The Tumalo Creek Trail is 3.5 miles one-way and parallels Skyliner road. Starting at the Skyliner trailhead, the trail runs up near the road on the ridge side to the Tumalo Falls trailhead. Since it costs $$ to park at Tumalo Falls but parking at Skyliner is free, this is a great trail to start on.
The singletrack itself is pretty easy: classic dusty Bend singletrack. There are a few gradual climbs and descents, but nothing serious. The trail does provide some pretty sweet views of the mountains above and the creek below.