How to Assemble the Rear Bottom Bracket on a Bicycle

Cycle days. Not a day without a bike!


The homemade carriage on the bike 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.

Integrated carriages

Are part of an integrated system. They are two cups with bearings pressed into them, screwed into the bottom bracket of the frame. In this case, the bearings, as a rule, are located outside the carriage sleeve, and the axle is pressed into one of the connecting rods and has a greater thickness, which achieves a high rigidity of the assembly. The cups are interconnected with a plastic or aluminum spacer that provides bearing preload and protection from dirt.

Road and mountain carriages, as a rule, are incompatible with each other, even from the same manufacturer.

Integrated carriages standards:

  • Shimano Compatible:
  • Shimano Hollowtech II
  • Hope
  • RaceFace X-Type
  • Token
  • Chris king
  • FSA Mega Exo
  • SRAM, Truvativ, Bontrager compatible:
  • GXP (GigaX Pipe)
  • Hope (via proprietary adapter)
  • Chris King (via proprietary adapter)
  • Campagnolo ultra-torque.
  • 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 are a single non-separable unit.
    • Dismountable. can be disassembled for cleaning, lubrication and replacement of worn parts (used in old bicycles).

    Non-integrated carriage standards:

    • Wedge-fit connecting rods (Soviet bicycles).
    • Under the square (square taper). the standard “floats” somewhat from different manufacturers.

    SQR. square connection

    • With spline fit of connecting rods:
    • Shimano Octalink v.1
    • Shimano Octalink v.2
    • ISIS
    • Truvativ Powerspline
    • Truvativ Howitzer
    • Truvativ HammerSchmidt

    Octalink. Shimano standard

    All of these standards are generally incompatible with each other.

    Types of carriages according to the used carriage glass

    Threaded fit

    Depending on the carriage glass of the frame, carriages are divided into the following types (the most common):

    • English thread (BSA, 1.37 in x 24 TPI) is the most common standard. Options depending on the length of the glass:
    • 68 mm. most common,
    • 73mm. used on a range of mountain bike models,
    • 83 mm. for extreme disciplines,
    • 100mm. fat bikes.
    • With Italian thread (BSC, 36 mm x 24 TPI), tube length 70 mm. used in old road bikes. Still (2013) in use by Campagnolo.
    • With French / Swiss thread M35 × 1. used in Soviet bicycles.


    Recently, integrated systems such as BB30 / Press-fit are gaining popularity. Design feature. bearings are pressed directly into the frame (plastic cups can be used), an aluminum axle with a diameter of 30 mm is threaded through them (instead of a steel one with a diameter of 24 mm). This promises a further increase in the rigidity of the knot with some weight reduction. On the other hand, bearing replacement tools are significantly more expensive than conventional carriage pullers.

    Press-fit carriage

    Classic Press fit for BB30 30mm axle systems:

    • BB30: cup inner diameter 42mm, cup width 68mm for highway or 73mm for MTB, bearings without cups.
    • Press fit 30 (PF30): inner cup diameter 46 mm, cup width 68 mm for highway or 73 mm for MTB, bearings with cups.
    • Press-fit carriages for standard systems with 24mm steel axle:
    • BB90 / 95: cup inner diameter 37 mm, cup width 90.5 or 95.5 mm, bearings without cups.
    • BB86 / 92: cup inner diameter 41 mm, cup width 86.5 or 91.5 mm, bearings with cups.
    • Unique standards requiring their own 30 mm axis system:
    • BBright Direct Fit: cup inner diameter 42 mm, cup width 79 mm, bearings without cups.
    • BBright Press Fit: Cup Inner Diameter 46mm, Cup Width 79mm, Bearings With Cups.
    • 386 EVO: bowl inner diameter 46 mm, bowl width 86.5 mm, bearings with cups.

