Stress marks on rims

Dan Shepperd said:

I wonder whether some kind person, wise in the ways of wheels, could
shed some light on this...

Quoted message said:

Having recently bought a few badly built wheels (and not really
being methodical enough to build my own) I traveled quite some
distance to a reputable wheel builder and had a set of wheels made
for XC MTB use. Anyway, I spent over 250 pounds on some Mavic XM719
rims, DT Competition spokes and Hope XC hubs laced up in a 36 spoke
three cross pattern.

Quoted message said:

After two weeks I noticed what I'm now pretty sure are stress marks
(one or two per eyelet) radiating out from the spoke holes towards
the braking surface (not hole to hole). There do not appear to be
any cracks or bulges - in fact the only signs of potential trouble
are these soft white marks. They look almost like reflections of
the spoke/nipple.

I don't know what sort of rims these are and whether they have sockets
and eyelets that distribute spoke loads to both inner and outer walls
of the rim. What you describe sounds like crazing of the anodized
surface, which may lead to cracking in the aluminum. It sounds like a
hazy appearance, suggesting that the anodizing is thin and may not
initiate cracks.

If you look at this area with bright grazing incidence light (sunshine
is great) and a magnifying glass, the fine structure of the surface
may be readily visible. In any case, anodizing cracks show up under
such inspection.

Quoted message said:

My concern is that the stress marks will develop into cracks
resulting in at best reduced lifespan of the wheels and at worst a
sudden failure. After a Google search of this newsgroup I now know
that there are some concerns about anodized rims and cracking.

Quoted message said:

Should I cautiously wait and see if they get worse? Or is it a
certainty that the stress marks will ultimately become cracks and
lead to rim failure? What would you do, if you were in my position?

What else can you do? This sort of failure is not dangerous because
it progresses slowly and gradually causes spokes to loosen... and
wheel misalignment.

Jobst Brandt

<[email hidden]> wrote: (clip) What else can you do?
(clip)
^^^^^^^^^^^^^^^
If the builder were in your town, I would take them in and show them to him.
Since, as you say, you traveled "some distance" to have these wheels made,
you will have to decide whether a return trip is justified. I would at
least call him and get his reaction. If you have trouble a year from now,
he could very well say that it is too late--you should have come in sooner.

I believe Jobst when he says the condition is not going to lead to sudden
failure, so, keep riding, and keep an eye on them.

Quoted message said:

I don't know what sort of rims these are and whether they have sockets
and eyelets that distribute spoke loads to both inner and outer walls
of the rim. What you describe sounds like crazing of the anodized
surface, which may lead to cracking in the aluminum. It sounds like a
hazy appearance, suggesting that the anodizing is thin and may not
initiate cracks.

Yes, it is quite hazy. It has a sort of holographic quality as it is
rather dependent on the light source and angle at which you view the marks.

Quoted message said:

Quoted message said:

Should I cautiously wait and see if they get worse? Or is it a
certainty that the stress marks will ultimately become cracks and
lead to rim failure? What would you do, if you were in my position?

What else can you do? This sort of failure is not dangerous because
it progresses slowly and gradually causes spokes to loosen... and
wheel misalignment.

Ah, that's probably the most important thing from my point of view. If
in a years time I have to pay for some new rims (& spokes) then so be it
- safety is another matter though.

Thanks for your advice.

Dan

Leo Lichtman said:

<[email hidden]> wrote: (clip) What else can you do?
(clip)
^^^^^^^^^^^^^^^
If the builder were in your town, I would take them in and show them to him.
Since, as you say, you traveled "some distance" to have these wheels made,
you will have to decide whether a return trip is justified. I would at
least call him and get his reaction. If you have trouble a year from now,
he could very well say that it is too late--you should have come in sooner.

I believe Jobst when he says the condition is not going to lead to sudden
failure, so, keep riding, and keep an eye on them.

That sounds sensible. I've only had them a month so perhaps with another
months riding it will become clearer whether things are deteriorating
and if so at what rate. Like I said to Jobst, the most important thing
from my point of view is whether the wheel is safe - I thought it
probably was, but I honestly don't know much about wheels so other
opinions are very helpful.

You make a good point about the pitfalls of leaving it too late, so I
might give them a call if only to cover my own back. Who knows, they may
have had similar problems before and some sense of whether the rim needs
replacing or not.

Thanks very much,

Dan