Anyone who has already changed a chain on a mountain bike has probably had the thought: can’t it be made more durable? Like they were on Soviet bicycles. And indeed, at first glance, the chain on them showed no wear, and on an MTB it lasts for a year (those who rarely ride, of course use it longer). In this article we will tell you why this is the case, as well as how to determine chain wear, how to change it and how to choose a new one.
Firstly, why do bicycles use a chain?, and not a belt or cardan drive? It is generally used (see picture), there are even more unusual solutions, but this is not the topic of this article. The disadvantages of a chain drive are obvious: fairly rapid wear and the need for frequent maintenance. But the chain is used because it is a fairly strong and rigid type of drive with low mechanical losses. And most importantly, it’s quite simple to organize gear shifting.
Why did the chain last longer on Soviet bicycles? Most Soviet bicycles were single-speed, and the chain was always in a parallel plane with the sprockets. And the greater the bend of the chain relative to the parallel, the greater its wear. On a mountain bike, for each of the chainrings of the system there are from 3 to 5 cassette chainrings! The system usually has 2 or 3 stars, and the cassette has up to 10 stars, so distortions are inevitable.
But there were also Soviet bicycles with speeds and the chains on them lasted longer. Why did this happen? Do you remember how they switched gears? To shift, you had to move the chain a little further than the sprocket, and then move it back. And how it switches now - there is a click and the chain is clearly in the right place, not to mention the possibility of resetting 3-4 speeds at once (of course, with the correct one). For such precise operation of modern index switches, the height of the teeth of the stars had to be sacrificed. On Soviet ones they were the same height as the chain links, but on mountain bikes they barely reach the middle. Hence the maximum stretch (to which we will return below) of the chain, at which it begins to slip over the teeth of the sprockets: for Soviet bicycles it is 6-8 mm per 24 links, and for MTB starting from 3 mm it is no longer possible to ride.
Modern chains are stronger and more reliable, but due to all of the above, as well as the dirt in which mountain bike chains sometimes have to work, their service life is lower than that of Soviet bicycles.
What is a modern chain? This is a single-row roller chain with a pitch of 12.7 mm, each link consists of two plates, the links are connected to each other by pins with a roller (see picture). Depending on the number of stars in the cassette, the chain can be of different widths. Accordingly, when the question arises about replacing the chain, you need to choose a chain for the cassette installed on the mountain bike. The most famous chain manufacturers are SRAM and KMC. They are all interchangeable, i.e. if the bike, for example, has a Shimano cassette, then it is not necessary to install a chain from the same manufacturer. You just need, as already mentioned, for a cassette with 7-8 stars, take a chain for 8 gears, for a cassette with 9 stars - a chain for 9 gears and for 10 - 10. As for the quality of chains, each manufacturer has chains of both high, and low level. But according to rough estimates, among the chains of the low and medium price range, the best are Sram, and the worst are KMC, high-level chains from all manufacturers of excellent quality.
To make it easier for you select a new chain, we present chain markings (for 2011) each of the mentioned manufacturers. For each company and for each cassette, the listing goes from simpler to more advanced. In almost all companies, the quality of the chain is included in the last 2 digits in the name: the higher this number, the better the chain (and, accordingly, more expensive). KMC chains also have color differences: the lower and middle levels are gray and silver, and the high (X series) are gold (except for the X8 chain for 8 gears).
