“Fun ride (shuttle or out-and-back) with great views over backcountry and the Santa Ynez valley.
— Bela Bauer
Most people do this as a shuttle ride from Camino Cielo down to Paradise Road. The fire road at the top starts at a metal gate on Camino Cielo, a few miles east of the junction between Camino Cielo and Painted Cave Road. It can also be done as an out-and-back ride by starting at the parking lot on Paradise Road (Adventure Pass required).
The climb is tough, but almost completely rideable if you have strong legs. The downhill is really fun and very fast. The top section is wide-open with a few jumps. In the middle section there are a few tight switchbacks and some rocks, but nothing scary. Towards the bottom, it gets narrow and steep in a few places, only to meet a fireroad and get wide-open again at the very bottom.
I recommend taking the short side-trip to Knapp's Castle, if just for the views.
Be sure to get a bike bell, distributed by the Santa Barbara Mountain Bike Trail Volunteers. The bells help other users on the trail be aware of mountain bikers. Also, please stay on the main trail and don't use the shortcuts!