@ rvoi you are correct they were on the east side of the base. And yes it is now a Marine Corps base. There is also plenty of signage along the route the riders were taking. I ride the area often but I access from a different spot that does not require trespassing on the base. There are a number of access points that avoid the base but they require a) a longer drive b) gasp some pavement riding or c) climbing over a ridgeline to start.
Regardless of how you get in, the trail system riders are trying to access is
on private land and 100% illegally built. Some
riders may be ignorant of this but most are not. Riders in San Diego are so habituated to trespassing and riding illegal trails without consequence that no one pays any attention to signs. And when enforcement does step up they keep riding as per
usual, only to cry and moan how unjust it is when they get busted.
Don't feel sorry for these people. Many are so entitled that they will cut
holes in fences, ride around barriers and vandalize signs. It is this sort of
attitude that led to the marine enforcement to begin with. A small number of
riders insists on riding further into the base along ridgeline fire roads that
are within line of sight of a rifle range that is heavily used. Guess what…
riders appear up there when the range is hot the training must be halted while the MPs chase after the riders.
While those who get caught are given a significant fine most of these will be
reduced significantly or waived entirely in Federal Court. The marines have
been citing riders for many years and issued a public warning they would begin
confiscating bikes. While this sounds extreme riders will get their bikes back
once they appear and pay whatever reduced fine they get off
with. Though I imagine they won’t get off so easy the second time….