    Features of carriage selection

    • When buying an integrated carriage, as a rule, you only need to know its standard (that is, the manufacturer of the system) and the length of the carriage glass, and for the most common varieties of 68 and 73 mm with English threads, the same carriage is used.
    • In the case of a non-integrated carriage, everything is much more complicated. The procedure is as follows:
    • First you need to find out the required carriage standard (square or one of the spline).
    • Find out the type of carriage glass (length, type of thread), and depending on the length of the glass (usually 68 or 73 mm), different carriages are required!
    • Refer to front derailleur manual for permissible chainline.
    • Refer to the system manual for the required carriage shaft length.
    • Find on sale a carriage of the required standard, for the required glass length and with the required shaft length.
    • If an E-Type front derailleur is used, then you need to look for a non-integrated bottom bracket of the corresponding variety, while all integrated ones are compatible with such derailleurs initially.

    Eccentric carriage

    Allows the use of a drive without external gear shifting (singlespeed, planetary hub) in conjunction with conventional vertical frame dropouts. These dropouts provide a faster and more comfortable wheel positioning compared to horizontal ones. The eccentric carriage is rotated 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 BSA thread for standard BB, requires special frame with 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 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. tells in great detail about the repair of carriages and how and how they can be removed. Let’s deal with this issue too.

    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 is 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. Use the gas wrench 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. you can damage the bike parts or injure your hands. Therefore, it is better to stock up on keys with sufficiently long handles.

    Removing the carriage of cartridge and collapsible types

    Before removing the carriage from the frame, both connecting rods must be removed from the carriage axis. The bottom bracket should then be cleaned of any dirt, as the frame bottom bracket is one of the dirtiest areas on a bike and is usually difficult to clean until the cranks are removed. Especially carefully it is necessary to scrape the dirt out of the cup slots. if there is a lot of dirt, then it is impossible to insert a stripper into the cup.

    It may be necessary to use considerable force when removing the carriage. Therefore, the bike must be securely positioned. If it is more convenient for you, you can turn it upside down.

    We begin to remove the carriage from the left side, that is, where there are no stars.

    Some carriages have a lock nut on the left side. It must be turned off special. key (if it is not there, then it is possible with an ordinary family member). This nut has a right hand thread. Unscrewing may require considerable force. It is necessary to unscrew carefully, not allowing the key to break off. you can damage the nut.

    If your carriage does not have such a nut, then go to step 2.

    Now we take the key for the carriage (slotted or special, depending on the design of your carriage. The pictures show the slotted one.) Insert it into the grooves, and turn the left adapter cup out of the frame with an adjustable wrench with a longer handle. It has a right hand thread. Unscrewing may require considerable force.

    We take out the left cup (together with the bearing, if the carriage is collapsible)

    We pass to the right side of the bike (where the sprockets are). Again we take the carriage puller and the long-handled key, insert it into the grooves, and turn the right cup out of the frame. It has a left-hand thread. Unscrewing may require considerable force.

    We take out the cartridge or the right cup with the axis.

    The carriage is removed. Now you need to pull out the bearings from the collapsible carriage (if they are not pressed into the cup), remove the old grease with a rag, and rinse all the parts in some kind of solvent (usually kerosene).

    Installation of the cartridge-type carriage is performed in the reverse order of removal.

    We start by applying a little lubricant to the carriage and adapter cup threads, so that later it will be easier to turn it out.

    We start on the right side. Using the carriage wrench and an adjustable wrench, screw the carriage into the frame until it stops. The moment should be 50-70 Nm.

    The carriage on the right side has a left-hand thread.

    We pass to the left side. Use the same key to screw in the left adapter cup. The cup on the left side has a right-hand thread. The moment should be the same. 50-70 Nm.

    Now you need to install the rods and the system.

    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 BB for damage and any debris. Several times I found shavings there, sawdust, 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.

    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.

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

    We put the 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 thick grease With the same grease we lubricate 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 adjust the carriage. (you can go directly to step 1)

    Adjusting the split carriage bearings

    After assembly, the carriage must be adjusted, but often it is necessary to adjust without disassembly. For example, sometimes after a long drive on uneven roads, a play appears in the carriage, which should be eliminated by adjusting. Backlash in the bottom bracket can, at best, lead to poor shift quality and, at worst, damage to bearings and cups. On a long trip, you can try to adjust the carriage without disassembling.

