USA Cycling announced today the 2007 American Mountain Bike Challenge (AMBC) calendar. The 26-race calendar provides off-road cyclists with the opportunity to qualify for the 2007 USA Cycling Mountain Bike National Championships July 17-22 at Mount Snow Resort in Vermont. With events in 18 states, the AMBC also provides entry level racing opportunities for competitors interested in participating in the sport of competitive mountain biking in a local or regional setting.