This route starts at the Gemini Bridges parking lot on US 191 and ends at the Poison Spider trailhead along the Colorado River. (Car shuttle option.) This is a tough, strenous route, and advanced skills are a must. Take a good map (and GPS, ideally), since the route-finding can get confusing. Be prepared with plenty of water, and rain gear if the forecast is at all dicey. This route took our group 6-1/2 hours. We weren't a fast group, but neither were we slow.
First few miles are smooth dirt jeep road -- a climb and a descent down into a valley. Then pick up 4WD route that climbs up to the ridge line for spectacular views of the Moab Valley. Lots of great technical with many drops and ledges. Along the ridge line you can pick up some GREAT (and challenging) singletrack. White jeep icons mark the jeep track along the upper portions, but watch for blue markings which mark the singletrack.
This route takes Poison Spider down, but I'll never do that again. It's ridiculously sandy and a real slog. Better to get over your fear of heights and take the Portal Trail down (a couple hundred yards of serious exposure where you'd best walk your bike). Portal is a trail where people trying to ride it through the exposed technical sections have died.
I want to come back to Gold Bar Rim / Golden Spike Jeep Trail and singletrack. But next time I'll park a car on Gemini Bridges Road where you take a left to head up Gold Bar. Then head out for a day of fun along the ridge, and head back to the car when done. You'll avoid a lot of nasty sand. And I don't think Poison Spider is so great that you should put up with the ordeal that the sand will dish out.
