Originally Posted by jimv
That's a really common problem with older campy and suntour cranks. There's a sharp edge there. If the crack is small, you can take a fine, round file to the area to get rid of it. The rounded area shouldn't crack again. I've done this to both Campy and Suntour cranks with great success, and if you're careful the rounded area can look really nice.
Jim
Jimv is absolutely right..I remember seeing a number of these cracks on cranks in the 70's..when you use the round file to remove
just enough material to eliminate the crack..you've eliminated what is called in engineering terms a "stress riser". Kinda like..give a crack an inch and it will take a mile. If it's no longer there, it won't progress up the spider any further.