Aspen is best known for its four ski mountains and astronomical real estate prices.  It is also a very picturesque place to go mountain biking in the summer.  In fact, the Maroon Bells, close to town, are the most photographed peaks in North America.  The best known trails in the area are the Smuggler Mtn / Hunter Creek Loop and the Government Trail.  There is also good riding to be had on the many jeep roads up and over various mountain passes.  Hikers have a definite advantage over bikers, though, because they are free to explore the several Wilderness Areas that pretty much surround Aspen.