:
______
/ \
/ \
___| |
| |
\ /
\______/----
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.
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.
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.
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.
the ma40 was junk. just throw it away. no, most modern rims do not
have this problem.
jb
BaCardi
> Oh? If all that welding, machining and heat treatment isn't a huge
Oh and the seam welding and machining is a waste too? Give me a break
:rolleyes:
--
David White
which seems, by now, to be old-hat. However, your responses have helped me
understand the situation a bit better and have given me new rim ideas. In
addition to avoiding anodized rims (if possible - seems difficult) I will
certainly swap out the 14 guage straight spokes I have traditionally used on my
36 hole rims and replace them with butted spokes. Happy holidays!
Chalo
> Avoid anodized rims. Well, good luck, there aren't any non-anodized
> rims on the (after)market to my knowledge except possibly the Torelli
> Master, and reports conflict on that rim.
Sun rims are, to the best of my knowledge, nearly all available in
polished bare aluminum, most with eyelets too.
Chalo Colina
Sorni
That's it -- next time I have a bike question, forget Sheldon and Jobst and
shop owners and mechanics; just ask BaCardi!
Bill "rum a dum-dum" S.
jobst....@stanfordalumni.org
>> 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 :rolleyes:
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....@stanfordalumni.org
jobst....@stanfordalumni.org
> 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 I. surface rim displays electrical continuity with a
flashlight battery on its bead edge.
> 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. 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. 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,
however, there have been star burst failures on rims with sufficiently
thick anodizing.
> 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.
> 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.
> 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. The
difference is that manufacturers are cutting back on anodizing
thickness.
Jobst Brandt
jobst....@stanfordalumni.org
Tim McNamara
Huh, cool. The only current polished Al Sun rims I have seen are the
CR18. Their Web site doesn't make much of a point of showing polished
rims, only the anodized ones. Oops, I take that back, the ME14a
apparently comes in polished form even though they can't be bothered
to show it:
http://www.sun-ringle.com/ShowRoom/ROAD/Rims/me14a.html
Several other rims are in the same boat. There's no discussion as to
the type of eyelets- whether a single ferrule or a socket style.
Oddly enough, the CR18 is listed only as coming in a polished finish,
but in the photo it is finished in black:
Werehatrack
said:
>...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.
--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.
jobst....@stanfordalumni.org
>> ...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. There is no equal to anodizing for
durability and easy application for blackening rims. As you see,
riders were ready to pay at least 50% more for the MA-2 when it it was
made black and labeled MA-40.
The same people who brought us the cracking hard anodized rims seem
not to have lost any credibility with their new gimmicks, such as
wheels with names that defy pronunciation. Ksyrium, give me a break,
oops, that's a station wagon in France.
Just think, you can get Mavic rims that have "SUP" "MAXTAL" "UB" "FTSL"
"QRM" "FORE" "ISM" "150PLUS" "ZIRCAL" and "SSC". Its obvious that an
MA-2 is no place, having none of these features and costing under $30.
Jobst Brandt
jobst....@stanfordalumni.org
A Muzi
> > Oh? If all that welding, machining and heat treatment isn't a huge
> > waste. Suckers!!! Jobst Brandt jobst....@stanfordalumni.org
BaCardi without taking the time to think first, wrote:
> Oh and the seam welding and machining is a waste too? Give me a break
> :rolleyes:
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
jim beam
> 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 I.
/is/ it laquer? are you able to remove with the correct solvent? 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.
> surface 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.
>
>
>>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. 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.
> 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.
> 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?
> 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.
>
>
>>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.
>
>
>>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.
> The
> difference is that manufacturers are cutting back on anodizing
> thickness.
measurements please.
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.
>
>
> Jobst Brandt
> jobst....@stanfordalumni.org
jim beam
> 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 :rolleyes:
>
>
> 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?
ho ho ho, you jest, yes?
BaCardi
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!
--
Richard Ney
>>> ...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.
Michael Nitabach
news:EH6Gb.4754$XF6.1...@typhoon.sonic.net:
> jobst....@stanfordalumni.org writes:
>
>> 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.
>
Hey, dude!
Tim McNamara
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. A few high-level pro racer
crashes that caused injury pointed this out very early in the game,
and pro mechanics started taking sandpaper to the braking surfaces.
But that made the rims look shitty, 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, 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.
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.
jobst....@stanfordalumni.org
>>> 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....@stanfordalumni.org
jim beam
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 shitty, 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
jobst....@stanfordalumni.org
>>>> 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 :rolleyes:
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....@stanfordalumni.org
jobst....@stanfordalumni.org
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....@stanfordalumni.org
Richard Ney
>>> 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.
jobst....@stanfordalumni.org
>> 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 shitty, 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....@stanfordalumni.org
jobst....@stanfordalumni.org
>>>> 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....@stanfordalumni.org
BaCardi
> BaCardi wrote:
> > Oh and the seam welding and machining is a waste too? Give me a break
> > :rolleyes:
> 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.
--
Tim McNamara
>> 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 shitty, 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.
jim beam
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...
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.
Phil, Squid-in-Training
> 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
A Muzi
> > BaCardi wrote:
> > > Oh and the seam welding and machining is a waste too? Give me a break
> > > :rolleyes:
> > 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.
Zog The Undeniable
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.
Zog The Undeniable
> 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!
BaCardi
> 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.
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.
--
Tim McNamara
> A Muzi without taking the time to thingk wrote:
>
> > 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.
