How the carriage is disassembled on a bicycle

The carriage is installed in the reverse order of removal.

When assembling the carriage, the most difficult thing is not to confuse the ends of the carriage axis. its right and left sides are different. Usually on the axle or on a plastic casing (on some carriages this casing is not provided) letters are applied corresponding to the sides of the axle.

The cups cannot be confused. they have different threads (the left cup has the right one and vice versa)

carriage, disassembled, bicycle

We put a plastic cover on the axle. We put the bearings in the cups. If the bearings have cages, then we lay them out with a cage (balls. inside the cups). Lubricate the bearings with a thick grease With the same grease we grease the threads of both cups.

We start assembling from the right side. We insert the axle into the right cup, and screw this cup into the frame until it stops. This requires a slotted wrench for the carriage. The right cup has a left hand thread.

Now screw the left cup in the same way on the other side. It has a right-hand thread. Let’s move on to adjusting the carriage. (you can go directly to step 1)

Assembly and installation of a collapsible carriage

The collapsible bottom bracket is very similar to the one used on Soviet bicycles, so the assembly and adjustment process is not difficult.

Before assembling, rinse all parts in some solvent (kerosene), wipe with a cloth, and dry. I do not recommend using gasoline. it can damage the plastic seals in the cups. The new carriage should also be washed. the grease on it is most likely preservative. It is also a good idea to check the frame bottom bracket for damage and any debris. Several times I found shavings, sawdust there, which fell into the carriage assembly from the seat tube of the frame. When caught in the bearings, the sawdust will not contribute to the easy ride of the bike.

Eccentric carriage

Allows the use of a drive without external gear shifting (singlespeed, planetary hub) in combination with conventional vertical frame dropouts. These dropouts provide a faster and more comfortable wheel positioning compared to horizontal ones. The eccentric carriage rotates in its seat, allowing the chain to be tensioned, then fixed with bolts and / or union nut. On serial bicycles, such carriages are rare, one of the most common examples is the Strida. Also usually installed on tandems as a front carriage, which makes it possible to tighten the timing chain.


  • 54mm standard. for example, Bushnell Eccentric Bottom Bracket. Has a BSA thread for a standard BB, requires a special frame with a 54 mm seat.
  • Standard 46mm. Fits into a standard Press Fit 30 frame. Integrated system (24mm axle) fits directly into the carriage.
  • BSA Standard. Fits into a standard BSA threaded frame. The integrated system (with a 24 mm axis) fits directly into the carriage. Provides chain length adjustment only within 1/2 link, requires use in conjunction with a half-link chain.

On it is described in great detail about the repair of carriages and how and how they can be removed. Let’s figure it out with this issue too.

Types of carriages according to the used carriage glass

Non-integrated carriages

They include an axle onto which the connecting rods are pressed, and a set of bearings located inside the bottom bracket of the frame. They are divided into two categories:

  • Cartridge. axle and bearings form a single non-separable unit.
  • Dismountable. can be disassembled for cleaning, lubrication and replacement of worn parts (used in old bicycles).
  • Wedge-fit connecting rods (Soviet bicycles).
  • Under the square (square taper). the standard floats somewhat from different manufacturers.
  • With spline fit of connecting rods:
  • Shimano Octalink v.1
  • Shimano Octalink v.2
  • ISIS
  • Truvativ Powerspline
  • Truvativ Howitzer
  • Truvativ HammerSchmidt

All of these standards are generally incompatible with each other.


The homemade carriage on the bicycle I assembled consisted of an axle and two 203x bearings driven tightly into the frame. Those were the times 🙂 Now the carriage has become much more complicated. Let’s try to deal with this tricky thing.

The bottom bracket is a bicycle assembly that connects the system to the frame and rotates freely using bearings (usually cartridge bearings). The carriage is screwed or pressed into the carriage glass of the frame. Separately, eccentric carriages can be distinguished. they can be displaced in the carriage glass of the frame in order to tension the chain on a singlespeed or on a bicycle with a planetary hub. Requires a special frame.

