When their young is threatened mother bears go to town on anything or anyone that feels threatening.

That's actually not true. I know it's been put forth as a sort of "common bear knowledge" but it's wrong.

The idea that a black bear will never attack unless it's a mother with young is a dangerous concept. It makes people feel too safe and ignore other warning signs.

The likelihood of a black bear attacking you is exactly the same regardless of it's sex or current parenthood. Mother's with cubs with bluff and run away just as much as the rest of the species.

Statistically black bears are more likely to bluff and retreat, regardless if they have cubs, just as statistically a brown (grizzly or kodiak) is more likely to kill you regardless if they have cubs.

It's all equal. The cubs make little difference.