    Before starting the adjustment, you need to remove only one left connecting rod, remove the lock nut (with a special wrench) and slightly loosen the left cup (with a slotted wrench). The nut and the left cup have a right hand thread. 1. We turn the left cup almost to the stop so that the carriage axis rotates easily, without jamming, and thus has no backlash. Then we loosen it with a slotted wrench about a quarter of a turn. Screw on the lock nut while holding the cup with a slotted wrench. We tighten the nut special. key all the way.

    Now you need to rotate the carriage axis by hand, and shake it from side to side. If everything is done correctly, the carriage should rotate freely, without jamming, and not have a noticeable backlash. If it sticks, or there is a backlash, then unscrew the lock nut, and repeat step 1, loosening or tightening the cup with a spline wrench.

    When the carriage rotates without jamming and backlash, you can put the connecting rods.

    Sometimes the carriage cannot be adjusted. That is, when you want it to rotate freely, then there is a backlash. Conversely, if you eliminate the backlash, then the axis rotates tightly, with jamming. This suggests that it is time to change either the bearings or the carriage itself.

    Carriage: 7 comments

    Thanks, helpful article

    Tell me how to use the key for the Bike Hand YC-155 carriage (see the photo in the article). I bought one, but I don’t understand how to use it. It slides off and does not fix in the grooves

    This amount of grease on bearings can increase the mass of a carbon bike by 10%! :))

    And in especially severe cases, by 11.5%;)

    There is at least one type not listed here yet. Shimano’s HollowTech. It is somewhat similar to the collapsible carriage described here, but everything is much simpler and more reliable.

    Good afternoon, tell me how to choose the length of the carriage axis for stars 37, for example, I put 127.5 and 122.5 ?

    Good day! Can you please tell me how you can replace the bubo type carriage on a MMVZ bike? there is no thread on the seat 🙁 found on prom bearings but under a wedge. but I want connecting rods for a square !

    How to change bearings on a bicycle. Maintenance and replacement of carriage bearings

    Periodic cleaning, lubrication and replacement of worn parts will help avoid sudden problems with cycling. Signs of a faulty carriage condition:

    • “Clamps” in the pedals. difficult rotation or cranking;
    • connecting rods dangle;
    • crunches.

    To remove the connecting rods and carriage cups, you will need special tools. pullers and an internal hex wrench. The dismantling process is as follows: 1. Turn over and fix the bike.

    Unscrew the retaining nuts with a hollow wrench. You can also use a hammer with a chisel, however, the nuts must be knocked out carefully so as not to damage the connecting rods.

    Using a puller, twist them off the axis. It will take considerable effort here.

    Pull the cups out of the glass with a carriage puller. The first is to unscrew the cup from the side opposite to the stars. Then remove the axle.

    Remove bearings, inspect and replace damaged parts.

    Clean in kerosene, refit and lubricate. When installing, carefully monitor the position: on one side, the bearing is placed with balls outward, on the other. inward.

    After replacement, cleaning and lubrication, reassemble the carriage in reverse order. After tightening the connecting rods, check their rotation: the lack of effort and cranking indicates that you need to tighten the cups, and vice versa. In these cases, you will have to repeat the disassembly and adjustment.

    Prom bearings are installed immediately, no adjustment required.

    Front fork damping system

    It is the presence of a shock absorber that allows the biker not to pay attention to obstacles and makes the bike passable. A good shock absorber resists the reaction of the support to the front wheel in a timely manner, so the fork must be kept in good condition

    How to lubricate shock absorbers

    Normally, it is necessary to lubricate the “legs” of the plug after 150-200 kilometers, after 700 kilometers (on average) the oil seals are disassembled and lubricated, and annually or after running 3-4 thousand kilometers. the oil in the shock absorber is completely replaced.

    It is better to show all the care of the fork in the video than describe it in detail in text. For example, here you can see all the preventive maintenance operations for the front fork and shock absorbers:

    Replacing wheel hub bearings

    The hub is not just a wheel pivot. Without the built-in articulation mechanism, forces would be transmitted unevenly to it, and the bicycle would not be able to move. The same symptoms appear when the bearings are worn.

