No biking within the park except for on paved roads. You can even rent cruiser bikes I think. But absolutely no trail riding. But…you will not be far from Flagstaff AZ and it has great trails. Like, descending 2000’ through pine forest and coasting for miles. And…if you’re riding in Flag, you may as well drop down an hour drive to Sedona where you might decide to never leave due to the riding there. Took the family to GC, Flag, Sedona, and Monument Valley three years ago and we all can’t wait to do a return trip. Sent from my iPhone using Tapatalk