How to change the rear bottom bracket on a bike

Rear wheel hub repair. Step-by-step instruction

Housing disassembly, cleaning and lubrication

It is necessary to disassemble the case only after the workplace has been put in complete order. It is extremely important to carry out all intermediate operations with a high degree of care and accuracy.

First of all, the cassette is removed from its axis. For the convenience of work, it is necessary to use a whip and a puller. Open the circlip, remove the bearings with washers. Remember the original positions of the bearings and washers. In the future, this will allow you not to get confused during assembly. Examine every detail carefully.

Noticing the slightest chips, scratches, damage, it is better to replace the parts without regret. Remove the axle, clean the bushing housing from dust, dirt, rust with a dry soft cloth. Lubricate each part with grease. This process is carried out as the elements are installed in their regular places.

If the cause of the breakdown is a malfunction or breakdown of any part, then you should simply replace it using the following recommendations:

  • After removing the workplace, dismantle the retaining ring.
  • We take out the hub axle. Disconnect the elements located on the side opposite to the asterisks first.
  • We check the condition of every detail.
  • We carry out replacement of worn-out parts.
  • Assembling the assembly, tightening the flare nuts and locknut.

Varieties of rear bicycle hubs, how they differ from each other

The division of the rear hubs into varieties allows them to be classified according to the possibility of braking and stopping the bike. Depending on their design, the rear hubs are divided into:

  • Without brake.
  • With built-in brakes.

change, rear, bottom, bracket, bike

Conversely, bushings that do not have a braking mechanism also fall into two categories:

  • Without freewheel.
  • Free running.

The bushings, which have a built-in foot brake mechanism, are structurally made according to the second category. The main feature of the hub with a brake mechanism is that at the moment of braking and stopping the vehicle, press the pedals in the opposite direction.

The bushings are fixed to the frame with two nuts. This method is inexpensive. The second mounting option is with the help of an eccentric, which is much more expensive, but more convenient. So the nuts do not need to be unscrewed with a wrench; to remove the eccentric wheel, you just need to squeeze its handle. Removal procedure takes only a few seconds.

The bushing material is of great importance for efficient operation. Bushings are:

  • Aluminum. They are not subject to decay, corrosion, lightweight, comfortable.
  • Steel. Extremely strong, but heavy, corrosive.

The hubs also vary in size. The standards regulate several dimensions. from 9 mm to 15 mm. The weight of the bushing is the greater, the larger is its cross section.

When to service the rear hub

Trouble-free operation of wheels, 100% serviceability of critical parts of the machine are possible only if they are maintained in proper condition. Lubricate the rear hub of the bike regularly as it visually dries. The spokes and rim must be tightened periodically. Bearing balls should also be changed, brake pads should be adjusted as often as possible.

The rear hub just needs to be serviced regularly. If this is not done, very soon a complex and expensive repair of the entire wheel will be required. It’s better to take care of your vehicle right away for the long term. The rear hub does not require much more effort to service than the front.

It must be serviced in the following situations:

  • The body makes noise when rocking or while driving.
  • Backlash.
  • Bearing crunch.
  • Roll-forward dynamics is insufficient.

It is dangerous to ignore these signs. In the future, the bicycle disease will worsen. Very soon, the whole car would just crumble. A complete renovation will cost much more.

It is best to service the wheels regularly, especially since it is easy to do it yourself. In the spring, when the cycling season is just beginning, they should be checked for play. All bearings must not be over-tightened.

Instructions on how to lubricate the rear bicycle hub

The bicycle is recognized worldwide as the most healthy, lightweight and practical means of transportation. But its owner should definitely learn how to eliminate at least elementary malfunctions, especially if you are traveling on a difficult and long cycle route. Otherwise, your two-wheeled friend will cost you a tidy sum.

You can master shallow recovery with patience and observation. These qualities are extremely necessary when disassembling units, lubricating, replacing worn parts. Often you have to service the wheels along with the rear hubs.

