The problem with this is, there may be structural damage that can't be seen that will eventually fail too. And if something has already begun to crack, especially if it's old, chances are it past it's useful life.

I'm a cheap bastard, but sometimes you have to know when to retire a part to the junk bin. Dental work is generally more expensive than a new set of cranks.

Sure..in some cases with a crack it's best to retire the part..in this instance though I'm thoroughly familiar with the crack and crank in question. The area where the crack started at the spider is thinner and sharper than the rest of the crankarm/spider. Therefore, the removal of a small amount of material enough to eliminate the crack, leaving a rounded profile will solve the problem. If this thinner material had been removed at the factory, the crack would have never started.

I absolutely agree. I have always felt that this was an error in tooling design rather than structural design. Having said that, I think that if anyone is uncertain about the safety of this approach then by all means simply replace the part. I have however, made this 'repair' with great success more than once ... and I'm no light-weight at 250 lbs. Naturally if you find one of these cranks without the crack, it's definitely a good idea to remove the sharp edge as a preventative measure.... I guess that goes without saying.

Jim

Ok, so funny you guys should mention aluminum catastrophically failing....

Check out what happened to my bianchi tourer's stem while my friend was riding it.

The only warning it gave was some creaking the night before between pubs.

Soooo, yeah - I wouldn't use a cracked crankarm.