Bull Canyon Trail
Bull Canyon is a popular ATV route off the Gemini Bridges Road north of Moab. It's worth doing, maybe not as a destination ride, but as a side dish to another ride in the area. The usual turn-around is the foot trail to below Gemini Bridges, but you can ride further up the canyon. Select one of the three rides below, or make up your own.
Trail conditions change. Use this guide at your own risk.
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
Mag 7 Tour de Bridge (w Little Canyon and Arth's):
0.0   From Gemini parking, start south and uphill
        N38 39.378 W109 40.689
4.6   Fork L on Gold Bar Rim
        N38 36.040 W109 40.454
5.1   Keep L, start uphill
5.2   Fork R on singletrack marked in yellow
        N38 35.881 W109 40.144 Easy to miss!
6.6   L on Bull Canyon road N38 35.729 W109 41.007
7.7   Keep straight (L = Two Tortoise Rock trail)
        N38 34.934 W109 40.899
8.1   Fork R and enter wash N38 34.934 W109 40.899
9.7   Hiking trail to arches N38 34.914 W109 42.027
        Hike then head back the way you came
12.8 L on Little Canyon ST
        N38 35.735 W109 41.005
13.6 Cross Gemini Bridges road to Metal Masher
        N38 35.773 W109 41.620
13.7 L on Arth's Corner singletrack
        N38 35.856 W109 41.653
15.2 R on Gemini Bridges road
        N38 35.246 W109 42.238
15.4 L toward bridges N38 35.271 W109 42.400
15.6 Foot trail to top of bridges
        N38 35.233 W109 42.604
        Retrace to Arth's Corner 
17.6 Little Canyon ST
18.4 Cross Bull Canyon rd
19.3 L on Gold Bar
19.9 R on Gemini
24.5 Back at TH
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.