It all depends where the crack is, and what caused it.
Some can be ridden forever without any repair, some will grow, but can be salvaged, and some are clear and present dangers and the frame should be given to the scrap man.
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FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.