A 20-inch bicycle is a type of bike designed primarily for children and some adults. The measurement refers to the diameter of the wheels, which are smaller than those found on standard adult bicycles. This size makes it easier for younger riders to handle and control the bike, promoting safety and confidence while learning to ride. These bicycles often come with features like adjustable seats and lightweight frames, making them suitable for growing children. Popular brands that manufacture 20-inch bicycles include Trek, Schwinn, and Diamondback. They are commonly used for recreational riding, neighborhood cruising, and learning basic cycling skills.