There's nothing worse than having your bicycle chain to fall off. Having to go back and handle a dirty chain interferes with enjoying the outdoors and having some fun. Preventing a bicycle chain from falling off its sprockets is as simple as shortening the length of the chain by removing one or more links from the chain's length. It is a simple task to shorten a bicycle chain and takes a few minutes.
Remove the rear wheel of the bicycle to get the chain off the frame. Using the correct sized wrench or adjustable, loosen the two nuts that secure the wheel to the frame. You will only have to loosen the nuts to be able to pull the wheel free from the frame. Once the wheel is removed, separate the chain from the bicycle. Now take the chain to a workbench or flat place to work.
Find the "key" link in the chain. The key link is the one link in the chain that has a top and a bottom that separates to open the chain's continuous loop. Once you have found this link, set the chain on its side to use a tool to separate the top and bottom portions of the key link.
Dislodge the top retaining face of the key link from the bottom two posts of the key link bottom. Using a flathead screwdriver with the thin gauge tip, place the tip of the screwdriver's head at the seam of the link to get entry into the securing grip used to secure the link. Tap the handle of the screwdriver with a hammer or mallet until the point of the screwdriver breaks the grip of the key link and releases the top plate from the bottom posts. You now have a chain that is ready to be shortened.
Remove links from the chain. Always retain the key link so that you will be able to reconnect the chain in a loop. Remove one link at a time to shorten the chain in small increments. Remove two or three links and you will have a much shorter chain than you the one with which you started.
Connect the shortened chain ends by inserting the key link into the links from each end of the length. Slide the key link posts up through the chain ends so that you place the key link top on the key link posts. Use a hammer or mallet to tap the top plate back onto the posts for a secure grip. Replace the chain to the bicycle frame and secure the rear wheel. Test ride the bike to be sure the length is correct and enjoy.
Lightly grease a bicycle chain after maintenance. Allowing a bicycle chain to oxidise and rust will decrease the performance of metals parts that make up the chain. Use quick taps on the hammer when breaking the key link's grip. The link is made to separate, so work it light a tight lid on a pickle jar. Quick taps and then a good pop should get the link to open easily.
A bicycle chain can be damaged if not properly handled during maintenance repairs like removing links. Wear protective eyewear and use the proper tools to avoid bending links that prevent a chain from working properly no matter what the length.