Carriage tools

To work with the carriage. the cartridge requires only a slotted wrench. It is also useful for many collapsible carriages.

But on some collapsible carriages, instead of a slotted one, another key will be required.

And this may be required. You can do with a regular open-end wrench for 36, or, in extreme cases, use an adjustable / gas wrench. The gas wrench must be used carefully. you can easily damage the frame.

On collapsible carriages, you will also need such a special key

Despite such a variety of tools required, the process of disassembling, installing and adjusting carriages of different types does not differ in variety. You just need different tools to perform the same operations on different carriages. The main difficulty when disassembling the carriage is not to forget that a left-hand thread is used on the right side. The second challenge. especially with aluminum frames. can be very, very hard to unscrew the cups. In this case, the key should not be allowed to break off. you can damage the bike parts or injure your hands. Therefore, it is better to stock up on keys with sufficiently long handles.

Types of bicycle carriages

Modern bicycle carriages are quite diverse. They differ from each other in many initial parameters: from the size of the shaft to the method of fastening. First of all, it should be noted that the design of the mechanism can be collapsible or non-collapsible. The first type is an assembly with cups and bearings (cones) fixed in a cage. The second design option is pre-engineered models. It is believed that they are more reliable and durable, as they are protected from any negative impact. If we talk specifically about the types of construction, then the following should be highlighted:

    Threaded. Fastened (screwed) directly into the frame.

Frame-and-frame. Bearings and shaft are matched with a housing that can be easily disassembled.

With one-piece axle made of metal.

  • Press fit. A kind of mechanism that is built into the frame.
  • As mentioned above, any carriage is a structure with an axle and bearings. In this case, the shape of the axis can be different. The most common is a square, but there are other types of connecting rods that deserve special attention. That is why, if the question arises of how to choose a carriage for a bicycle, then first of all you need to study the basic standards for attaching the connecting rods. And although there are a lot of such standards, first of all, it is necessary to take into account the following options:

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      SQR square. Such designs are the most common. They are found on many inexpensive bicycles that are not particularly fancy. However, this is the case when cost does not affect the quality and reliability of the carriage. As for the characteristics of the mechanism, they are approximately the following: the shape of the shaft is a cut pyramid, the length is up to 126 mm, the fixing method is bolts.

    Hollowtech 2. Such carriages have an integrated axle, which is combined with outrigger cups. Consequently, the mechanism consists of several standard elements, which affects its weight and functionality.

    Mexa Exo. This carriage system practically does not differ from the previous model in terms of design features, so it can be safely used as an alternative when it is not possible to find a suitable part.

    Octalink. Standard carriage with 8 studs. At the same time, the size of the Spitz can be different, depending on the type of system (there are two main types. V1 and V2).

    GXP. In general, the mechanism functions according to the standard principle, but it is better not to buy it if such a parameter as the compatibility of the Spitz is important.

    ISIS. It is radically different from all the presented models in the size of the shaft. In fact, the length of this structural element never changes, although the shape of the carriages may vary.

    Power Spline. A mechanism that is not fundamentally different from the rest, but involves the use of 12 spitz.

    BB30. A modern carriage system that does not look like standard mechanisms. The diameter of the integrated axle here reaches 30 mm, which is much larger than that of the standard models. In this case, the axle is made of aluminum, which reduces the weight of the structure, while simultaneously increasing its strength.

  • Wedges. Carriages that are fixed in this way are far from the most reliable, but they also need to be said. Such mechanisms do not differ in high cost, but it is unlikely that it will be possible to save money, because they will have to be changed often.
  • Obviously, there are other bicycle carriages that are not on the list, but the range presented will be enough to select the right mechanism.

    Carriage design features

    Modern systems have the same type of design, which consists of the following elements:

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      Base with built-in axle and several bearings.

    Cups that perform the function of fastening. They are used to hold the mechanism in a certain place (carriage glass). These cups can be of different types, depending on the type of carriage attachment.

  • A body axle that rotates during movement. At the same time, bicycle cranks are usually fixed at its ends.
  • If you position and fix the carriage system, then it will be in a kind of glass.

