West of Moab, the Captain Ahab Trail is a purpose-built mountain bike trail recently sanctioned on BLM land. Designed as an advanced trail, the Capt Ahab is a 4.3 mile route offering a 1,100 foot descent over slickrock benches. The route is accessed from the top of the Amasa Back Trail climb, and is signed for one-way traffic downhill. It is designated for experienced riders only.
To reach the Capt Ahab trailhead for mountain biking from Moab, head west on Kane Creek Road for about 6 miles. As the road turns away from the Colorado River at the Kane Creek Trailhead, continue on to the Amasa Back Trailhead.
After parking, the trail is another 0.5 miles beyond the parking area on the right. From this trailhead (no parking), there are two routes up Amasa Back to the start of the Captain Ahab Trail. First, there is the older, rugged Amasa Back 4WD road that has many unridable hike-a-bike sections. Second, there is the new HyMasa Trail which is a single track riding up 3.2 miles to the pass. Both start with a steep descent from the trailhead down to Kane Creek before starting the 800 foot vertical ascent up to the pass. Both routes ascend a peninsula of sandstone surrounded on three sides by a huge sweeping turn in the Colorado. The climb will get your heart pounding: its about 800 feet up in less than three miles. The interesting part is the ledgy Kayenta sandstone that makes the climb much like going up loosely spaced stairs.
On the way up, there is a signed entry for the mid-point of the Captain Ahab Trail. If you enter here, you will only ride what is called the Lower Captain Ahab Trail. At the highpoint on the 4WD road or the HyMasa Trail, the Captain Ahab Trail veers off to the left. From the start of the Captain Ahab Trail, there is still another 300 feet of climbing before the rolling descent begins.
Overall, Captain Ahab Trail is the 61st most popular mountain bike trail of all 74 mountain biking in Utah.