How to Fix a Slipped Bicycle Chain?

Slipped bike chains may be caused by several different problems including poor shifting technique, the chain being too long, or a worn out chain or rear casters.

Step 1

• Before getting off the bike, downshift bike into lowest front gear (using the left shifter).

• Being in the lowest front gear means the chain will be riding on the largest chain ring.

• Continue pedaling. This step alone may realign the chain.

Step 2

• If Step 1 did not work, get off the bike and lift the rear tire while spinning the pedals with your hand.

Step 3

• If Step 2 is not enough, push rear derailleur forward to release tension on the chain.

• Lift the chain and put it back on the chain ring.

• Turn the pedals with your hand while lifting the rear wheel to realign the chain (as in Step 2).

• Bike chains are very greasy and your hands will get messy. Use a pair of latex gloves, if available, or use a twig or leaf if you can.

• This step may take several attempts, but it will work eventually.

Step 4

• If you experience a lot of slipped chains, your chain might be too long. In this case, you will need to use a chain breaker.

• Put the chain on the outer chain guide of the chain breaker.

• Turn the handle on the chain breaker to push the chain pin part of the way out.

• This step may take quite a bit of force so don't be afraid that you are going to break something if the pin seems stuck.

• Do not push the pin all of the way out or else it will be nearly impossible to put back together.

Step 5

• Remove the chain breaker by backing up the drive pin.

• Pull the chain apart.

Step 6

• Repeat Steps 4-5 to remove a link:

• There are two parts to one link (one is narrow and one is wide). Both need to be removed for the chain to fit back together again.

Step 7

• If the chain fell off the rear derailleur, it needs to be re-fed through the proper pulleys.

• Feed the chain along the guide pulley (the highest of the two pulleys).

• Thread the chain inside the derailleur cage in between the tension and guide pulley.

• Thread the chain in front of the tab.

• Then, thread the chain over the tension pulley.

Step 8

• To rejoin the chain, align the open ends of the chain.

• Put the chain on the outer guide of the chain breaker with the pin facing the driving pin.

• Turn the driving pin until the pin is equally spaced in between the face plates like all of the other links.

Step 9​

• Wiggle the link you just reattached. If it's too stiff, continue on to the next part.

• Put the chain on the inside guide of the chain breaker and turn the driving pin just a little. Check as you go along and continue until proper looseness is achieved.

• As before, do not push the pin all the way out.