Bicycle wheel hub. What kind of bushings are there? Bicycle hubs: design, manufacturers, care Modern hubs for bicycle wheels

With this article I will begin a series of descriptions under the general title “Choose”. And we will choose all the spare parts that make up our bike. Sometimes, when you come to a store, one question from the seller can confuse you. To prevent this from happening and you know exactly what you want, these articles were written. I will mainly focus on mountain bike owners, because... Most people are like that.

Wheels

Any wheel consists of: a hub, spokes, a rim, a tube and a tire.

The wheels are different:

1) Diameter - 20, 24, 26, 28 inches. 20 is a standard wheel for bmx, 28 is a road wheel, for a mountain bike I use 24 or 26 inches. The easiest way to find out which one you have is to look at the tire. There will be numbers written on it, for example 26x2.2 - the diameter and width of the tire (and its diameter = the diameter of the wheel), but they are noticeably smaller by eye.

2) The number of spokes - this property relates directly to the further consideration of bushings. There are two standards: 32 and 36 (36 is used to increase strength, for example on bmx's). The easiest way to find out how much you have is to count.

In all stores you can buy an already assembled wheel, but if your hub is broken or the rim is bent, then there is no point in changing the whole thing.

Bushings

English - Hubs

The hub is the main part of the wheel; the spokes are attached to it and the wheel rotates due to it. Bushings for bmx are different from bushings for mtb, so be careful.

Main differences:

1) Front and rear:

The top photo shows the front hub, the bottom photo shows the rear hub. The main difference is in the drum (cylinder with grooves on the right), on which the cassette (set of sprockets) is placed.

2) Disc brake mounts - both front and rear hubs may have such mounts. In the photographs, both have 6 holes for bolts - fastening such brakes. If you had conventional brakes, then in case of replacement it is better to take one with such a mount, then if you want to install disc brakes you will not have to change the bushing.

3) Fastening the bushing - an eccentric (top photo) and bolts (bottom). This is not for everyone and the only difference is that the eccentric is much more convenient (to remove the wheel you just need to press the handle), but the bolt mount is stronger (it is used mainly in extreme riding and for a regular bicycle the eccentric is the best option).

4) Axle bushing - a special type of bushing (again used in extreme skating to increase strength) that fits on an axle of a certain diameter. This type of bushing is easily recognized by the large through space in the center of the bushing.

Example of a front hub for an axle, without mounting for a disc brake:

5) Bearings - are divided into conventional ball and industrial (closed). And here there is only one piece of advice - only industrial ones, most of the bushings are exactly like this, which saves you from the hassle of cleaning, installing and using the bushing.

6) Number of knitting needles - 32 and 36 (this was discussed above).

7) Fastening the cassette (set of sprockets) - the second photo shows the most common type of fastening - a drum, on which the cassette is placed on top. In this case, the ratchet is an integral part of the bushing. Roughly speaking, a ratchet is a mechanism that allows you, while turning the pedals, to transmit torque to the rotation of the wheel, but when you stop, ensure free movement (at the same time, the characteristic sound of a ratchet is heard). There are bushings with threaded fastening:

Such bushings have a ratchet connected to a star (called freewheel). They are mainly used in trials.

Freewheel example:

Example cassette:

Recently, in extreme skating, hubs with an already built-in sprocket are common (in the amount of one piece - to create a “single speed”):

8) Another innovation in the world of bushings is the “freecoaster”. These bushings have a special type of ratchet that allows the wheel to rotate freely in the opposite direction. On any hub, when you ride or carry the bike backwards, the pedals themselves begin to rotate following the wheel. Freecoaster removes this property, opening up new opportunities in extreme skating. Externally, these bushings are not very different.

When choosing a bike, many novice cyclists most often look at the rear derailleur, frame, and the presence or absence of a shock absorber. At the same time, insufficient attention is paid to such an important component as the wheel hub.

Types of bicycle hubs and their components

Bushing classification

There are two types of bushings - front and rear. The front is simpler and is not subject to the same loads as the rear, especially if the bike has a fork with a shock absorber. serves to transmit torque from the pedals to the rear wheel; the dynamic characteristics of the bike depend on it, so we will talk about it further.

They differ in the material from which they are made, as well as their internal structure. They usually consist of an axle, a hub with flanges to which the spokes are attached, and bearings. The following types of rear wheel hubs are distinguished:

  • Ratchet, in which a set of sprockets is combined with a ratchet mechanism into a single whole. Such hubs are often installed on bicycles in the lower price segment.
  • Cassette, in which a set of rear sprockets is installed on a special drum using a splined connection.
  • Planetary with internal gear shifting, in which the gears are located inside the housing of the hub itself. They have a high weight and cost, but are reliable and require virtually no maintenance.

Rear cassette hub Novatec d042sb-ss

The first two types are most widespread, and planetary ones remain rather exotic, although they are quite often used in city bikes.

Ratchet hubs are cheaper, but less reliable and considered obsolete, so it is better to choose the cassette option.


Rear bushing JOY TECH 434 for ratchet

Bearings

An important factor to consider when choosing a bushing is the type of bearings installed in it. Bulk ball bearings remain the most common type, but they are more reliable in cartridges.

In the first case, cone nuts are attached to the bicycle axle, which press the balls against the cups, which are structurally part of the body of the hub itself. Units with such bearings are easy to maintain and repair, but they quickly become clogged.


Industrial bearing R8RS rear hub KT-155

In products with industrial bearings, the balls in a cassette are pressed directly into the hub. They are great for a sports bike, as they have greater efficiency and better protection against 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 quite difficult to disassemble.

Bush body

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 bulk bearings, the inner surface has tracks along which the balls move.

Rear axle

The rear axle of a bicycle is a threaded rod rigidly fixed in the dropouts, which does not transmit torque, but at the same time bears the main load when the bicycle moves. It is usually made of steel, titanium or aluminum alloy, and is an integral structural element of the bushing.

Depending on the type of fastening, the axles can be hollow or solid. Hollow ones are used in conjunction with eccentric couplers, making it easier to install and dismantle the wheel. Such axles have greater rigidity and less weight.

Another way to fasten a 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 more reliable and durable wheel mounting.


