If your bike chain falls off, follow these steps to fix it: 1. Stop pedaling and find a safe spot to pull over.
2. Shift the gears to the smallest chainring and the smallest rear cog.
3. Use your hands to carefully put the chain back onto the chainring.
4. If the chain is twisted or jammed, use a flathead screwdriver or a bike tool to gently pry it loose.
5. Check the chain tension by pulling it up and down. It should have some slack but not be too loose.
6. If necessary, adjust the tension by loosening or tightening the rear derailleur.
7. Test the bike by pedaling slowly to ensure the chain stays in place. Remember, if you're not comfortable fixing your bike chain yourself, it's best to take it to a professional bike mechanic.