It is a nice park though. Fern Canyon in Redwood national park has the ossagon trail about 22.5 miles nice XC, part trail, part old highway, and part gravel road. Watch out for elk as i have ridden within 15-20 ft. of them a coupl of times before i saw them, good way to jump start the old battery. Anyways the forest has a bunch of fireroads and a few legal singletracks. Too hard to explain where the good stuff is, ask a local.
Revolution knows whats up too.
This place is a mud hole for half the year. I take a different one everyday. Than, if your special you can find the super secret stoner path through the back 9 of the frisbee golf course. All in all I've put together a few different loops in the park all about 2 hours and all fun as hell. If you're visiting Arcata there is no reason not to check out these trails, they offer a little of everything, There bad ass man.