The trails at the Fort Ord National Monument are multi use. Equestrian, non motorized bicycle, and foot travel. The trailheads are easy to find and the skill level is mostly easy to moderate hiking with an occasional sections being a little more challenging. Google the monument and find info on trail maps, history, flora/fauna, etc. I find the trails to be in fair condition considering the multi uses. There are sections a bit more worn so be prepared for berms, holes, ruts, etc. The trails all seem to tie together in some form so don't worry about getting lost. Carry water and a hat on warmer days, a light jacket and maybe layering on cooler days. Be careful wearing personal listening devices as bicyclists are about, mostly on downhill sections. Please be courteous to all users.
There are MILES of trails on FT Ord. Mostly well travelled, mostly for Mountain Biking. Beautiful terrain, great scenery. Not a lot of services. If you need it, pack it...if you use it, take it out with you. The Monterey Off-road Cycling Association (MORCAmtb.org) has some good maps and information about the trails. They are also pretty active in builing and maintaining the trails.