I've seen many instances of similar surface patterns that tuned out to be creeping trails of corrosion. I'm not sure of the mechanism involved, but it's not a structural thing beyond the depth that such defects might eat into the surface. In the case of these lines, it seems from the photo that these lines are fine indeed, and no more damaging to the structure than a normal scratch.
Those old Zeus cranks, like any structural parts, could fail, but I really doubt that failure would originate at such a small surface flaw. I don't believe the lines resulted from stress or would result in much stress concentration at all.
David Snyder
Auburn, CA
USA
>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/
> http://www.os2.dhs.org/
> http://www.os2.dhs.org/
>
> Anybody have anything to share on the significance of such cracks?