Since he's been "in the game" 32 years (and more), I'm betting he
knows more than you, Rummie. Not that it's all that hard to know
more than you, from the drivel you post.
> 1) Buy a oldie rim with a seam that you can actually feel when you
> run your fingers across the seam.
In other words, bias your test to "prove" yourself right.
> 2) Buy a new rim with the seam welded and machined flat.
What benefit do you think the welding has?
> 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.
Well, Rumhead, given the choice between the opinions of a mechanical
engineer, a 30+ year veteran of running a bike shop, and a troll
hiding behind a goofy screen name- let's just say you come in last in
that race.
Tim McNamara
The troll is becoming irritable as he is called on his bullshit.
Tim McNamara
There are several options. If it's a front wheel, try turning it
around; that often all but eliminates the bump. Second option is a
gentle tap or two with a hammer. Third option is a few seconds with
a file taking down the high spot.
Robin Hubert
<jobst....@stanfordalumni.org> wrote in message
news:%c9Gb.4774$XF6.1...@typhoon.sonic.net...
Please tell how to correct this mismatch, if and when it should happen.
Thank you,
Robin Hubert
Qui si parla Campagnolo
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Alex Rodriguez
says...
>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.
That is a function of your brake pads, not the rim.
>and before you ask, yes, i've tried plain, cd and ceramic. my
>experience is that ceramic are best in the wet.
At the expense of your brake pads. When you brake, your forward motion
kinetic energy is converted to heat. That heat has to be dissipated some
how. Cermics are insulators, so much heat is not going to go to the rim
and it stays on your pads. So you eat through your pads very quickly.
A plain aluminum rim provides excellent braking without eating through
your pads as quickly.
>> 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?
I've never had a brake lock up at a bad rim joint. It will go thump,
thump, thump as the pad goes over the joint, but never lock up. After a
few brake applications in wet weather, the uneven joint will be even.
>> 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?
Yes. Mavic would not anodize a rim and not charge extra for it. :)
Terry Morse
> 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.
I've been using the "Carbon 12" 25mm wire-bead Avocets for about a
year now, and I'm getting just about 2500 miles on the rear before
threads start to show. The front lives on forever, until it cracks
or gets a deep cut.
--
terry morse Palo Alto, CA http://www.terrymorse.com/bike/
jim beam
correct. in the case of the cxp14 however, it's a low spot. "removal"
of the bump would require machining the whole rim.
comparative width measurements of some unbuilt rims i have:
ma3 cxp14
21.10 19.88
21.10 19.92
21.10 19.90
21.10* 19.66*
* at the rim joint.
jobst....@stanfordalumni.org
> Please tell how to correct this mismatch, if and when it should
> happen.
If you have such a rim, it is best to fix it before fully tightening
the spokes. I have used large Vise-Grip pliers for this, oriented
them radially to the wheel using the smooth nibs to press across the
rim. Once aligned the rim will not become misaligned after spokes are
tightened because the joint is pressed together with about 1000lbs
force. This force is N*T/2pi, N=number of spokes, T=tension. In fact
you could take a rim made of individual N unattached segments, each
with a spoke at its midpoint, butted together without an alignment
spud and ride it with no perceptible difference from a one piece rim.
Curiously the ancients also had dupes among them. Some Fiamme tubular
rims had rivets at the joint to "keep then from coming apart in use"
and some did not. There was a fable about spokes adjacent to the
joint needing to be crossed to keep the rim together. That ignored
that 32 spoke wheels had parallel spokes at the stem and joint as do
any regularly spoked wheels with spoke numbers evenly divisible by
four. N MOD 4 = 0.
Jobst Brandt
jobst....@stanfordalumni.org
Carl Fogel
[snip]
> IME the brake pad soon smooths off the join - and I'd hardly describe it
> as a "thud".
[snip]
Dear Zog,
I'm ignorant of the seamy side of things.
I'm guessing that the rim seam can't
align itself by moving ever so slightly
sideways because the tremendous tension
on the rim holds the ends firmly together.
If so, I can understand one side of the
rim seam being smoothed off by braking as
the abrasive pad runs into the tiny curb.
But does the other side of the rim seam
smooth out so easily? From the brake pad's
point of view, the rim seam is depressed,
so the brake pad just flies off a curb on
that side with little abrasion.
So does one side of a mismatched rim seam
smooth out first, followed by the other side
only when the whole rim is worn down?
I understand that you're saying that it's
not much of a thud anyway and that the seam
is minute. I'm just curious whether the raised
bump side of the rim (from the brake pad's point
of view) is what smooths out in your experience,
leaving a less noticeable dip on the other side
that lasts much longer.
Carl Fogel
A Muzi
> > 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.
BaCardi wrote:
> 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.
Thanks for your wise and educated comments. And such grace!
A Muzi
>>>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.
Tim McNamara wrote:
> There are several options. If it's a front wheel, try turning it
> around; that often all but eliminates the bump. Second option is a
> gentle tap or two with a hammer. Third option is a few seconds with
> a file taking down the high spot.
A file maybe, but I've found the issue is less a wide spot
than that the two sides usually don't meet exactly square.
Hold the rim (lightly!) in a smooth-jaw vise with the seam
just at he edge of the jaw. Press the rim to one side until
the seam is smooth . Takes a moment and hand pressure only.
That can be done with a built wheel in the same way.
Tim McNamara
> you're assuming a high spot. as you say, that would be trivial to
> correct. in the case of the cxp14 however, it's a low spot.
> "removal" of the bump would require machining the whole rim.
