All bicycle chains will wear out over time. The way you treat your chain can lengthen, or shorten its life. It is not a big deal if you end up having to replace your chain, but there are many things you can do with simple bicycle chain maintenance steps that will help it last longer. Even if you spend more than $100 for a high-end chain, you will still need to perform some maintenance to keep it in good condition.
Taking care of your bicycle chain is not only healthy for the chain, but for the other components of the drive train. Your chainrings and the cogs on your freewheel will last longer with a well maintained and clean chain. As a chain "stretches" it will begin to wear these parts to the point that they will need to be replaced. Replacing a cassette or chainring is several times more expensive than replacing a chain.
Bicycle Chain Maintenance: Chain Cleaning
There are many different methods for cleaning a bicycle chain. They all involve some kind of solvent. It can be something as gentle as a biodegradable degreaser like Simple Green, or as explosive as gasoline. The thing you are looking for in a cleaning solvent is that it will break down the grease and clean out the sand and grime that gets between the links and rollers of a chain.
You can clean the chain on or off the bike. For routine cleaning you can probably get the chain sufficiently clean with a cleaning solution and a brush while the chain is on the bike. For a more thorough cleaning in which you want to let the chain sit in the solution, you can use a chain tool and open one of the links to pull the chain completely off. If you need the chain to soak in a solvent, but cant remove a link you can remove the chain from the dÃ©railleur guide rollers and allow part of the chain to sit in the solution while the rest is still attached to the bike. Rotate the bicycle chain around so it can all have its turn in the cleaning solvent.
Scrub the chain with a stiff nylon bristled brush. For more intricate cleaning you can use a toothbrush. It is important to also clean the chainrings, dÃ©railleurs and freewheel or cassette. If you don't your cleaning will be less effective.
There are specialty chain cleaner machines you can get that will scrub the chain for you. For the bulk of the cleaning task these work well. More detailed cleaning may need a little time with the toothbrush.
Bicycle Chain Maintenance: Chain "Stretch"
Bicycle chains don't actually stretch, but they do get longer. Huh? None of the inner and outer plates that make up the link get any longer. Yet the way that the rollers and bushings wear down cause the parts to be more sloppy. Each one of these connections now allow the next link to be a little longer. When you measure a new and a used bicycle chain you will see that the used one is longer, though it didn't really stretch. The worn bike chain wore out the metal that held it together. Therefore all the connections a bit thinner making the chain appear as if it stretched.
The way to measure and see if your chain needs to be replaced is fairly simple. Measure your chain with an accurate ruler for 12 complete links (or 24 rivets). A good chain will be no more than 1/16 of an inch longer than 12 inches. If a chain is between 1/6 and 1/8 of an inch longer than 12 inches, it definitely needs to be replaced and the chainring and freewheel need to be inspected for possible replacement. Otherwise you will be buying new chains but wearing them out quickly while wearing out your drive train faster than if you had left the old chain on there. If the chain is more than 1/8 of an inch longer than 12 inches for 12 links, then your chainring and freewheel more than likely need to be replaced.
You can check to see if your drive train parts are also chewed away to a point of needing to be replaced. If the teeth of these parts are pointy and look like shark's fins then they are badly worn. There should be a flat spot at the top of the teeth. Place the new chain on chainring or cog in question. Does it sit flat around the chainring into the valleys? When pressure is applied as if you were riding the bike, does the new chain pull only on the top side of the chainring and get forced out of the valleys on the bottom side? If so you are at a point where a new chain will eat away the metal faster than normal. It is time to look at replacing expensive parts.
Bicycle Chain Maintenance: Chain Replacement or Re-installation
If you are re-installing a chain, or have finished cleaning it and determined that it does not need to be replaced, make sure that all the links move freely. Inspect to see that there are no damaged links. Sometimes link pins can be sheared off. This causes a weak link that needs to be replaced or the chain will snap when enough pressure is applied. Usually this happens when you are pouring on the power trying to get away from a car coming at you. It is better to find the weak links while cleaning the chain, than when you are in the middle of an intersection with a car coming your way.
If a new chain has been installed you can skip the lubrication step that comes up next. New chains are sold with a factory lubrication. This is usually a grease based lube and will last longer than other lubricants.
Bicycle Chain Maintenance: Chain Lubrication
After the chain has been washed and reinstalled (if necessary), it is time to lubricate it. There are special lubrications you can buy. Check with your local bike shop as to which one they recommend. If you live in an area that does not get a lot of rain, you might find a dry chain lube is ideal. However, these don't work as well during wet winter months. If it rains quite a bit where you live, you will need something a bit more durable. There are chain oils that can protect your chain from the rain better. However, these lubricants are messier and more likely to pick up sand which is damaging to a chain.
It is recommended that whatever lube you choose that you lubricate the inside of the chain. This means that when you are looking at the chain there are two long length going from front to back. Lubricate the bottom of the two chain sections from the top. This will put the majority of the lubricant closest to chainring teeth instead of outside to the dirt. After about 15 minutes of sitting, wipe the chain dry with a clean cloth. This is enough time to allow the lube to soak into the chain as much as it is going to. Then you are wiping the excess that would normally end up on your leg or pants.
It is a shame to see people replace bicycle chains when they don't need it. However, don't do more damage to your bike by leaving a dirty, un-lubricated chain on it that will wear out and destroy more expensive parts.