    Disassembling the hub is as easy as disassembling a fork. For the rear wheel, the procedure will be slightly more complicated than for the front wheel, since you will first need to remove the sprocket cassette. On a single-speed bike, the retaining ring and the sprocket itself are dismantled.

    In general, disassembly looks like this: 1. Remove the wheels from the dropouts.

    Dismantle the stars with a cassette puller and a locking whip. On single speed open the stopper with a screwdriver or a special spreader.

    Unscrew the fastening nuts with a 15 wrench. For the rear wheel hub, unscrew the nut on the side opposite to the stars.

    Pull out washers and bearing units. Bulk ones are being moved, industrial ones are being replaced by new ones.

    Clean parts and replace damaged components.

    Pull out the axles, wipe the inner cavities of the bushings.

    Reassemble in reverse order

    It is important to place the bearings correctly and press the cones in the same way as before disassembly. In no case should it be skewed, the details should fit exactly into their rightful places

    It is not advisable to swap them during a bulkhead. This threatens with backlash and deterioration of wheel travel.

    New bearings are selected in advance according to the old ones. they must be the same as they were before the repair. Lubrication is the key to rebuilding and replacing (in the case of “bulk”). When installing the “flush”, the assembly itself does not need to be lubricated, only the inner cavities of the bushing and the axle. After installation, we check the performance of the wheels: smooth running without play and clamps indicates that the parts are installed correctly.

    Bicycle bearings

    In this article, we will analyze what are the bearings used in a bicycle, and how they differ from each other.

    Basically, a bearing is a product that is part of a support or stop that supports a shaft, axle or other movable structure with a given stiffness. It also gives an easy rotation of the bicycle mechanisms, ensures the operation of its main units, a clear fixation of individual parts.

    According to the principle of operation, all bearings used in a bicycle can be divided into three types:

    • Rolling bearings
    • Plain bearings
    • Ceramic bearings

    Rolling bearings consist of two rings, rolling bodies (of different shapes) and a cage separating the rolling bodies from each other, holding them at an equal distance and directing their movement. Bicycle rolling bearings are divided into two types:

    bulk (“cone-cup”) and industrial (non-separable (“cartridge”)).

    Each type has its pros and cons.

    The advantage of bulk bearings is their simplicity and the ability to adjust them. Unfortunately, the latter quality is also a big drawback, since the possibility of adjustment obliges you to perform it regularly. Adjustment is carried out using a flare nut. With its help, the clamping force is selected. Bulk (“cone-cup”) is a set of balls that roll on a cup, removable or pressed into the body of a part.

    You need to be careful, because if the force is too weak, the bearing will have a play, and if the force is strong, the wheel does not spin well (this can lead to rapid wear of the bushing and poor roll-up).

    Industrial bearings (non-separable (“cartridge”)) are a non-separable unit with two rings between which balls roll. Such bearings are pressed into the seat and can be replaced if necessary. Industrial bearings generally do not require adjustment.

    The downside of industrial bearings is the higher price (compared to bulk bearings). If dirt gets into the bearing, it will not be possible to fully wash it. Most likely, a replacement will be needed. In this regard, bulk bearings have a complete advantage. even in the field, they are easy to wash and lubricate.

    Both types of industrial bearings can use a cage that creates a gap between the balls and keeps them from falling out.

    A plain bearing is a support or guide of a mechanism in which friction occurs when mating surfaces slide. The design of such a bearing is a pair of rubbing materials that have a low coefficient of friction.

    Over time, a material that wears out softer and a backlash occurs, then the part needs to be replaced (most often its design provides for replacement). These bearings are used in the construction of inexpensive pedals as well as rear derailleur rollers.

    Plain bearings require regular overhaul and replacement of worn elements; they are widely used in assemblies that do not experience heavy loads and impacts and in assemblies where there is no requirement for backlash.

    The most common type of such bearings is mixed or hybrid, in which only balls (or other body of revolution) are made of ceramics, and both rolling rings are made of steel. This is the most common option in the cycling industry. Cage in hybrid ceramic bearings made of low friction synthetic materials.

    There are also bulk ceramic (ceramic balls are used) and plain bearings (for rear derailleur rollers).

