A cyclo-cross bike is a type of bicycle designed for cyclo-cross racing, which involves riding on a mix of surfaces such as dirt, grass, and paved roads. It has a lightweight frame and thin tires, similar to a road bike, but with more grip to provide better hold on rough terrain. Cyclo-cross bikes also have a more upright riding position and are built with strong brakes to handle sudden stops or changes in speed. They are designed to be durable and versatile, allowing riders to handle both smooth and bumpy paths during races or training.