>
> comparative width measurements of some unbuilt rims i have:
>
> ma3 cxp14
> 21.10 19.88
> 21.10 19.92
> 21.10 19.90
> 21.10* 19.66*
>
> * at the rim joint.
Well, now, that's an interesting scenario. Is the rim equally
pinched on both sides of the seam or just one side?
BaCardi
Tim's had too much turkey. You're line of reasoning is nonexistent. And
since, you prefer to blindly close your eyes and spout off about who you
choose to follow based on so called "experience" and degrees, then go
ahead and be a fool.
Seams in rims? Foolish! And the argument from the old farts are that
they are even better than newer machined rims without a seam! HAHA!
Whatever! The sky must not be blue in your world!
--
Mark Janeba
> Curiously the ancients also had dupes among them. Some Fiamme tubular
> rims had rivets at the joint to "keep then from coming apart in use"
> and some did not. There was a fable about spokes adjacent to the
> joint needing to be crossed to keep the rim together. That ignored
> that 32 spoke wheels had parallel spokes at the stem and joint as do
> any regularly spoked wheels with spoke numbers evenly divisible by
> four. N MOD 4 = 0.
Did you mean divisible by 8, and N MOD 8 = 0?
Otherwise all traditional wheels would meet the criterion.
Mark (I've built 32s,36s,40s and 48s, but not 30s or 34s) Janeba
jim beam
afterwards. the abrasion extends about 2" before & after the join which
is why the pads sink into the depression and have a tendency to wedge on
the way out.
imo, welded rims are better because they offer more even weight
distribution - no heavy spots at the insert. however, as this case
illustrates, subsequent machining is pretty much mandatory.
jobst....@stanfordalumni.org
>> Curiously the ancients also had dupes among them. Some Fiamme
>> tubular rims had rivets at the joint to "keep then from coming
>> apart in use" and some did not. There was a fable about spokes
>> adjacent to the joint needing to be crossed to keep the rim
>> together. That ignored that 32 spoke wheels had parallel spokes at
>> the stem and joint as do any regularly spoked wheels with spoke
>> numbers evenly divisible by four. N MOD 4 = 0.
> Did you mean divisible by 8, and N MOD 8 = 0?
Yes, I slipped a bit binarily. Of course, all standard spoke patterns
are N MOD 4 = 0 having left and right, leading and trailing spokes.
The 36 and 24 spoke wheels have crossed spokes on the seam (that lies
opposite the stem) and 48's, 40's, 32's and 16's have parallel spokes
at the seam if they are parallel at the stem, where they should to be
parallel.
> Otherwise all traditional wheels would meet the criterion.
> Mark (I've built 32s,36s,40s and 48s, but not 30s or 34s) Janeba
Thanks,
Jobst Brandt
jobst....@stanfordalumni.org
Tim McNamara
> Tim McNamara wrote:
> > BaCardi <usenet...@cyclingforums.com> writes:
> > > Zog The Undenia wrote:
> > >
> > > > 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.
> > >
> > > 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.
>
> > The troll is becoming irritable as he is called on his bull****.
>
> Tim's had too much turkey.
Not yet, dinner isn't until 8:00. Come to think of it, I'd better go
check the sweet potatoes.
> You're line of reasoning is nonexistent.
Your grammar is atrocious. Be that as it may, I offered no line of
reasoning, merely an observation that the troll is becoming irritable
as his BS is revealed for what it is.
> And since, you prefer to blindly close your eyes and spout off about
> who you choose to follow based on so called "experience" and
> degrees, then go ahead and be a fool.
A fool is one who persists in a course of action that repeatedly
leads to failure. My preference for rims that last 10,000 to 20,000
miles or more has led me away from failure- such as the failures I
repeatedly experienced with anodized rims.
> Seams in rims? Foolish! And the argument from the old farts are that
> they are even better than newer machined rims without a seam! HAHA!
> Whatever! The sky must not be blue in your world!
It seems to be you that needs to brush up on reasoning, logic and
argumentation. We had a beautiful blue sky here today, with
dazzlingly beautiful hoarfrost on the trees and tall grasses along
the side of the road. Merry Christmas (or the holiday of your
choice) to you, too.
BaCardi
Yeah, Merry Xmas to you too and even to the ones who still believe that
Elvis is alive and that a uneven rim seam is better than a smooth
machined one.
--
Carl Fogel
> you're assuming a high spot. as you say, that would be trivial to
> correct. in the case of the cxp14 however, it's a low spot. "removal"
> of the bump would require machining the whole rim.
>
> comparative width measurements of some unbuilt rims i have:
>
> ma3 cxp14
> 21.10 19.88
> 21.10 19.92
> 21.10 19.90
> 21.10* 19.66*
>
> * at the rim joint.
Dear Jim,
Am I correct in thinking that your cxp14
rim's two ends meet smoothly on each side,
but are slightly narrower than the rest
of the rim?
(I vaguely expected the rim to be the same
width, but slightly misaligned at the joint.)
If so, do you know if this this a normal result
for however rims are bent into hoops? That is,
are the two ends grabbed so hard by some gizmo
that they're routinely squeezed a little bit
narrower than the rest of the rim?
It's Christmas, so I'm staring at shiny
round objects with fascination. Thanks
for raising an interesting point.
Carl Fogel
Dave Kahn
Campagnolo) wrote:
>Bacardi is a loon, don't feed him...
An unpleasant one at that.
--
Dave...
jim beam
> jim beam <u...@ftc.gov> wrote in message news:<mqkGb.1851$1O6...@newssvr27.news.prodigy.com>...
