Cracks?!

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my
Zeus crank arms. These are not like the cracks I've seen on failed
cranks, and appear to be quite superficial, perhaps only involving
the anodized layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Quoted message said:

Anybody have anything to share on the significance of such cracks?

These are highly unlikely to be cracks but rather some odd corrosion
in the anodized surface. The reason for my belief is that cracks neck
in so that there is no continuous surface as your excellent pictures
show. With such good lighting and unblemished surface, these do not
appear to be cracks at all. Besides that they are in the wrong places
on the crank. I've broken a lot of cranks and they didn't have that
sort of surface, quite aside form the tiny wormy squiggles.

http://pardo.net/bike/pic/fail-001/FAIL-005.html

As you can see, the surface of this crack sucked in right at the onset
just as those that I observed on my crank failures. Grazing incidence
light reveals whether this is a surface feature or a crack.

Jobst Brandt

"John Thompson" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I found a couple suspicious-looking meandering cracks on one of my Zeus
crank arms. These are not like the cracks I've seen on failed cranks,
and appear to be quite superficial, perhaps only involving the
anodized
layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

Crankarms undergo torsion and bending. For bending, it's odd that
fatigue cracks would propagate first from the compression surface.

Phil H

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my Zeus
crank arms. These are not like the cracks I've seen on failed cranks,
and appear to be quite superficial, perhaps only involving the anodized
layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

Looks like a corrosion track. I would expect that to be on a
clearcoat painted surface more often than an anodized one, but it's
not uncommon. The extremely meandering character and the flatness of
the surface are the two keys which lead me to say that I believe
there's no crack involved.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

John
I doubt that those are cracks. If you are still concerned, two methods
could help allay your fears.
!. Polish the areas of interest, w/ Scotch Bright pads manually. If
that goes too slowly, try a SB pad on a drill.motor or Dremel tool.
2. If you are still not convinced that the indications are benign, buy
a dye penenetrant test kit. It consists of 3 aerosol cans. One of
cleaner, one of red dye, and one of white developer. Each can costs
~$8. It's best if all three cans come from the same manufacturer. It
would also help if you researched the details of how to do the test.
It's easy, but there are a few points to pay attention to.

Zeus Cranks? Are they still being made? IIRC they were made in Spain in
the '60s & '70 and were a poor man's Campy.

If you have further questions, please feel free to e-mail me, John

In article <[email hidden]>, Werehatrack

Quoted message said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my Zeus
crank arms. These are not like the cracks I've seen on failed cranks,
and appear to be quite superficial, perhaps only involving the anodized
layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

Looks like a corrosion track. I would expect that to be on a
clearcoat painted surface more often than an anodized one, but it's
not uncommon. The extremely meandering character and the flatness of
the surface are the two keys which lead me to say that I believe
there's no crack involved.

Is this a defining feature of cracks: that the surface 'sucks in' (as
JB described his post)? That is, there is a depression in the material
adjacent to the fracture?

Would this also be a characteristic of cracks in, let's say, an
aluminum frame?

Luke

Dans le message de news:[email hidden],
Luke <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

In article <[email hidden]>, Werehatrack

Quoted message said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my
Zeus crank arms. These are not like the cracks I've seen on failed
cranks, and appear to be quite superficial, perhaps only involving
the anodized layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

Looks like a corrosion track. I would expect that to be on a
clearcoat painted surface more often than an anodized one, but it's
not uncommon. The extremely meandering character and the flatness of
the surface are the two keys which lead me to say that I believe
there's no crack involved.

Is this a defining feature of cracks: that the surface 'sucks in' (as
JB described his post)? That is, there is a depression in the material
adjacent to the fracture?

Would this also be a characteristic of cracks in, let's say, an
aluminum frame?

Luke

With all the monitoring I understand the USA is doing of internet traffic, I
wonder if this thread isn't being scrupulously watched as either :
- a place where software keys are exchanged ; or
- a distribution network for illicit drugs.

Had a stray thought - never mind ...
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

On Sun, 15 Jan 2006 06:59:12 -0500, Luke <[email hidden]>

Quoted message said:

Is this a defining feature of cracks: that the surface 'sucks in' (as
JB described his post)? That is, there is a depression in the material
adjacent to the fracture?

I have seen cracks resulting from vibration which did not present a
surface distortion factor, but the ones I can recall resulting from
yield due to tension beyond the material's limit did, indeed, have
that as a typical characteristic, though not always along the entire
length of the crack. Since the marks in this case show no signs at
any point of such a feature, it serves as an indicator that the
underlying material is undisturbed.

