How to disassemble a sports bike bottom bracket

Replacing the bottom bracket on a bicycle

But, as is often the case, inexpensive bike parts do not have a very long lifespan. So on our Stels there was a knock in the front carriage, later. a play of the connecting rods.

When the chain slipped off during the ride, it became clear that repairs were essential. Therefore, having studied the issue, we decided to disassemble the carriage and eliminate the cause of the backlash. It turned out that it is almost impossible to do this without special knowledge, so we decided to share our experience in this article so that people who have encountered this problem can quickly fix a similar situation.

The first step was to turn the bike upside down and remove the plastic carriage plugs. It became visible the nuts screwed on the shaft.

They can only be unscrewed with a tubular wrench of 15. But, as it turned out, unscrewing the nut is the simplest thing that can be done.

Having screwed the puller into the connecting rod until it stops, a special pin must be screwed into it (into the puller). He, resting on the carriage shaft, will squeeze the connecting rod from the seat.

Remove the opposite connecting rod from the bike in exactly the same way.

Now you need to unscrew the nuts that hold the carriage in the frame. From the side of the asterisk, this operation is extremely inconvenient to do. The protrusion of the nut is so narrow that both a regular open-end and a gas wrench jump off it. In our case, a chisel and a hammer helped. With a precise strong blow, you need to move the nut from its place, then it can be easily unscrewed with a wrench. Here it is imperative to know that the thread of the nut on the side of the sprocket is reverse, that is, it must be unscrewed clockwise.

The opposite nut has projections for a special key, so it is much easier to unscrew. The thread on it is ordinary, it is unscrewed counterclockwise.

Taking out the carriage, it became clear that the rubber sealing rings had broken and the bearing had collapsed.

And there is a nuance here. To install it, you also need a special key. It must be purchased so that you can not only install, but also remove the cartridge in the future, if necessary.

Insert the cartridge into the bike frame, tighten it with a key.

Having installed the connecting rods in their seat, we press them with a bolt, tightening it all the way. When tightening the bolt, the connecting rods will be pressed in.

At the end, insert the plugs, tighten the chain and use the bike.

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Such a set is not always found in a cyclist’s set, so you will have to purchase some tools separately.

The procedure is as follows:

  • Free up space around the carriage before replacing the carriage.
  • Remove dirt with a soft cloth. This is done so that dirt does not get inside the structure during parsing.
  • The plug is removed from the connecting rod. In most cases, a plastic cover is used as a plug, which is enough to touch with a screwdriver.
  • The next step is to unscrew the nut, which secures the connecting rod to the carriage.
  • Next, a special squeeze is applied, for which it is put on the fastening element.
  • The next step is to remove the connecting rod. For this, a special release tool is also used. As a result of applying force, the knot gradually leaves its place.
  • It should be borne in mind that the carriage is fixed by a special cup and rings. With light movements and blows, the rings rotate in the seat. Similar actions are taken to remove the cup.
  • The carriage bearing can be removed with a regular screwdriver, for which light blows are carried out.
  • A special removable tool is used to pull out the carriage shaft. It is almost impossible to dismantle with a conventional tool.

Closed carriage

open (collapsible) are a shaft rotating in bearings that are in cups.

How to properly remove the carriage from the bike and put it back

Active riding on two-wheeled vehicles requires initial skills for quick repairs. When packing for a long trip, you need to think over possible breakdowns, take with you the necessary set of tools. Many athletes are interested in how to remove the carriage from a bicycle with their own hands to adjust, restore the element. Thanks to the detailed description, you can figure out how to maintain the mechanism, eliminate breakdowns, and carry out assembly.

Take the survey

The bicycle carriage is used to connect the cranks, their circular movement while cranking the pedals. Depending on the vehicle model, the optimal parts are selected, which are classified according to several parameters:

  • The size. The most popular knots are 68 mm. In a professional environment, parts with a length of 110, 113 or 122.5 mm are more often used.
  • Possibility of repair. Cartridge bike carriages last until the first break. If there is a backlash, an unpleasant creak, you will have to replace the part. Collapsible models are serviceable.
  • Materials. The budget carriages are complemented by a plastic cup that breaks easily when disassembled. Oil seals protect the bearings from moisture, so they must be of high quality.