>
>>you're assuming a high spot. as you say, that would be trivial to
>>correct. in the case of the cxp14 however, it's a low spot. "removal"
>>of the bump would require machining the whole rim.
>>
>>comparative width measurements of some unbuilt rims i have:
>>
>>ma3 cxp14
>>21.10 19.88
>>21.10 19.92
>>21.10 19.90
>>21.10* 19.66*
>>
>>* at the rim joint.
>
>
> Dear Jim,
>
> Am I correct in thinking that your cxp14
> rim's two ends meet smoothly on each side,
> but are slightly narrower than the rest
> of the rim?
yes
>
> (I vaguely expected the rim to be the same
> width, but slightly misaligned at the joint.)
>
> If so, do you know if this this a normal result
> for however rims are bent into hoops? That is,
> are the two ends grabbed so hard by some gizmo
> that they're routinely squeezed a little bit
> narrower than the rest of the rim?
doubt it. the cxp14 appears to be welded, so some form of post-join
finish work is mandatory for smooth braking - but doing it in just the
weld area is not the solution - needs to be machined all the way around
to maintain dimensional accuracy. from what i've seen, most unmachined
rims are simply joined with an insert.
Ted Bennett
> even to the ones who still believe that
> Elvis is alive and that a uneven rim seam is better than a smooth machined
> one.
This is a technical newsgroup, and your comments deserve fuller
explanation.
Please let us know your arguments in favor of machined rims. Please
address the effects of the weld on strength an durability of the alloy
used. Compare the weights of machined rims versus unmachined rims.
Compare the cost to produce, and consider the cost against the simple
procedures used, or not used, to eliminate an uneven rim seam.
--
Ted Bennett
Portland OR
Tom Sherman
Or we could just machine rims from aluminium billets, and pay several
hundred dollars for each rim. ;)
Tom Sherman - 41½ N, 90½ W
BaCardi
Read page 2. Then come back and talk to me.
--
BaCardi
And another thing. This is a technical newsgroup. Please let us know
your arguments in favor of seamed rims. Since you are so heavily in
favor of the old seams in rims, please let us know why. Compare weights.
Compare cost. Compare cost per weight ratios. Finite Analysis is also
desirable.
--
David Reuteler
: On 24 Dec 2003 16:29:19 GMT, vecc...@aol.com (Qui si parla
: Campagnolo) wrote:
:
:>Bacardi is a loon, don't feed him...
:
: An unpleasant one at that.
carl, this loon business is your fault.
--
david reuteler
reut...@visi.com
Chalo
> 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.
I have built many Rhyno Lites, and I have found them to come in four
variations (not including the Rhyno Lite XL, a wider and taller rim).
Those are black with black sidewalls, black with bright
machined/sanded sidewalls, satin silver anodized, and bright polished
bare aluminum. The most common by far in the aftermarket (in my
experience) are the latter type, which have no anodizing at all and a
near-mirror finish.
It is that highly buffed bare finish that I have come to associate
with Sun rims. It looks especially nice on the Venus deep-section
road rim and the Big City BMX rim, 34mm wide and 20mm tall.
> [1] actually about 1" wide...you should see the non-lite version!
The Sun Rhyno rim is noticeably narrower than the Rhyno Lite, just
much heavier. I have seen it in only two finishes: satin silver
anodized, and chrome plated for BMX wheels. As a very heavy, not very
oversized rim, it never gained too much popularity outside of
almost-exclusive use on triplets and quads! I have a set of 48 spoke
wheels built with 700c Rhynos, and they're just so strong it's boring.
Chalo Colina
Carl Fogel
[snip]
> . . . In fact
> you could take a rim made of individual N unattached segments, each
> with a spoke at its midpoint, butted together without an alignment
> spud and ride it with no perceptible difference from a one piece rim.
[snip]
> Jobst Brandt
> jobst....@stanfordalumni.org
Dear Jobst,
Am I correct in thinking that this N-section
rim with N spokes and no alignment spuds is a
thought experiment, not anything actuallly tried
like the Kevlar-string spoked wheel?
I can see an imaginary rim with miraculous cuts
half-way between each spoke working as you suggest.
But how would you assemble it in reality? Wouldn't
tightening the single spoke N at each mid-point pull
and tilt each rim section N sideways in alternate
direction out of the intended hoop before the
section-to-section tension was enough to hold
the rim sections steady torsionally?
(I like imaginary engineering, but would love to
learn that it's actually been done. Maybe the
sections could be pre-tensioned by assembling them
inside a tire with loose spokes, inflating the tire
to jam the sections firmly together, and then
tightening the spokes?)
Gotta go--I hear someone at the chimney.
Carl Fogel
jobst....@stanfordalumni.org
>> You're assuming a high spot. As you say, that would be trivial to
>> correct. In the case of the CXP14 however, it's a low spot.
>> "Removal" of the bump would require machining the whole rim.
>> Comparative width measurements of some unbuilt rims I have:
>> ma3 CXP14
>> 21.10 19.88
>> 21.10 19.92
>> 21.10 19.90
>> 21.10* 19.66*
>> * at the rim joint.
Hold the phone! Is there a discontinuity at the joint or a width
variation, and how abrupt is it? This has the classic form of lies of
the second kind, where the statement although accurate conveys an
untrue message. Nowhere is there a mention of discontinuity in the
rim in a misaligned rim joint that purportedly causes wheels to lock
when braking. That the claimed lockup is untrue is apparent from the
lack of end-over crashes cause by rims that aren't welded and machined.
