Abstract: A sprag one-way clutch (OWC) used within a cassette driver of the rear hub assembly of a bicycle. The new cassette driver delivers improved performance the reduction of rotation of the crank arm required before engagement within the cassette driver when the cyclist applies force to the pedals. Additionally, the sprag clutch smooth engagement minimizes friction loss during free-wheeling, therefore increasing drivetrain efficiency. These enhancements provide both safety and performance benefits by giving the cyclist greater control in moving between pedaling and free-wheeling. The current cassette driver design utilizes a sprag OWC for engagement without any modifications to current bicycle designs. A sprag cage may be used to provide a framework to support and properly position the sprags.