    What is a carriage and its purpose

    • time for seasonal maintenance (lubrication change, cleaning, bulkhead);
    • the need to eliminate backlash;
    • tight rotation of the axis;
    • detection of extraneous sounds during the operation of the device.
    • Please note: if the bike has a cartridge carriage, it will be replaced without repair.

    Puller application

    A special device that is designed to dismantle hard-to-remove parts is called a puller. This is a no brainer. In our case, to remove the connecting rod from the bicycle carriage shaft. It looks like this.


    This type of connecting rod puller provides the ability to remove the pedal as well.

    The connecting rod is held on to the shaft by a heavy-duty 8mm head bolt. It is not difficult to unscrew the bolt. But the difficulty is that the connecting rod sits on the shaft with a slight interference fit and has a tapered fit. Very often, in wet weather, water and dirt penetrate into the interface between the connecting rod and the shaft. Then it sticks to the shaft and it is almost impossible to remove the connecting rod. But in our toolbox, of course, there is a puller for connecting rods, which is a complex turning part. a screw with a two-level head for an open-end wrench and a socket. A cunning nut with external and internal threads is screwed onto the screw. It takes a long time to explain, but in the photo everything is very clear.

    Regulation of the carriage mechanism

    To begin with, remove the left connecting rod arm and lock washer. The left bowl is unscrewed with a slotted wrench so that the carriage axis rod rotates freely without backlash and jamming:

    • The bowl is loosened with a slotted nut wrench by a quarter turn;
    • While holding the bowl, the lock washer is screwed in until it stops;
    • Rotation is regulated: the bowl is loosened or tightened;
    • When the carriage mechanism is spinning without interference, you can install the connecting rods.

    If, after all the work performed, the carriage jams, replace the bearings or the entire carriage.

    For more information on carriage maintenance, see

    Dismantling technology

    Here is a step-by-step photo guide explaining the process visually.

    Remove the right connecting rod

    Remove the right connecting rod in exactly the same way as you removed the left one. There is an asterisk on the right connecting rod. If there is a need to replace it, unscrew the bolts that hold the sprocket on the connecting rod with a hex wrench.

    How to disassemble a connecting rod without a puller?

    The simplest method is to use a special puller. If there is no such tool, then in order to disassemble, remove and make repairs, you need to make some effort and skill. During the ride, dirt and dust gets into the attachment area of ​​this element, the element literally sticks to its attachment due to heavy loads. In this case, you need to know how to remove the cranks from the bike without using a puller. You can fix the problem and make repairs on your own, and this will help you get to the place of equipment repair.

    In unsuitable conditions, you can try the following methods in order to remove the part. If you unscrew the nut or bolt that secures the connecting rod and drive a certain distance, then the element can be disassembled and removed much easier, and in the future, replace or adjust what is required. The method is to pour boiling water over it. Consequently, all dirt and dust will get wet and making repairs to the bike, it will be easier to remove the element. This option is also suitable when it is important to remove the pedals. It is important to know and not to be confused in which direction which pedal is unscrewed. The left pedal has a left-hand thread, and the right one, respectively.

    If the bottom bracket of the bike requires adjustment, the cranks must also be removed from the bike. Other recommendations will also help in case of unforeseen breakdowns. If the cable of the gearshift or brake is damaged, you need to replace it with a new one, and if there is none, then tie the torn ends. Bicycle spoke failure is also a common problem. Then a wire with a diameter of about 2 mm will help. The end of the spoke next to the rim is crocheted, and then a piece of wire is inserted, which must be passed through the socket of the hub. This replacement is far from perfect, but it will allow you to reach the goal and the place where you can repair the equipment well. Regular viewing and maintenance of two-wheeled vehicles will avoid many of these problems and make the trip enjoyable.

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    Device and purpose of the part

    A bicycle connecting rod is a metal lever that has a large and a small head on the rod. This element is of several types:

    • One-component. They represent a single structure. left, right connecting rod, axle. The advantages of this type are great strength, easy maintenance, but they have a significant weight;
    • Two-component. Here, the drive sprocket, the right connecting rod and the axle are connected, and the left one is connected separately with a nut;
    • Three-part. This most famous and popular system is the axle, the left connecting rod and the right one together with the sprocket.

