Tipperary Creek Trail: Considered by many to be Colorado's very best mountain-biking trail, this 30-mile ride from Fraser to Winter Park runs through dense forest and wildflower-covered meadows, offering views of rugged snowcapped peaks. It is strenuous, rising from an 8,600-foot elevation to more than 10,000 feet.

Crested Butte: Crested Butte vies with Winter Park for the title of mountain-biking capital of Colorado. The highly skilled should try Trail 401, a strenuous single-track loop that combines scenic beauty with steep grades and rough terrain. The less ambitious can explore the Cement Creek Trail, a dirt road that follows Cement Creek, with many side trails leading to higher terrain.