Disassembly and maintenance of the rear hub
The rear wheel mechanism of a bicycle requires periodic maintenance and repair, and often inexperienced cyclists have problems disassembling and assembling it. However, this is a fairly simple operation, and after a little practice it becomes more difficult. The main thing is to choose the right tool and be patient. You should also be very careful, otherwise a small part or ball rolling somewhere can cause serious problems, and it will be impossible to assemble the mechanism correctly. If you are not sure of your actions, then you can even record the process on video, so that during reassembly it is clear where this or that element should be installed.
All conventional bushings are designed to be disassembled from the side opposite to the sprockets, that is, to the left. Consider the sequence of actions when disassembling a product on bulk bearings, since this design is the most common:
- First you need to unscrew the nuts and disconnect the wheel from the frame. With eccentric clamps, you don’t even need tools. After the wheel is removed, you can start disassembling.
- Now you need to remove the sprockets, otherwise it will be impossible to get full access to the inside of the bushing. If the wheel has a cassette, then you will need a tool called a whip and a puller. The whip is thrown over the large sprocket and holds it, and the puller is inserted into the cassette and rotated counterclockwise. After dismantling the cassette, you need to remove the brake disc from the left side of the hub (if disc brakes are installed).
- To disassemble the ratchet wheel, you need a puller and a wrench with good leverage. You have to put in quite a lot of effort, because the ratchet twisted all the time you were cycling. The ratchet also needs to be unscrewed counterclockwise.
- For further work, you need two keys. A special cone wrench has a small thickness, it holds the bushing cone, and with the second wrench you need to unlock the left nut that fixes this cone. The unlocked nut can be unscrewed, and now the rear axle of the bicycle can be easily removed from the hub, giving access to the bearings and the inner surface of the wheel hub.
- The balls can be covered with metal anthers. Both must be carefully removed and folded into some kind of box. That’s all, the sleeve is disassembled, now you can start maintenance and repair.
The scheme for disassembling the sleeve on industrial bearings is even simpler, a certain difficulty is only removing the cassettes with balls, since they are pressed quite tightly into the hub. The cartridge will have to be removed with a special tool or knocked out with hammer blows along the axis, but this must be done extremely carefully so as not to damage the flange.
Sometimes you have to disassemble the drum itself, on which the cassette with stars is attached. In this case, a special slotted puller is required. But such a need arises extremely rarely, and in this case it is still better to contact the workshop.
Maintenance of the rear bushings consists of removing old grease, cleaning parts from dirt, checking their integrity and applying new grease. It is necessary to thoroughly rinse not only the bearings and the inner surface of the hub, but also the threads on the nuts and axles, since sand is often packed into it. When twisted, it collects on the surface of the cone, can cause crunching and even damage to the balls. For this, gasoline, thinner or special detergents are usually used. After cleaning, apply grease to all moving parts.
Fixing A Wobbling Rear Wheel Hub
The assembly of the bushing is carried out in the reverse order. If the details are not lost, then everything will go without any difficulty.
When installing a wheel in the dropouts, you should pay attention to one important point: the axle with the hub should fit into them quite tightly. If a gap develops, insert the spacer washers. Otherwise, the feathers will contract and bend when the wheel is locked, which can lead to permanent stresses in the feathers and, ultimately, to the destruction of the structure.
Classification of bushings
There are two types of bushings. front and rear. The front is simpler and not subject to the same stresses as the rear, especially if a fork with a shock absorber is installed on the bike. The rear hub is used to transfer torque from the pedals to the rear wheel, the dynamic characteristics of the bike depend on it, so further we will talk about it.
Bicycle hubs vary in material and interior design. They usually consist of an axle, a hub with flanges to which the spokes are attached, and bearings. There are the following types of rear wheel hubs:
- Ratchet, in which a set of sprockets is combined with a ratchet mechanism into a single whole. Such hubs are often used on bicycles in the lower price segment.
- Cassette, in which a set of rear sprockets is installed on a special drum using a spline connection.
