I've been having trouble with my bicycle shifting gears. On November 20th I had an accident going up a bridge while standing on the peddles to try to gain speed and the gears shifted and it made me fall. I had to replace the handlebar and handlebar stem, buy a new computer and a new wheel. I could've bought a new bike with all the money I spent replacing those parts.
It didn't occur to me that the reason the bike kept shifting gears while I was riding because it needed some WD-40. I've had bicycles my entire life and not once have I ever had to spray WD-40 on the chain or the gears. So, now I know and I will keep the WD-40 with all my bicycle tools from now on lol.