Renthal TwinRing Rear Sprocket 51T Black 1540-520-51GPBK

If you're running a 520 chain setup, sprocket wear directly impacts your acceleration response and chain longevity. The Renthal TwinRing 51T delivers the durability of a steel sprocket with the weight savings of aluminum—a combination that standard designs simply can't match. By pairing a 7075 T-6 aluminum core with a nickel-coated steel outer ring, this sprocket outlasts conventional all-aluminum alternatives by three times while staying significantly lighter than all-steel options.

The dual-ring construction uses thermal expansion bonding at 200°C to create a permanent, flex-free interface that won't separate under the demands of aggressive riding or racing. Flat socket head screws reinforce the assembly against side-load impacts, while strategically placed mud grooves between each tooth prevent dirt accumulation—keeping your engagement clean and your wear predictable across long sessions.

• Tooth Count: 51T
• Chain Size: 520
• Inner Ring: 7075 T-6 aluminum
• Outer Ring: Nickel-coated steel
• Bonding Method: Thermal expansion
• Design Feature: Self-cleaning mud grooves
• Fastener Type: Flat socket head
• Lifespan: 3x standard aluminum
• Color: Black
• Part Number: 1540-520-51GPBK