Shimano BB-RS500-PB Tiagra / Sora Hollow Tech II Bottom Bracket Press Fit For Road. Hollowtech II is using 24 mm axle and bearings. Shimano made the decision to adopt the 24 mm diameter axle and bearings to provide the best balance of rotating performance / stiffness / strength / sealing / weight in Shimano Quality.

Shimano Hollowtech II is a crank bottom bracket system designed to achieve an ideal ratio of stiffness, weight, and rotational efficiency. It is based on an integration of the bottom bracket and the right crank arm and works with a 24 mm axle or bearing diameter, which has proven to be optimal in terms of stability. In many cases, the bearing cups are on the outside so that the load is better distributed. High-quality precision seals ensure long service life.

Features :

-Tiagra-level BB86 press-fit Hollowtech II bottom bracket

-Compatible with all road Hollowtech II cranks