Bicycle carriages are open and closed. The first ones need frequent maintenance, are subject to repair, disassembly, repainting. The latter are reliably protected from rust, water ingress, dirt, dust, are unpretentious in operation, however, after a breakdown, the damaged part will have to be replaced with a new one.

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Open carriage Closed

Bicycle bottom bracket: what is it and why?

The carriage is a unit located in the middle of the frame, placed in a special cavity. a glass. Where to looking for? It’s simple: it is hidden where the cranks with pedals and stars are located. The main function of the bottom bracket is to connect the crankset to the frame of the bike and provide torque when pedaling.

A quite reasonable question may arise: what, without this device, you can not do at all? There is no bicycle without a carriage. If such a person is still caught, it means that he is not in use now.

Depending on the bike model, carriages differ in size and maintainability. The most common are 68mm knots, but other diameters can also be found. Carriage shaft length range: 110mm, 113mm and 122.5mm.

  • cartridge (disposable);
  • collapsible to be repaired.

The first type includes carriages that are installed in the frame and cannot be disassembled. Obviously, the service life of such a mechanism is equal to the time of complete wear of the bearings or axle. Full sealing of the unit allows you to operate it for a long time even in extreme conditions, not to mention measured driving.

Collapsible mechanisms will require periodic inspection and maintenance from the owner. The latter consists in replacing worn bearings and lubricating the entire assembly. We will just talk about them further: how to remove the carriage, eliminate the malfunction and reassemble the assembly.

Bicycle bottom bracket design

Before proceeding with the direct repair, you should consider what a carriage is and what design features it has.

The bottom bracket is an element located in the middle of the frame along with the pedals and sprockets, as well as the connecting rods. The main purpose is to connect the connecting rods to the skeleton of the bicycle, due to which the transmission of torque is ensured.

The carriage may vary significantly. Among the features, we note the following:

  • The most widespread is the knot of 68 millimeters. It fits many bikes.
  • Carriage shaft length range is 110mm, 113mm, 122.5mm.

There are several different carriage assemblies, the most common are the following:

  • Collapsible. This design is characterized by the fact that it can be disassembled for maintenance or repair.
  • Cartridge or disposable. This option is much cheaper, but even with an insignificant breakdown, you have to carry out a complete replacement.

Carriage repairs may include:

  • scheduled carriage maintenance (lubrication and bulkhead);
  • elimination of the carriage backlash;
  • tight rotation of the carriage axis;
  • extraneous sounds in the area of ​​the carriage assembly.

How to remove the carriage from the bike, how to disassemble and repair the carriage with your own hands

You will need a tool to remove the carriage.

A bicycle, like any other type of movement, requires maintenance, which can be performed both in specialized workshops and at home using a special tool. Today we will talk about the repair (maintenance) of the carriage, which includes disassembly, lubrication, installation and adjustment of the bike carriage.

As discussed in the previous article, a bicycle bottom bracket is a bearing assembly that connects the crank arms to the frame and provides a torque function to the crank arms. The carriage is located in the bottom bracket of the frame, which is located between the down tube and at the intersection of the chain stays. Because the bottom bracket is located at the very bottom of the bike and when the bike is used throughout all seasons of the year, it is often exposed to external influences, i.e. saws, dirt, moisture, etc. Over time, in the area of ​​the bottom bracket crunching, backlash, clicking can occur and the carriage begins to go out of its usual work. the smoothness and accuracy of work decreases, sometimes even jamming can occur. All of this can be corrected with carriage maintenance.

Closed-type carriages (cartridge) cannot be repaired, therefore, if problems arise with this type of carriage, it simply changes to a new one. But the carriages of an open type (collapsible) lend themselves to maintenance, since they are a shaft (axis) that rotates with the help of bearings that are installed in the carriage cups and screw directly into the carriage cup of the bicycle frame. Therefore, they can be easily removed, lubricated, replaced bearings and reassembled, or simply replace the old carriage with a new one.