    Such bearings have several advantages:

    They can work at high temperatures, which, of course, increases the speed of work. Ceramics are not subject to corrosion, as well as aggressive acid and alkaline environments. It does not magnetise, does not transmit electricity, it has higher elasticity and hardness. All characteristics of ceramics are superior to steel. However, if you look at it, then in fact the gain is only in weight.

    Other advantages of ceramics over steel, such as resistance to aggressive environments or high operating temperatures on a bicycle, are not needed. Corrosion resistance is a big plus. But, to a greater extent, this applies to bearings made entirely of ceramics, mixed ones are still subject to corrosion. The cleaning frequency is the same for both steel and ceramic bearings.

    READ  How to Lubricate Bicycle Cables

    When buying bearings, remember that there are no good bikes without good bearings.

    Lack of lubrication, incorrectly selected or installed bearing can not only cause damage to the bike, but also lead to an accident and become a serious threat to its owner.

    “Don’t eat yellow snow”. the mountaineer’s rule

    Immediately upon disassembly, we make a defect. Fold the balls in groups of the left-right side. Cones too. It is highly advisable to pour the balls from the same side from which you took them. And tighten with the same cones. Because they have already got used to each other.

    If you saw yellow balls from one of the sides (or maybe from all sides), then do not reassure yourself that they are gold, bronze, or, at least, cadmium-plated. This says only one thing. On this side, water got under the boot and they got rusty. and this is the main reason to go over the bearings (50:30 is a wild jamb of cheap rear wheel hubs). And if they are rusted, then, most likely, they hooked and knocked the cone. Like mine:

    Corrosion has corroded the flare nut on the rear hub bearing, so it crunches

    New cones are on sale, are inexpensive. If possible, it is better to replace it. Otherwise, the balls will cover, and then the sleeve.

    How to disassemble and remove the bicycle carriage yourself

    • Bicycle bottom bracket: what is it and why?
    • Fault definition
    • Removing the carriage: doing it right!
    • Troubleshooting: maintenance, cleaning, replacement
    • Carriage Lubrication and Assembly

    Perhaps lovers of simple periodic bike reels are not familiar with this term, but those who often use a bicycle as a vehicle, and even more so, professionals in the field of cycling, are aware of what a bottom bracket mechanism is.

    Like any mechanism, this part over time is exposed to external influences, wears out or even becomes unusable, which requires maintenance, full or partial replacement. In any case, you first need to remove the carriage, establish the suitability of the part, and then decide whether to repair it or replace it with a new one.

    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 look? 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 bike frame 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, the 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.

    Types of carriage assemblies:

    • 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.

    Fault definition

    The fact that the carriage has become “buggy” can be found only when pedaling. Visually, knot problems are difficult to identify, so it is best to prick up your ears and move your attention to the area of ​​the lower frame. You should not listen too much, especially if you are driving on a busy road. However, if the state of the carriage is unimportant, it will “scream” about itself without delay.

    A faulty bottom bracket will prevent you from cycling quickly. Blocked dirt, worn bearings and lack of lubrication will continually impede movement. All this is accompanied by an unpleasant creak and a characteristic knock from below. Also, the unit may start to play (broken bearings and axle misalignment).

    You can finally check whether it is really worth disassembling the carriage using the “standing ride” method. To do this, you need to accelerate a little, get up from the seat and twist the pedals. When the carriage mechanism is jammed, the sounds and deterioration of pedal travel will only intensify.

    Removing the carriage: doing it right!

    It makes perfect sense to remove the assembly from the bike frame first to fix the problem. To be precise, take it out of the glass. Just about how to do it yourself, and the conversation will go.

    So, before proceeding with the removal procedure, you will need a set of tools:

    • Connecting rod squeeze.
    • Wrench. If the size of the nut is unknown, then an adjustable wrench will go.
    • Flat screwdriver.
    • Small hammer.
    • Carriage puller for removing from the glass.

    Before proceeding with disassembly, you should clean all the space around the carriage. A damp cloth removes all dirt and dust from the frame, bottom bracket area and connecting rods. This will be enough to prevent excess dirt from getting inside during parsing. But it will be better if you wash the whole bike. Cleanliness is the best repair assistant. Proven!

