Your bicycle chain broke. All you need is a new link or two and it will be as good as new. Or maybe you were replacing the entire bike chain and made it too short. You might be wondering if there is a way you can add links to your bicycle chain.
Can you add links to your bicycle chain? Yes, you can add links to a bike chain, but you need to be careful that you have the right tools (Chain Tool/Master Link Pliers) and correct methods.
To check if your chain is undersized, shift onto the largest chainring and the largest cog. All bikes should be able to make this shift, and the derailleur should not appear stretched too tight. If you were to ride your bike like this, you risk jamming, bending and possibly breaking the derailleur.
Why You Need to Add Links to a Bicycle Chain
If you are repairing a broken bike chain or replacing it entirely with a new one, you need to make sure that you don’t end up with a chain that is too short.
Too short of a chain is actually more of a concern than too long. A chain that is too long will result in it drooping and the possibility that your bike won’t be able to shift into all its gears. But when you have a chain that is too short, it can either fall off or damage the derailleur.
The chain may fall off if it is too short because there won’t be enough slack. Drivetrains need some chain slack to operate smoothly and efficiently and provide a margin of error.
As stated, there are two main reasons you may need to add links to your bike chain:
- If your replaced chain is too short
- If you break your chain and need to repair it by adding links
But why do you need to replace your chain, and why would it break?
Why You Need to Replace Your Bicycle Chain
When you replace your chain regularly, you prolong the life of the drivetrain on your bike. Typically, you should replace your chain every 2,000 to 3,000 miles, depending on your riding style.
The easiest way to determine if you need a new chain is with a handy tool called a chain-checker. The chain-checker measures how badly your chain has worn and stretched. (This one is great and what we would recommend)
Also, there’s no stopping gritty grunge from sticking to your chain lubricant. This grime acts as a grinding paste, causing the pins and rollers to wear down. When this happens, the center-to-center distance of your chain increases and your gears may wear out sooner.
Besides fully replacing your chain, you really need to clean it often. It is recommended that you wipe down the chain with a clean cotton rag after every ride. If it becomes too clogged up, use a nylon brush and scrub it with hot water and mild, de-greasing dish soap.
Why You Need to Repair Your Bicycle Chain
Bike chains break for a number of reasons, but the two most common are through wear and from impact.
- Wear – If a chain has been ridden for too long, it will actually stretch out. A worn-out chain will then be longer from link-to-link than a new chain. As it stretches, metal fatigue is more prone to failure. As the chain wears, the chainrings and cassette (rear gears) will wear down, as well. Combine your compromised chain with a bad gear shift, and you can end up with a broken chain.
- Impact – Your chains, just like anything on your bike, can get damaged by a hard impact. This can happen if a rock or other hard object strikes the chain. Unlike with wear that typically damages just one chain link, the impact can damage many links in the chain.
Understanding Your Bicycle Chain
Bicycle chains are made of multiple pairs of steel outer plates and inner plates (or links) held together by rivets. A roller separates each pair of inner plates. The rivet (pin) is pressed tightly through both outer plates. The rivet then pivots freely on the inner plates and roller.
All modern bicycle chains are made to the “one-half inch pitch” standard, meaning from rivet to rivet it’s nominally 0.5 inches. The sprocket teeth are cut for this same one-half inch standard to accept bicycle chains. However, this does not mean all makes and models of chains are interchangeable.
There are two basic types of bicycle chains: “one-speed” chains, and derailleur chains.
The common one-speed chain is designed for bikes with one sprocket on the crankset and second sprocket on the wheel. The width of the roller is nominally 1/8-inch wide (3.3 millimeters). The one-speed chains are not designed to shift on the multiple rear cog sets of derailleur bikes.
There are rear hubs with multiple internally geared speeds, but the chain is still commonly called a one-speed chain. They are also referred to as an eighth-inch chain. The 1/8-inch chain will measure approximately 9 millimeters across the rivet.
Some freestyle bikes use a wider sprocket and a wider 3/16-inch, one-speed chain. The idea is that this wider chain provides longer chain life for the purpose of grinding, which is sliding down a rail or other long fixture on the chain.
Derailleur bike chains are designed to be moved from sprocket to sprocket and come in many different design standards. When selecting a chain, the first consideration is the number of rear sprockets.
The rear cog sets have been made with 5, 6, 7, 8, 9, 10, 11, or 12 sprockets. As the number of cogs on the rear hub increases, the spacing between cogs tends to be reduced. Consequently, chains tend to get narrower as the number of rear cogs increases.
Nominally, derailleur chains are called a 3/32-inch chain. However, that is not a true measurement, as modern derailleur chains can vary from that sizing.
