I would best describe Bronco Canyon as a choose you own adventure trail. Use Lagomarsino Canyon Trail to access Bronco Canyon and enjoy the sites along the way. Once to Bronco Canyon Trail the difficulty will increase until you are confronted with the canyon itself.
Bronco Canyon is a wide riverbed, typically dry with the exception of the rainy season and is filled with boulders from one side to the other. While making your way up the river bed you can choose difficult lines or seek out the slightly more tame routes. Either way you go lockers, 35" tires and at least three rigs are strongly recommended.