How strong are border collies?

it depends on how well you train your dog. most border collies are a little shy with strangers, so if someone pushed them beyond their comfort zone, they might snap. i have been snapped at by a border collie aussie shepherd mix, it was my fault, though. they are a herding dog, so they will nip at childrens heels. but hten there are the ones that just want to give kisses and love everyone, mine is like that. so, the border collie is not really agressive, but they are certanlly not a golden retriever.