    Plugs are removed from the connecting rods. Basically, these are plastic covers that can be easily pry off with a screwdriver and are also easily inserted back. Next, you need to unscrew the nuts securing the connecting rods to the carriage. A squeeze will help in this matter: we put it on a nut, then we take the key and unscrew it. Depending on the type of thread, the direction of loosening and tightening the nuts may vary. There is an option where the thread is right on the left side (counterclockwise. loosening), and on the right side. left (counterclockwise. tightening). Maybe only right-hand thread on both sides, it won’t be difficult to figure it out.

    The next step is to remove the connecting rods. The squeeze is inserted at the other end and twisted into the connecting rod. The squeeze bolt is forcibly screwed into the connecting rod, as a result of which it gradually comes off the axis. It is recommended to start removal from the side where there are no transmission stars.

    The bicycle carriage is held by special cups fixed with rings. A screwdriver is attached to the ring so that its end points to the left. By lightly tapping the hammer on the screwdriver, the ring smoothly turns to the left and jumps off. Similarly, by turning to the left, using the shock method, the cup is also removed.

    So, finally we got to the bottom bracket bearings. These small parts can be removed with the same screwdriver: pry, and they will pop out.

    And, finally, a removable device pulls out the carriage shaft from the glass. a rotating part that plays a major role in the mobility of the bicycle cranks.

    Troubleshooting: maintenance, cleaning, replacement

    Disassembled the carriage, pulled it out of the frame and what do we see? The condition of the bottom bracket depends on how much dirt has got into it and how much the bearings are worn out. Sometimes the bearings simply shatter and require a complete replacement. This often happens if the carriage assembly has been in operation for more than three to five years.

    First, all parts must be checked for defects. This primarily applies to bearings. Then we inspect the carriages, cups with clamps. If any component has visible damage, then you need to change it to a new one. The rest of the parts are cleaned in a solvent. The most difficult thing will be to clean the bearings: dirt is very firmly adhered between the balls.

    The space inside the carriage glass is cleaned with a rag. Fine dirt is best sprinkled with a lubricating spray (WD-40, for example) and wipe the walls with a soft dry cloth.

    Carriage Lubrication and Assembly

    Using a screwdriver, the walls of the glass are processed. Apply the product in an even thin layer. No need to put grease inside the mountain. It’s useless. Then grease is applied to the bearing, which is inserted from the side of the stars. The flat frame should face outward. Then you need to lubricate the carriage shaft and insert it so that the long end is on the transmission side. In general, the carriage is assembled in the reverse order.

    The bearing on the other side is inserted in reverse, with a frame into the glass. The cups are lubricated from the inside and then put on. It is necessary to tighten until the axial play is completely eliminated. In this case, the rotation of the shaft should be slightly constrained. As soon as the fastening rings are mounted, the cup will move slightly and the axis will rotate freely.

    It remains to collect the connecting rods. The most important thing here is to put them on so that when pedaling, God forbid, they do not fall off. Procedure for Effective Connecting Rod Assembly:

    • The square is lubricated with a small amount of grease, this will help to push it deeper onto the axle.
    • Processing a screw with a thread lock.
    • Tighten the connecting rod nut with maximum effort until it stops. You can even lengthen the key. the thread will not break.
    • Inserting plugs.

    The carriage is assembled and ready for use. In general, the procedure is simple even for the first time, and in the future it will not be difficult to disassemble and install the mechanism.


    To repair a bicycle with your own hands, you need to have certain skills and knowledge. In this article, we will tell you how to repair the rear wheel hub of a bicycle, repair a bicycle carriage, and also tell you how to fix a puncture in the rear wheel of a bicycle on your own, and for novice cyclists, we will tell you what pressure in a bicycle tire should comply with.


    The most common problem that a bike’s rear hub can upset you is a loose or tight taper. If weakening is observed in the cone, then the wheel will begin to play strongly. In the second case, when the cone is tightened, the bicycle will move much more “tight” than in normal mode, and the bearings may crackle. One way or another, you need to repair the rear wheel hub of the bike as soon as possible.

