No Bear Jetpacks

Bears on top of your house?

walking straight up a 4 meter high wall during winter? 

chasing you at a sprint while you're holding a spear and poking at them down a sheer stone cliff?

Seek no more! Now bears can only climb a reasonable distance at speed!

 

This mod reduces the stepheight of bears, their "leap" height to 2.25 blocks from 3.1. That means a wall of 2 blocks and 1 slab should reasonably keep them out most of the time as long as you make sure to keep it's outside clean. A wall of 3 blocks meanwhile should be more or less safe. Without this bears can occasionally climb up to 4 (and rarely 5) blocks with janky physics which just makes for entirely ridiculous looking animal pens if you want them bear-proof.

 

This mod should barely affect bears chasing the player as 3 block cliffs are at best unusual for the player to be traversing at speed, and they will generally path around it.

Nothing else to it!