Yes, I believe those are cracks. While it might be possible for some other kind of surface mark to look like that, I doubt it.
If you catch the cracks while they're shallow enough, you can file away all the cracked metal, leaving the edge rounded and smooth, and have a potentially better than new crank. Yours look like they've progressed too far though.
For a good description, with pictures, of what might happen (to the
crank, not to you) if you keep riding them, check out:
http://materials.open.ac.uk/
Mark Bulgier Seattle WA USA
> -----Original Message-----
> From: classicrendezvous-bounces@bikelist.org
> [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of
> ryan hildebrand
> Sent: Sunday, October 15, 2006 7:59 PM
> To: classicrendezvous@bikelist.org
> Subject: [CR]Stress cracks on Super Record cranks?
>
> While cleaning my bike today I noticed some very small marks on my
> 1979 Super Record spider:
>
> http://www.flickr.com/
>
> http://www.flickr.com/
>
> http://www.flickr.com/
>
> http://www.flickr.com/
>
> Are these stress cracks? How worried should I be? Please advise!
>
> Ryan Hildebrand
> Costa Mesa, Calif.