Shimano BB-RS501 Hollowtech II English Bottom Bracket It's Threaded Whether you're building up a fresh bike or replacing a worn-out bottom bracket, you'll want something that is high quality. The Shimano BB-RS501 Hollowtech II English Bottom Bracket features an enhanced seal construction to provide long-lasting performance and service life. This is designed for a perfect fit with Hollowtech II 24mm crank spindles and English-thread bottom bracket frames. Features Anodized aluminum cups are high-strength and lightweight Designed for a perfect fit with Hollowtech II 24mm crank spindles For use with English-thread bottom bracket frames Shimano part number: EBBRS501BWeight: 93g | Shimano | Bb-Rs501 Hollowtech Ii English Bottom Bracket English Bottom Bracket