- Planetary with internal gear shifting, in which the gears are located inside the housing of the hub itself. They are heavy and expensive, but reliable and require little or no maintenance.
The first two types are most widespread, and planetary ones remain rather exotic, although they are often used in city bikes.
Ratchet hubs are cheaper, but less reliable and are considered outdated, so it is better to choose the cassette option.
The most common problems and how to fix them
If the locknuts of the bushing are not tightened sufficiently, then during the rotation of the wheel, the rear axle beats against the bearings. As a result, cavities appear on the tracks of the cones, and the balls are deformed. If the backlash is not eliminated in time, then chips will form on the cones and the inner surface of the sleeve. In especially advanced cases, the balls can even jump out of the tracks and begin to rotate inside the bushing, grinding the axle and destroying the hub, then you will have to replace the entire unit and re-spoke the wheel.
To avoid backlash, the cones must be correctly adjusted. To do this, gradually tighten the flare nut, trying to find a state in which the wheel rotates freely without beating. When the correct position is found, lock the cone with the locknut. When locking the cone, the axle often starts to rotate, and the correct position is lost, so you can clamp the right end of the axle in a vice.
The rear axle of a bicycle is a threaded rod rigidly fixed in dropouts, which does not transmit torque, but at the same time carries the main load when the bicycle is moving. It is usually made of steel, titanium or aluminum alloy and is an integral part of the bushing.
Depending on the type of attachment, the axles can be hollow or solid. The hollow ones are used in conjunction with eccentric braces to facilitate wheel mounting and dismounting. Such axles have greater rigidity and less weight.
Another way to fix the wheel is to fix its axle in the frame stays with special nuts. For a frame with horizontal dropouts, an axle with nuts is more suitable due to a more reliable and durable wheel attachment.
Some mountain bikes and cyclocross bikes use thru axles with a threaded end. These axles are part of the frame design and are usually supplied with it.
The thickness of the rear axle depends on the type of bike, and its length is determined by the distance between the dropouts of the frame stays. In some models of bushings, the diameter can be changed using special adapters. The following axes are usually used (the first number is the diameter, and the second is the length):
- 10×135 mm. used in most modern bicycles;
- 10x130mm. Mounts on road bikes;
- 12x150mm. bike axles for downhill and free ride;
- 10×170 mm. such axles are installed on fat bikes;
- 10x120mm. Suitable for high-speed track bike.
On bicycles for extreme sports of the High End level, special axles of increased thickness can be used, which have increased strength.
Broken or bent axis
Another common problem is axle curvature or violation of its integrity, caused by low-quality materials used in their manufacture, or by the design features of the bushing itself. Such breakdowns are mainly characteristic of ratchet bushings, since their support bearings are too far from the axle attachment point in the dropouts of the frame feathers. The result is too large a lever, and when the load increases, the axle becomes unusable.
An important factor to look for when choosing a hub is the type of bearings installed in them. Bulk ball bearings remain the most common type, but industrial bearings in cartridges are more reliable.
In the first case, tapered nuts are attached to the axle of the bicycle, which press the balls to the cups, which are structurally part of the housing of the hub itself. Units with such bearings are easy to maintain and repair, but they quickly become clogged.
In products with industrial bearings, the balls in the cassette are pressed directly into the hub. They are great for a sports bike as they have more efficiency and better protection from dirt. Another advantage of bushings on industrial bearings is that they do not require adjustment of the axial clearance and frequent lubrication, but they are rather difficult to disassemble.
Typically, the hub body is the wheel hub. It has flanges on which the spokes are attached, and due to the presence of a set of sprockets on the rear wheel, the spokes have a slightly shorter length on one side. In bushings with loose bearings, the inner surface has tracks along which the balls move.
Padding the cone
This situation is the opposite of the previous one: the flare nuts are tightened too tightly, which causes excessive friction in the hub and the wheel loses roll. In this case, adjustment of the cones is also required, and all actions are similar to those described above.
