Yes, Shimano components can be used on a custom-built bike, and they are quite popular among cycling enthusiasts for this purpose. Shimano offers a wide range of components, including groupsets, derailleurs, shifters, brakes, and wheels, designed to fit various bike styles such as road, mountain, and hybrid bikes. When selecting Shimano parts for a custom build, it is essential to ensure compatibility among the components, as Shimano designs their products for specific standards, such as bottom bracket types and hub spacing. Additionally, you should consider the bike frame, wheel size, and intended use of the bike to select the appropriate components. Many riders appreciate the reliability and performance of Shimano products, making them an excellent choice for a custom project. For detailed specifications and compatibility information, visiting the Shimano website could be helpful.