Originally Posted by mac
#1 - it's not your property. Respect the wishes of the owner or get off of his property
#2 - liability. We live in the lawsuit capital of the US. If you get hurt on his property doing that dangerous bicycle-riding thing, you can sue him for all he's got because he didn't warn you to not ride. That sign protects him for those lawsuits. Sadly, that's the world we live in.
Mac,
You're right about the private property issue and correct about why these rules would be put in place. And my reaction to such a rule would be to avoid such a retailer and inform them about why they won't be receiving my business. This probably won't change a thing, but in this day and age voting with one's pocketbook is more productive than visiting the voting booth.