My daughter's new-ish bike started making grinding sounds and pedaling rough. I took it apart and the bearings in the pedal system were shot. Really rough shape. My wife was going to take it to the bike shop and see if it was an inexpensive repair.
I saw a junk bike in the trash on my way home from work. Snagged it, took it home, took it apart, and was happy to find that the bearings LOOKED the same. So I used them as replacement parts... and they fit! Bike seems fine now. I was happy, as I am not mechanically inclined. I probably only saved $20 in the grand scheme of life, but I was able to take something out of the trash and use it to fix something at home. The rest of the bike will probably go to the scrap
yard this summer with the next load, so it will stay out of the landfill too!
I don't know if there is an underlying problem that will make the new bearings wear out... but I can cross that bridge another day. It was a new bike, so it seemed odd that they wore out like they did.
Note: the good bike and the donor bikes were different brands, styles, and sizes from each other, yet seemed to have the same bearings. I love it when things are simple-ish and parts are redundant. Makes home repairs much more do-able.