Shimano chains
for 7-8 gears: CN-HG40, CN-HG50, CN-IG70, CN-HG70, CN-HG91
(there are also chains of the CN-UG** series - but they are of very low quality)
for 9 gears: CN-HG53, CN-HG73, CN-HG93 and CN-7701
for 10 gears: CN-HG74, CN-HG94 CN-5600, CN-5701, CN-6600, CN-6701, CN-7901 and CN-M980
SRAM chains
for 7-8 gears: PC-830, PC-850, PC-870 and PC-890
9 gears: PC-951, PC-971, PC-991 Cross step and PC-991 Hollow pin
for 10 gears: PC-1031, PC-1051, PC-1071, PC-1091 and PC-1091R
KMC chains
7 gears: Z50, Z51, Z51RB
8 gears: Z72, Z82, Z92, Z7, Z8, Z8RB, Z92RB and X8
9 gears: Z99RB, Z99, X9, X9L and X9SL
for 10 gears: X10, X10L, X10EL and X10SL
for 11 gears: X11L, X11SL
Why do you need to be able to determine chain wear? The chain wears out evenly throughout its service life, but its resource is approximately 3 times less than the resource of the cassette (the sprocket block on the rear wheel). And if the chain is heavily worn, then it will quickly “kill” the cassette, and possibly also 1 or all the stars of the system. And then you will have to change them all and spend a lot of money accordingly. To prevent this, you must not waste time
Determining the life of a chain by mileage (which can be viewed at) is incorrect, because One ride through fords and mud is equivalent to several times more mileage on asphalt. There are other factors that reduce the life of the chain. Therefore, a more accurate method is used - measuring the length of 24 chain links (distance L in the figure). 
With the new chain, this distance is exactly 12 inches (304.8 mm). You need to measure a slightly tensioned chain and it is better to use not a ruler, but a more precise tool - a special-caliber caliper. Based on the measurement results, one of the following conclusions can be drawn: 
Now about that how to remove and install a chain. Nowadays, almost all chains have a special connecting link. For Shimano chains, you used to have to buy it separately, and even now only some of their chains come equipped with it. If it is not there, then to install the chain you will need a special tool - a squeezer. In general, it will be needed in any case when installing a new chain, which will need to be shortened to the same number of links as the old one. Using a squeeze, one of the pins (see picture above) is pressed out of the circuit - thus the circuit is disconnected. For connection, a new reinforced connecting pin is pressed in (included with new Shimano chains). But the next time you remove the chain, you need to press out the regular pin! Reinforced pin widens slightly 
hole in the chain link, and when it is pressed out, the chain will be weakened in this place (a break is possible). There is an opinion that it is better not to use a reinforced pin at all, but to press in a regular pin that was removed. Or use a connecting link and everything will be much easier.
This is one of the main elements of the transmission unit. It transmits torque to the rear wheel from the drive sprocket. This is what makes the bike move. During travel, it becomes clogged, stretched, and wears out. It must be removed periodically for cleaning and lubrication. And if it is stretched, then the chain on the bicycle will need to be replaced.
Removing a bicycle chain with a lock
On singlespeed and multi-speed bikes, the dismantling process is identical. If the bike has a bicycle chain with a lock, then removing it for cleaning, shortening or replacing is easy. The entire removal process takes just a few minutes.
How to remove a bicycle chain with a lock? To do this, you first need to find a link with a clamp. To do this, you need to carefully examine it from both sides. If it is not very dirty, the lock link can be found almost immediately. There is an inscription stamped on it and a special clip is put on top, which holds the adjacent links. If, upon careful inspection, the lock is not found, then your lock is solid.
Locks from different manufacturers are slightly different, but the removal process is similar. You need to close the adjacent axes together and remove the clamp. You can pry the lock with a screwdriver or any other pointed object. If you still can’t pry the latch, you can use special pliers to open the locks. It is important here not to damage the clamp or lose it, otherwise you will not be able to install the bicycle chain back.
A lockless one is much more difficult to remove. To do this, you will need a special puller - a chain squeezer. You can, of course, remove it without tools. For example, placing the axle on the edge of something solid. Next, using a regular knitting needle, tap the axle (pin) and separate the links. However, it will not be possible to connect them this way. You will still need a puller for this.
To do this, select any link, insert it into the puller, placing it directly opposite the release axis, and secure it with a screw. Next, slowly turn the screw, thereby squeezing out the pin. It is important not to push the axle out completely. Otherwise, it is almost impossible to install it in place later.
