I've seen a biker at Potrero. He came a couple of times, and got up in people's faces when they told him he had to leave. I told him, and a couple of the other more mellow locals told him back then. He didn't listen. We all joked about what would happen if he came when somebody "less polite" was there. It happened one night. He got the shit broken out of his nose and was bleeding everywhere. He tried to ride for a minute, but pretty much everybody at the park taunted him about his bloody ass face. Then he called the cops, but the perp was gone by the time they arrived. He never has been back since. I have seen a couple other guys doing the early morning routine before anybody got there.
Bladers can be seen in the city from time to time, but its usually like one dude all by himself and not waxing anything, and for some reason a mixture of pity and respect comes over most people when they see that sad soul
The thing is though, if you are on a skateboard at that park, you are down, and don't have to worry about locals at all, aside from collisions
Here's some other info for you-
there's another park called the dish, its in hunter's point, and apparently people get jacked up there all the time. I've never been fucked with there, but apparently it happens all the time.
There are HELLA backyard/warehouse ramps and bowls in Oakland
Deluxe sells dlx decks for like $45. That's cheap even by California skateshop standards. The dudes who work there are super cool too.
Crocker is fun if you don't expect too much from it. Its basically a weird bowl that fades to nothing.
The flowershop is sick, but they've gotten more and more protective of it as time has gone by. When I left the city if you showed up with a bag of weed or a case of beer you were in.
Take the bart from downtown to 24th street, then go east and you'll be at potrero. There are super fun brick banks that have been in a bunch of videos there
Also sick brick banks- China banks. You may not want to do street stuff, but if you are a tranny dude in SF, at least carve a bench
Most of the good parks are in the east bay and san jose. If you can get out of town some good parks are:
Berkeley
Richmond
Sunnyvale (one of the bag of suck montages was filmed there)
Benicia (new park, old is cool, but I think gone)
Fairfield
The free San Jose park with the two bowls
Redwood city is pretty fun
That one park that is technically a rollerblade park and has hella spines in it
Santa Rosa
Petaluma
San Rafael
There's a bunch more I'm sure I'm forgetting too. By the end of my time in the bay area I was mostly a tranny skater. Too bad bordertown and wastelands are gone!