> Dear Jim,
> Am I correct in thinking that your CXP14 rim's two ends meet
> smoothly on each side, but are slightly narrower than the rest of
> the rim?
> (I vaguely expected the rim to be the same width, but slightly
> misaligned at the joint.)
> If so, do you know if this this a normal result for however rims are
> bent into hoops? That is, are the two ends grabbed so hard by some
> gizmo that they're routinely squeezed a little bit narrower than the
> rest of the rim?
Rim extrusions are coiled (rolled) into a helical multi-turn hoop and
made into rim hoops by a cut perpendicular to the extrusion edge (a
slight angle to the coil axis. Resulting short end pieces are
recycled while the hoops in between are made into rims. There is no
end effect other than pushing them onto a filler spud that closely
fits the inside contour.
> It's Christmas, so I'm staring at shiny round objects with
> fascination. Thanks for raising an interesting point.
I don't have such a variation in my MA-2 rims and also have no offset
at the joint. As I said, the wheel that was run over by a motorcycle
had a bad wow and a misaligned joint, but that was repairable and is
not readily visible now.
Jobst Brandt
jobst....@stanfordalumni.org
jobst....@stanfordalumni.org
>> ... In fact you could take a rim made of individual N unattached
>> segments, each with a spoke at its midpoint, butted together
>> without an alignment spud and ride it with no perceptible
>> difference from a one piece rim.
> Dear Jobst,
> Am I correct in thinking that this N-section rim with N spokes and
> no alignment spuds is a thought experiment, not anything actually
> tried like the Kevlar-string spoked wheel?
In a way I have experienced that in a rim in which the alignment
insert at the joint was so loose that the rim was easily separable by
a little pull and alignment was neither radially or laterally properly
constrained. With effort I aligned the ends while tensioning the
spokes and realized that when finished, this would be, in effect, a
compression-friction joint that was stable purely from the compressive
force.
It was these considerations from which I developed the equation
N*T/2pi for rim compression and those of rim compression by tire
inflation. I suppose you saw the effect of tire casing cord angle
from inflation pressure, and how the cord angle visible in clear
reinforced Tygon tubing was arrived on, the angle found in any good
pressure hose that prevents it from changing length when pressurized.
> I can see an imaginary rim with miraculous cuts half-way between
> each spoke working as you suggest.
> But how would you assemble it in reality? Wouldn't tightening the
> single spoke N at each mid-point pull and tilt each rim section N
> sideways in alternate direction out of the intended hoop before the
> section-to-section tension was enough to hold the rim sections
> steady torsionally?
In wheel building, no one spoke is tensioned alone. The whole
complement is tightened incrementally. As I said, the sloppy rim
joint with which I worked had just such a characteristic and it was
apparent that only friction and compressive force held it in place.
> (I like imaginary engineering, but would love to learn that it's
> actually been done. Maybe the sections could be pre-tensioned by
> assembling them inside a tire with loose spokes, inflating the tire
> to jam the sections firmly together, and then tightening the
> spokes?)
Well that depends on whether you have to do it 36 times to believe or
if once is enough. Not everything has to be repeated to the limit to
assess its results. For me one free joint is enough, for others two
adjacent ones may be enough. I don't see doing it 36 times although
if I had such a rim, it might be fun to do. The only problem would be
making 36 zero thickness saw cuts.
> Gotta go--I hear someone at the chimney.
Don't feed the animals.
Jobst Brandt
jobst....@stanfordalumni.org
Tim McNamara
>> Read page 2. Then come back and talk to me.
Ah, that explains it. BaCardi is Paul Harvey on a bender.
Tim McNamara
> And another thing. This is a technical newsgroup. Please let us know
> your arguments in favor of seamed rims. Since you are so heavily in
> favor of the old seams in rims, please let us know why. Compare
> weights. Compare cost. Compare cost per weight ratios. Finite
> Analysis is also desirable.
You're a little late to the party, mon. But Google can help you get
caught up.
Tom Sherman
BaCardi wrote:
> ... Finite Analysis is also desirable.
I believe in Finite Analysis, since Infinite Analysis never reaches a
conclusion.
Qui si parla Campagnolo
opposite the stem) and 48's, 40's, 32's >><BR><BR>
Or lace the 32 ones so that the spokes cross at the seam...and at the valve
stem hole. I used to do this for older rims but customers didn't like how tough
it was to get a pump onto the valve.
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
jim beam
> Well that depends on whether you have to do it 36 times to believe or
> if once is enough. Not everything has to be repeated to the limit to
> assess its results. For me one free joint is enough, for others two
> adjacent ones may be enough. I don't see doing it 36 times although
> if I had such a rim, it might be fun to do. The only problem would be
> making 36 zero thickness saw cuts.
sacrifice two rims and you can do it. i'm interested to see the result.
jb
jim beam
<snip>
>
> Hold the phone! Is there a discontinuity at the joint or a width
> variation, and how abrupt is it? This has the classic form of lies of
> the second kind, where the statement although accurate conveys an
> untrue message. Nowhere is there a mention of discontinuity in the
> rim in a misaligned rim joint that purportedly causes wheels to lock
> when braking. That the claimed lockup is untrue is apparent from the
> lack of end-over crashes cause by rims that aren't welded and machined.
just where exactly is the lie? have you ever /seen/ a cxp14 rim? have
you examined its join? have you ever measured one? don't just assume
it's made the same as an ma2.
those are straight figures from braking surface caliper measurements.
they may not suit your preconceptions, but they are independently
verifiable facts. just because something isn't convenient does not make
it a lie.
lies come from;
"experts" that know nothing of the dynamic properties of carbon
composites but feel qualified to postulate their vibration transmission
inferiority.
