I don't have any specific knowledge about this, but one of the things I do when buying bicycles second hand is lift them up and give them a good shake. Any nois

I don't have any specific knowledge about this, but one of the things I do when buying bicycles second hand is lift them up and give them a good shake. Any noise should be easy to attribute and once addressed, it should be quiet. This helps discover weak joints between components. I also visually inspect the frame – especially on the underside and around the bottom bracket and head tube, and look for any deformations or cracks. I have always wanted to try to apply bending forces to the frame and listen for creaking, but I haven't figured out a good technique to do so with a stationary bicycle. The best I can achieve is a test ride where I try things like accelerating hard on a high gear, doing little front-wheel hops, etc.