Design Difference Between Road Bike and Road Bike Bushings
Typically the classic road bike is a singspeed with a foot brake.
The road bike is equipped with a high-speed transmission and rim brake. Because of this, the components for road and road users are very different.
The main difference is in the hub body. If we talk about high-speed road bikes, then a nut is attached to the hub body, and a cassette is put on it.
Ratchets are rarely used in high-speed road bikes. The torque is transmitted to one of the stars, and then to the wheel itself. Any cassette has a free play, which allows the wheel to rotate even if the star does not rotate.
As for the device of the road singspeed bushing, it is a little more complicated. With this arrangement, the driving sprocket interacts with the driving and braking cone. When the pedals rotate forward, the drive cone transmits torque to the wheel itself.
To brake, you need to start pedaling back. In this case, the drive cone starts to rotate the brake cone. He, by means of special rollers, pushes the brake drum inside the hub, and that, in turn, stops the wheel.
The stronger the impact on the pedals, the stronger the braking effect.
There are a huge number of different bicycles in the world and for each there is a specific hub for the rear wheel of the bicycle. All of them can be divided into groups according to various classifying characteristics.
There are hubs for speed bikes and singlespeeds. The high-speed ones have either a ratchet thread or a cassette mount. The first type is cheaper and is used on amateur budget bikes. Cassette is not much more expensive, but more reliable.
There are also planetary ones. Their device is more complicated than usual and is used mainly on city bicycles.
The sports hubs have free play. Those. on these bikes, you can idle back pedaling. On bikes with a foot brake, there is no free wheeling. When pedaling in the opposite direction, the drum brake installed in the rear wheel is applied.
There are also fixers. These are bicycles with one speed, the pedals on which can rotate in both directions. It turns out that on such bicycles you can ride both back and forth.
The hubs are also different for bikes with disc and rim brakes. Disc brake compatible hubs are equipped with brake rotor mounts. For bikes with rim brakes, this is not necessary and there are no mounts.
If in the future it is planned to replace rim brakes with disc brakes, then it is better to immediately install a bushing for the latter. There are those on which the rotors are bolted, and there are those with the CenterLock mount
structural element and purpose
Any wheel hub, regardless of its type, consists of 4 main parts:
- Bolts, boots and seals.
For hubs compatible with cassettes, a drum is also distinguished, or, as cyclists call it, a nut.
The axis can be conventional, or it can be made in the form of an eccentric. The first type of axle is practically not used today and is installed only on budget bicycles. The axles for the eccentrics are hollow inside, but still strong enough.
Good quality modern axles will rarely break and bend if used as intended. The eccentric allows you to quickly and easily mount the wheel and secure it.
The body covers and fixes all the insides. It has flanges. protrusions for fastening the spokes. Depending on the cost, this part can be made of various materials. Most often it is aluminum.
The drum and rotors are attached to the body. If the bushing is for a ratchet, then there is a thread on the body, instead of a mount for a drum.
Bearings are installed on the axle, connect it to the housing, but at the same time provide rotation, since the axle is always in a fixed position. Bearings are available in bulk and industrial. The second type is a little more expensive, more reliable and less clogged.
Bolts and spacers are needed to connect all parts to each other and fix them. Anthers are designed for a sealed connection and do not allow moisture and dirt to enter.
In general, the design of the rear hub of a bicycle is quite simple.
Bicycle rear wheel hub: DIY chassis assembly
The rear hub of a bicycle has undergone various changes throughout history. Today, a lot depends on it: from ride comfort to the result in competitions.
They require constant maintenance and, if necessary, repair. Therefore, you should know exactly all its components and device. But first you need to figure out what kind of rear bushings are.?
Standard sizes by bike type
There are different rear hub standards for different types of bicycles. The fact is that some types of bikes require stronger components, while others, on the contrary, require lighter ones. Today, the standard sizes for various bikes are:
- 10×120 mm. track;
- 10×130 mm. road;
- 10×135 mm. budget and amateur MTVs;
- 12 × 135 mm. downhill;
- 12 × 142 mm. professional cross-country;
- 12×150 mm. freestyle, slopestyle, detr, street;
- 14 × 110 mm. BMX.
