Rotor BSA Bearing:

Description of Rotor BB1 Road Ceramic Bottom Bracket Cups BSA-68-24.
Rotor BB1 bottom bracket equipped with ceramic bearings and advanced non-contact labyrinth seals that give buttery-smooth spinning with unparalleled protection against dust, water and mud. New plastic caps offer significantly improved lateral compression and deformation resistance, facilitating crisp shifting. Elegant new cup design guarantees a sleek modern look combining striking angles with smooth curves.

Compatible with all conventional Rotor cranks, Shimano and Shimano compatible cranks with 24mm integrated axle.

This is the lightest and smoothest bearing.