Bicycle Cranks

Bicycle Cranks

Bicycle cranks are the component of a bicycle's drivetrain that transfer the power from the rider's legs to the chain, ultimately propelling the bicycle forward. The cranks are located on either side of the bicycle's bottom bracket, and are connected to the pedals by a spindle. When the rider pedals, the cranks rotate, which in turn rotates the chainring(s) and drives the chain forward. Bicycle cranks are typically made from aluminum, carbon fiber, or steel, and come in a variety of lengths to accommodate riders of different heights and leg lengths. Longer cranks provide more leverage and are often preferred by taller riders, while shorter cranks are generally more efficient and better suited for riders with shorter legs. There are two main types of bicycle cranks: square taper and external bearing. Square taper cranks are the older of the two designs and feature a square-shaped spindle that fits into a matching hole in the bottom bracket. External bearing cranks, on the other hand, use a separate set of bearings that are mounted outside the bottom bracket shell, which allows for a larger spindle diameter and increased stiffness. In addition to their length and material, bicycle cranks can also vary in their number of chainrings. Single-speed bicycles typically have a single chainring, while road bikes may have two or three chainrings to provide a wider range of gears. Overall, bicycle cranks are an essential component of any bicycle's drivetrain, and play a crucial role in transferring the rider's power to the wheels. By choosing the right length, material, and number of chainrings, riders can optimize their pedaling efficiency and achieve their desired level of performance.

drivetrain, bottom bracket, spindle, chainring, pedaling efficiency

— Mark Nelson

CITATION : "Mark Nelson. 'Bicycle Cranks.' Design+Encyclopedia. https://design-encyclopedia.com/define/bicycle-cranks?E=319740 (Accessed on October 14, 2026)"