"experts" that know nothing of work hardening differentials between mild
and stainless steels, their deformation & fatigue mechanisms but feel
free to postulate radical theories of fatigue elimination that would
turn the entire materials world on its head.
"experts" that yet again know nothing about material deformation
mechanisms but feel free to postulate that plastic deformation of steel
bearings is impossible.
"experts" that consider their materials knowledge superior to an entire
industry of rim manufacturers that dare to protect their product by
anodizing, manufacturers that dump millions into research. all because
this "expert" reads a little about one of /many/ different possible
failure modes but feels by some strange intuition that the story stops
there, further research is irrelevant and that they are now suddenly
qualified to apply this small subset of convenience to all failures they
see.
it's mysterious how such an "expert" has not similarly persecuted
manufacturers of anodized hubs, cranks, brakes, handlebars, forks,
stems, seatposts, etc. funny how things work out.
"Men occasionally stumble over the truth, but most of them pick
themselves up and hurry off as if nothing had happened.
-- Winston Churchill"
happy holidays.
SMMB
opinions, not personal anecdotes, and just as much by honoring the
limitations of his own expertise. Nasty words, hostile repostes, and
self-indulgent vanity don't make any sort of expert.
Bonne route,
Sandy
Paris FR
"jim beam" <u...@ftc.gov>
--
a écrit dans le message de :
news:92HGb.2361$vK1...@newssvr25.news.prodigy.com...
jobst....@stanfordalumni.org
>> The 36 and 24 spoke wheels have crossed spokes on the seam (that lies
>> opposite the stem) and 48's, 40's, 32's don't.
> Or lace the 32 ones so that the spokes cross at the seam... and at
> the valve stem hole. I used to do this for older rims but customers
> didn't like how tough it was to get a pump onto the valve.
And why did you do this (for older or newer rims)?
Jobst Brandt
jobst....@stanfordalumni.org
jobst....@stanfordalumni.org
>> Hold the phone! Is there a discontinuity at the joint or a width
>> variation, and how abrupt is it? This has the classic form of lies
>> of the second kind, where the statement although accurate conveys
>> an untrue message. Nowhere is there a mention of discontinuity in
>> the rim in a misaligned rim joint that purportedly causes wheels to
>> lock when braking. That the claimed lockup is untrue is apparent
>> from the lack of end-over crashes cause by rims that aren't welded
>> and machined.
> Just where exactly is the lie? Have you ever /seen/ a CXP14 rim?
> Have you examined its join? Have you ever measured one? Don't just
> assume it's made the same as an MA-2.
You are dodging the question. Is there a discontinuity on the rim and
does it cause brake problems. Having ridden on severely damaged rims
with no braking problems, I don't see what your recitation of these
measurements have to do with the question at hand. Juxtaposed with
the discussion, they imply proof for the need of machining, without
evidence of a functional reason to do so. Therein is the "lie of the
second kind". You build your case on trusting or gullible readers to
take your statements of evidence as proof of your contention.
This is much like advertisements that put forth qualities of their
product after saying "improve your speed by 22.3 percent" there being
no connection between that statement and the claims other than
proximity on the printed page.
> Those are straight figures from braking surface caliper measurements.
> They may not suit your preconceptions, but they are independently
> verifiable facts. just because something isn't convenient does not make
> it a lie.
The lie is the implication and, as I explained, these are "lies of the
second kind". Your figures may be accurate, although after having read
your postings over time, I am even doubtful.
> Lies come from;
> "Experts" that know nothing of the dynamic properties of carbon
> composites but feel qualified to postulate their vibration
> transmission inferiority.
> "Experts" that know nothing of work hardening differentials between
> mild and stainless steels, their deformation & fatigue mechanisms
> but feel free to postulate radical theories of fatigue elimination
> that would turn the entire materials world on its head.
> "Experts" that yet again know nothing about material deformation
> mechanisms but feel free to postulate that plastic deformation of
> steel bearings is impossible.
> "Experts" that consider their materials knowledge superior to an
> entire industry of rim manufacturers that dare to protect their
> product by anodizing, manufacturers that dump millions into
> research. All because this "expert" reads a little about one of
> /many/ different possible failure modes but feels by some strange
> intuition that the story stops there, further research is irrelevant
> and that they are now suddenly qualified to apply this small subset
> of convenience to all failures they see.
> It's mysterious how such an "expert" has not similarly persecuted
> manufacturers of anodized hubs, cranks, brakes, handlebars, forks,
> stems, seatposts, etc. Funny how things work out.
This is a compendium of allusions to your expertise in these subjects
although not explicitly stated, Being placed in contrast to an implied
expert who knows about these things, implies that expert to be the
speaker, or you. This is consistent with other things you have
offered.
> "Men occasionally stumble over the truth, but most of them pick
> themselves up and hurry off as if nothing had happened.
> -- Winston Churchill"
Where's the beef. I saw no stitch of substance in this posting. These
are truly "lies of the second kind". I could not have constructed a
better example.
Jobst Brandt
jobst....@stanfordalumni.org
BaCardi
No son. Try again. You've got nothing on Paul Harvey. Come back after
you've done some legitimate research.
--
BaCardi
> You're a little late to the party, mon. But Google can help you get
> caught up.
