http://www.ncbi.nlm.nih.gov/pubmed/20086406

Abstract: Anterior knee pain and patellofemoral pain syndrome are among the most common leg overuse injuries in cyclists. Bicycle fit, recent change in equipment, training distance and intensity, and individual anatomic factors are important evaluation considerations. Clinicians need a basic understanding of bicycle fitting and how anatomic factors and training errors contribute to repetitive stress injuries. After problems are addressed, a gradual return to activity is recommended to avoid further injury and improve performance.