Rear hub axle Quando KT-262R 175mm with nuts

Some mountain bikes and cyclocross bikes use thru axles, one end of which is threaded. These axles are part of the frame design and are usually supplied with the frame.

The thickness of the rear axle depends on the type of bicycle, 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. Usually the following axes are used (the first number is the diameter, and the second is the length):

  • 10x135 mm – used in most modern bicycles;
  • 10x130 mm – installed on road bikes;
  • 12x150 mm – bicycle axles for downhill and freeride;
  • 10x170 mm – such axles are installed on fat bikes;
  • 10x120 mm – suitable for a high-speed track bike.

On bicycles for extreme sports High End level can use special axles of increased thickness, which have increased strength.

Rear hub disassembly and maintenance

The rear wheel mechanism of a bicycle requires periodic maintenance and repair, and often inexperienced cyclists have problems disassembling and reassembling it. However, this is a fairly simple operation, and after a little practice it ceases to cause difficulties. The main thing is to choose the right tool and be patient. You should also be as careful as possible, otherwise a small part or ball that has rolled somewhere can cause serious problems, and it will be impossible to assemble the mechanism correctly. If you are not confident in your actions, then you can even record the process on video so that during reassembly it will be clear where one or another element should be installed.


Rear hub and its components

All conventional bushings are designed to be disassembled from the side opposite to the sprocket placement, that is, on the left. Let's 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 cam clamps, you don't even need tools. Once the wheel is removed, disassembly can begin.
  • Now you need to remove the sprockets, otherwise it will be impossible to gain full access to the inside of the bushing. If the wheel has a cassette, you will need a tool called a whip and a puller. The whip is thrown over the large star and holds it, and the puller is inserted into the cassette and rotates counterclockwise. After removing the cassette, you need to remove the brake disc on the left side of the hub (if disc brakes are installed).
  • To disassemble a wheel with a ratchet, you need a puller and a wrench with good leverage. You will have to apply quite a lot of force, because the ratchet was twisted the entire time you were riding the bike. The ratchet also needs to be unscrewed counterclockwise.
  • For further work you will 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 secures this cone. The loosened nut can be unscrewed, and now the rear axle of the bicycle is 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 need to be carefully removed and placed in some kind of box. That's all, the bushing has been disassembled, now you can begin maintenance and repair.

The scheme for disassembling a bushing on industrial bearings is even simpler; the only difficulty is in removing the cartridges 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 a hammer 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, you will need a special puller with slots. But such a need arises extremely rarely, and in this case it is still better to contact a workshop.

Maintenance of the rear bushings consists of removing old grease, cleaning the 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 axle, since sand often gets packed into it. When twisted, it collects on the surface of the cone and can cause crunching and even damage to the balls. For this, gasoline, thinner or special detergents are usually used. After cleaning, apply lubricant to all moving parts.

The bushing is assembled in the reverse order. If the details are not lost, then everything will go without any difficulties.

When installing a wheel into the dropouts, you should pay attention to one thing: important point: the axle and bushing should fit into them quite tightly. If a gap occurs, spacer washers should be inserted. Otherwise, the stays will tighten and bend when the wheel is secured, which can lead to permanent stresses in the stays and, ultimately, to structural failure.

The most common problems and ways to solve them

Backlash

If the hub locknuts are not tightened sufficiently, then when the wheel rotates, the rear axle will hit the bearings. As a result, cavities appear on the cone tracks and the balls become deformed. If the play is not eliminated in time, chips will form on the cones and the inner surface of the bushing. In particularly advanced cases, the balls may even jump out of the tracks and begin to rotate inside the hub, grinding down the axle and destroying the hub, then you will have to replace the entire assembly and re-spoke the wheel.

To avoid backlash, the cones must be adjusted correctly. To do this, you need to gradually tighten the flare nut, trying to find a state in which the wheel rotates freely without causing runout. When the correct position is found, the cone should be secured with a lock nut. When locking the cone, the axle often begins to rotate, and the correct position is lost, so you can clamp the right end of the axle in a vice.

Cone waisting

This situation is the opposite of the previous one: the flare nuts are too tight, 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.

Broken or bent axle

Another frequently occurring problem is the curvature of the axis or disruption of its integrity, caused by poor-quality materials used in their manufacture, or the design features of the bushing itself. Such breakdowns are typical mainly for bushings with a ratchet, since their support bearings are located too far from the axle attachment point in the dropouts of the frame stays. The result is too much leverage, and as the load increases, the axle becomes unusable.


Broken rear axle of a bicycle

Unfortunately, if the axle is broken or bent, you will have to install a new one, since they cannot be restored. Good news is that axles are inexpensive and easy to replace. Please note that manufacturers use different threads, and cones may vary in size and fullness. Therefore, when going to the store, it is better to take them with you so as not to make a mistake when buying a replacement and choose the product that suits your bushing.

Crunching or noise inside the bushing

Noises, squeaks and crunching noises are signs that it's time for your hub to be serviced. And this should be done as soon as possible, otherwise everything could end very badly. First you need to disassemble the bushing, change the lubricant and check the parts for defects. Damaged components must be replaced. If after all this the problem remains, then you should consult a specialist. It is possible that it arose due to the poor quality of the bushing itself, and you will have to install a new one.

The rear hub of a bicycle is a very important and often underestimated element of the bicycle, and its axle is subject to increased loads. Sand, dirt, microscopic debris and dust have abrasive properties that destroy metal. Breakdowns of the mechanical part of the rear wheel require expensive repairs or even replacement of the entire unit, so timely and correct Maintenance bushings will significantly extend the life of your bike and help avoid unnecessary expenses.

Be it an expensive sports bike or a simple teenage one. The rolling ability, and therefore the efficiency of the bicycle, very significantly depends on their quality, which is important - after all, when riding, a biker spends not just anything, but his own strength. It is not without reason that rolling bearings first appeared en masse on bicycles, and only later spread to many other machines and mechanisms.

General design features

Hubs designed for different bicycles differ in parameters such as the presence of additional devices, strength and type of protection from external influences. Accordingly, both weight and price differ significantly. And if mountain and road bike hubs have approximately the same structure, then hubs with built-in brakes differ quite significantly, and hubs with planetary gear shifting differ radically.

