It's really hard to tell, from a picture, if something like this is a crack or just some kind of surface imperfection. (Cosmetic surface flaws that look like this are very common.) Often it's even difficult to tell by direct visual inspection of the part; sometimes you have to use a microscope, and even then it's hard to be sure. In general, though, real cracks don't meander the way the features in your pictures do, and usually you can see them extending into the perpendicular surface. I'd be 90% sure that the one nearest the center is just an anodizing flaw, but the one in the first jpg might be more worrisome. Can you find a microscope somewhere to get a better look at it? Or, put some weight on it and at least inspect it with a good magnifying glass to see if it separates?
Of course, the conservative approach is to stay off it until you're completely certain it's OK.
Steve Maas Long Beach, CA
John Thompson wrote:
> 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?