Removing the carriage from the bike and maintaining it

In this article, we will cover the maintenance of Shimano open bottom bogies. The carriage can be with loose bearings, so when removing it, be careful, as the balls can scatter in different directions, as well as in the form of a non-separable cartridge.

In order to remove the connecting rods from the carriage axis, we need a connecting rod squeeze. The squeeze consists of two components: the right side is for squeezing the connecting rod from the carriage axis, and the left side is for removing the connecting rod fixing bolt.

First of all, we unscrew the connecting rod tightening bolts or, in other words, the screw. which are located at the end of the carriage shaft using a pedal wrench. In some cases, these screws can be hidden under plastic covers, which can be easily removed with a flat screwdriver.

disassemble, bike, bottom, bracket

After removing the fixing bolts, using the squeezing of the connecting rods, we screw the puller with the threaded part into the connecting rod until it stops, but here you need to tighten it progressively and without much effort so as not to break the thread. We remove the connecting rod from the carriage axis and wipe the seats. After removing the connecting rods from the carriage shaft, you need to remove the carriage itself, for this you need a shimano carriage puller.

If you have a different carriage type, you will need other carriage pullers. In addition to the puller for shiamno, there is also a puller for integrated carriage cups and is suitable for HOLLOWTECH II, GXP, Howitzer. Another ISIS Bottom Bracket Puller with 8 Splined Puller Mount and is suitable for Shimano, Truvativ and SRAM. All types of pullers can also be equipped with handles, and you do not need an adjustable wrench.

When unscrewing the carriage, it must be remembered that the carriage must be removed from the left side, that is, from the side where there are no stars on the connecting rod. We take a puller, insert it into the carriage slots on the left side and turn it counterclockwise with an adjustable wrench. It is very important to avoid any distortions of the stripper when unscrewing the carriage cups, so as not to damage the cup itself and the stripper.

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You need to twist until the carriage cup unscrews. After that, we perform similar actions on the right side, only here you need to take into account the fact that you need to turn clockwise. After the performed actions, the bicycle carriage will be removed. When replacing the carriage, the old carriage can be thrown away and the new one can be put in. When servicing the carriage, the bearings can be simply replaced with new ones.

After the carriage has been removed, it is necessary to check the carriage cup for dirt, sand and other things that could get there, both through the carriage and the seat tube of the bike.

To service the carriage of a collapsible type, we take the carriage cups and check the condition of the bearings. Carefully wipe the bearings and seats from the old grease and what remains of it with a clean rag. The carriage threads can be flushed using kerosene, gasoline or WD-40. Wipe dry with a rag. After that, we take any thick grease and grease the seats with a small amount and, putting the bearings, add a little more grease. However, collapsible carriages are short-lived and require frequent maintenance and bearing adjustments.

If the carriage is non-separable (cartridge type) and you have any problems with it, then it is better to replace it with a new one. To buy a new carriage, you need to know the shaft length, width (68 or 73 mm) and the type of connection with the connecting rods.

If you have an integrated carriage, then you can change the bearings by replacing the seals. To check the condition of the industrial bearings, remove the boot and see the old bearings. They can be removed with a special puller for internal bearings or disposed of with a hammer and chisel (not recommended). We clean and lubricate the seat, after which we put new industrial bearings.

How to Remove a Square Taper Bottom Bracket

Before installing the carriage, wipe and lubricate all threaded connections.

Bicycle bottom bracket installation

When assembling the carriage, the main thing is to place the cups correctly. Let me remind you that they have different threads, namely, the right cup has a left-hand thread, and the left one has a right-hand thread. Before installing the carriage, grease the carriage cup, bearings and cup threads with grease. The assembly of the carriage must be started from the right side. To begin with, we insert the carriage axis into the right cup and twist it with a carriage puller, and then the left one until it stops. After the carriage cups have been screwed in, it is necessary to check the carriage for any backlash (the carriage should rotate easily and silently). To do this, we twist the carriage axis in different directions. Be careful and make sure that the cup runs smoothly along the thread, as it is very easy to damage it. We put in place the connecting rods and fixing screws.