The simplest design is found on the front wheel hub of a regular bicycle. A cylindrical body, at the ends of which there are flanges with holes for attaching spokes. Inside the housing there are an axle and bearing units covered with anthers. The design of the rear hub of any bicycle is noticeably more complicated.

Rear hubs of multi-speed bicycles, not counting planetary ones, can be of two types. Outdated threaded bushings, where the ratchet, i.e., a block of stars together with a ratchet mechanism, is screwed onto the bushing, or modern - drum ( Freehub), where the ratchet is part of the hub and the cassette is just a set of sprockets. In addition to bushings with a traditional ratcheting mechanism, there are so-called “roller” bushings, which withstand shock loads on the freewheel mechanism much better and with a star mechanism, for example, in DT Hügi.

The bodies of modern bushings can be cast, turned or stamped, made of aluminum alloys and, partly, titanium alloys. Nowadays, turned and stamped aluminum bushings are the most common.

Hubs designed for radial spoke wheels have reinforced flanges to withstand radial loads. Bushing axles can be steel, aluminum or titanium. Bicycles designed for extreme disciplines now have front hubs with axles with a diameter of 20 mm and rear hubs with axles with a diameter of 12 mm.

Mountain bike hubs are divided into “regular” and “disc,” i.e., those designed to accommodate disc brake rotors. There are currently two common incompatible standards for mounting rotors: ISO on six bolts and splined with a locking ring, the so-called Shimano Center Lock.

The wheel can be mounted on the frame or fork either with nuts - only on inexpensive bicycles, or using an eccentric mechanism ( quick release). The convenience of using an eccentric coupler lies in the ability to quickly remove and install the wheel without the use of tools. The 20mm DH axles are secured using a cam and fork leg bolts.

Modern mountain bike hubs from mid-level up have a double contact seal. In expensive hubs, such as DT Swiss, and bushings road bikes A labyrinth seal is used, which creates less resistance to wheel rotation than a contact seal, but protects somewhat less well from dirt and water.

Bearing types

To date, bushings with angular contact cone rolling bearings. For example, all Shimano hubs use these bearings. Bearings consist of an outer and inner race, a set of balls and, sometimes, a cage.The inner race is a cone that is screwed onto the bushing axis, and the outer race is pressed into the bushing body.

The main advantages of bearings of this type are maintainability And possibility of adjustment as it wears out. Among the shortcomings - difficulty of assembly(lots of details) and need for adjustment.

Another type of bearing previously found only in road bike hubs is radial cage (industrial) bearings. Now they have spread to mountain bike hubs.

The advantages include lower friction losses, ease of assembly bushings, no need for adjustment. Taking into account the easy replacement of the bearing, the life of the bushing increases many times. But radial bearings do not tolerate axial loads well, sometimes occurring in bicycle wheels. Interesting feature some similar bushings high class is that they are disassembled using only one hex key.

About replacing spokes

For a front hub that does not have a disc brake, replacing broken spokes does not present any problem, since the spoke can be easily inserted into the hub flange from the side. But this option is of little use if a hub with a disc brake or rear hub. To install the spoke into the flange, you will have to remove the brake rotor and cassette, which greatly complicates the work and requires the use of special tools.

Mavic uses segmented flange hubs for special straight spokes. Replacing a spoke in a wheel assembled on such hubs is very simple. Shimano took a different route with new wafer hubs. DDH(directional design hub). Knitting needles of a traditional shape (with a curved, riveted head) are inserted into special slots on the body.

The only serious drawback is that during operation, the slots on the body become clogged with dirt, and removing the spokes from the wheel becomes very problematic. Apparently, this was the reason that DDH bushings never became widespread.

The second obvious reason is that the company began producing entire wheels (wheelsets). Their distinctive features were the use of a small number of spokes placed with nipples to the hub (stepped flanges) with fastening not in the center of the rim, as is usually the case, but on its sides.

Manufacturers

Most widespread in this moment Got Shimano hubs. In the opinion of many cyclists, the Deore LX hubs ($15 and $30 for front and rear) weigh 205 and 426 grams. - the best Shimano hubs in terms of price/quality ratio for a mid-level bike. For very inexpensive bicycles, the choice of Shimano Alivio hub can be considered acceptable ($10 and $15, respectively).

To the bushings high level This also includes Shimano XTR hubs. Their cost can range from $100 to $300. And the weight of the same American Classic non-disc hubs is only 120 and 225 g!

Results

In conclusion, it is worth mentioning that the quality of the bushing very much depends on the type of bearings, the quality of their processing, as well as the quality of the seals. The softness and ease of rotation of bearings is determined by the precision of manufacturing of parts, the type of polishing of the raceways and bearing balls, their surface hardening and compliance with tolerances. But remember that no matter how high the level of bushings on your bike are, you still shouldn’t dip them in water again, it won’t do any good.

Andrey Grigoriev

This article contains detailed information regarding one of the most important elements of a bicycle drive - of course, we will talk about the “hub”. Its varieties include a system with a planetary mechanism for shifting gears. This type of bushing got its name due to its design features.

Indeed, this complex mechanism, which includes more than forty parts, speaking in the colorful language of metaphors, can be compared to the Universe in which the planets of the solar system rotate exclusively along a given trajectory.

For several years now, the leading position in the production of such hubs has been occupied by the American concern SRAM, which since 1997 has also owned Sachs Bicycle Components, a company that is extremely popular among motorists and cyclists. The Japanese corporation SHIMANO, which produces four- and seven-speed hubs, is not lagging behind in this area.

As history says, the first drive in which it was implemented internal system gear shifter was manufactured by SACHS back in 1904, when external shift systems were in their infancy.

They were first implemented in 2-speed Torpedo models. By 1914, more than 833 thousand of them were sold. The Second World War caused devastating damage to the company. World War, when most of its production facilities were simply destroyed. The concern was facing bankruptcy. However, already in 1945 production actually began to improve. Of course, the company was not spared from numerous structural changes, and in mid-1997 it acquired the Sachs Bicycle Components concern, in the development of which more than $1 million was invested.

So why are planetary hubs so popular? First of all, it should be said that SRAM-SACHS currently offers a wide range of products, which include hubs that provide 3-, 5-, 7-speed gears and an internal braking system. Speed ​​hubs are also produced with a roller brake. Relatively recently, the company mastered the production of the Dual-Drive system 9x3, 7x3 and 8x3: a combination of a planetary hub for three gears of a 7/8/9-star cassette. An external classic-style switch is installed on the frame, which moves the chain along the cassette sprockets. The result is 21, 24, 27 gear combinations.

