Tools you will need:
- Chain tool or chain breaker
- New chain
- Pliers (optional)
- Replacement quick link (optional)
Step 1: Remove the old chain If the old chain is still on the bike, shift the chain to the smallest chainring and the smallest rear cog. This will create slack in the chain and make it easier to remove. Use a chain tool or chain breaker to push out one of the chain pins, then remove the chain from the bike.
Step 2: Determine the length of the new chain Lay the old chain on a flat surface and measure its length from one end to the other. Alternatively, you can count the number of links in the old chain and use that number to determine the length of the new chain.
Step 3: Size the new chain Using your chain tool or chain breaker, remove any excess links from the new chain to match the length of the old chain. Be sure to size the chain correctly or it may cause shifting issues or damage the drivetrain.
Step 4: Install the new chain Thread the new chain through the rear derailleur and over the smallest rear cog. Thread the chain through the front derailleur and onto the smallest chainring. Use the chain tool or chain breaker to push in a new chain pin or install a replacement quick link to join the ends of the new chain.
Step 5: Check the chain length Shift the chain to the largest chainring and the largest rear cog. Check the tension of the chain by pulling it up and down at the midpoint of the chain. There should be a small amount of slack in the chain, but not enough to touch the ground or derailleur pulleys.
Step 6: Test the new chain Take the bike for a short test ride to ensure that the new chain is shifting properly and the drivetrain is functioning smoothly.
That's it! You have successfully replaced a damaged chain on a bicycle.