This is probably one of those "never again" trips because it is a rather grueling climb for 11 miles at the start, though it was pretty much all downhill after that. The first half of the loop is on Sulfur Mountain recreation trail. It's a beautiful ride, especially in the spring, as the hills are very green. There are great views of Ojai, mountains, and the ocean/islands in the distance. The return part of this loop is on highway 150 to Ojai.
Sulfur Mountain Road, from Casitas Springs is a wide dirt road, but it's hard-packed and very good for biking. Once you reach the parking area at the locked gate near the summit, you'll be riding on a paved road. From there, it's downhill, followed by a disappointing uphill (because I had just climbed 11 miles straight and thought I was done climbing), and then a wild and long downhill all the way to highway 150 in the upper Ojai Valley. At this point, you'll have a flat to slightly uphill climb to Dennison Park, and then another wild and steep downhill to Boccali's Restaurant. Then it's a straight, level shot into downtown Ojai. Just opposite the Ojai arcade is Libby Park. If you need a sugar rush, Ojai Ice Cream is one of the arcade shops, and there are plenty of places to eat as well. Work your way to the back of Libby Park, past the tennis courts, to pick up the Ojai Valley Bike Trail to return to the starting point. (NOTE: the Ojai Valley Bike Trail passes on the opposite side of hwy. 33 from the turn-off for Sulfur Mtn. Road and your starting point. When you get close, shortly after crossing the bridge over San Antonio Creek, be on the look-out for a paved road going off to your left toward the highway, about 250 feet away. Sulfur Mtn. Road is directly across the highway. It is very busy, so be careful crossing. Don't worry about the gate you see. There is a gap on either side wide enough to push your bike through. If you miss this turn-off, you can also stay on the bike trail a short distance (about 0.15 mile) until you get to Casitas Springs (just opposite Nye Rd.), and follow the highway back to Sulfur Mtn. Rd.)
To get to the starting point, head north on Hwy. 33 from Ventura, enter Sulfur Mtn. Rd. on the right just after passing through Casitas Springs. Drive about 1/4 mile to parking area at a locked gate. Any time of year is suitable for this trip, but winter/spring is best because of usually cooler temperatures, green countryside, and those clear days when you can see for miles.
A full mountain bike is not required, since the dirt road going up in the beginning is wide, solid and not rutted. After the initial 11-mile climb, you will be riding on a paved surface. I made the trip with a hybrid. You will encounter hikers, no cars, on the dirt road part of this trip, but since you will be going slowly on this portion, they won't present a danger. You will be sharing the road with cars coming down from the mountain to hwy. 150 and all the way into Ojai, but usually traffic is light.
For a much easier trip (all downhill and in the reverse direction from my trip), park at the locked gate on top of Sulfur Mountain (take Sulfur Mtn. Rd. from the Upper Ojai Valley, Highway 150), and ride downhill to the gate by Casitas Springs (where I began my trip). Of course, you will have to use two cars (one at top and one at bottom) to accomplish this.