Bicycle rear hub and its device

The wheel has long been ranked among the most important units. It usually experiences more stress from the back than from the front. Why? Yes, because it is equipped with a ratchet and an additional cassette.

During movement, the main emphasis is carried out on it. Competent repair, maintenance of the rear wheel is possible only after familiarization with the device and the functional purpose of its hub.

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A hub is a wheel component that attaches to the bike frame, specifically drop points. It is located in the very center of the wheel and provides free rotation for it. Sleeve composition:

  • Axis.
  • Lock-nut.
  • Washer.
  • Cone.

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.

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 (this casing is not provided on some carriages) letters are applied corresponding to the sides of the axle.

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

We put a 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 a thick grease With the same grease we grease 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)

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 form a single non-separable unit.
  • Dismountable. can be disassembled for cleaning, lubrication and replacement of worn parts (used in old bicycles).
  • Wedge-fit connecting rods (Soviet bicycles).
  • Under the square (square taper). the standard “floats” somewhat from different manufacturers.

All of these standards are generally incompatible with each other.


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 🙂 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.

Bicycle Repair: How to Maintain a Rear Hub on Industrial Bearings

Today our test subject will be the Hope Pro 2 EVO hub, and it will be accompanied by an old Axiom hub, which used to be on complements from Norco.

List of tools that we need:

  • Hex keys to remove the wheel
  • Whip key or old chain
  • Cassette remover
  • Clamps or vise
  • Open-end wrenches 17 and 19
  • Mallet

Let’s start the service. But first make sure you have a bike and free time.

Obviously, you first need to remove the wheel from the bike. If you have a Shimano derailleur with Shadow, remember to turn the SHADOW control lever to the OFF position.

Or maybe you have a SRAM Type Technology derailleur, remember to lock the derailleur foot with the lock button. This will forgive the removal of the wheel.

Now remove the wheel. For me, on the Iron Horse Sunday frame, I need to unscrew the 2 4mm hex bolts that fix the axle, and then unscrew the axle with a 6mm hex. It is likely that you have a slightly different design, but I am sure that removing the wheel will not cause any problems for you.

We remove the cassette. To do this, we need a puller, like this:

If you start turning the puller, then the cassette will simply turn with the drum, you need to fix it. For such a case, a “whip key” was invented, a kind of lever with a piece of chain. Throw it clockwise around the star.

If there is no key, then don’t be upset. The old chain will help you out! We take the chain, make a couple of turns around any open-end wrench / stick / curling iron of the wife. put it on the floor and press it with your foot. You can clamp the chain in a vice, if any. We wrap the free end around the cassette. We twist the puller with a key.

Voila, the lock nut has been removed and the cassette can now be removed.

Notice the serifs on the drum, these are the cassette star serifs. If you’re using a cassette cassette with an aluminum drum, then strong pedaling leaves such serifs. They can cause the drum to crack. So, either use cassettes with an aluminum “spider” or you should take a closer look at the steel drum if the manufacturer produces them for your hub.

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We remove the drum. To remove the drum on a Hope hub, you need to remove the spacer that presses the drum against the hub and hub axle. This spacer is simply inserted into the drum, but can be removed “tightly”. To remove it, you must use clamps or a vice, having previously wrapped the spacer with any cloth so as not to scratch it. Just pinch and pull the spacer towards you.

We also have the AXIOM bushing, which uses a different design. To remove the drum on it, you need to unscrew from the axle two lock nuts located on the side of the brake disc. To do this, you need 2 open-end wrenches, 17 and 19 mm.

Please note that the 17 mm wrench should be quite narrow, so if you have a similar sleeve, it is better to get such a wrench initially. We just had an old key, which we previously grinded off on the sides.

Different bushings have different designs, so which side should you start to disassemble your bushing from, it is better to first find out by the name of the model from the manufacturer’s manual or search on the Internet.

Having removed the spacer on the HOPE hub, simply pull the drum towards you, the hub axle remains on the wheel.