Types of connection of carriages and connecting rods

There are several generally recognized types or standards for connecting bogies and connecting rods:

  • SQR. square;
  • Truvativ Howitzer;
  • Truvativ Powerspline;
  • Truvativ HammerSchmidt;
  • Shimano Octalink v. 1;
  • Shimano Octalink v. 2;
  • GXP;
  • ISIS Drive;

Bicycle carriage repair

Bicycle bottom bracket is a characteristic structural element. The muscular efforts of a person rotating the pedals (more precisely, the cranks) are transmitted through the chain drive to the drive wheel of the bicycle precisely through the pedal carriage (front carriage or just the carriage).

Bicycle bottom bracket is a characteristic structural element. The muscular efforts of a person rotating the pedals (more precisely, the cranks) are transmitted through the chain drive to the drive wheel of the bicycle precisely through the pedal carriage (front carriage or just the carriage).

The carriage is a block of bearings that is attached to the frame and transfers torque from the connecting rods to the sprocket of the chain drive. The bottom bracket is located at the bottom of the frame in the bottom bracket at the intersection of the bottom tube and chainstays.

The rear wheel carriage is a different assembly with a different purpose, which is sometimes also called a carriage, which is not entirely accurate. It can be removed from the bike along with the entire wheel as an integral part of it. The rear carriage of the bicycle has a different design: it consists of a bearing block, a package of chain gears and serves as a hub for the rear wheel.

Carriage sleeves are available in a number of standard sizes. The most common glasses are 68 mm long, the BSA type for mountain bikes is 73 mm, for especially loaded carriages. 83 mm, the Italian type. 70 mm, used on Soviet road bikes, 100 mm. for fat bikes. The carriage shaft length has the following most common dimensions (mm): 110,113,118.5, 122.5 and 127.5.

Carriage types

Structurally, carriages are divided into open and closed (cartridge).

The closed carriage is a dust and moisture resistant bearing block. cartridge mounted in its own housing. The main advantage is that the faulty carriage is simply replaced with a new one. These carriages cannot be repaired. In operation, they are unpretentious, do not require adjustment, bearing misalignment is excluded, reliably protected from dirt.

The open-type carriage is assembled directly in the carriage glass of the bicycle. Almost any old bike has this type of bottom bracket. To ensure the normal operation of the carriage and dirt protection, competent assembly and adjustment is required. Maintenance of the open-type bicycle carriage consists of periodically flushing it and changing the bearing grease. The bearings themselves. two types: separator or closed. Separator bearings are the most vulnerable in operation; for them, the carriage shaft serves as the inner ring, and the carriage cup serves as the outer ring. If a crunch and increased resistance appear during operation, then it is time to change the bearings; for a cage bearing, this can also mean changing the shaft or the bottom bracket. Sealed bearings can be easily replaced with new ones.

According to the level of versatility and interchangeability, carriages are conventionally divided into integrated and non-integrated.

Features of carriage repair

Mountain bike carriage repair differs from road bike carriage repair only in nuances. Mountain bikes are designed for relatively high dynamic loads.

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In general, repairing a bicycle carriage is not a technically difficult task, since special high-precision measuring equipment and machine tools are not required. It is important to correctly determine the parameters of the carriage and purchase the corresponding spare parts or assemblies. In particular, to replace an integrated carriage, as a rule, you only need to know its manufacturer (standard) and the length of the carriage glass, and for models 73 and 68 mm (English thread) the same carriage is used.

When repairing a non-integrated carriage, the procedure is as follows:

  • determine the required carriage standard (square or spline);
  • determine the parameters of the carriage glass (length, type of thread);
  • check the operating manual for the front derailleur for the permissible chainline;
  • the front carriage of the bicycle must have a certain shaft length. take from the instruction manual;
  • purchase a carriage of the required standard, with the required shaft length and for the required glass length;

If the front derailleur is E-Type, then it is required to search for the corresponding non-integrated carriage, while the integrated carriages are compatible by definition.

Carriage assembly repair. A guide on how to repair or service your bike yourself at home.

To disassemble the carriage assembly, you must first remove the crankset with stars. On walking bikes and inexpensive mountain bikes, a conventional carriage assembly is installed:

We unscrew the lock nut on the left side (for the key, see fig.):

We turn off the carriage cup on the left side (key 16):

ATTENTION: On the left side there is a right-hand thread, respectively on the right side a left-hand thread.

