How to disassemble the bottom bracket on a forward bicycle


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 ūüôā Now the carriage has become much more complicated. Let’s try to deal with this tricky thing.

bottom, bracket, bicycle

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.

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 out the dirt from the slots of the cups. if there is a lot of dirt, then it is impossible to insert a stripper into the cup.

Removing the carriage may require considerable force. 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. with a key (if it is not there, then you can also use an ordinary family member). This nut has a right hand thread. It may be necessary to apply considerable force when unscrewing. 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 photos show the slotted one.) Insert it into the slots, 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)

Move 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.

How to Take Apart and Service the Bottom Bracket on a Bicycle

We start by applying a little grease 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 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.

How to Remove and Install Bottom Brackets. Threaded Shell (BSA, T47, Cartridge, etc.)

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 connecting rods and the system.

Integrated carriages

They 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 by 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.

  • Shimano Compatible:
  • Shimano Hollowtech II
  • Hope
  • RaceFace X-Type
  • Token
  • Chris king
  • FSA Mega Exo
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  • Compatible with SRAM, Truvativ, Bontrager:
  • GXP (GigaX Pipe)
  • Hope (via proprietary adapter)
  • Chris King (via proprietary adapter)
  • Campagnolo ultra-torque.
  • 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.

    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.


    Recently, integrated systems such as BB30 / Press-fit are gaining popularity. The design feature is that the 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.

    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): cup inner 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.

    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 shifting accuracy 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, it is necessary 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. Turn the left cup almost all the way so that the carriage axis rotates easily, without jamming, and at the same time has no backlash. Then we loosen it with a slotted wrench by 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 turn the axis of the carriage by hand, and shake it from side to side. If everything is done correctly, then 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.

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    Sometimes the carriage cannot be adjusted. That is, when you try to make it rotate freely, then there is a backlash. And vice versa, 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.

    Removing the carriage from the bike

    Next, we will consider the process of removing the carriages using the example of a Shimano open bottom bracket.

    When removing the carriage, you need to be careful, since it can be with loose bearings, which, when removed, can fly apart in different directions.

    To remove the connecting rods from the carriage axis, you need a tool such as a connecting rod squeeze. This tool has two functions: its right side is intended directly for squeezing the connecting rod from the carriage axle, and the connecting rod fixing bolt is removed through the left side.

    First, using a pedal wrench, unscrew the connecting rod tightening bolts located at the end of the carriage shaft. Plastic plugs (if present) can be easily removed from the bolts using a standard flat-blade screwdriver.

    After removing the fixing bolts, proceed to the connecting rods. We take the squeeze of the connecting rods and screw the puller with the threaded part into the connecting rod until it stops. It is very important not to overdo it with pressure, so as not to disrupt the thread. Having successfully removed the connecting rods from the carriage axis, do not forget to wipe the seats.

    How To Overhaul A Bike Bottom Bracket. Remove/Clean/Install New Bearings

    Then, using a special puller, we remove the carriage itself. In our case, we are using a Shimano bottom bracket puller. A suitable puller is available for each individual carriage model. So, for Hollowtech II, Howitzer, GXP carriages, a puller for integrated carriage cups is used, and for Shimano, SRAM and Truvativ carriages, a so-called ISIS standard carriage puller can be used. It is worth noting that the set of pullers often includes handles, which frees you from the need to additionally use an adjustable wrench.

    It is important to know that the carriage is removed only from the side where there are no stars on the connecting rod, that is, on the left.

    So, we insert the puller into the carriage slots on the left side and twist it with a handle or an adjustable wrench counterclockwise. In the process, you need to ensure that there are no distortions of the puller. Otherwise, he or the bowl itself may be damaged.

    After the carriage bowl is unscrewed, you need to perform the same actions on the right side. Only in this case you need to turn the handle clockwise! As a result of such simple actions, the carriage will be removed and ready for service or replacement.

    Want to see how to remove the crankset and bottom bracket? Watch the video review:

    Open carriage

    The latter, in turn, are screwed directly into the bottom bracket of the bicycle frame. This type of carriage is serviceable and can be easily removed, lubricated, sorted out and reassembled. If necessary, it can also be replaced with a new one.

    Maintenance of a bicycle carriage means disassembly, lubrication of its parts, installation and adjustment.

    Closed carriage

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

    Non-separable carriage service

    If problems arise with a carriage of this type, it is replaced. When choosing a new carriage, it is important to know the length and width of the shaft, as well as the type of connection with the connecting rods.

    Maintenance of bicycle carriages

    After removing the carriage, check the condition of the carriage glass for contamination.

    Bicycle carriage maintenance

    The bottom bracket is a bicycle bearing assembly that connects the crankset to the frame. Thanks to the bearings inside the carriage, the system can rotate freely. Through the carriage, the torque from the pedals is transmitted to the bicycle wheel.

    The carriage is located in the carriage glass of the frame, where it is either screwed in or pressed in. Because the bottom bracket is located at the very bottom of the bike (between the down tube and at the intersection of the bike chainstays), the bottom bracket itself is highly susceptible to dirt. Such a negative external influence over time affects its work: crunching, clicking, backlash, jamming occur. To prevent these negative consequences and exclude the possibility of carriage failure, it is necessary to regularly carry out its maintenance.

    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.

    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.

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    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.

    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.

    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.

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

    Bicycle carriage repair (maintenance)

    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 ‚Äč‚Äčthe 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.

    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 ‚Äč‚Äčthe carriage assembly.

    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.