A bike's crank replacement must be properly maintained to keep your bike operational. These are the arms connected to the Bottom Bracket (consisting of axle, bearings, etc.) via the axle(usually square on the ends). If you need to change your cranks, you can do so as long as you have the proper tools. First, you’ll need to detach the pedals from the crank. Then, you’ll need to use an Allen key to remove the center bolt from the crank before replacing it. You can use this process to replace Shimano two-piece, SRAM self-extracting two-piece, and three-piece cranks.