Now let's move on to the advantages of planetary gear systems.

Firstly, such bushings have a fairly wide range of gear ratios. For example, an off-road bike with a 42-32-22 chainring and an 11-30 cassette has a gear range of as much as 520%. As for the seven-speed hub, for it this range is 303%. Moreover, if we take the 4th gear as direct (100%), then the remaining gears relative to it will have the following indicators: the first accounts for 75%, and the seventh – 174%. In simple terms, bicycles with such gears accelerate perfectly on the highway and successfully overcome even the steepest climbs. 5- and 3-speed hubs have a slightly smaller gear range: 249% and 186%, but they have less weight and a more attractive price for the consumer.

Secondly, precise and fast transitions between gears are achieved. In this case, the position of the switch handle is clearly fixed. It is worth noting that for these devices it is possible to perform these actions while standing still.

Thirdly, and importantly, minimal maintenance is required. The instruction manual generally states that the bushing does not require any routine maintenance. The only restrictions include one condition: you should not direct direct jets of water under high pressure at the hub when washing your bike. Also, during routine operation, minor adjustments to the drive may be required, that is, when the cable is stretched, sometimes its tension should be adjusted.

Fourthly, these systems implement the simplest and strongest chains that can operate without any distortions and movements along the stars, as is often the case with external mechanisms. This advantage contributes to a significant increase in the service life of all drive components.

Fifthly, the possibility of braking with feet also becomes an advantage if the consumer initially used a regular road bike. After all, under this condition, there is no need to waste time on adaptation and retraining. By the way, braking with one wheel has always been less effective than with two. In most cases, such models are equipped with a front hand brake, but most cyclists still do not use it. If we talk about braking using only the rear wheel, then this method is completely wrong. Well, just imagine an ordinary car whose front wheel brakes have completely failed!

At the same time, braking efficiency cannot be taken into account at all if you plan to drive calmly on a straight road. Namely, bicycles that have an internal drive and a planetary hub are designed for this case.

Of course, nothing is perfect. And in this regard, the mechanism with a planetary hub is also no exception. But the disadvantages of such a system are so insignificant that in some cases they can simply be ignored.

First of all, the disadvantages include a slightly larger mass. For example, a seven-speed hub system plus a brake will weigh about 1.7 kilograms. Rolling friction also has relatively high values, which imposes restrictions on the use of these systems in sports bicycles.

In addition, the bushing has a very complex design. Therefore, it is highly not recommended to show initiative in this regard. If any malfunctions are detected, it will be faster and cheaper to contact a specialist.

However, there is no need to worry too much about this. Malfunctions in the internal mechanism are extremely rare, and the service life of the bushing itself is quite long. As practice shows, the vast majority of malfunctions arise precisely because of unqualified intervention, which provokes breakdowns of external parts. It is highly recommended not to even try to disassemble the planetary hub yourself, and before removing the wheels you should carefully read the operating instructions.

As a conclusion, it is worth noting that bicycles with such drives are quite popular in many European countries: Austria, Germany, France, Finland, Spain, Holland, etc. This fact is explained primarily by excellent roads with high-quality surfaces, the spread of bicycles as an affordable means of transport, the reluctance of Europeans to tinker with more complex transport equipment and their high purchasing power. These conditions explain the fact that the largest European manufacturers, such as GAZELLE, PANTHER, ACCELL, STEVENS and others, prefer to use exclusively drives with planetary hubs in bicycles.

Naturally, when choosing a bike, you should correctly set your priorities. On models equipped with planetary bushings, it will still be better to take walks on the highway, park or country road, that is, ride where there are no prerequisites for extreme use of the bicycle. Thanks to the design features of the bushing mechanism, it becomes possible to provide reliable protection against dust and moisture. However, in this case, abundant mud baths are still extremely undesirable. Maintenance of this type of drive does not require complex manipulations: all that needs to be done is to lubricate the chain and keep the mechanism dry and clean.

Provided that the buyer gives preference to operating comfort over high-speed driving, drives with a planetary hub are the only right choice!

popularity: 32%

Cycling is a very difficult activity that requires skill and a lot of patience. However, this is not enough. It is very important that the components of this product meet all the latest technology requirements.

In this regard, many manufacturers install a planetary hub on their models, which ensures uniform movement and regulates speed while driving. It is worth noting that many have no idea what this element is and what it is.

The planetary hub is an important element of the bicycle drive system. The design of this device consists of a complex gear mechanism for changing the gear ratio. Regulation of the relative positions and engagements of the gear occurs through the speed shift knob, which is usually located on the handlebars of the bicycle.

This device works as follows:

  1. In low gear, the gear wheel begins to move with the help of the rear sprocket. The bushing, due to the planetary cage, moves and lowers the gear. Due to this, the wheel makes 3 rotations for every 4 rotations of the sprocket, during which the gear is reduced by 25%;
  2. In direct transmission, the sprocket causes the gear to move, which causes the sleeve to move. Due to this, direct transmission occurs;
  3. In high gears, the sprocket transmits force to the cage, which in turn causes the gear to move. Next, the gear makes the sleeve move. During a set of this, for every three revolutions of the sprocket, the wheel makes 4 rotations, during which the gear increases by 33%.

It is also worth paying attention to the features of planetary bushings:

  • Modern devices can have up to 14 speed gears, although such bushings are very rare and their cost is quite high;
  • Some fixtures have reverse gear. This is very convenient for tricycles;
  • It is possible to use mechanisms with a fixed feed. It is very convenient for driving in winter;
  • Together with the bushing, a chain protection housing is additionally installed. Thanks to this, the duration of use of this device is greatly increased.

Planetary hub device

The working process of the planetary hub is the same as that of a car gearbox - speed control. There are no difficulties or unexpected problems while driving. With the help of this device, speed modes are switched quickly and in a timely manner. The figure shows the complete mechanism of this device.

Elements included in the planetary hub device:

  • Sun gear (yellow). It is located in the central part of this device, and serves as the axis of the rear wheel;
  • Carrier (blue). This is a group of several planetary gears or satellites, which are very firmly fixed on their axes and are firmly locked with the sun gear;
  • Ring gear (red). This is the outer gear or epicycle. It consists of an internal gear train. This transmission provides strong coupling with the satellites.