Some nominal widths measured across the rivet between chains are:
- 12-rear cogs – 5.3 millimeters
- 11-rear cogs – 5.5 millimeters
- 10-rear cogs – 6 millimeters
- 9-rear cogs – 6.5 to 7 millimeters
- 8-, 7-, and 6-rear cogs – 7 millimeters
In addition to the chain working on the rear cogs and rear derailleur, the chain must be compatible with the front chainrings. Front cranksets are also designated for varying “speeds” to give an indication of the right width chain to use.
The spacing between front rings for an 8- or 9-speed chainring set will be relatively wide. Using the narrow 10- or 11-speed chain may result in the tendency for it to fall between the two rings during a shift.
Drivetrain manufacturers design their chains to work as a system with the derailleurs, rear sprockets, and shift levers. Chains can vary in side plate shape, sizing, and height. Differences can cause variations in shifting performance between brands and models.
Additionally, chains will vary in the quality of steel used. Better chains that are more durable and longer-lasting tend to have harder rivets. Riding a bike tends to wear and thin the rivet as it is pulled against the inner plates.
If you need a new chain or need to repair your existing chain, it is usually best to stick the drivetrain manufacturer’s chains. It does get more complex when components become mixed.
For example, a bike may have an SRAM® chain but Shimano® derailleurs, or a Sun Race® cassette and MicroShift® shifters. Some chains can be used between different brands, but many can’t, so it’s best to know which chain is you have.
Replacing Your Bicycle Chain
As the driving force of the bike, your chain sees a lot of wear and tear. Over time, distance and cycling conditions, the rivets and rollers begin to wear out, causing the chain links to actually stretch in length.
A brand new chain will measure 12 inches across 12 links, so if you measure your chain and it is 12-1/16 inches across 12 links, then it’s time to replace it. If it is stretched even further, it has most likely damaged your cogs.
There are two main types of chains – master link and connection rivet chains. Master link chains use two removable outer chain links to connect the chain, whereas connection rivet chains use a special rivet to make the connection.
The tools needed to replace your chain will vary depending on which type you have:
- Chain Tool – for cutting the chain
- Master Link Pliers – to disengage chains with master links.
The first thing you’re going to need to know is the necessary length for your new chain. There are a few methods to accomplish this.
Methods to Determine Chain Length
Size to Existing Chain Method
If your old chain was sized correctly, it could be used to determine the length of your new chain. To check if it was the correct size, shift the bike to the smallest sprockets, and check the chain for any slack. There should be no slack in the chain, but the derailleur should not pull back far enough for the chain to make contact with itself.
Next, shift to the largest front and rear sprockets. The chain should easily make this shift and have two slight bends at each pulley.
Once you’ve determined that your old chain was sized correctly, remove the chain and lay it out on a flat hard surface. You can either layout the new chain next to the old one (ensuring that it is lined up link-by-link to eliminate any disparity due to chain wear) or simply count the links on the old chain, and cut the new chain to match the number.
Largest Cog and Largest Chainring Method
The easiest way to determine bike chain length is the largest cog to largest chainring method.
Once the old chain has been removed, shift the front derailleur to the largest chainring, and the rear derailleur to the smallest. Then follow these steps:
- Wrap the new chain around the largest chainring (at the rear), making sure that if the chain has an outer plate, it is routed toward the front chainring.
- Pass the chain through the front derailleur cage and onto the largest front chainring.
- Hold chain at the 5 o’clock position.
- If you are using a master link chain, install half of the master link onto the front end of the chain to account for the extra half link the master link provides.
- Pull the lower section of the chain snug towards the front chainring, bypassing the derailleur altogether.
- Find the closest rivet where the two ends could be joined and add two links. This is your cutting point.
Chain Sizing by Equation
It is possible to determine chain length by using a simple equation. Remember, you can only join the inner plates to the outer plates of a chain, so you can only calculate to whole-inch increments.
This equation below can help you determine chain length: L = 2 (C) + (F/4 + R/4 + 1)
- L = Length – your chain length in inches (rounded to the nearest inch).
- C = Chain stay – the distance between the middle of the crank to the rear axle. Measure to the closest 1/8-inch, and convert this to decimal form.
- F = Front chainring – The number of teeth on the largest (front) chainring. This number is often printed on the sprockets and cogs, but if not you’ll have to count.
- R = Rear cog – The number of teeth on the largest rear cog. Again, this number is usually printed on the sprocket.
Once you have determined the proper chain length, then you will be able to replace your chain or repair your chain. Don’t forget to measure correctly, so you don’t end up with a chain that is too short.
We’ve added lots of chain articles over the years – here’ a few that may be of interest;