Rear Sprocket 42T 6.43 BC 520 Chain

The M AND W ALUMINUM PRODUCTS Rear Sprocket 42T 6.43 BC 520 Chain is a precision-engineered aluminum sprocket designed for high-performance micro sprint racing and specialized motorsport applications. This 42-tooth rear sprocket delivers the gear ratio control critical for competitive off-road and sprint racing, where power delivery and acceleration demand exact drivetrain specifications matched to track conditions and engine performance characteristics.

Built from aluminum for minimal rotating mass, the sprocket features a 6.43-inch bolt pattern engineered to interface with standard 520-pitch chain systems—the industry baseline for high-speed, high-torque racing applications. The 42-tooth configuration provides a midrange gear ratio suited to acceleration-focused racing scenarios where driver control and mid-range power matter more than top-end velocity. Natural aluminum finish resists oxidation while maintaining lightweight construction critical for reducing unsprung weight and rotational inertia in competitive powerplant setups.

This sprocket is engineered for micro sprint racers, off-road competitors, and motorsport enthusiasts who demand exact drivetrain matching to their specific engine output and track profile. Whether optimizing for desert racing, short-course competition, or specialty off-road applications, the 42T rear sprocket allows fine-tuned gear selection without changing primary chainring sizes. Weighing only 0.49 pounds, it minimizes parasitic rotating mass while maintaining structural integrity under sustained racing load—essential for maintaining acceleration response and throttle feel across varied terrain and competition conditions.