Definition:
A bicycle pedal is a component attached to the crank arms of a bicycle drivetrain, serving as the interface between the rider’s foot and the mechanism that transfers human power to the bicycle's rear wheel through the chain and drivetrain system.
Overview:
Bicycle pedals are essential elements of human-powered bicycles, enabling the conversion of rotational force (torque) generated by the rider’s legs into forward motion. They are affixed to the distal ends of the crank arms, which rotate around the bottom bracket. As the pedals are depressed in a circular motion, they drive the chainring, propelling the chain and ultimately turning the rear wheel.
Pedals have evolved significantly since the invention of the modern safety bicycle in the late 19th century. Early designs were simple platforms, while contemporary models include a range of variations tailored for different cycling disciplines, such as road cycling, mountain biking, and commuting.
Etymology/Origin:
The word “pedal” originates from the Latin “pedalis,” meaning “of the foot,” derived from “pes” (genitive “pedis”), meaning “foot.” The term has been used in English since the 17th century, initially referring to foot-operated levers in musical instruments like the organ. Its application to bicycles began in the 19th century with the advent of pedal-driven velocipedes.
Characteristics:
Bicycle pedals typically consist of the following components:
- A spindle or axle that screws into the crank arm.
- A body that houses the spindle bearings and provides a platform for the rider’s foot.
- A threading standard (commonly 9/16" x 20 TPI) on the spindle for attachment, with right-hand threading on the right crank and left-hand threading on the left to prevent loosening due to precession.
- A surface designed for either flat contact (platform pedals) or engagement with specialized cycling shoes (clipless pedals) via a cleat.
Pedals fall into two primary categories:
- Platform Pedals: Provide a flat surface for the rider’s shoe. May include studs or grips for improved retention.
- Clipless Pedals: Use a mechanical cleat system to securely attach the cyclist’s shoe to the pedal, enhancing efficiency and control. Despite the name, they do not involve toe clips; the term “clipless” distinguishes them from older “toe-clip” pedals.
Some pedals are dual-sided, offering a platform on one side and a clipless mechanism on the other, providing versatility for casual and performance riders.
Related Topics:
- Bicycle drivetrain
- Crankset
- Bottom bracket
- Cycling shoes
- Toe clips and straps
- Pedal threads and standards
- Power transfer efficiency in cycling