New Bicycle Bike Crank Extractor Bottom Bracket Removal Tool Set Kit For Shimano This tool is used to remove SQUARE type crank arms, all you need is either a 5/8 or 16mm spanner or just an adjustable spanner. This tool is incredibly simple to use and requires no rocket science. 1 Remove the bolt in the crank arm . 2 Screw the lower black part of the tool into the crank till tight . 3 Screw in and continue to tighten the silver piece of the tool until the crank starts to move.