This is one of the nicest trails we've ever ridden - a real treat. It's clearly made by and for mountain bikers, curving back and forth through pine and fir forest on a buffed singletrack. The smooth firm surface is interspersed with occasional hazards to liven things up. The hazards mostly consist of groupings of sharp volcanic rocks that you must pick your way through - or you can walk them if you're so inclined. The grades are gradual except for a few short steeper climbs.
The Sisters Trails Alliance is in the process of extending the trail system this year (2009) and marking all the trails, with the goal of creating 28 miles of equestrian, hiking, and mountain biking trails. Major junctions are already marked, new trails are being cleared, and an interim map is already available showing all the trails currently in use. Only mountain bikes and hikers are allowed on the bike trails; the equestrians have their own marked trail system.
We took the West Peterson Ridge Trail south from the trailhead and biked up to the Peterson Ridge Lookout, which has a nice view of surrounding mountains and forests. We returned on the East Peterson Ridge Trail, which had less volcanic embedded rock sections and some fun downhills. The northern half of each trail was mainly smooth going, with only a few sections of rounded river rocks to bounce over. The loop has many "connectors" which allow you to ride as short a loop as you wish - a very nice design. Our loop was just over 11 miles.
We can hardly wait to return next year and enjoy this trail, and are happy to send the Alliance a donation toward their efforts even though we live out of the area (www.sisterstrails.com).