I was out at Joshua Tree National Monument about a month ago for a short two day trip for rock climbing. I brought my Muni along just for kicks. The priority was to climb and not get all worn out from Muni, so I did very little. My buddy Carew, took a few pix of me riding near Hidden Valley Campground.
There is some fun riding near in the campground, but there are signs that say your supposed to stay on roads. Errrrr, I didn’t for these photos. I dropped off my first picnic table here, but didn’t really get any decent photos of it. The images are of me riding with the surreal rock formations in the background. The best is here in this thread below. There are several others. I ended up putting this one on my desktop at school.
The MUni and trials options out at “Josh” are limited only by summertime heat–after May it’s blazing. Chris H. tells me in his active climbing days he used to MUni all over Josh. The rock is so grainy and the friction so great that I suspect you could actually MUni up soem of the lower angled slab climbs. That’s a whole new frontier out there for So. Cal riders.
Beau and I have ridden out at HVCG as well. Back in the '80s when I was out there all the time climbing, we used to go on some awesome night mountain bike rides, including a climb and insane descent of Ryan Mountain which I will remember all my life! Unfortunately all the interesting stuff is illegal there, but a night ride up to Keys View is legal and fun - would be great on a Coker I bet.
Josh is a great place for trials and MUni, except as you say for the restrictions. I did some fun riding there on climbing trips in '92 and '95. The rock is definately grippy although not much fun to fall on!