How to assemble the rear bottom carriage of a child’s bike

Bicycle carriage repair

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.

1. 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 with the wheels. We begin to remove the carriage from the left side, that is, where there are no sprockets.
2. 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 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 it 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.
3. 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)
4. 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.
5. We take out the cartridge or the right cup with the axle. 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 (I use kerosene).

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

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.

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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.

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 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.

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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 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 carriage and adapter cup threads, so that later it will be easier to turn it out.

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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.

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.

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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.

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 bottom bracket, and the axle is pressed into one of the connecting rods and has a greater thickness, which achieves a high rigidity of the unit.

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)
  • Adjusting the split carriage bearings

    After assembly, the carriage must be adjusted, but often you have to adjust it without disassembling.

    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, 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. We wrap 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 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.

    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 allowed 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 it is required to look for a non-integrated bottom bracket of the corresponding type, while all integrated ones are compatible with such derailleurs initially.
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    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 an unusual noise, there are difficulties with control when driving at high speed.

    If there is a backlash, you can suspect misalignment of the axles, damage to the bearings.

    Maintenance of bicycle carriages

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

    What kind of lubricant is used for bearings

    For them, it is chosen so as to ensure uninterrupted operation for a long time. One can count as such a lithium one, capable of serving a year without replacement. Before application, the bearings are thoroughly washed with kerosene, allowed to dry, then the lubricant is placed in the separator. It holds the bearing balls together. It is allowed to apply it directly into the cup, then squeezing the balls.

    Chain tensioning mechanism

    Rear derailleur rollers. They are often “clogged” by grease and dirt deposits that have thickened around the perimeter. They must be removed carefully, for example with a flat-head screwdriver.

    It is necessary to apply a dotted liquid lubricant on the roller axles to avoid squeaking and tight rotation. Only lubricated, they are able to keep the chain taut.

    rear, bottom, carriage, bike

    Main run carriage

    We can say that this is the “main” axis of the bicycle. It is from her that the impulse is “distributed” to other elements. Therefore, the speed, ease, and comfort of the stroke depend on the state of the carriage. The carriage elements are:

    A different, “thick” grease is put into the carriage, not the one that drips onto the chain or cables.

    What to use to lubricate your bike

    There are a huge number of oils and lubricants on the market suitable for this purpose:

    • liquid oils belong to the category intended for lubrication of all types of chains, which ensures their reliable operation;
    • two-component aerosols are used to lubricate: switches, cables, threads. When spraying aerosols, the oils contained in their composition penetrate into hard-to-reach places, providing lubrication of parts that cannot be processed in any other way. Some aerosols contain kerosene, so they are an effective assistant for separating worn parts (“LM47”, “LM40”);
    • plastic lubricants are used if you need to lubricate or seal any kind of connections. Some contain calcium. They are used as a lubricant for joints and assemblies. This type of bicycle lubricant includes: “Unitol”, “Solidol”, etc. Their advantages include the ability to stay on the elements for a long time, ensuring their efficient operation. Another type of plastic grease for a bicycle is grease with lithium: “Fiol”, “Litol. 24”, etc.
    • chassis elements retain their characteristics for a long time.