    The load on the connecting rod is very high, and therefore they are most often made from solid steel, but there are also options from aluminum alloys, for example, in sports type bicycles or imported models. Inexpensive two-wheeled vehicles have a front sprocket block, combined with a connecting rod and non-separable. In this case, when replacing the sprockets, both connecting rods must be replaced. New ones are selected depending on the type of existing carriage.

    This part of the bicycle can also have various types of fastening, for example, a square, a slot. The first is used in professional sports models of equipment, and there is also the latest development. a rotary system.

    Removing the carriage

    Removing the carriage is the most time consuming part of the job. You may not be able to cope yourself and will have to contact a bike mechanic. Please note that there are a large number of carriage models and there are specific keys for them. The article deals with the dismantling of the ISIS carriage. The carriage cups have a standard thread, while the carriage has a reverse thread.

    Place the carriage wrench on the carriage spindle, which itself is shallow. The key is easy to put on. Work carefully, do not rip the threads and splines on the carriage.

    The ISIS carriage has 2 parts. a body and a stop cup. On them the thread is applied in different ways, check which side of the retaining ring is put on. In most cases, the retaining ring has a regular thread, it should unscrew easily enough (when compared with the other side).

    Choose the other side, turn the key counterclockwise until the cup is removed.

    How to remove the cup from the spindle, turn the frame over and pull out the carriage, first rotating it clockwise.

    Bicycle carriage repair

    Bike bottom bracket problems are familiar to every cyclist. It happens that it loosens up or emits characteristic annoying clicks. This does not always mean that the part needs to be completely replaced. It is enough to competently repair the carriage on a bicycle, without postponing this matter for later.

    Installing a collapsible bicycle carriage

    This type of carriage has a standard device that is well known to all owners of domestic bicycle bikes, which is why it is quite simple to install and configure it.

    • Before starting the installation, we thoroughly rinse the newly purchased carriage and other parts in kerosene (it is better not to use gasoline: it is harmful to plastic, the oil seals in the cups may suffer). We check for small debris and scratches in the frame unit to which the carriage will be attached. If something gets into the bearings from there, the bike will squeak.
    • We carefully study the ends of the carriage axis (the main thing is not to confuse them!). There must be a special mark on the axle or casings (they are not available everywhere). The bowls have a special thread, thanks to which it is impossible to confuse them.
    • A plastic casing must be placed on the axle. We put bearings in the bowls so that the balls are on the inside of the bowls. The bearings and threads on the cups are thickly coated with grease.
    • We start to collect on the right. We attach the axle to the cup on the right side and screw it all the way into the frame mount using a slotted wrench. Left hand thread on the cup.
    • In the same way, we screw in the left cup from the opposite side.

    After the installation of the carriage is completed, proceed to the adjustment.

    Disassembly and lubrication of the bicycle carriage

    We remove and repair

    The carriage can be integrated or non-integrated. The latter, according to the type of device, are divided into cartridge (axle, cups, connecting rods. a single system) and collapsible (parts can be unscrewed so that they can be repaired and cleaned). Usually, the carriages of a walking bike or an average mountain bike are arranged in a standard way, so they can be repaired according to the worked out scheme.

    To make it more convenient to operate, it is better to turn the bike with the wheels up and put it on the handlebars.