Google is just your calling. Give it a try.
--
Qui si parla Campagnolo
>><BR><BR>
Lace with the spokes crossed at the seam on 32h..Something I learned from the
gent that taught me how to build, when using older and not really tight seamed
older rims, Like some Fiammes. I haven't done it for years. I use 36h, like all
rims should b, so it's not an issue.
Jeff Starr
little guy's running out of gas. Or more likely, it was past his
bedtime.
Jeff
Carl Fogel
Dear Jobst and Jim,
As a bewildered layman, I'd like to ask a
few obvious questions in hopes of learning
more about what I thought was the subject.
Which kind of rims provide better caliper
braking, constant or varying width? How
much better? That is, at what point does
varying rim width become noticeable when
braking?
How much material is actually removed from
machined rims compared to how much is left?
Do manufacturers compensate by making such
rims thicker before machining, just as
toilets are made oversize to compensate
for the way that they shrink in the kilns?
(Sorry, but comparing rims to toilets was
irresistible.)
Does anodizing significantly weaken
aluminum parts like rims, handlebars,
and so forth? How?
How does anodizing affect braking,
regardless of how the width of the
rim varies?
Curiously,
Carl Fogel
A Muzi
> >><BR><BR>
>
> Lace with the spokes crossed at the seam on 32h..Something I learned from the
> gent that taught me how to build, when using older and not really tight seamed
> older rims, Like some Fiammes. I haven't done it for years. I use 36h, like all
> rims should b, so it's not an issue.
Aside from being ugly (and clumsy with a hand pump), there's
zero benefit. Crossing the spokes over a seam will not be
any tighter, not more secure, not better in any way than a
radial. It's spoke tension, not pattern, which compresses seams.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
jim beam
the decreased spoke angle, but it is relatively small. gets even
smaller with smaller flange size too.
jobst....@stanfordalumni.org
> Dear Jobst and Jim,
> As a bewildered layman, I'd like to ask a few obvious questions in
> hopes of learning more about what I thought was the subject.
Please stop this pseudo self deprecating style. Just ask the question.
> Which kind of rims provide better caliper braking, constant or
> varying width? How much better? That is, at what point does
> varying rim width become noticeable when braking?
I think that should be apparent. A step function, such as a lateral
shift at a non-welded rim joint causes an audible but non-functional
brake noise. A sudden necking of the rim, in contrast, assuming
average friction in the brake cable, would make a pulsating brake
retardation. However, a change in rim width of a millimeter in a
continuous cross section would not cause as much brake variation as a
drop of water on the rim, something commonly encountered by bicyclists.
> How much material is actually removed from machined rims compared to
> how much is left? Do manufacturers compensate by making such rims
> thicker before machining, just as toilets are made oversize to
> compensate for the way that they shrink in the kilns? (Sorry, but
> comparing rims to toilets was irresistible.)
I don't know anything about these cross sections, having only seen them
displayed.
> Does anodizing significantly weaken aluminum parts like rims,
> handlebars, and so forth? How?
No, it doesn't but as I have often mentioned, it is a hard crust, just
like a scab on a wound that when stressed, cracks and causes bleeding
on your knee or causes cracks to propagate into the aluminum. Crack
initiation is what causes the rim to fail and I use the scab analogy
to make that palpable for those who cannot play the Maxwell's demon
and get right down into the psyche of the metal surface.
> How does anodizing affect braking, regardless of how the width of
> the rim varies?
I thought you were the wizard of Google searches. This has been beat
to death many times but it seems to have more lives than a cat
squared.
Anodizing is a ceramic insulator about half the density of aluminum,
anodizing eats into the surface about as much as it raises the surface
of an aluminum extrusion. Heat in a friction pair is generated in the
surface of the softer material, in this case the "rubber" brake pad
that is itself an excellent insulator. Its only coolant is the
aluminum rim that is an excellent conductor, has large surface area,
and is moving swiftly through the cooling medium, the atmosphere.
By coating the rim with ceramic, its heat absorption is diminished.
Even a thin layer considering the short residency of the pad at any
location, looks to the hot surface of the brake pad like a mirror,
accepting little to no heat. Therefore, the surface temperature of
the pad becomes hotter than it normally would and thereby loses its
designed drag coefficient against the braking surface. For rim
protection some dirt bike rims have ceramic coatings but require a
different brake pad that can take the heat. They also don't brake as
well as common brakes when dry.
> Curiously,
I suppose.
Jobst Brandt
jobst....@stanfordalumni.org
jobst....@stanfordalumni.org
>>> And why did you do this (for older or newer rims)?
>> Lace with the spokes crossed at the seam on 32h... Something I
>> learned from the gent that taught me how to build, when using older
>> and not really tight seamed older rims, Like some Fiammes. I
>> haven't done it for years. I use 36h, like all rims should be, so
>> it's not an issue.
> Aside from being ugly (and clumsy with a hand pump), there's zero
> benefit. Crossing the spokes over a seam will not be any tighter,
> not more secure, not better in any way than a radial. It's spoke
> tension, not pattern, which compresses seams.
Thanks Andrew. It's tales like these that inspired writing "the
Bicycle Wheel". There were so many of them it was hard to decide
which ones should be slain first. Although the book has lain many of
them to rest, it is hard to get wheel builders, who propagate these
old saws to read, so they infect new bicyclists with these myths.
Myths that, for unknown reasons, have a good sprint and long duration.
