How to change the bottom bracket on a stealth bike

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 threads M35 × 1. used in Soviet bicycles.

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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). Nut and left cup have right hand threads.
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.

Sometimes the carriage cannot be adjusted. That is, when you want it to 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.

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 assembly, all parts must be rinsed in some solvent (kerosene), wiped with a cloth, and dried. 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 preserving.
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.

Types of carriages according to the used carriage glass

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.

How to remove a Specialized Levo and Kenevo Crank and Chain Ring

  • Shimano Compatible:
  • Shimano Hollowtech II
  • Hope
  • RaceFace X-Type
  • Token
  • Chris king
  • FSA Mega Exo
  • Compatible with SRAM, Truvativ, Bontrager:
  • GXP (GigaX Pipe)
  • Hope (via proprietary adapter)
  • Chris King (via proprietary adapter)
  • Campagnolo ultra-torque.
  • 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 splined).
    • 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 allowable 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 type, while all integrated ones are compatible with such derailleurs initially.

    Features of carriage selection

    ljvelo

    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.

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    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.

    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 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 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 http://www.bike-repair.ru it is told 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.

    Press-fit

    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.

    Types of carriages according to the used carriage glass

    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 connected to each other by a plastic or aluminum spacer, which 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

  • Compatible with SRAM, Truvativ, Bontrager:
    • GXP (GigaX Pipe)
    • Hope (via proprietary adapter)
    • Chris King (via proprietary adapter)
    • Campagnolo ultra-torque.
    • 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.

      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 debris, 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.

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      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 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)

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

      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 solvent (usually kerosene).

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

      We start by applying a little grease to the threads of the carriage and adapter cup, 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.

      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.

      Briefly about the main thing:

      Fault definition

      The fact that the carriage has become “naughty” can be found only when you rotate the pedals. 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 bottom of the frame. You should not listen too much, especially if you are driving on a busy road. However, if the state of the carriage is not good, 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 assembly 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 the pedal travel will only increase.

      Checking the carriage by pedaling while standing

      Troubleshooting: maintenance, cleaning, replacement

      Dismantled the carriage, pulled it out of the frame and what do we see? The condition of the bottom bracket depends on how much dirt gets 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 latches. 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. It is better to sprinkle fine dirt with a lubricating spray (WD-40, for example) and wipe the walls with a soft dry cloth.

      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 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? Imagine. no! There is no bicycle without a carriage. If such a person is still caught, it means that he is not on the move right now.

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      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.

      Non-collapsible carriage option

      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.

      Inexpensive, but periodically serviced carriage option

      Removing the carriage: doing it right!

      It makes perfect sense to first remove the assembly from the bike frame 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, all space around the carriage should be cleaned. A damp cloth removes all dirt and dust from the frame, bottom bracket area and connecting rods. This will be enough so that excess dirt does not get inside during parsing. But it will be better if you wash the whole bike. Cleanliness is the best repair assistant. Proven!

      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.

      This is a connecting rod puller

      The bicycle carriage is held in place by means of 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 percussion 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.

      Carriage cups and bearing (installed incorrectly in the picture!), Lock nut

      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.

      Carriage shaft (carriage axis)

      How to replace a bicycle bottom bracket yourself

      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. This is useless. Then grease is applied to the bearing, which is inserted from the side of the stars. The flat bezel 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 axle 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 Efficient 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 wrench. the thread will not break.
      • Insert plugs.

      That’s all.
      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 at all.