Craig Fry's excellent guide to Southern California Bouldering is a must for any avid boulderer spending time in this area. SoCal, like the rest of California, is packed with quality bouldering areas, but without this book you'll definately feel lost among the freeways and sprawling suburban landscapes. Mt. Rubidoux has over 300 recorded problems. The granite tends to be high quality, but a bit harsh on the tips. Bring a skin kit and wait for the cool, dry conditions.
Landings are usually hard and obstacles abound, so pads and a good spotter are highly reccomended.
Experts will find an abundance of highballs that are sure to bring some excitment to any circuit. The road to the top is now closed to vehicle traffic, and it's reccomended that you stay off trails closed for rehabilitation. May. Summers at Rubidoux are usually sweltering and smoggy, but evening sessions may be bearable on occation. The winter months bring mild temps and clear skys - this is the time to go.