Cross threading a bottom bracket is easily the dumbest thing I’ve done. I had the bike turned upside down and was replacing the original loose ball bottom bracket on a Trek 930 with a Shimano cartridge. With the bike upside down, I must have gotten confused about the threading direction. Then I screwed the plastic piece in first, cross-threading it. Of course, I didn’t notice any resistance when I screwed in the plastic piece, because it’s plastic, and I was using a 12″ Crescent wrench. Only when I tried to screw in the spindle piece of the cartridge on the opposite side and it wouldn’t engage did I realize what I had done. Thankfully I was able to back the plastic bit out, destroying it but not the frame’s threads in the process.