Application area of ​​planetary bushings


Planetary hubs are used primarily on city and recreational bicycles. Due to the fact that they are quite heavy, they are very inconvenient to use on sports bikes.

Sports bicycles are mainly used for riding on terrain with many bumps, and if a planetary hub is installed on them, this will create a lot of inconvenience and problems.

Therefore, it is better to install it on bicycles for city riding, because these bicycles do not encounter heavy loads and are used mainly for smooth roads.

Since city bikes are used for daily riding, it is best to install planetary hubs on them at 3, 8 and 11 speeds. This, of course, will cost more than a regular classic bushing, but the planetary bushing has a much longer service life, they do not break and due to this, chain wear increases.

Bushing Manufacturers

The main manufacturers of these devices can be identified:

  • SRAM;
  • Sturmey-Archer;
  • Rohloff


Firm Rohloff ranks first in terms of the complexity of the manufactured device. The models consist of 14 planetary components.


The company ranks second in production SRAM. Models from this manufacturer have up to 12 speed gears. Their gear range reaches up to 420%.


Shimano is a popular manufacturer of bicycle parts and hubs. The range of this manufacturer has hubs from 3 to 11 gear speeds.


Sturmey-Archer is a manufacturer of hubs with hybrid cassette-planetary mechanisms. In addition, this company produces other types of bushings with speeds of 3, 5 and 7.

Depending on the properties and functions of planetary bushings, the main advantages of these devices can be identified:

  • High strength and durability. The mechanism of this device is located under the protective housing. In addition, it ensures complete lubrication of all elements with transmission oil;
  • Fast and precise gear shifting speed. Due to the fact that the switch is located on the handlebars of the bicycle, you can change the speed while standing still;
  • High set of gear ratios. For example, if a bicycle has a 42-32-32 sprocket set and an 11-30 cassette, then its gear ratio can reach up to 520%. It's also worth noting that seven-speed hubs can have a gear range of up to 303%. While riding, the load is evenly distributed, and therefore bicycles with these bushings can easily overcome various bumps and potholes;
  • Availability of simple and durable chains. Thanks to these chains, uninterrupted operation is ensured, and there are no distortions or movements along the stars. In addition, these elements significantly increase wear on the entire drive system.

Disadvantages of planetary bushings

In addition to the advantages, these devices have some disadvantages:

  • Heavy weight. Unlike conventional bushings, these elements are quite heavy, for example, an average planetary hub with a seven-speed gearbox weighs approximately 1.7 kilograms;
  • Cannot be used on sports bikes. Due to the fact that these bushings have high rolling friction;
  • Complex design. If you find any breakdowns or malfunctions, you do not need to fix them yourself, it is best to contact specialists;
  • High price;
  • During strong and aggressive driving, the risk of gear failure increases.

Folding bicycles with planetary hub


Many manufacturers of folding bicycles include a planetary hub. These are very comfortable to ride, and it is possible to evenly regulate the load distribution while riding. In addition, they have a number of advantages. In this regard, we should consider the most famous models of these bicycles.

Review and comparison of models

  1. Folding bicycle FORWARD Enigma 154. It is very comfortable and light. It is adapted for any road - it can be used for driving both on city roads and on roads outside the city. Thanks to the planetary hub installed on it, you can quickly change gears and adapt to any road; with an even distribution of the load, it perfectly overcomes bumps, various ascents and descents. In addition, it is convenient to transport it in the subway and in public transport. True, this requires a special bag case;
  2. Comanche Lago folding bike. It is very convenient to use in megacities. It adapts perfectly to any road. In addition, it has good maneuverability when turning and excellent speed. These bikes are equipped with a Shimano Nexus Inter-3 sg-3c41 planetary hub with three speeds. In addition, they are very compact and easily fold into special bicycle bags. Therefore, they can be easily transported on the subway and public transport;
  3. Folding bicycle. These models are designed for everyday use. They can be used for driving on roads with asphalt or dirt surfaces. They also overcome bumps, bumps, descents, and climbs very well, so they are well adapted for mountainous terrain. These vehicles have a three-speed planetary hub with rear-wheel drive. This bushing is very easy to use and has a very long service life. In addition, these bike models can be customized for both adults and children;
  4. Mountain folding bike Volume Generator. This bike is made from single speed bike and MTB. It is mainly used for mountainous areas, since it perfectly overcomes large descents and ascents, bumps, and large potholes. It has a Shimano Alfine SG-S700 hub and two disc brakes. Thanks to this, you can perfectly regulate speed transmissions and adapt to any terrain.

How to change gears correctly when riding a bicycle with a planetary hub

Bicycles with planetary hubs are very comfortable to ride, and riding with these devices is very easy, since there are no problems with shifting gears. Because these devices themselves change speed when necessary. However, you should familiarize yourself with certain principles and rules for changing speeds:

  1. It is best to shift gears when the pressure is completely removed from the chain, otherwise you may simply not shift and break the entire mechanism and break the chain;
  2. The gear needs to be increased right before the mountain, and not while overcoming it;
  3. You should not change into several gears at the same time. Everything needs to be done sequentially - first you need to switch the first gear and accelerate a little, then the second one should go to third according to the same principle, and so on. The whole operating principle is the same as that of a car gearbox;
  4. It is necessary to avoid all possible distortions of the chain.

Switching process:

  • All modern bicycles have 2-3 stars in the front and 8-10 stars in the rear;
  • The numbering of the stars from 1 to 3 occurs in the direction of increasing stars, and the numbering of the rear stars from 1 to 6, in the direction of decreasing stars.

To make this process clear, consider the example of a bicycle with a 3x8 drive:

  • A large chainring should be used when driving on smooth asphalt surfaces. In conjunction with this sprocket, it is necessary to use rear sprockets with numbers 8 to 4;
  • The middle front sprocket is used when driving on a dirt road with poor asphalt surface. It uses rear sprockets 6 to 2;
  • A small front sprocket is used when driving on steep ascents and descents, over potholes and bumps. Rear sprockets from 5 to 1 are used with it.