If necessary, unscrew the cup on the right side (key 32):

Taking out the parts of the carriage assembly. it is recommended to flush and clean the carriage tube, especially the thread.

We wash all the parts (gasoline, kerosene), evaluate the integrity of the bearings, cups and carriage axle. Replace unsuitable parts if necessary.

Next, we do the reverse operations: screw in the cup, on the right side (left-hand thread) until it stops.

We put grease (lithol). We put bearings on the axle and insert it (for the location of the bearings, see the figure above).

We screw in the cup on the left side (right thread), until the rotation of the axis stops, then we turn the cup until the axis starts to rotate without experiencing any, even small, efforts (there should be no backlash).

We check the rotation and absence of backlash of the carriage axis. Repeat steps 9-10 if necessary.

How to repair and maintain a carriage

With regular maintenance of the carriage, its service life is significantly extended. Much depends on how much dirt gets into the structure. With a negligent attitude towards the vehicle in use, the wear of parts is significantly accelerated.

Oftentimes, the carriage of a bicycle is lubricated without disassembly. If the bike belongs to the category of expensive, it is better to give it to specialized workshops, where they will be able to properly disassemble and assemble the carriage, as well as select the right amount of oil. During service, the item will be checked for defects.

A solvent is used to clean the surfaces. Use a soft cloth to clean the inside of the carriage well.

Lubricating the bike bottom bracket without disassembling

Not all cyclists are well versed in the structure of a two-wheeled vehicle. For example, if carriages break, many have no idea what can be done to correct the situation.

Removing Cranks and Bottom Bracket

The study of the design of this element allows several times to increase the service life.

Features of the design of the bicycle carriage

A carriage is an element that sits in the middle of the frame along with sprockets, pedals and cranks. Its function is in the connection of the connecting rods with the skeleton of the vehicle, due to which the transmission of torque is carried out.

The carriages differ in the length of the shaft. Carriage assemblies can be collapsible, as well as disposable or cartridge.

How to disassemble a bicycle bottom bracket

To disassemble the carriage on a bicycle, you will need the following tools:

  • A set of keys.
  • Extractor for connecting rod.
  • A hammer.
  • Flat screwdriver.
  • A puller with which the glass is removed.
  • Prepare the workplace, tools.
  • Remove dirt from the elements with a soft cloth.
  • Remove the plug from the connecting rod.
  • Unscrew the nut with which the connecting rod is fixed to the carriage.
  • A squeezing tool is put on the fastener.
  • Removing the connecting rod.
  • The cup that fixes the carriage is removed.
  • The bearing is removed with a screwdriver.
  • The carriage shaft is pulled out using a special tool.
disassemble, bike, bottom, bracket

After the carriage is removed, you will need to install a new assembly. In this case, it will be necessary to add a lubricant in the required amount to the friction zone. Otherwise, the item will not last long.

How can you tell if the carriage is faulty?

You can find out about the malfunction of this element by rotating the bicycle pedals. It is difficult to visually determine the breakdown. It is worthwhile to be wary if during movement the parts emit unusual noise, there are difficulties with control when driving at high speed.

If there is a backlash, it is possible to suspect a misalignment of the axles, damage to the bearings.

Bicycle bottom bracket lubrication and assembly

For proper lubrication of the mechanism, the following instruction is offered:

  • Using a screwdriver, the walls of the glass are processed.
  • An even layer of lubricant is applied.
  • Grease is applied to the bearing.
  • The bearing element is lubricated. the carriage shaft.

When all the elements are thoroughly lubricated, it’s time to move on to assembly. Its order is as follows:

  • Insert the bearing backwards.
  • Lubricate the inside of the cup.
  • Thorough tightening is carried out until the backlash is eliminated.
  • Connecting rods.
  • Plugs inserted.

If the owner of the bike knows the construction of the carriage well, it is possible to disassemble it and assemble it yourself. But it is worth knowing that at the slightest error, the strength of the element turns out to be reduced. Therefore, in the absence of experience, it is better to entrust the vehicle to specialists.