Lol,that sign is almost enough to make you want to turn around-almost.
I should make a disclaimer to mine as it appears I'm riding illegally.
Whenever the snowmobile club around here integrates a pre-existing trail into their system they immediately post signs telling everyone to stay off it-even in the summer-I have no idea why(though I own one,I don't consider myself to be one of them).In the first case it's public land,the second is private woods road of which the landowner told them not to do that and told me to tear them down if I saw one when I stopped in to ask her about it.