Repair and maintenance of planetary bushing


Planetary bushings very rarely break. They have a very long service life and are very wear-resistant. Of course, if the rules of use are not followed, sometimes the mechanism of these devices may fail, then it is best to contact specialists to troubleshoot the problem.

You should not repair these elements yourself, since you can significantly damage the entire structure of the mechanism, and the bushing will become unsuitable for further use.

The main idea of ​​this device is to collect all gear shifting mechanisms in one compact housing, thus protecting them from dirt and possible physical damage.

You will say that there are already planetary hubs, but Pinion engineers were not satisfied that the weight distribution in this case is shifted back, and when using a gearbox that is installed between the connecting rods in a specially equipped bottom bracket unit, the weight is located ideally in the center of the bicycle. This is what it looks like:

I do not believe in the commercial success of this invention, firstly, because of the weight - the box weighs 2.35 kg, and secondly, a special frame is required that can accommodate the described device.

As for me, only a very wealthy geek can buy such a bike; the thing turns out to be highly dependent on the reliability of the box - the manufacturer will most likely go down the drain and if it breaks, the whole bike will go to waste. I have no idea how much the complete bike costs, but I'm sure the price is impressive.

I don't know about you, but I'm sure that in the coming years, and maybe even decades, no gearboxes or planetary hubs will be able to compete with conventional index switches.

What I am also sure of is that electronic shifting systems, while currently quite expensive and rare, will sooner or later become standard equipment on mid-price bike models.

And as a result, full-fledged automatic gear shifting is just around the corner; it can work like this: a power meter in the pedals measures the force of pressing and cadence, and the computer clicks the gears, trying to keep this force in a given interval. All sorts of gyroscopes and accelerometers can also be connected to more adequately assess the landscape. All this is customized for a specific person via a smartphone. In this case, you can always switch to manual mode.

To the question “why the hell do you need automatic shifting on a bicycle,” I will answer - it’s convenient. If it works clearly and reliably and costs reasonable money, many will want to drive an automatic car.

Here's an example from the motorcycle industry - attempts to make an automatic transmission are made there from time to time, but it does not find widespread use, seemingly because of this notorious “to hell with it.” In fact, the matter is not popular with people, because the automatic machine weighs a lot, is expensive, unreliable, and shifts inadequately.

As soon as a really working product appeared, people became interested in motorcycles with automatic shifting. Honda has made a robotic transmission with two clutches DCT, which weighs almost the same as a regular one, costs reasonable money, and most importantly, shifts clearly and in a timely manner. So, there will be a demand for a bicycle “automatic machine”.

Tell us what you think about all these flights of fancy, both mine and the inventors of Pinion, and whether something new is needed at all in a well-functioning switching system.

Gear shifting is used on almost all types of bicycles. This mechanism is located on the rear wheel. One of these types is a planetary hub for a bicycle. How does it work and is it worth using?

Important! The main difference between a planetary transmission and a sprocket transmission, which can be done easily, is that the mechanism is hidden inside the bushing, and is not located near the wheel - this protects its elements from external influences, making it more reliable and durable.

A planetary hub for a bicycle consists of a set of gears. Its design is quite complex, as it works on the principle of a car gearbox.

The mechanism includes the following elements:

  • a sun gear rigidly coupled to the wheel axle;
  • planetary gears, or satellites;
  • carrier - connects and fixes the satellites;
  • epicycle - ring gear.

Outside the transmission housing there is a single sprocket connected to the mechanism via a spline drive. When you change gears with the handle on the steering wheel, it changes the speed of rotation of the carrier relative to the epicycle.

The simplest type of hub has three gears that work as follows:

  1. Reduced- the epicycle engages with the satellites, which rotate the sun gear. For every 4 revolutions of the sprocket, the wheel makes 3 revolutions.
  2. Straight- the epicycle is connected to the sun gear directly, bypassing the transmission gears, thereby achieving a 1:1 rotation ratio of the wheel and sprocket.
  3. Increased. When it is turned on, the mechanism works in reverse - the sprocket transmits force to the planetary gears, which rotate the epicycle, the torque from which is transmitted to the sun gear. Due to this, transmission increases by 33–36%.

Depending on the number of satellite gears, there can be from 3 to 14, but the most common are planetary bicycle hubs, the design of which provides 5 or 7 speeds.

But if you are just about to buy a bike, you will also have a difficult task: which one to choose. You can give preference to one of them or try to choose one if you are already of advanced age.

Advantages and disadvantages

The planetary gearbox has the following advantages:

  • low chain and sprocket wear;
  • high reliability and durability of the mechanism due to protection from external influences and constant lubrication with gear oil;
  • no need for adjustment;
  • ease of gear shifting - you can do this both on the move and while standing still;
  • no risk of damage to the transmission mechanism when the bike falls on its side;
  • possibility of installing a foot brake;
  • reduced likelihood of the chain flying off the sprockets;
  • a wide variety of gear ratios - up to 520%.



The disadvantages of the mechanism include:

  • large mass, reaching 3 kg. In addition, the weight is unevenly distributed between the front and rear wheels;
  • complexity of repair and installation planetary hub for a bicycle; installation on an existing bicycle is completely impossible, even if you use a special tool to simplify the work. If it breaks, you will either have to buy a new hub or a new bike. Therefore, installing a planetary hub on a bicycle with your own hands is a difficult or almost impossible process;
  • low gearbox efficiency, associated with an increased coefficient of gear friction. Because of this, such transmissions are not used on sports bikes;
  • limited torque. Although the upshift range is wide, you won't be able to get into a gear low enough to climb a very steep mountain;
  • high price.

Thus, the planetary bike will be a good choice for pleasure rides, city rides and others for a leisurely and comfortable ride. If the bike is used for racing, cross-country or downhill riding, such a mechanism is more likely to become a burden than an improvement.

Manufacturers

This table shows the four main manufacturers.

Price

The price of a planetary hub for a bicycle is quite high. It depends on the complexity of the mechanism. So, 14-speed Rohloff hub costs from 53 to 89 thousand rubles. depending on the model. Significantly more affordable than Shimano transmissions - from 2700 rub. for 3-speed device up to 21 thousand rubles. for the model with 11 gears. SRAM Mechanism Prices Start from 5000 rub. Sturmey-Archer products will cost 4,700–10,500 rubles.