Installing a bicycle chain
If you are installing a new bicycle chain, you should first check whether it matches your bike in length and width. If it does not fit in width, then it cannot be installed on this bike. But the length is easy to adjust. To do this, it is enough to remove the extra links using a squeeze.
If you have, then for installation you need to fix the rear and front speed derailleurs on the smallest sprockets. After this, pass the chain through the derailleur tension frame so that the upper roller passes it on the right, and the lower one on the left. Then you connect the extreme links and insert the pin. After putting on the chain, insert the axle into the squeeze, fix it with a screw and press the pin. When installed correctly, it should be completely flush with the edges of the chain. After this, take it out of the squeeze and break off the end of the axle (if there was one).
It is very important to check the chain movement after installing the pin in place. It should not sag, the pedals should scroll freely. If it walks slowly and bends poorly, then using the same puller, using the second seat, you need to adjust the axis.
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In my life I have come across 3 types of bicycle locks. Today I’ll tell you how to easily install and remove a chain lock in any of its forms.
Type 1: Chain lock with two pins
I haven’t seen such locks for a long time, but they are still used for single-speed chains and on old Soviet bicycles. For example, lock KMC MissingLink 1 sp Z410-SO.
Design
Their design is extremely simple - there is a cheek on which 2 pins are located. They are inserted into the holes in the chain links and pressed with a washer with two holes. Everything is fixed with a locking cheek.
How to install a two pin chain lock
To close this lock, you need to rest the pliers against the pin and against the cheek of the lock on the side where there is no cut. We press with pliers, and the lock is installed. If there are no pliers, use a screwdriver. We press the screwdriver against the edge of the cheek, where there is no cut, and press until the lock closes.
How to open a chain lock with two pins on one side
These locks are the easiest to open. It is enough to grab the pin and the locking cheek from the side of the cut with pliers, apply a little pressure - and the lock is opened. If you don't have pliers, you can use a screwdriver. We press the screwdriver against the edge of the cheek from the side of the cut and press until the lock opens.
Video on installing and removing the lock:
Type 2: Chain lock with 2 symmetrical parts
The most common and convenient type of locks. Installed on almost all modern multi-speed bicycle chains. These locks are often difficult to remove. When I removed such a lock with my hands for the first time, my hands were bloody, but the lock remained in place. Most often found on KMC, Sram, FSA chains. Surprisingly, Shimano does not use such locks. Can be used for almost any number of speeds from 1 to 11.
How to install a chain lock with 2 symmetrical parts
Installing a lock is very easy. It does not need to be latched, since we will do this as soon as we press the pedal for the first time. But you can try pulling the chain in different directions to hear the click of the lock. The main thing is to make sure that all parts of the castle fit into each other.
How to remove a chain lock with 2 symmetrical parts
To remove the symmetrical lock, you will need regular pliers. We bend the chain so that it resembles the letter “P”, where the top of the letter is our lock. In this position, we need to press the lock with pliers diagonally (diagonally) to move the two parts of the lock (press with pliers from the sides where the pin comes out of the cheek). The method works perfectly! And the hands are intact, and it takes 15 seconds.
Watch the video for more details:
There is also a way to remove it using your hands 🙂, rope or cable - this is when the pins are wrapped with rope and then pulled together, but usually “tight” locks are not opened in this way.
Type 3: Chain lock with spring-loaded jaw
One of the most difficult locks to install and remove, it causes a lot of problems. This lock is found mainly on Shimano chains in the following models: HG91, CN-HG70, CN-HG50, CN-UG51, CN-HG40, CN-UG51, and KMC Z610RB also has such locks.
Design
The castle consists of two parts. The first part is two pins located on one cheek, and another cheek (bar) with a hole in the middle, which keeps the chain links from opening.
