Group indoor cycling is the brainchild of Johnny G—the wiry, energetic, spiritual leader of Mad Dogg Athletics' and Schwinn's Spinning program. But other companies have quickly jumped into the burgeoning market to satisfy cycling mania. Today, the Big Three include not only the original Spinning, but also Studio Cycling by Reebok, and Power Pacing by Keiser. Independent instructors have developed their own programs, and other companies are also trying to break in. Don't be surprise if you see something called Power Cycling, Precision Cycling, All Body Cycling, or Body Biking, on a cycle built in Denmark that is breaking into the United States market.

Each of the Big Three approach indoor cycling differently:

Spinning/Mad Dogg -- Developed from a strict cyclists' view, Spinning revolves around visualizing your indoor ride -- complete with wind, hills and butterflies -- as if you were outdoors. Johnny G stresses the importance the classes flow as a real ride, and that exercisers learn to empower themselves.

Studio Cycling/Reebok -- Created by a team of group exercise specialists and scientists -- including a biomechanist and sport psychologist -- Reebok's program is steeped in science, safety for the masses, detailed analysis of body alignment, and conservative exercise progression.

Power Pacing/Keiser -- Developed by former dancers and group exercise specialists -- with choregraphic wizard Karen Voight as its figurehead -- Power Pacing is set apart by its emphasis on moving with musical rhythms, applying more body choregraphy (such as swaying), and incorporating upper body exercises into rides.

Knowing a program's philosophy could help you choose the one that best suits your fitness personality.