    To eliminate the backlash or, on the contrary, tighten the cone, wrenches are needed, most often they use a 15 mm open-end cone wrench and a 17 mm open-end wrench. First, you need to start loosening the locknut, after which you need to proceed to loosening or tightening the flare nut to the required position.

    Ideally, there should be no backlash. Finally, the lock nut must be screwed into place. If the cone is adjusted properly, the wheel will turn easily due to the force of gravity acting on the reflector or nipple.

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    It also happens that the rear axle of the hub can be broken or bent. The main cause of such a malfunction is usually poor quality parts. If this happens, you need to completely replace the hub axle with a new, better quality.

    When replacing the axle, or when going through routine maintenance, or during the repair of the rear wheel hub of the bike, so that it is more convenient to dismantle the ratchet. If the essence of the repair is just tightening or loosening the cone, then this action is not necessary.

    To avoid possible damage, you need to periodically undergo maintenance. Its essence most often comes down to adjusting the cone and washing, cleaning the components and lubricating the bearings.

    Less often. they change bearings, oil seals or washers. The cost of repairs can result in high costs, in the event that maintenance was rarely carried out and in general the bushing was not particularly monitored.

    For example, it happens that the bearings “eat out” the grooves in the bushing housing, this can happen because the axle was bent or not lubricated enough. In this case, in order to repair the rear wheel of the bike, you will need to completely replace the hub body, and maybe the wheel itself.

    Therefore, in order to avoid such a situation, before going on a long bike trip, you need to carry out maintenance of your bike, and if problems are found, then fix them in a timely manner.


    One of the most difficult parts of a bicycle is the bottom bracket. What to do if on the way she let you down, and there is no one to ask for help? Everything is simple, and after reading the text written below, using the minimum number of tools, you can easily disassemble and repair the bicycle carriage.

    To disassemble the carriage assembly, the first step is to dismantle the stars and the connecting rod system. We will not dwell on this in detail, since it is not so difficult, and there is plenty of information on this topic on the net.

    On pleasure bicycles and inexpensive “mountaineers” the carriage of standard modification is installed. The disassembly procedure is shown below:

    • First of all, you need to unscrew the lock nut on the left using a special key;
    • After that, we remove the carriage cup on the same side, using a 16 key for this (note that the right-hand thread is cut on the left side, and the left-hand thread is similarly made on the right);
    • If necessary, you will also need to unscrew the cup on the right. This requires the use of a 32 key;
    • Now we take out the carriage assembly. It is best to immediately flush and, accordingly, clean the carriage tube, first of all, the thread;
    • Next, we are engaged in flushing the parts of the carriage assembly with gasoline or kerosene, along the way we look at the whole bearings, cups and axles. If necessary, you need to replace worn parts;
    • The next step is the same operations, only in reverse order: screw the cup to the right to the very end;
    • Now you need to thoroughly grease everything with grease (lithol), put bearings on the axle, and insert it into place;
    • Next, you need to screw in the cup on the left, until the axis stops rotating. And now the cup needs to be gradually released, until nothing interferes with the rotation of the axis, and it will be smooth. It is worth remembering that backlash is not allowed;
    • The lock nut should now be tightened;
    • We make a final check of rotation and absence of backlash. If this is necessary, then you need to repeat paragraphs 8-9.


    To begin with, it should be said that the repair of the rear wheel of a bicycle can be associated with the elimination of the “eight” on the wheel or the filling of the wheel hub. However, since these are specific operations that require certain experience and tools, they deserve separate consideration and will not be described in this text. Below we will tell you how to cope with a puncture of the rear wheel, since everyone can face this.

    assemble, rear, bottom, bracket, bicycle

    Before repairing a wheel, you need to dismantle it. The front wheel is easy to remove, but removing the rear wheel for a beginner bike enthusiast may not be such an easy task. Let’s take a closer look at how to dismantle the rear wheel.


    • If your bike has rim brakes, the first step is to unfasten them. This is done as follows: you need to heap the levers to which the pads are attached, and raise the part that secures the cable.
    • Now you should turn the bike over with the saddle down, so that it finds its support on the handlebars and saddle. If your bike has a headlight or bike computer, you should be careful not to damage them.
    • Next, we will loosen the eccentric of the wheel that holds the wheel on the frame.
    • Take a position behind the bike. Now you need to slightly unbend the lever in the rear gear selector, pull out the rear wheel, which should rise up without much difficulty.
    • All that remains is to remove the chain from the wheel sprockets. Now the wheel is disconnected.


