Renthal 179U-520-42P-HA Ultralight Rear Sprocket 42T 520 Chain Hard Anodized Aluminum

The Renthal 179U-520-42P-HA is an Ultralight rear sprocket engineered for road and road racing applications. Designed for use with a 520 chain pitch and featuring 42 teeth, this sprocket delivers a winning combination of lightweight performance and exceptional durability demanded by serious riders.

Renthal's Ultralight rear sprockets are CNC-machined to extremely tight tolerances from high-strength 7075-T6 aluminum alloy, making them up to 66% lighter than comparable steel sprockets without sacrificing strength or longevity. The computer-aided Ultralight design maximizes the reduction of unsprung weight at the rear wheel, translating directly into improved power transfer and throttle response.

The hard anodized surface finish is an integral surface coating specifically developed for road and road racing use. This process significantly increases the hardness and wear resistance of the sprocket surface, extending service life well beyond standard anodized or bare aluminum alternatives. A specially engineered tooth profile allows the chain to seat and release smoothly, reducing noise and wear on both the sprocket and chain.

Key Features:

• 42-tooth rear sprocket for 520 chain pitch
• CNC-machined (not stamped) from 7075-T6 aluminum alloy
• Up to 66% lighter than steel for maximum unsprung weight reduction
• Hard anodized surface finish for increased hardness and wear resistance
• Computer-aided Ultralight design for optimized tooth profile and load dispersion
• Precision manufactured to extremely tight tolerances for concentricity and accurate fitment
• Sold individually — includes one (1) rear sprocket

Renthal Ultralight rear sprockets are trusted by factory race teams worldwide and are a proven upgrade for street, track, and road racing builds where every gram of rotating mass matters.