Maybe it's the angle of the picture, but the rim metal looks really thin where it cracked.
@
Noahma, do you know if the spokes are double-butted? Those are generally kinder to the rim than straight gauge -- if you have straight-gauge spokes now, consider upgrading when you have the wheel rebuilt.
Ultimately, this is the risk we accept with lightweight aluminum rims. A rim that *couldn't* be made to crack would be so thick and heavy that few of us would want to ride it.