Bicycle Rear Hub Assembly
Assembly or disassembly may be needed to repair or clean the bike rear hub.
This process does not require any special knowledge. You just need to know the correct assembly order and be patient.
Incorrect or inaccurate assembly can result in either backlash or difficult rotation of the rear wheel. But more about everything.
So, first of all, you need to determine the right side of the axis. It has a cast cone. All parts must be thoroughly cleaned. The assembly process for a component with industrial bearings does not require as much labor as assembling bulk bearings.
First of all, it is necessary to apply a thick grease, for example lithol, to the bushing housing, in the place where the bearings are located. If the bulk bearings are without a crown, then they must be carefully placed one by one in this grease.
Next, an axis is inserted. After the axle is inserted, it is necessary to lay the bearings and on the left side.
The cone on the left side must be tightened so that there is no play and the axis rotates freely. If tightened too much, there will be too much resistance when riding.
Before fully reassembling the rear hub of the bike, check the tension force of each bolt and cone.
Before installing the wheel, you can grasp the axle with your hands and turn the wheel on the floor. While it rotates, tilt it to the sides. If any knocking is heard or play is felt, then it is necessary to check the nuts, cones and bearings.
After you have lubricated the threads on the spokes, they need to be placed in the hub flange. Be sure to leave some white space in between. Then find the free hole that is located on the right side of the rim. Your reference point is the valve, it should be on the right. The first spoke is placed in it, which is fixed with a nipple. When you are done inserting the knitting needles on the right side, move to the left. Accordingly, the first spoke should be to the left of the valve. The knitting needles that we will install during the knitting process are called drive needles. And there are also tensioners that need to be inserted only after all the drive ones have been enumerated. To insert the idler knitting needles, place their ends on the inside of the hub flange. Each tension spoke must have an intersection with three drive spokes. Check the correct position of the spokes. Two drives must intersect at the top and one at the bottom. After you have secured all the idler knitting needles, tighten the nipples.
Rear Bicycle Wheel Assembly Secrets
If you are a happy owner of a bike, then at least once in your life you had to disassemble the rear wheel of your iron friend. And there are a great many reasons for this. Worn parts require systematic replacement, and maintenance in a specialized workshop is not cheap, so it is better to learn how to carry out simple repairs with your own hands.
The rear wheel has a more complex structural principle than the front, so the main thing is to master the skill of assembling and disassembling it. If you succeed, then there will definitely not be any problems with the front wheel.
Align wheel geometry
Before proceeding to this stage, it is necessary to say what kind of wheel damage there are. There are two problems:
- Vertical unevenness (ellipse)
- Horizontal roughness (figure eight)
If there are several irregularities, do the one that is larger in size first.
How To Fix Loose Wobbly Wheel Hub
Regardless of what type of unevenness is detected on the wheel of your bike, there is a single algorithm for its elimination. You just tighten the left nipples and loosen the right ones the same number of turns.
Tighten the nipples the same distance. The optimal choice is 3 turns. Now you need to tighten the knitting needles. It is very simple to do this, it is enough to turn each nipple one turn. Observe the correct order and move from the valve hole.
Do-it-yourself disassembly and assembly of the sleeve. it is quite a difficult skill, but it can also be mastered. There are enough reasons why you will need to disassemble this component. It is necessary to lubricate the bushing, replace a worn bearing or other parts. Disassembly is indispensable here.
When all parts are lubricated and free from dirt, you can start the assembly process. We start with bearings that fit into bowls. Do not forget that the bowls also need to be greased before this. After that, we put a cone on the bearings and insert the axle of the bushing. It twists until the cone snaps into place. The final step is putting on the washer and locknut.
As you can see, everything is quite simple. The main thing is to stock up on the necessary amount of time, patience and quality cycling tools.