    After you have made sure that the bike is level and firm, you can proceed to repair:

    • Carefully remove from the axle first the left, then the right connecting rod.
    • Thoroughly rinse the carriage assembly, remove the old dirt that has accumulated behind the connecting rods. We clean the splines in each cup very carefully. if they are clogged, it will not be possible to install the puller.
    • We proceed to remove the carriage itself. We start on the left (where there are no stars). If your bike has a lock nut, carefully unscrew it with a wrench (you can use a family man). Nuts of this type usually have a right-hand thread, so you have to make some effort, but try to tighten the nut carefully so as not to rip the wrench.
    • After that we take a spline key or a special key for the carriage. As soon as it enters the grooves, we immediately unscrew the cup with an adjustable wrench with a long handle. If you have a collapsible carriage, the cup must be removed together with the bearing.
    • On the right side (where the asterisks are), we perform similar actions using the same long key. The thread on the cup, accordingly, is no longer right, but left, so force is required.
    • Next, you need to remove the right cup with the axis or the cartridge (depending on the type of carriage).
    • If you have a collapsible design, we remove the bearings from the removed carriage. The places where the old grease remains are thoroughly cleaned. We wash all parts in kerosene or any other solvent.

    After the carriage is cleaned and the parts are dry, we install in the reverse order.

    Adjusting the bearings

    Loose bearings are often the cause of extraneous noise, backlash and unpleasant rattling in the rear wheel carriage. Doing so can damage them, deform the cups or impair the clarity of gear changes. If you experience any suspicious symptoms, you need to consider how to tighten the bottom bracket on your bike. In this case, it is better not to postpone the adjustment. If you have the skills, it will be possible to pull up the carriage even during the trip, bypassing the disassembly stage.

    • Starting work, remove the left connecting rod from the rear carriage and unscrew the lock nut with a special key. Then, using the slotted wrench, slightly loosen the left cup.
    • We twist the left cup almost all the way. It is worth wrapping it loosely or too tightly, as the axle starts to play or jam. To avoid the latter, slightly (about ¼ turn) loosen the cup with a long wrench.
    • After that, screw on the lock nut from above and tighten it all the way with the same wrench that was used to unscrew.
    • Checking how the carriage axis works. To do this, we twist it by hand, then we swing it back and forth on the sides. Even a small lift or a barely perceptible jam is a good reason to repeat the adjustment from the beginning.
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    If you cannot find a balance between play and seizure even after several attempts, you will have to replace either the entire carriage, or worn out or insufficient quality bearings.

    By integration with the system

    • The integrated bike carriages are integrated with the system. In this case, the axle is integral with one of the connecting rods, which reduces weight and cost, and also increases the reliability of the entire structure.
    • Non-integrated models. a separate unit that allows you to attach certain types of cranks.
    • Most of the models are cartridge, i.e. bearings make up a cartridge, inside which they are factory-pressed. Non-cartridge carriages require constant maintenance, as there are much more opportunities for dirt to get inside the unit.

    Carriage design

    The carriage for a bicycle consists of four parts:

    • The body is the main part of the carriage, on which the bearings are attached, into which the axle is wound, and on which the cup is placed.
    • Cup. an element for attaching the device to the glass. Depending on the standard and type of fastening, either pressed or screwed into the frame in a special way.
    • The carriage axis is a movable part inside the body that can rotate freely. Ends with connecting rods attachment points. It is one of the sources of typing by the type of connecting rods.
    • Slots or connecting rods.

    The place of its attachment can be attributed to the carriage system. This is a frame element called a bottom bracket.

    Thus, the carriage of a bicycle is a fairly simple and small element, which, however, can be quite high-tech and expensive.

    Types of carriages and elements

    There are a huge number of standards and types of carriages. Basically, they are subdivided according to the following parameters:

    • shaft length. it is the length of the axis, it is important for the position of the system and pedals, it can vary;
    • body length. must correspond to the dimensions of the glass, but there is a possibility of deviation;
    • thread type. dimensions of the thread for mounting in the glass. Cannot vary, exact match is required;
    • type of connecting rods. the size and method of fastening the connecting rods of the system to the shaft. Full match required.

    The history of standards development is very interesting because it contains standardizing organizations, patent disputes and continuous improvement of design.

    There is also a division in principle.

    On the carriage glass

    Threaded fit for various sizes:

    • English thread;
    • 68 mm;
    • 73mm. Common on MTB bikes
    • 83 mm. in Trial and BMX disciplines;
    • 100mm. wide frame cruisers;
    • Italian 70 mm glass thread. this product is easy to find in old road bicycles;
    • French thread. used in Soviet road bicycles.

