Awesome trail, lots of rocks, roots, climbs, and some killer downhill. You can really get speed on some parts so be careful of hikers and other bikers. Trail is cut out of pine and aspen trees, incredible views of the surrounding mountaings at times. Aerobic level may be higher for some - especially those coming from sea level, this trail head starts at about 9600 (Breckenridge) feet, goes up to around 10,500 then back down to 9000 (Frisco).
Go to the end of 2nd Ave off Main St in Frisco, or go to Peak 8 at Breckenridge Ski Resort
http://www.singletracks.com/item.php?c=1&i=981