    To gain access to the punctured tube, you will need to disassemble and remove the tire from the wheel rim. It takes some skill to do the sorting, so don’t be discouraged if you don’t get it right away. It happens as follows:

    • The wheel you removed must be placed upside down with asterisks.
    • Now you need to remove the nipple cap.
    • The next step is to cling to the edge of the tire with the help of the bead blade and turn out into the middle of the wheel.
    • After fixing the bead blade, you need to take another one of the same, and perform the same actions along the circumference, thereby disassembling the wheel completely.

    Since the tire has already been disassembled, it can already be easily removed, and the process of removing the camera will not complicate you at all.

    Glue the camera

    • First of all, you need to determine where the camera was pierced. To do this, the camera needs to be pumped up and examined carefully. A characteristic hiss will be heard at the puncture site. This place needs to be marked somehow.
    • Then you need to free the chamber from air by pressing the nipple tongue.
    • Your repair kit should have fine sandpaper, you need to take it and rub well the place where the tire pierced.
    • Now you need to apply the adhesive in a thin layer. This is done in such a way that the piece on which the glue is applied is slightly larger than the patch in size.
    • Let the glue lie down for a couple of minutes, and then you should glue the patch from which the protective film has been removed in advance. Be careful not to get air bubbles under the patch.
    • Now press the patch against the camera as hard and as long as possible.

    After gluing the inner tube, run your hand over the inside of the tire. It is not uncommon for the cause of the puncture to get stuck in the tire, and if so, then it must be removed. Don’t forget this moment.

    That’s it, the wheel is repaired.


    Cycling enthusiasts have always been worried about the question. how much should the tires be inflated? This is especially true for beginner cyclists who do not yet have special skills and cannot immediately tell how much pressure should be in the tires of a bicycle to ensure a comfortable and safe ride.

    In fact, there is no difficulty here. Most bikes have a tire pressure indication on their tire that best matches this particular model. Most often, the pressure range ranges from 2.38 to 4.08 atmospheres.

    These tire pressures are optimal when riding off-road or in the mountains. The volume of air in the tires of the “mountain” is quite a lot, therefore, there is no need to pump his tires.

    Also, do not forget that, given the low pressure and large volume, the pumping of the “mountain” wheels should be carried out no more than once a week.

    To determine the pressure to which you need to inflate the wheels of the bike, you just need to read the inscriptions on the tire. Tire manufacturers usually indicate the value of the upper and lower pressure limits.

    But unlike a mountain bike, tires in a road bike need to be inflated to a slightly higher pressure, since the volume of the wheels is small. The value of the pressure in the tires of the “road bike” should be in the range from 6.46 to 9.18 atmospheres. And the pressure check must be done daily.

    The traditional way of checking is to press the wheel with your fingers, and if it does not push through, then you can move on the road. Everyone did this when they were little. But it is better not to engage in amateur performances and just pump up the wheels, depending on the indicators that the pressure gauge gave.

    Bicycle tire pressures can also change depending on how much weight the cyclist has and what the road is made of. If the route of your trip consists, for the most part, of off-road, mountains or an ordinary rocky road, then pumped wheels are clearly not what you need.

    Lower tire pressure will allow you to worry less about bumps while driving, and maximize traction control, while it is easy to fall with inflated tires. But the situation changes on a good highway, where well-inflated wheels feel much better.

    If the tire pressure is too low (1.9. 2.17 atmospheres), then this is the cause of many problems. To begin with, the tire can break through from the slightest collision with a stone or bump, and if during this the camera is clamped by the rim, it will be punctured in several places and it will be almost impossible to repair it.

    In addition, there is also the likelihood of damage to the rim, and this, not only does it take a long time to repair, but also is expensive. And last, but most unpleasant. during a sharp turn, a tire with low pressure can come off the wheel, in which case both the rim and the cyclist will be damaged.