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A bicycle chain is simply a roller chain that transfers the power you put into your pedals to the wheel of your bike. The harder you pedal, the faster your bike goes. Of course, that’s an oversimplification but that is essentially the role your bike chain plays in how the bike functions.

History Of Bike Chains

Bicycles actually precede bike chains. We’ve all seen those goofy looking bikes where the front wheel is ridiculously huge. That was because the pedals were attached directly to the wheel. This meant that the larger the wheel was, the faster the top speed of the bike was. Today we have bike gears and what’s known as chain-drive.

Obsolete bike chains include a block chain, slip-link chain, and the Simpson lever chain. They were all discarded due to lack of efficiency, power, etc. The modern bike chain is known as the conventional industrial bushing chain. The system consists of a single chain paired with a rear wheel sprocket.

Furthermore, today’s bike chains boast an efficiency of 98.6% maximum. Researchers found that while lubrication did not have an impact on efficiency, a tenser chain and larger sprocket had positive impacts.

Length And Width Of Chains

The next thing you need to know about your bike chain is the width and length because they both play a major part in how your bike functions. The length of a bike chain usually comes in a stock size and needs to be fitted by removing links. The chain has to be just the right length in order to shift from one gear to another without jamming or falling off. Fitting a chain to a bike is usually done by an expert.

Likewise, the width of the chain is equally important. The width of a chain usually determines what sort of bike it can function with. A chain that is 3/32” wide is common on bikes with derailleurs which are mountain bikes, racing bikes, and touring bikes. A chain that is ⅛” wide are commonly paired with a single rear sprocket and are seen on track bicycles (BMX).

Wear And Tear

The simplest sign of a worn out chain is something called chain stretching. It can be checked easily with a chain checker tool. Also, the life of your chain is directly related to how much dirt and debris is lodged in the chain links. Keeping the bike chain clean and well lubricated will give your chain a longer lifespan.

Be nice your you chain and keep it clean!
"There is no glory in Practice.. But without Practice there is no glory"
A Clean Chain is a Happy Chain Smile

The chain and drivetrain are typically the dirtiest parts of your bike, and this dirt spells bad news for bike longevity and performance. Specifically:

The rate of chain wear.
The flexibility of individual chain links.
Wear and tear on derailleur assemblies and drivetrain cogs.
Impaired shifting performance.

Basic knowledge you need to keep a clean-running machine.
When to Clean and Lube
Regular, On-Bike Cleanings

Before each ride, look at the entire chain by standing to the side of your bike and lifting the rear wheel off the ground. Use your free hand to slowly rotate the closest pedal, inspecting individual chain links for dirt buildup, rust and/or tight links (links that do not bend easily as they pass through the rear derailleur). Check for adequate lubrication by listening for squeaks while riding. If you find either condition, your chain needs at least a spot-cleaning.

To spot-clean the chain while it's still on your bike:

Brush out the links with a firm brush (an old toothbrush can also work well).
Relubricate the links from time to time with a chain lubricant.
Wipe off excess lubricant with a clean, dry rag. Over-lubricating can actually attract new dirt.

For a more thorough cleaning, use a chain-cleaning tool. Attach it to your chain for a quick, deep cleaning.
Occasional Off-Bike Cleanings

Every few months or so (more often for mountain bikes), completely remove your chain using a chain-removal tool. Brush it well and completely immerse it in a chain solvent to get rid of built-up grime that brushing can't remove. Let the chain soak until most of the dirt has been freed from the links and bushings. Dry the entire chain using a clean rag. Make sure that the solvent has completely evaporated, then relubricate the chain and re-install.

A Word on Lubricants


There are 2 key properties to any chain lubricant. They must:

Minimize the accumulation of dirt, because dirt accelerates wear.
Be durable, because lack of lubricant also increases chain wear.

Durability is the lesser issue as you can and should lube your chain often. Oils that are specifically marketed as bicycle-chain lubricants are superior to non-bicycle-specific products. They generally contain Teflon® and are designed to repel dirt and water.

Note: Always use a cleaner and lubricant designed for bike drivetrains. I would not recommend using WD-40 on your bike chain as it is a cleaner but not a lubricant.

Problems to Watch for When Cleaning

Tight Links

Chain links that don't bend smoothly as they pass through the curves of the chain path may contain tight links. To spot them, pedal your chain slowly backwards and watch as individual links pass through the tight turns of your rear derailleur.

Most tight links are caused by dirt or corrosion between link plates and can be fixed with a good cleaning, some lubrication and a little flexing back and forth. Others are the result of improper pin installation (the pin that holds the chain links together is not fully inserted through the links and rollers) or serious chain damage. Occasionally, poorly installed link pins can be worked back into position by shifting them back and forth inside their chain plates by using either a chain tool or your hands. Damaged chains should be completely replaced.

