Aluminum alloy construction Crafted from aluminum alloy, this bottom bracket delivers longlasting performance and durability, making it a reliable choice for your bike. Compatible with multiple models Designed to fit BSA, BB68/73, BB51, BB52, and BB70 shells, providing versatility for various bike setups. Nylon seals for protection Equipped with nylon seals outside the bearing, this design helps keep dirt and moisture out, enhancing the longevity of your components. Lightweight design Weighing approximately 99 g, this bottom bracket minimizes added weight to your bike without compromising strength or stability. Use scenarios Replacing a worn bottom bracket on a bike with BSA, BB68/73, BB51, BB52, or BB70 shells to restore smooth pedaling and reliability. Building a lightweight, durable drivetrain for a road or cross bike that requires a lowweight component without sacrificing strength. Upgrading a bike that operates in damp or dirty conditions by relying on nylon seals to protect the bearing from contaminants and extend service life.