Quoted message said:

Would this also be a characteristic of cracks in, let's say, an
aluminum frame?

I would expect it there as well, though the presentation would vary.

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my
Zeus crank arms. These are not like the cracks I've seen on failed
cranks, and appear to be quite superficial, perhaps only involving
the anodized layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Quoted message said:

Anybody have anything to share on the significance of such cracks?

These are highly unlikely to be cracks but rather some odd corrosion
in the anodized surface. The reason for my belief is that cracks
neck in so that there is no continuous surface as your excellent
pictures show.

What does "neck in" mean?

Tim McNamara said:

Quoted message said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my
Zeus crank arms. These are not like the cracks I've seen on failed
cranks, and appear to be quite superficial, perhaps only involving
the anodized layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Quoted message said:

Anybody have anything to share on the significance of such cracks?

These are highly unlikely to be cracks but rather some odd corrosion
in the anodized surface. The reason for my belief is that cracks
neck in so that there is no continuous surface as your excellent
pictures show.

What does "neck in" mean?

good question. necking is a feature of gross plastic deformation, not
the essentially brittle cracking of fatigue failure.

Luke said:

In article <[email hidden]>, Werehatrack

Quoted message said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my Zeus
crank arms. These are not like the cracks I've seen on failed cranks,
and appear to be quite superficial, perhaps only involving the anodized
layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

Looks like a corrosion track. I would expect that to be on a
clearcoat painted surface more often than an anodized one, but it's
not uncommon. The extremely meandering character and the flatness of
the surface are the two keys which lead me to say that I believe
there's no crack involved.

Is this a defining feature of cracks: that the surface 'sucks in' (as
JB described his post)? That is, there is a depression in the material
adjacent to the fracture?

brandt is "confused" on that one. fatigue cracking doesn't exhibit
"necking" or "sucking in" in the crack zone.

Quoted message said:

Would this also be a characteristic of cracks in, let's say, an
aluminum frame?

no. fatigue cracking, the type you're worried about, typically either
follows the heat affected zone of the weld or is perpendicular to a
stress axis. these pics are /not/ fatigue cracking.

Quoted message said:

Luke

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my Zeus
crank arms. These are not like the cracks I've seen on failed cranks,
and appear to be quite superficial, perhaps only involving the anodized
layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

they look like surface corrosion, similar to one of the organic
corrosion systems like galleonella. [g. is for steel systems, and i'm
not current on any equivalent aluminum corrosion, but doubtless one
exists.] they could also be gross inclusions showing on the surface as
revealed by the machining process, but i think that unlikely - they
don't typically look like that.

whatever they are, they're /not/ fatigue cracking - wrong morphology.
as stated by others, you can polish them out and live with it, but if
this bike is /not/ an historic restoration project or low mileage show
piece, i'd not use these cranks. the machining profiles are copies of
the old campy record style cranks, and with the exception of *one*
n.o.s. in-box item, every single record style crank i've ever seen at
bike swaps shows tell tale arm/spider junction cracking initiation - and
this one /will/ follow suit. get a new crank with the modern "rounded"
machining profiles - they're much more fatigue resistant.

Tim McNamara said:

What does "neck in" mean?

Rube's location.

Quoted message said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my
Zeus crank arms. These are not like the cracks I've seen on failed
cranks, and appear to be quite superficial, perhaps only involving
the anodized layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

Quoted message said:

These are highly unlikely to be cracks but rather some odd corrosion
in the anodized surface. The reason for my belief is that cracks neck
in so that there is no continuous surface as your excellent pictures
show. With such good lighting and unblemished surface, these do not
appear to be cracks at all. Besides that they are in the wrong places
on the crank. I've broken a lot of cranks and they didn't have that
sort of surface, quite aside form the tiny wormy squiggles.

Thanks, Jobst.

They didn't appear to be quite right to me -- being so superficial and not
terminating on any obvious stress risers -- but I thought I'd fish for
some other opinions.

Thanks for responding. I'm glad I won't have to shelve them.

--

John ([email hidden])

Werehatrack said:

Looks like a corrosion track. I would expect that to be on a
clearcoat painted surface more often than an anodized one, but it's
not uncommon. The extremely meandering character and the flatness of
the surface are the two keys which lead me to say that I believe
there's no crack involved.

What? Corrosion already? But that crank is barely 30 years old! :-)

Thanks for responding; the concensus seems to be that they are superficial
corrosion rather than cracks, which pleases me greatly.