Optimal movement efficiency, pedaling frequency, speed and load on the bike are adjusted using a mechanism. Unlike a singlespeed, a bicycle with several torque transmission modes is able to adapt to specific riding conditions. The “high-speed” system is used on almost all types of bikes: from city and stunt bikes to racing and mountain bikes.

A common type of bicycle transmission is a planetary hub, inside of which there is a gear mechanism for changing the gear ratio. The relative position and engagement of the gears is regulated by the speed switch, which, in turn, is driven by a handle on the steering wheel. The fundamental difference from the “star” transmission allowed this gear shift system to gain a good foothold in the cycling environment.

What does a planetary hub consist of and how does it work?

The design of planetary bushings is quite complex and resembles the mechanism of a car gearbox. For clarity, we will show standard scheme for the entire planetary gear:

Components of the gear compartment of the speed hub: 1 – sun gear, 2 – satellites, 3 – carrier, 4 – epicycle

The sun gear is shown in yellow. The “sun” is rigidly fixed to the axle of the rear wheel of the bicycle. It is with this that the blue planetary gears engage. To fix them, a “carrier” (green color) is used. This part does not allow the satellites - this is how planetary gears can be called - to move apart and engage with each other, and also determines their direction of movement.

The mechanism is completed by an epicyclic gear, which rotates by pedaling. In the figure it is shown in red.

The sprocket is mated to the sleeve mechanism using a spline drive, the sleeve actuator. When changing the gear, it changes the speed of rotation of the carrier relative to the ring gear, due to which the bicycle is adjusted to the angle of the direction of the road and its speed is regulated.

An interesting feature of this type of mechanism is that it works as a gearbox. The sun gear plays the role of a stationary element, the epicycle is a driven element of the chain, the carrier is closed to the bushing body. For example, let's look at how the planetary gear mechanism works on a simple three-speed planetary gear:

  • Low gear. The ring gear advances the carrier due to its engagement with the planetary hub housing. The gear ratio is less than unity and is 0.733.
  • Main gear. Torque from the epicycle is transmitted to the bushing by engaging it with the planetary gear. In other words, it is not the carrier that is connected to the bushing, as in first gear, but the sprocket gear. What happens when this happens? The hub rotates faster than the carrier, and to achieve maximum speed you will need more effort compared to a low gear.
  • The overdrive, or third, gear ratio is greater than one, and for three-speed bicycles it is 1.364. The direction of movement of the carrier and bushings is opposite, due to which its acceleration is achieved compared to the main gear.
  • For planetary hubs with 5, 7, etc. speeds, the range of gear ratios is higher than that of a three-speed due to the larger number of gear mechanisms. The operating principle of multi-speed and simple hubs will be the same. The only difference is that each planetary component will have its own fixed (like a 3-speed planetary gear) values ​​of gear ratios, and in general the mechanism will have several times more of them.

Bushing manufacturers: pros and cons

Several manufacturers manufacture planetary hubs for bicycles:

  • Shimano
  • SRAM
  • Sturmey-Archer,
  • Rohloff.

The latter occupies a leading position in the complexity of the invented mechanism. The hub from this manufacturer includes 14 planetary components. The large number of gear ratios and high efficiency easily compete with those of advanced star gear shift systems.

High-speed unit from Rohloff in section

Second place is occupied by SRAM - its planetary gear has 12 speeds, and the gear range exceeds 400%. Shimano is a well-known manufacturer of bicycle parts and speed hubs. Its well-proven 3, 4, 7 and 8-planet hubs are complemented by an updated version - an 11-speed shift system. Sturmey boasts hybrid cassette-planetary gearsets, as well as other types of standard hubs with three, five and seven speeds.

Advantages of using planetary bushings

  1. Straight chain travel and low wear on drive and driven sprockets. From the outside, the transmission looks like a regular signalspeed.
  2. The gear shift mechanism, hidden from external influences, is highly durable compared to cassettes and ratchets. All gear ratios can be used. Reviews from cyclists who switched from “standard” high-speed bicycles to planetary bicycles can clearly say this.
  3. There is no need to constantly maintain the device, and it is also difficult to accidentally damage it.

Like everything else, bushings with planetary gears have their “buts”:

  1. Unsuitable for use in bicycle racing due to high friction and sensitivity of the gears.
  2. Noticeable weight gain: only some three-speed hubs weigh just under a kilogram. In motion, the weight gain on the rear wheel makes itself felt.
  3. Repairing such mechanisms is almost impossible at home, and it’s rare to find a service that repairs planetary bushings. The disposability of planetary planets does not allow them to be brought into working condition profitably, the best option there will be a new installation.
  4. Exorbitant cost. Of course, it is completely justified, but there is no point in installing a gearbox from scratch on signalspeed. It is much easier to buy a ready-made bike with it.

How to change gears correctly when riding a bicycle

It is difficult to harm the mechanism of a bicycle gearbox, but it is possible if it is systematically misused. When riding a bicycle with a planetary gear, there is a simple rule: change gears without pedaling.

Strange? Not at all. The planetary mechanism is similar to a manual transmission of a car, and there, too, when switching from one gear to another, the gas is released. And “gas” for a cyclist means pedaling.

You need to switch from one gear to another a little in advance, and this is done like this:

  • The bicycle coasts, the effort on the pedals is minimal.
  • The gear is changed using the handle.
  • After a few rotations of the wheels (about 2 seconds), you can pedal.

Driving uphill is accompanied by a transition to a lower gear, that is, the gear ratio should be less than before the transition. On three-speed planetary gears it's simple: go to first gear. With other options, it is quite normal to switch, for example, from third to second.

You need to go for promotion sequentially, that is, first the first, then the second and so on. When you slow down, you can step over. In monotonous conditions where it is impossible to develop speed (a sidewalk with pedestrians, for example), it is better to use only the main gear without shifts.

Bicycles with planetary hubs are able to cover considerable distances without a lot of descents and ascents, so they can often be found in large cities with a developed network of roads and populated areas on flat terrain. This transmission option is ideal for those who do not want to constantly tinker with cassettes and chains and at the same time often drive around the city, countryside villages and flat roads.

Planetary carriage.

This is something similar to a planetary bushing, only it is located in the carriage

There are many detailed information about the development of planetary carriages with precise dates and numbers. We don’t want to burden ourselves and you with this information, so we’ll tell you the most interesting things.