Chain Stretch

Chain wear indicator tool

As chains wear, they become longer. This is called stretch, which is a misnomer because nothing actually stretches. Chains lengthen as wear occurs between the rollers and the link pins. This creates slop or free play that leads to gear "skipping" in some cases. It also causes extra wear and tear on your chain rings and rear cog teeth.

It's much cheaper to replace a chain than it is a cog set. To check for chain wear, use a wear-indicator tool such as the one above. When the prong no longer fits into the chain gap as in pic 2, the chain has lengthened and should be replaced.
Last update on March 1, 10:43 am by Les Stoner.
"There is no glory in Practice.. But without Practice there is no glory"
Take the Old Chain Off for a good Clean or to Replace it

Taking the old chain off of the bike is the first task that requires a chain tool.

Before you get started make a mental note of how the chain runs thru the Derailer if this is the first time you've changes a chain. You need to get it back that way when installing the new one.

Here's how to use the chain tool. Position the chain across the slotted jaws of the chain tool such that one of the chain pins aligns with the slot. Then screw the pin extractor till the mandrel comes in contact with the chain pin. Make sure everything is aligned perfectly, and then start turning the handle pushing the pin out.

Don't push the pin all the way out. If you do, it's very tricky to get it back in. Always stop when the pin is hanging out of the side plate opposite the mandrel. How do you know when to stop? Well go slow, and remember the pin is as wide as the chain, so almost that width will be hanging out when it's far enough. Also, there will be a slight increase in resistance when you are "far enough". This resistance is caused by the ends of the pin being ever so slightly fatter than the middle, and this fat part has to squeeze thru the side plate.

Periodically stop before you push the pin all the way out and see if you can pull the chain apart yet. (It's ok if the pin extends a bit on the inside of the plate, because slightly bending the chain from side to side will overcome this). Removing the OLD chain from the bike is the proper time to experiment with this, not on the NEW chain. After a couple tries it becomes second nature.

You should end up with something like this.

As you finally break the chain, if this is the first time you changed a chain WATCH the Derailer. It will swing back. Carefully note how the chain was routed through it. It looks different in this swung back mode. You have to route it the same upon re-assembly.
Last update on March 1, 11:15 am by Les Stoner.
"There is no glory in Practice.. But without Practice there is no glory"
Put the New/Clean Chain back On

Since the chain passes through the frame's rear triangle, you can't just assemble the chain and then put it on the bike.

I find it's easiest to do this with the bike on a Cicle Stand or if you don't have one laying your cycle on its left side, chain side up.

Note: if your Derailer pulleys are excessively worn now is an excellent time to replace them. Get a new set from your local bike store (you need to tell them the name and model number of your Derailer). You may need an Allen wrench to unscrew the bolts that hold them in.

It's easiest to do this is string the (as yet un-joined) ends thru both detailers, in roughly the normal path of the chain. But first run the front Derailer all the way in (over the smallest chain ring) and shift the rear Derailer over the smallest cluster gear.

This way, you will have the maximum slack to work with instead of having to fight the spring tension of the rear Derailer.

String the chain through the front Derailer from the rear, and to the side of the smallest chain ring (missing both chainrings altogether, just lay it on the bottom bracket next to the chainrings). Let enough hang down to get half way to the rear Derailer.

String the other end of the chain over the rear side of the smallest cog, in FRONT of the upper Derailer pulley, (remember you have to pull the Derailer arm (some times called a Derailer cage) down to its normal position against its spring). Then down to and BEHIND the lower pulley and toward the other end of the chain. (See red-line at right)

Watch out for metal tabs on some models of Derailer arm. Don't loop over these tabs, go behind them, between the left and right arm-members.

Now you are ready to join the two chain ends together. Carefully push the narrow end of the chain between the side plates of the other end. Align it so that the pin is in line with the hole in the link.

Use your chain tool to drive the pin back in, as shown here. If you are careful when stringing the chain back on the bike, the pin will be pointing away from the bike, making it somewhat easier to use the chain tool. It's no big deal, though, and you can have the pin pointing either way by simply turning the chain over before you string it.

Push the pin in till it is flush with the other side, and no further. Remove the chain tool.

You will find the chain is stiff at this link. That's because the side plates are pushed tightly together by the chain tool. Flex the chain by bending it with your hands.

Bend it up and down (they way it was designed to bend) and also left and right, (the way it wasn't meant to bend). This will free up the side plates so that the chain will flex a bit easier. Sometimes a small regular screw driver blade can be inserted between the outer side plates and twisted just slightly to push the plates apart giving smooth chain movement.

Now put your chain on the front chainring, and crank it around a few times slowly. Watch for kinks going thru the rear Derailer. If the Derailer jumps or twitches, it's a sign that the link you joined is still stiff.
Last update on March 1, 11:20 am by Les Stoner.
"There is no glory in Practice.. But without Practice there is no glory"
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