The Gemini Bridges ride is one of the more famous mountain bike routes in Utah. It's popular with families and beginning riders. It's also popular with the moto crowd, so be prepared to share the road with motorcycles and ATVs. The trail isn't tricky, but it's long. Beginners can do this ride, but consider the length of the ride and the long uphill climbs before deciding whether it's right for you.
As an out-and-back to Gemini Bridges from the highway, it's 16 miles round trip. Total climbing is about 1500 feet, in 3 sections of 500 feet each (two on the way out, one on the way back). This trip (with one short push-a-bike, see below) is within the ability of most fit beginner riders.
Many riders -- particularly those with less leg power or "early season endurance" will want to consider a shuttle ride. Drop-off is at the top of the Gemini Bridges Road where it leaves Highway 313 (13 miles from 191). It's all downhill until you hit the little hill near the end, where you'll do about 300 vertical to get up and over to reach Highway 191. From here, you can coast all the way back to Moab via the paved Old 191 bike path.
As you approach the bridges, the road forks into a small loop. There are a couple of viewpoints, then a 1/4 mile hiking trail that takes you to the arches. GPS N 38° 35.123' W 109° 42.456'. A bike rack is provided for cycle parking.
By bike from Moab: Pedal 7 miles up the Old 191 bike path. For the out-and-back, turn off at the Gemini Bridges road. For a big loop, go another mile up Old 191 then 13 miles on highway 313 to the top of Gemini Bridges.
Camping: Primitive, in designated sites along Gemini Bridges road