How to install a spring-loaded chain lock
After we connect the chain with the first part of the lock with two pins, we must secure the bar. There is a hole in the bar where one of the pins can be inserted. We insert the 1st pin and move the bar with the hole towards the 2nd pin. Next, we need to bend the chain with both hands so that the pin fits into the pin hole in the bar. As soon as the pin enters the hole, you will need to bend the chain a little in the opposite direction so that the pin is in its working position. At the beginning I was afraid to bend it, I thought I would break it, but it all worked out!
More details can be seen in the video:
How to remove a spring-loaded lock
This is the most difficult stage; it is not always possible to do it with bare hands. We will need a screwdriver to remove the lock. As with installation, you need to bend the chain so that the pin fits into a place on the bar where it can come out, but without a screwdriver this does not happen. You need to help the pin free itself from the bar, so you need to hold a screwdriver in one of your hands and bend the chain, pressing on the pin with the screwdriver as it approaches the expansion in the bar. As soon as the pin comes out, you will hear a click - this means that everything turned out correctly.
These locks are not intended to be reused; they usually bend after removal. But you can always try to bend it back and put the lock again if you don’t have another lock at hand.
View 3.1: Spring-loaded cheekpiece with two holes
There is another type of lock with a spring-loaded cheek. This is when the cheek itself has not one hole, but two, but the principle of installation and removal does not differ from type 3.
How this type of lock opens and closes can be seen below:
It is important to note that depending on the number of stars on your cassette or ratchet, the width of the chain changes, and, accordingly, the lock itself. Therefore, you need to pay attention when buying a lock so that it is the same width as the chain.
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Keeping a bicycle chain in perfect condition guarantees an adequate response to the cyclist’s actions from the entire mechanism while driving. When purchasing a new vehicle, there is no need to separately purchase a new chain and install it. However, in the future you will still have to learn how to remove the chain from the bicycle for maintenance or replacement.
When should you change your bicycle chain?
A good bicycle chain lubrication can significantly increase the service life of the entire system responsible for movement. At the same time, you need to be able to notice the moments when it begins to need maintenance or repair.
Excessive wear on a bicycle chain not only causes constant discomfort while riding, but also causes active deformation of the chainrings. If a worn chain is left unattended for a long period of time, it is guaranteed to lead to the need to replace a whole set of expensive mechanisms.
In order to assess its condition as objectively as possible, it is necessary to look not at the mileage, but first of all to measure the length of all its links. The chain length in normal condition is approximately 305 mm. The reason for its replacement is its stretching to 308 mm or more.
How to deal with chain stretching?
A common problem with a bicycle chain is its sagging. The reason for the development of this process is the gradual wear of the links. Moreover, it is almost impossible to prevent wear of individual chain elements. The problem can be eliminated only by removing excess links as they stretch.
To correctly perform the necessary actions, you must:
- Decide how to remove the chain from the bicycle by first disconnecting the rear wheel.
- Disconnect the chain using pliers.
- Determine the number of unnecessary links.
- Remove unnecessary elements.
- Connect the links, install the chain, check its mobility and functionality.
How to remove a chain from a bicycle to replace it?
When an old chain becomes physically and morally obsolete and does not satisfy the bicycle owner with operating conditions, it must be urgently changed. As a replacement, select a chain with the same number of links. However, its length should be somewhat shorter.
How to remove a chain from a bicycle correctly? To do this, you need to use a special tool - a squeeze. Having placed the squeeze opposite any of the rollers, you need to tighten the screw so that this leads to the pin being squeezed out. Next, you should loosen the tool and then remove it. In a similar way, using a squeezer, the chain is removed for regular scheduled cleaning.
Quite often, experienced cyclists use special locks for quick maintenance, removal and cleaning of the old chain. The use of this device makes it possible to instantly remove it for replacement. However, some bicycle owners have prejudices regarding the effectiveness and reliability of using a lock. After all, if it is present, the risk of a sudden break in the chain increases. It is not known for certain how often chains break when there is a lock, but without it the mechanism still looks more reliable.
