High quality hybrid ceramic bearings with specially designed cups to allow for the smoothest and longest lasting bottom brackets BB30-24: Fits all 24mm spindles on a BB30 frame & includes step-down 2-piece non-driveside reducer for use on GXP spindles. See included instructions for spacer & reducer configurations (alloy cups) Choose (Road) for low friction designed for Road use, or (Cross) for weather resistant seals designed for MTB, Cyclocross, or Commuting use Choose (Road) for low friction designed for Road use, or (Cross) for weather resistant seals designed for MTB, Cyclocross, or Commuting use