    Press-fit, otherwise the BB30 standard is completely new, but very promising. The bearings are pressed into the bottom bracket, and a shaft with a diameter of 30 mm is threaded through them, which increases the overall rigidity of the assembly and its reliability. This standard is broken down by carriage sizes:

    • BB30. glass diameter 42 mm, width 62 mm for road and 73 mm for mountain bikes;
    • PF30. glass diameter 46 mm, width 68 mm and 73 mm;
    • Press-fit. models for an axis of standard sizes (24 mm);
    • BB90, BB95. glass diameter 37 mm, width 90.5 or 95.5 mm;
    • BB86, BB92. glass diameter 41 mm, width 86.5 or 91.5 mm;
    • BBright Direct Fit. glass diameter 42 mm, width 79 mm;
    • BBright Press Fit. cup diameter 46 mm, width 79 mm;
    • 386 EVO. inner diameter 46mm, width 86.5mm.

    Offset mount eccentric devices that allow quick and convenient installation: the bike crank is rotated in the glass by tightening the chain and then secured with a nut or bolts. These devices are commonly used on bicycles with fixed gears or planetary hubs, and are very rare on production bikes. There are also several sizes:

    • Landing diameter 54 mm;
    • Standard 46 mm, under the Press Fit 30 frame, usually supplied integrated with a 24 mm axle;
    • BSA standard. with the thread of the same name, used with a special half link, allowing the chain tension to be shifted.

    The device and types of carriages for a bicycle

    The carriage of a bicycle is one of the components that a modern bike cannot do without. Similar to ears, legs and tail, a bicycle consists of a frame, a steering wheel, our heroine, wheels and a transmission. This is a simple unit, but very strict requirements are imposed on it in terms of accuracy, installation and reliability of the component parts, therefore it is vitally important for maintenance to know the structure of the carriage.

    Actually, this node has a heavy load:

    • power. pedaling energy, the total weight of the cyclist in the case of pedaling;
    • abrasive. forceful action, plus the location of the assembly close to the ground leads to a high risk of dirt particles entering the bearings, which will very quickly lead to the destruction of key elements of the part.

    By fastening the connecting rods

    • Square (SQR). a standard square, a very old mounting system, which, however, is quite inconvenient. with frequent disassembly, the connecting rod looses, and when pedaling it will damage the shaft, leading to the need for replacement due to wear of the carriage shaft, and not, as is usually the case. wear or damage to bearings.
    • Splined. in several standard sizes, avoids square problems by keeping the shaft and connecting rods from loosening against each other.
    • Octalink is Shimano’s standard for low-cost bikes. There are two shipments. Octalink v1 and Octalink v2;
    • ISIS Drive is a common spline standard for many companies. The main manufacturers are FSA, Truvativ, Race Face. The latter company pioneered the development of the standard due to Shimano’s limitations on the Octalink;
    • Hollowtech II. used in high-end Shimano integrated systems;
    • Giga X Pipe (GXP). An alternative to Holowtech II from Truvativ, Noir and Stylo;
    • Howitzer. a variant similar to ISIS for extreme bikes.

    Carriage selection

    Some tips for choosing a new model when the bottom bracket needs replacement or repair. For example, if a backlash appeared or physical damage was received:

    • Pay close attention to the size and type of carriage.
    • Find out from the documentation the type of carriage glass.
    • From the documentation for the rear derailleur, find out the chainline. the line of the chain (it is affected by the way the connecting rods are attached to the shaft).
    • Obtain the dimensions of the glass from the system documentation.
    • Select a non-integrated model depending on the type of front derailleur.

    Very often, along with a new device, you will have to buy a specialized key for the carriage, since modern models require a unique tool.

    The carriage in a bicycle is a small but very important structural element, the operation of which is very important for the cyclist. The choice of a model for professionals is especially important. a set of cranks, a front derailleur and sprockets, which can even be oval, depend on this unit. In practice, we are faced with integrated cartridge carriages for a bicycle, and other types are solutions for specific, most often sports, tasks.