How do I perform a bicycle crank bearings replacement?

To perform a bicycle crank bearings replacement, you will need to first remove the crank arms using a crank puller tool. Once the crank arms are off, you can access the bearings inside the bottom bracket. Remove the old bearings and clean the area thoroughly. Install the new bearings, making sure they are properly seated. Reattach the crank arms and tighten them securely. Finally, test the bike to ensure the bearings are functioning smoothly.