A bicycle disc brake is a high-performance braking system. Based on the actuation medium, it can be classified into mechanical disc brakes (cable-actuated) and hydraulic disc brakes (fluid-actuated). Hydraulic systems are further divided into open systems (with reserved space for fluid expansion) and closed systems (with isolated hydraulic circuits). Brake pads are available in different materials, including organic pads (heat-resistant) and metallic pads (wear-resistant), and must be compatible with either mineral oil or DOT-standard brake fluid. Disc brakes are widely used on modern mountain bikes, road bikes, and some urban bicycles. Compared with traditional rim brakes, they offer significant advantages in braking performance, stability, and overall safety.

A wheelset is a core component of a bicycle, consisting of four main parts: spokes, rim, tire, and hub. It supports the bicycle’s weight, transmits riding power, and adapts to various road conditions. Spokes reduce aerodynamic drag through bladed or butted designs. Early rims commonly used 32–36 spoke holes, while modern designs gradually reduce the number of holes to achieve lower weight and improved aerodynamic performance. Tires include inner tubes with Presta or Schrader valves, as well as high-end outer tires reinforced with Kevlar puncture-resistant layers.The evolution of wheelset systems has focused on component optimization. Hubs have transitioned from cup-and-cone designs to cartridge bearing structures to improve rotational smoothness. Spokes now use lightweight materials and drag-reducing cross-sectional profiles. Rims are optimized for different riding conditions by reducing spoke hole counts and refining cross-sectional shapes. Tires continue to evolve through advances in materials and puncture-protection technologies. Rims can be classified into deep-section (aero) rims, which offer strong resistance to longitudinal impacts, and box-section rims, which provide better lateral impact resistance. The cross-section of deep rims leverages aerodynamic principles to reduce air resistance. During assembly, close attention is paid to rim trueness, spoke lacing angles, and balanced spoke tension, ensuring riding stability and efficient power transfer.