Shimano SM-UG51 Quick-link For 6/7/8 Speed Chain - 1 Link

What Is the Shimano SM-UG51 Quick-Link and When Do You Need One?

The SM-UG51 is Shimano's quick-link for 6, 7, and 8-speed chains, providing tool-free installation and easy chain removal without needing a chain tool to push a pin. Sold as a single link, it's the correct chain quick-link for mid-range and entry-level drivetrains running Shimano's UG-series chains in 6, 7, or 8-speed configurations, covering a huge range of city bikes, hybrid bikes, entry-level MTB, and older road builds. The two opposing link plates slide together and lock under chain tension, closing the chain into a complete circuit with no tools required during installation. Shimano's UG-compatible quick-link is designed to match the internal width specification of UG-series chains, which is wider than the narrower HG chains used in 9-speed and above, making speed-specific chain hardware critical for proper link seating and shifting function.

Shimano specifies the SM-UG51 as non-reusable. Once the link has seated and ridden under pedaling load, the locking mechanism should be considered spent and replaced with a new quick-link the next time the chain is removed. The SM-UG51 is compatible with Shimano chains including the CN-HG40, CN-HG71, and other Shimano 6, 7, and 8-speed chains. For anyone building, replacing, or maintaining a 6, 7, or 8-speed Shimano drivetrain who wants a simple, tool-free chain connection with a factory-spec quick-link, the SM-UG51 is the correct part.