Do not lose the metal washer that is between the bushing prombearing and the drum.!

Having removed the nuts on the AXIOM bushing, we also pull the drum towards ourselves, the axle is removed together with the drum, since the drum is well pressed onto it.

We clean the insides. Carefully inspect the ratchet teeth in the hub and the spring pawls on the drum. Make sure they are not damaged, remove dirt and old grease.

Twist the bearings in the bushing and in the drum. The bearing should rotate smoothly, without jerking or sticking. Industrial bearings are usually considered maintenance-free, but if your bushing has industrial bearings with rubber boots, then they can be easily removed. A small knife is needed with which you can pry the oil seal. Be careful not to damage the boot, take your time and get exactly between the inner bearing sleeve and the boot!

Inspect the bearing for wear. Remove old grease with gasoline or kerosene and a small brush. Try not to use acetone and other solvents, they are detrimental to the oil seals. Pack the cleaned bearing with new grease. Use only silicone or Teflon based rubbing greases! Do not use “grease” or graphite grease.

It is worth disassembling the bearings only if you feel that the bearing “sticks” during rotation. Otherwise, it is better not to climb inside, so as not to damage the boot.

Apply grease to the dog seats and springs where they come into contact with the dogs, remove dirt from the anthers, this will extend their service life.

You shouldn’t go over it with grease on the ratchet, you don’t want your dogs to slip when you pedal? And the amount of lubricant affects the sound of the bushing. So take a small amount of grease and lubricate the ratchet walls so that they are just greased, no frills. If you want the hub not to crack so loudly (are you from this planet at all?), Then lubricate the ratchet a little more abundantly.

How to remove your mountain bike bottom bracket

We collect the sleeve. Put the drum back on the axle first in the case of the HOPE bushing, don’t forget the spacer between the drum and the bearing. Insert the drum into the hub body in the case of AXIOM. Do not use too much force, the drum will not be inserted immediately, because the pawls released by the springs do not allow the drum to be inserted into the bushing. Walk in a circle with a screwdriver, pressing down on the dogs and lightly pressing on the drum to insert it.

Insert the spacer back into the drum and lightly tap on it with a mallet, it will return to its place.

For AXIOM bushings, re-tighten 2 nuts per axle. Make sure the nuts are tight and there is no looseness in the axle.

Reinsert the cassette. Be careful, there are grooves on the hub drum and cassette that need to be matched. The easiest way is to turn the drum so that the widest groove on the drum is on top.

Tighten the cassette using the puller with the supplied nut. You do not need to use a whip here, the dogs will unclench in a ratchet and prevent the drum from turning.

Put the wheel back on the bike. Make sure the brakes are working properly, the gears are shifting, and the wheel has not moved anywhere.

Rear hub service requires skill and courage. Not everyone will dare to climb inside an unfamiliar device. But there is nothing supernatural in this, and having well prepared and finding a diagram of your bushing on the Internet, you will be able to crank it up yourself without any problems!

By the number of stars in the package

A modern cassette can have 7 to 12 stars. Most common cassettes with 8-10 stars.

Classification of cassettes

Depending on the type of bike

Mountain bikes are fitted with cassettes with sprocket ranges from 11-28T to 11-36T, 8-10 stars.

How To Change A Shimano Bottom Bracket

Road bikes have a sprocket range of 11 (12). 22T to 11 (12). 27T, cassette 8-11 stars. The 12-27T cassette is considered to be intermediate between road and mountain packages.

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Road bike cassettes, excluding Compagnolo, interchangeable with mountain bike cassettes, with the same number of stars in the cassette.

Bike cassette

A bicycle cassette is a multi-sprocket assembly on the rear axle of a modern bicycle. The kit is fastened with projections (slots) on the inner surface of the cassette, which engage with the counter projections on the rear hub drum. This mounting method is called “slotted”. The cassette is prevented from turning by the slots, and the stop nut prevents displacement along the axis of the bushing. Rigid mounting of the cassette on the axle is necessary for reliable transmission of torque from the pedals to the rear wheel.

