We own a ranch in Californias San Bernardino mountains. There is a trail around our ranch that the Forest Service put in for the bikers, but they prefer to go through our place. They throw snack wrappers and drink bottles on the ground, and mouth off if confronted. I am vertically challenged, and put “NO TRESPASSING” signs as high as I can, and they always manage to rip them down. They go over gates and fences and destroy it as much as possible. One of these days someone will get hurt. They may have problems with a bear or cougar or rattlesnake, or possibly even some of my livestock. These jerks would not hesitate to sue me if they hurt themselves in the process of violating my rights.
Sounds like you need to invest in a big dog and train him to eat cyclists.
This is what cameras are for. Put some up and start posting their pics on the internet. Start a blog called Rude Arrogant Anti-Nature Lawbreakers.
I suggest fishing line. 100lb. test. Strategic height.