How to tension a chain on a bicycle?
Managing chain tension on standard road bikes is quite easy. It is enough to pull it back towards the fork. The main thing is to perform such a manipulation carefully so as not to overdo it by applying too tight a tension.
However, both a strongly and weakly tensioned chain can create some discomfort while driving. So, when trying to figure out how to tighten a chain on a bicycle, it is important to stop in time so that it is in a state of medium tension.
Bicycle chain tensioners
A special bicycle chain tensioner can be an effective and useful accessory, the use of which allows you to maintain the necessary chain tension while riding. This accessory is used mainly by fans of extreme, aggressive driving.
Chain tensioners are usually installed on single-speed bicycle models. Such accessories consist of one or more rollers, a lever and a spring. Tensioners work on the principle of systematically pulling the bicycle chain in the required direction, which creates the required tension. Moreover, the presence of a tensioner prevents the chain from falling from the drive sprocket located on the bushing.
Experienced cyclists are advised to always have several chains in stock. Each of them should be operated with a rolling distance of no more than 600 km. After which the bicycle chain is replaced. A new, shortest one is put in its place. As a result, the life of not only all existing chains, but also the transmission of the two-wheeled vehicle is significantly extended.
During the operation of the bicycle, a situation may arise in which it is necessary to remove the chain from the bicycle frame. There may be several reasons: replacing the chain due to wear, the need to remove the chain for complete cleaning, work to increase the number of links (increasing the chain) or reducing the number of links, breaking the chain during operation. As you can see for yourself, it will not be possible to remove it from the bicycle frame without disconnecting one of the links of the chain - which means you will have to disconnect it.
Chains from different manufacturers differ in the type of link connection. For example, some Shimano chains do not have connecting links, and some are supplied with a special connecting pin (pin) to facilitate the first installation of the chain on the bicycle. There are also chains with special locking links. Such a lock link is usually highlighted on the chain with a color. It can be easily disconnected and reconnected without the use of special tools.
Removing the chain with lock
Unlocking a bicycle chain is very easy. To do this, you need to take the lock link in your hands and move its pins (pins) with your hands or pliers towards each other. After this, the two halves of the lock link should separate from each other, and each will remain with its own pin.
In order to disconnect the circuit, it is necessary to press out one of the pins using a squeezer. In this case, you should pay attention that you cannot press out the connecting pin, which is available in some circuits. The fact is that this pin is slightly thicker than the others and is subject to more wear. Reusing it dramatically increases the risk of chain breakage. The connecting pin is different from the rest - so it is quite easy to distinguish it.
So, when the squeeze pin is selected, you need to install the squeezer on the circuit. Many wringer have two seats for the chain. The chain should be placed closer to the adjusting screw, otherwise its links or the squeeze itself can be hopelessly damaged. The second seat for the circuit is not involved when disconnecting it. To understand how to insert a chain, it is best that the squeeze is in a state like the image below:
Next, you need to tighten the adjusting screw and tighten the squeeze screw until the squeeze is held on the chain. It is worth checking that the adjusting screw does not allow the link to bend, and that the tip of the squeezer presses exactly on the pin, and not on the link. In this case, there should be no distortions or any strange positions of the chain in the squeeze.
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| The chain is fixed in the squeeze. |
Once you have made sure that everything is installed correctly, you can begin to rotate the squeeze screw. At the same time, it can rotate with decent effort. You should not rotate quickly, because if you want to later reconnect the link in this place, then it is necessary that the pin does not come out of the outer part of the link, otherwise it will be very difficult to put it back. If you are doing this procedure for the first time, do not be lazy, rotate slowly, remove the chain often and check how far the pin has come out.
If everything is done correctly, the circuit will be disconnected. Remember that if you frequently disconnect and connect a circuit, it is best to press different pins. After each pin squeeze, the reliability of this node decreases.