MARIPOSA TRAIL is the pass to the right: very beautiful trail: even though open to biking I believe that is should not, as it present serious danger to accidents both to mountain bikers, bur especially to hikers! The trail is very narrow and presents many terrain accidents and lacks a solid shoulder to the very steep ravine. On top of that most bikers do not warn (as the regulations require) of their full speed approach, putting the life of hikers at risk! Puente Hills Nature Preserve Authority should do something in these regards: There are other trails, restricted to dogs and bikers (Sycamore Trail) Again, this is for a trail, but the request that every biker shall have a appropriate horn, etc. to warn hikers in a timely manner of their approach is the LAW!