The Complete Handbook of Cycling

Chapter 1: Understanding Cycling

Cycling is the act of riding a bicycle, and a bicycle is a human-powered vehicle with two wheels, a frame, pedals connected to a drivetrain, and brakes. That mechanical definition is correct but incomplete. To understand cycling as a category—and as a business or professional discipline—you need to understand what bicycles actually do, how they work, why they matter beyond casual recreation, and what the cycling industry looks like in practice.

How Bicycles Work

A bicycle converts human leg power into forward motion through a straightforward mechanical chain: the rider's legs push the pedals, which are attached to a crank arm. The crank arm rotates a chainring (a toothed ring), and that chainring drives a chain. The chain pulls teeth on one or more sprockets attached to the rear wheel hub, which causes the wheel to spin. Brakes—either rim brakes or disc brakes—use friction to slow or stop the wheel rotation. The frame, handlebars, and seat position allow the rider to steer, balance, and transfer power efficiently.

This chain of power transfer has several key features. First, it is geared—the ratio of chainring teeth to sprocket teeth determines how many times the wheel rotates per pedal rotation. A low gear ratio (small chainring, large sprocket) requires less leg force per rotation but covers less distance; a high gear ratio (large chainring, small sprocket) requires more force but covers more distance per pedal stroke. Most modern bikes have multiple chainrings and multiple sprockets, allowing the rider