Bicycle modifications refer to changes made to a bike to enhance its performance, comfort, or appearance. Common modifications include upgrading components like the saddle, handlebars, or tires to improve riding experience. Some cyclists also add accessories such as lights, fenders, or baskets for practicality and safety. Another popular modification is adjusting the bike's gearing system, which can make it easier to ride on different terrains. Custom paint jobs or decals can personalize a bike's look. Overall, modifications allow cyclists to tailor their bikes to better suit their individual needs and preferences.