West of Nederland, the Caribou Flats Road (FS505) is an 11 mile route open to off-road motorcycle trails riding. Except for spring mud and a steep grade near Eldora, this is a fairly easy route. It passes the Caribou Townsite.
To reach the southern trailhead, head to Eldora. The trailhead is located at the eastern end of Washington Avenue. Once you get to Eldora stay straight and take the dirt road to the Hotel and turn right. Take another right and take a small road between a house and a garage (Yes, thats a public road).
The northern trailhead is off of CR 166J 1 mi from the Rainbow Lakes Campground.
Note: Colorado residents must register their off-highway vehicle with the Colorado State Parks (303) 866-3437. Non-residents are not required to register in Colorado, if they are registered in their home states. All off-highway vehicles must have an approved muffler and spark arrester. These requirements are subject to change so make sure to contact the Colorado State Parks prior to using your off-highway vehicle.
Overall, Caribou Flats Road is the 20th most popular dirt bike trail of all 93 dirt biking rides in Colorado.