I get the idea that people like to believe unbelievable things no
matter how absurd, as long as there is a faint thread of credibility,
the fainter that thread the stronger the belief.
Jobst Brandt
jobst....@stanfordalumni.org
jim beam
> jobst....@stanfordalumni.org wrote in message news:<%FHGb.4939$XF6.1...@typhoon.sonic.net>...
>
> Dear Jobst and Jim,
>
> As a bewildered layman, I'd like to ask a
> few obvious questions in hopes of learning
> more about what I thought was the subject.
>
> Which kind of rims provide better caliper
> braking, constant or varying width?
your phrasing implies you already have an answer carl.
two factors:
amplitude of any difference
length of any difference
an amplitude example is a "low spot" such as a wear indicator drilling.
it's on a very small scale compared to the brake pad and makes no
detectable difference.
but if that were now a "high spot", suddenly you'd have wheel lock.
similarly, if the low spot is now large relative to the pad size, that
becomes noticeable too. going into the low spot is ok, but coming out
again is the issue.
> How
> much better? That is, at what point does
> varying rim width become noticeable when
> braking?
a good question and i don't have an immediate quantitative answer for
you. but we've all experienced this in a qualitative way whether it be
on a bike with a lumpy rim or a car with a warped rotor. other than a
bike with an old style rim, the only other application i can think of
where braking surfaces do /not/ rely on precision machined surfaces are
old railroad brakes. but r/r wheels sometimes develop flat spots and so
these types of brakes suffer the same lockup problems as bikes.
>
> How much material is actually removed from
> machined rims compared to how much is left?
> Do manufacturers compensate by making such
> rims thicker before machining, just as
> toilets are made oversize to compensate
> for the way that they shrink in the kilns?
> (Sorry, but comparing rims to toilets was
> irresistible.)
good and somehow appropriate example. can't say how much gets machined
off in practice, but if you had a variance of say +/- 0.1mm, you'd have
to machine off at least 0.2mm to ensure uniformity. and of course,
you'd make sure the unmachined component had correspondingly sufficient
material to allow this.
>
> Does anodizing significantly weaken
> aluminum parts like rims, handlebars,
> and so forth? How?
assuming that anodizing is the /only/ variable, it makes no difference
to static strength but it does to fatigue. it's the relevance that is
debatable. if you have a rim whose braking surfaces wears through in
say 25,000 miles, how relevant is it that anodizing may reduce fatigue
life from 50,000 miles to 45,000 miles?
>
> How does anodizing affect braking,
> regardless of how the width of the
> rim varies?
no figures, but my experience is that hard anodized braking surfaces are
better in the wet because the pads pick up less grit and therefore
continue to be more effective.
>
> Curiously,
>
> Carl Fogel
jobst....@stanfordalumni.org
>> Aside from being ugly (and clumsy with a hand pump), there's zero
>> benefit. Crossing the spokes over a seam will not be any tighter,
>> not more secure, not better in any way than a radial. It's spoke
>> tension, not pattern, which compresses seams.
> Technically, there /is/ an additional compressive component caused
> by the decreased spoke angle, but it is relatively small. Gets even
> smaller with smaller flange size too.
What means "technically"? With any reasonable cross pattern, angles
of all spokes are the same, so their effect is zero. The compressive
force at the joint is the same for any given tension regardless of
cross pattern and location of the joint, as is mentioned above.
Jobst Brandt
jobst....@stanfordalumni.org
jim beam
<snip>
>> Does anodizing significantly weaken
>> aluminum parts like rims, handlebars,
>> and so forth? How?
>
>
> assuming that anodizing is the /only/ variable, it makes no difference
> to static strength but it does to fatigue. it's the relevance that is
> debatable. if you have a rim whose braking surfaces wears through in
> say 25,000 miles, how relevant is it that anodizing may reduce fatigue
> life from 50,000 miles to 45,000 miles?
>
sorry, forgot the "how". anodizing can decrease fatigue performance
because if it cracks, those cracks act as stress concentrations. fatige
can then initiate at those points.
but conversely, anodizing can protect significantly agains wear and
corrosion and that can enhance fatigue life.
jb
jim beam
to enlighten us.
jb
Jay Beattie
"jim beam" <u...@ftc.gov> wrote in message
news:0L1Hb.2321$W67....@newssvr27.news.prodigy.com...
I found no difference in sidewall longevity between the Mod
E/Gentleman/E2/MA2 and G40/GP4/MA40. I did notice that most of the
anodizing on the sidewalls was gone within days or weeks of daily riding in
the rain. I also noticed that the anodized rims had a much higher incidence
of cracking around the spoke holes. I also found no significant difference
in braking between any of these old rims (including some old dimpled Super
Champ Mod 52s) and the modern machined uber-rims. The only problem I ever
had with bad breaking surfaces was when I wore through the sidewalls, or was
sloppy with rim cement -- but even that did no throw me over the bars.
Machining is another one of those solutions in search of a problem. -- Jay
Beattie.
dianne_1234
wrote:
>Jim Beam writes:
>
>> [snip] And in
>> what way is that worse than an unmachined braking surface habitually
>> locking up at the rim join - like my CXP14 does?
The CXP 14 rims I've built with are welded at the joint, but the
sidewalls are not machined. It looked to me as if the weld area had
been sanded locally (about an inch either side of the weld).
That would explain Jim's CXP 14 rim that is narrower at the weld than
elsewhere.
Sort of like the first Weinmann and Araya welded aluminum rims I can
recall, the not-hollow ones that fitted 27 x 1 1/4 tires.