The park tool bbt 18 bottom bracket is a heavy duty investment cast tool for installing and removing the following eight notch bottom bracket cups shimano octalink right cup with external notches and isis drive the bbt 18 has 8 notches with an outside diameter of nominally 434mm the inside to inside width is approximately 38mm each notch is approximately 39mm wide the hole in the center of the casting is 225mm and will not fit over the 30mm spindles