crankset

A crankset is the bicycle drivetrain component that converts the rider's pedaling motion into rotational motion of the crankset, transmitting power through the bottom bracket spindle to the chain. It consists of crank arms, a spindle or spider to which one or more chainrings are attached, and, depending on design, may include a power meter or other hardware. Chainrings may be single, double, or triple.

Crank arms come in various lengths and materials, including aluminum alloy and carbon fiber. The interface between the crankset and the bottom bracket defines the system: traditional square-taper and splined interfaces (such as ISIS Drive and Octalink) were common on earlier bikes; many modern road and mountain bikes use external bearings and hollow spindles (for example Hollowtech II) or press-fit spindles. Compatibility depends on bottom bracket shell width and diameter, spindle diameter, and the crank's mounting interface.

Chainline is the distance from the centerline of the bicycle to the chain when in the middle chainring; most road doubles aim around 47.5–50 mm. Q-factor measures the width of the crank from left to right; 145–170 mm is common. In front of the chainset, the number of chainrings determines gearing: 1x, 2x, or 3x configurations, with front derailleurs designed for each.

Maintenance involves ensuring proper installation torque, checking for play, cleaning, and replacing worn chainrings or crankarms as needed. Cranksets differ by application: road, mountain, track, and single-speed styles, with materials and constructions optimized for weight, stiffness, and durability. Power meters can be integrated into certain models.