A bottle boss is a threaded mounting point found on bicycle frames, typically beneath the downtube, designed for attaching accessories like water bottle cages. These small fixtures offer a convenient way to carry hydration and other essentials without requiring specialized bags or racks. A typical cage, secured by bolts to these bosses, can support a standard water bottle.
The load-bearing capacity of these mounting points is a critical factor for cyclists. While designed primarily for water bottles, riders often utilize them for heavier items like tools, pumps, and even small bags. Understanding the limits of these fixtures is essential to prevent damage to the frame or the loss of carried items. Historically, their primary function was hydration, but their versatility has led to increased usage for carrying other equipment, pushing the boundaries of their intended design.