--

John ([email hidden])

john said:

Zeus Cranks? Are they still being made? IIRC they were made in Spain in
the '60s & '70 and were a poor man's Campy.

No, they're not still being made. Zeus went belly-up back in the mid 90's.
They may have been a "poor man's Campy" but I like them. The cranks have a
wider chainring range than Campy at the time (Zeus goes down to 36T, while
Campy Record/Super Record only went down to 41T). That, and the company
seemed a little more willing to experiment than Campy, with more extensive
use of Titanium, drilling and milling, etc.

--

John ([email hidden])

John Thompson <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

john said:

Zeus Cranks? Are they still being made? IIRC they were made in Spain
in the '60s & '70 and were a poor man's Campy.

No, they're not still being made. Zeus went belly-up back in the mid
90's. They may have been a "poor man's Campy" but I like them. The
cranks have a wider chainring range than Campy at the time (Zeus goes
down to 36T, while Campy Record/Super Record only went down to 41T).
That, and the company seemed a little more willing to experiment than
Campy, with more extensive use of Titanium, drilling and milling, etc.

I have a Zeus seatpost that's a really nice copy of the first-gen Super
Record, with the flutes of the SR, but the 2-bolt head of the NR. Great
polished finish.

"Sandy" <[email hidden]> wrote:

snip[several remarks about crack and cracks]

Quoted message said:

With all the monitoring I understand the USA is doing of internet traffic, I
wonder if this thread isn't being scrupulously watched as either :
- a place where software keys are exchanged ; or
- a distribution network for illicit drugs.

Had a stray thought - never mind ...

The security-snoop apparatchiks are less interested in crack than:
explosives, bombs, plans, soft targets, dirty bombs, U.S Army
installations, bridges, planning, networks, water treatment plants,
shopping malls, physical plants, security arrangements, Muslim
fundamentalists, chemical attacks, subways, sports arenas, security,
cells, terrorists, suicide bombers, truck bombs, Internet research on
acquiring explosives, email Al-Qaeda, penetrations, chatter, border
security, plausible threats. . .did I miss anything, whoever is reading?

--
Ted Bennett

Hello,

I like Zeus stuff, I have a Zeus seatpost bolt that I've transfered from
bike to bike since my first racing bike in the early eighties. I also
think this crack looks superficial

However, I was sprinting out of the saddle about fifteen years ago and
snapped a Super Record crank in half. My crank was one of the later
unfluted ones that was supposed to be stronger than the earlier ones. I
wasn't lucky enough to see the crack in time. It must have been there.
After it broke you could clearly see the lines in the fracture
surface, kind of like the rings on a tree, and then the frosted looking
area where it failed catastrophically. I was in grad school for
mechanical engineering at the time.

I broke my shoulder blade and had to have stitches on my hand, elbow,
shoulder and hip. I was riding on a road that was paved with asphalt
and then had a layer of pea gravel kind of embedded in the surface. It
really did a number on me.

Even though I think you're right and this crack isn't structural I
wouldn't ride on it. I wouldn't take the chance of it breaking while
riding if I were you.

-Eric

jim beam said:

John Thompson said:

I found a couple suspicious-looking meandering cracks on one of my Zeus
crank arms. These are not like the cracks I've seen on failed cranks,
and appear to be quite superficial, perhaps only involving the anodized
layer:

http://www.os2.dhs.org/~john/cracks1.jpg
http://www.os2.dhs.org/~john/cracks2.jpg
http://www.os2.dhs.org/~john/cracks3.jpg

Anybody have anything to share on the significance of such cracks?

they look like surface corrosion, similar to one of the organic
corrosion systems like galleonella. [g. is for steel systems, and i'm
not current on any equivalent aluminum corrosion, but doubtless one
exists.] they could also be gross inclusions showing on the surface as
revealed by the machining process, but i think that unlikely - they
don't typically look like that.

whatever they are, they're /not/ fatigue cracking - wrong morphology. as
stated by others, you can polish them out and live with it, but if this
bike is /not/ an historic restoration project or low mileage show piece,
i'd not use these cranks. the machining profiles are copies of the old
campy record style cranks, and with the exception of *one* n.o.s. in-box
item, every single record style crank i've ever seen at bike swaps shows
tell tale arm/spider junction cracking initiation - and this one /will/
follow suit. get a new crank with the modern "rounded" machining
profiles - they're much more fatigue resistant.

E Goforth said:

Even though I think you're right and this crack isn't structural I
wouldn't ride on it. I wouldn't take the chance of it breaking while
riding if I were you.

I guess I'll have to find myself a wall queen and install it on that. :-)

--

John ([email hidden])