For nearly four decades, Keiser has influenced the training of athletes, fitness enthusiasts and rehabilitation experts worldwide with better fitness products that unite both components of human performance: the force you produce, and the speed at which you produce it. Keiser M Series Indoor Bikes revolutionized the world of group fitness when they came on the market over two decades ago, and have set the standard for the category ever since. The first bike to use eddy current magnetic resistance and an aluminum flywheel, the M Series continues to offer users and owners innovations that improve the group cycling experience.