Park Tool BBT-9 Bottom Bracket ToolThe Park Tool BBT 9 Bottom Bracket Tool is used to remove and install external bearing crankset bottom brackets. One end of the BBT 9 securely engages the 16 notches of the bottom bracket cups. The other end of the tool engages the 8 internal splines of the crank arm adjustment cap. The BBT 9 fits cups and lockrings with 16 external notches and an outside diameter of approximately 44mm. Details The BBT 9 works with many external bearing crankset