Originally Posted by
Monster Pete
You should examine the helmet around the crack. Helmets theoretically absorb impacts by the foam crushing. If the foam isn't significantly compressed, it's unlikely it did much to help you. I'm not denying helmets can help you in the right circumstances (which may have been the case with you) but am very skeptical of the 'my helmet saved my life' claims that pop up from time to time.
Bicycle helmets are basically pieces of foam that are compressed to the point of almost being worthless in their "foam crushing" factor. There was a very small indentation in the helmet, but due the hardness of the foam, all the helmet really had left to do was crack, like an egg shell.
I ended up with a low throbbing headache for a few days, especially more noticeable when pulling hills.