The Bull Canyon road starts as a wide dirt/gravel road. Once it forks away from the Dry Fork Bull Canyon road, it becomes a narrow ATV track in a wash. The scenery starts to get pretty. There are a few sandy spots, but I only bogged down once when I didn't pick the right line, which was fixed by moving the bike 10 feet. On the way out, I rode clean.

Option: Mag 7 "Tour de Bridge" with Bull Canyon.
My ride recommendation for Bull Canyon is to combine it with bits of the Mag 7 singletrack for a tour of the top and the bottom of Gemini Bridges. Here's the plan: Up Little Canyon Singletrack to the Bull Canyon road, visit the arches from below and double back. Resume Little Canyon ST, continue on Arth's Corner to Gemini Bridges Visit the arches from above. Now head back down Arth's and Little Canyon. See the mile-by-mile ride directions below.

Option: Two Tortoise Loop with Bull Canyon add-on.
Another option is to hit Bull Canyon as an out-and-back add-on to the Two Tortoise Loop If done from the bottom of the Gemini Bridges road, that ride is 20 miles; 23.5 if you go all the way up to the turnaround in the upper canyon. If you do only the "local loop" of Two Tortoise Rock, it's about 10 miles.

Option: Classic Bull.
The "classic" Bull Canyon ride is a simple dirt-road crank up the Gemini Bridges road to the Bull Canyon road. Or, as is more often done, as an out-and-back off the Gemini Bridges road when you're riding it top-to-bottom as a shuttled ride.

From the Gemini Bridges road, Bull Canyon starts out wide and smooth. After 0.1 mile, you'll pass the Little Canyon Singletrack crossing. At 1.2 miles, you'll pass the Two Tortoise Rock trail coming in from the left side.

At 1.6 miles from the Gemini Bridges, there's a critical fork. The broader fork veers slightly to the left, and continues to the Dry Fork of Bull Canyon -- not the one you want. Bull Canyon forks 90 degrees right and promptly drops into a wash. You might think you took the wrong fork until you see carsonite trail posts later on.

The walls of the wash become deeper and become tall cliffs of Wingate sandstone. There are a few sandy patches, but with a 29er, 2.1 tires, and a bit of speed I could ride them all. There aren't any tech sections. It's just straight-ahead dirt-road riding while you enjoy the scenery.
At 3.2 miles, you'll reach the hiking trail to Gemini Bridges. I didn't see a "no bikes" sign, but the carsonite marker showed only a "hiker" icon. So I assume you're NOT welcome to ride up the hiking trail. The trail is 0.6 miles long, arriving at a spot under the arches.

I had the whole canyon to myself on the way in. It was cool and peaceful. As I came back from the arches, a whole herd of ATVs had arrived. By the time I returned from the dead-end in the upper canyon, there were 25 vehicles in the parking area and more arriving. Early morning is definitely the time to ride.

The usual turn-around spot is the foot trail to below Gemini Bridges. But the trail continues another 1.6 miles up the canyon then dead-ends. Just before the end, a side path goes down into the canyon to old mines. It also dead-ends. So stay high and enjoy the view at the end.

Turn around and bomb back down the ATV track. Few vehicles venture beyond the parking area for the bridges trail, so you've got the canyon to yourself.

Once you're back on the main Bull Canyon road (after rejoining the Dry Fork road), consider a variation on your ride. Two Tortoise Rock and the Little Canyon Singletrack are alternate ways down the mountain.

Classic Bull Canyon out-and-back:
0.0   From Gemini parking, start south and uphill
        N38 39.378 W109 40.689
4.6   Keep R on Gemini, steep uphill section N38 36.040 W109 40.454
        (L = Gold Bar to Little Canyon ST or Two Tortoise)
5.1   Fork L on Bull Canyon road  N38 35.807 W109 40.867
5.2   Pass Little Canyon ST N38 35.729 W109 41.007
6.3   Keep straight (L = Two Tortoise Rock trail)
        N38 34.934 W109 40.899
6.7   Fork R and enter wash N38 34.934 W109 40.899
8.3   Hiking trail to arches N38 34.914 W109 42.027
9.4   Keep R uphill N38 34.557 W109 42.933
9.9   End of trail, turn around N38 34.318 W109 43.356

With Two Tortoise, from Gold Bar:
Park at "Dead End" 0.5 miles up Gold Bar
0.0   L uphill  N38 35.830 W109 40.221
0.1   Pass Gold Bar Singletrack  N38 35.881 W109 40.143
0.6   Fork R on Two Tortoise  N38 35.866 W109 39.742
2.6   Fork R (L = dead end) N38 34.797 W109 40.306
2.8   Keep L N38 34.830 W109 40.379
3.4   L on Bull Canyon Rd N38 34.934 W109 40.899
3.8   Fork R and enter wash N38 34.934 W109 40.899
5.4   Hiking trail to arches N38 34.914 W109 42.027
        Double back
7.4   Pass Two Tortoise N38 34.934 W109 40.899
8.4   L on Little Canyon ST N38 35.737 W109 41.006
9.8   L downhill on Gold Bar  N38 35.881 W109 40.143
9.9   Back at parking

Getting there:
Gemini Bridges TH. From I-70 drive south on US-191 for 22 miles. From Moab, drive 7 miles north of the Colorodo. Turn west (left if you're coming from Moab) into the parking area. GPS N 38° 39.381' W 109° 40.672'. To avoid a parking fee (private lot), go across 191 to the Bar M parking.
Gold Bar Rim road parking. (Use this parking spot for shorter rides heading uphill on the Little Canyon Singletrack or the Two Tortoise Rock trail.) Drive up the Gemini Bridges road 4.6 miles, and fork L toward Gold Bar Rim and drive along the wash 0.5 miles. You can park near the wash at N38 35.849 W109 40.304. Begin by riding up the hill.

Bathroom: Gemini TH
Water: none
Camping: primitive on Gemini Bridges Rd (bring your toilet!)