The bike ratchet is part of the drivetrain. The ratchet system appeared earlier, but today it is gradually giving way to a more progressive cassette system. In fact, this is the same package of sprockets as in the first case, but combined (through a ratchet mechanism) with the bushing into one piece. When free running or rotating in the opposite direction, the ratchet emits a crackle, for this feature the design was named.

Ratchets are often found on cheap and old bicycles. A ratchet usually contains fewer gears than a cassette and is less reliable. When hitting hard obstacles, jumping, the chance of bending or breaking the rear hub on a ratchet bike is much higher compared to a cassette system due to the design of the ratchet. In addition, if the sprockets in the cassette are worn out, it is possible to replace an individual sprocket from the cassette set. With a ratchet, such manipulations are difficult.

Among the pluses of the ratchet. the price is lower, however, the reliability is also lower. Cassette and ratchet are not compatible with each other. If you want to change from one system to another, you will also need to change the rear hub. Typically, a cassette has more gears than a ratchet. In addition, on mass ratchets, the minimum sprocket usually contains 14 teeth, on cassettes, small sprockets of 11-12 teeth are used.

Ratchets differ in the number of stars in the set and the number of teeth on the stars. 6-star ratchets with 14-28 teeth (the type is called 14-28T) are considered mass, 7-star ratchets (14-34T) are also often found. The procedure for replacing a ratchet requires the use of a special tool. a “ratchet puller” and is difficult to perform in the field. In addition, due to the design features of the attachment on the axle, when dismantling the ratchet, much greater physical effort is required than when dismantling the cassette.

Cassettes are also divided into groups according to the number of stars in the package, as well as the minimum and maximum number of teeth for the stars in the cassette. For example, marking 11-36T 10 speed means that we have a cassette of 10 stars with a range from 11 teeth on the smallest chainring to 36 on the largest. If we are talking about cassettes for road, then they can be compatible with one of two systems. SHIMANO or Compagnolo. Cassettes from other manufacturers may or may not be compatible with the two major standards.

By design

Dismountable. the cassette is assembled from individual sprockets fastened with rivets or screws. The easiest and hardest option. It is theoretically possible to replace individual stars in a cassette if the package of stars can be divided.

On a spider. Star rings are attached to a light alloy center hub (spider) with beam mounts. The system is lighter than collapsible, but more expensive. The advantages of the design include high resistance to pollution.

Several spiders. The stars are fastened in groups of 2-3 pieces, each group on its own spider. The advantages of this scheme include the ease of replacing worn out star groups without changing the entire cassette.

OpenGlide. Developed by SRAM’s road bike brand. The cassette is assembled as a hollow cone from individual ring-shaped stars. There are only two points of attachment of the cassette to the hub. through the largest and smallest sprocket of the usual shape. Very lightweight and very expensive construction.

X-Dome is an evolution of SRAM OpenGlide technology, used in SRAM XX cassettes. Ultimately lightweight but also extremely expensive system. The large sprocket of the system is made of aluminum with slots for mounting on the bushing. The smaller stars are machined from a single piece of steel in a hollow cone that attaches to the largest and smallest stars. The cassette is installed on the bushing through the splines on the outer stars. Very expensive construction that wears out almost faster than the cheapest steel bag.

Depending on the materials used

Steel stars. The vast majority of cassettes are made of chrome-molybdenum steel. Inexpensive and not the most durable option.

Titanium based alloy. Finds use in more advanced designs, often only on large stars. The cost is higher than that of steel, the weight is less. There is no consensus regarding the superiority in durability of titanium cassettes compared to high-quality steel cassettes.

Anodized aluminum alloy. Super lightweight cassettes for high-end competition. They weigh very little, the cost is the highest of all possible, they wear out extremely quickly. Durability at the level of the simplest steel cassettes.