The main goal of the planetary carriage was compactness and a multiplying factor. The weight of the developments ranged from 1200 grams to 2000 grams along with connecting rods. There were developments from the Nikolai company, which had a magnetic gear shift drive.

The main disadvantage of all developments was the incompatibility of the sizes of planetary carriages with standard sizes carriages But the advantages are also visible. Firstly, you don’t have to pedal to change gears, and secondly, the small front sprocket allows you to install a rear caliper with a short leg. It is known that such calipers are more resistant to shock and wear. Thirdly, the phenomenon of chain misalignment practically disappears, which means the service life of the chain itself increases.

Still, the planetary carriage is an interesting development, but it was the planetary bushing that received greater success, which we will describe below.

Planetary bushings.

History says that the first planetary hub of the modern type was born back in 1898, can you imagine? Personally, it’s hard for us to imagine. The hub had a built-in brake mechanism and several gears. Then developments went up and hubs with 3 gears appeared. Faster and more successful hubs began to appear closer to the beginning of the 20th century. One of the most famous manufacturers is Sachs Bicycle Component, now this company is part of the SRAM corporation. It was the production of planetary hubs that turned the cycling world upside down a bit and eliminated the production and development of other types of internal gear shifting.

Nowadays there are planetary bushings for 3rd, 5th and 7th gears. If 5 years ago there were only ordinary hubs, recently planetary hubs with a disc brake and with a built-in brake have become widely available on the market. And another difference between the old bushings and the new ones is compatibility with the front gear derailleur. And recently - with the installation of a cassette on the rear wheel. That is, you have, as it were, ordinary 3x8 gears and also a 3-speed planetary gear. And one more thing, for comparison. The gear ratio range of a standard 3x7 shift system is about 500%, and some 14-gear hubs from Rohloff have as much as 600%. Cool, isn't it?

Brief advantages of planetary bushings:

Large range of gear ratios, as we wrote about above.

Ease and smoothness in gear shifting.

High switching speed.

Easy to maintain and eliminates the need for constant maintenance.

And also a few disadvantages:

Repairs are rare, but accurate.

Planetary hubs found their purpose mainly in city bicycles. It's convenient and simple.
Cardan drive for torque transmission.

The advantages of a driveshaft over a chain are enormous, and it is very strange that this type is not used now. Main advantages:

Protection from external influences.

Greater reliability.

Doesn't stain clothes or snag pants.

The efficiency indicator is not higher, but is independent of the amount of dirt and swamp on the cardan.

And here are the disadvantages:

The cost is much higher.

The weight is also higher.

The cardan broke a little, but, like the planetary gears, it required special knowledge to repair.

Inability to set gear shift.

Difficulty removing the rear wheel.

Modern developments have been able to eliminate a number of the above-described disadvantages, especially the problem with shifting gears - installing a planetary hub made it possible to still change gears.

Belt drive.

Belt drives have been used for a very long time and have been discontinued over time, because the main disadvantage is insufficient strength and slippage. But again, science and engineering do not stand still and today there is clear competition between belt and chain drives. The main disadvantage of the belt is its integrity, the impossibility of installing gear switches and the difficulty of repairing and replacing components.

CVTs.

The advantage of a CVT is its continuously variable gear shifting and the possibility of a wide range of gears. But the disadvantages, unfortunately, are significant. The most important thing is the low efficiency, due to slippage in the variator itself. The disadvantages also include loss of power and cost.

Now CVTs are starting to regain popularity due to the development of technology and thanks to the sleepless nights of engineers. The weight of the bushings used to be about 5 kilograms, but now the speed drops to 3. Let's see what comes of this in a few years, for now only one thing is clear - CVTs will have a future.

And so, now let’s try to understand why all these developments didn’t take root? So much new, so much interesting, but everything remains: the chain and gears. Do you know why? But because everything ingenious is simple. Everyone loves a bicycle for its simplicity. And there is no need to complicate anything. Two wheels, a frame, brakes and a steering wheel, what else do you need? That is why, before upgrading your bike, think carefully about whether you need it and whether it will benefit you on a cycling trip.

Andrey Grigoriev

Bushings are one of the most important and often expensive components of a bicycle, be it an expensive sports bike or a simple teenager. The rolling ability, and therefore the efficiency of the bicycle, very significantly depends on their quality, which is important - after all, the biker spends his own strength when riding. It is not without reason that rolling bearings first appeared en masse on bicycles, and only later spread to many other machines and mechanisms.

General design features

Hubs designed for bicycles differ in such parameters as the presence of additional devices, strength and type of protection from external influences. Accordingly, both weight and price differ significantly. And if mountain and road bike hubs have approximately the same structure, then hubs with built-in brakes differ quite significantly, and hubs with internal gear shifting differ radically.

The simplest design is found on the front wheel hub of a regular bicycle. A cylindrical body, at the ends of which there are flanges with holes for attaching spokes. Inside the housing there are an axle and bearing units covered with anthers. The design of the rear hub of any bicycle is noticeably more complicated.

Rear hubs of multi-speed bicycles, not counting planetary ones, can be of two types. Outdated threaded bushings, where the ratchet, i.e., a block of stars together with a ratchet mechanism, is screwed onto the bushing, or modern - drum ( Freehub), where the ratchet is part of the hub and the cassette is just a set of sprockets. In addition to bushings with a traditional ratcheting mechanism, there are so-called “roller” bushings, which withstand shock loads on the freewheel mechanism much better and with a star mechanism, for example, in DT Hügi.

The bodies of modern bushings can be cast, turned or stamped, made of aluminum alloys and, partly, titanium alloys. Nowadays, turned and stamped aluminum bushings are the most common. Hubs designed for radial spoke wheels have reinforced flanges to withstand radial loads. Bushing axles can be steel, aluminum or titanium. The mid-2000s saw the introduction of front hubs with 15mm or 20mm thru-axles and rear hubs with 12mm thru-axles.

Mountain bike hubs are divided into “regular” and “disc,” i.e., those designed to accommodate disc brake rotors. There are currently two common incompatible standards for mounting rotors: ISO on six bolts and splined with a locking ring, the so-called Shimano Center Lock.

The wheel can be mounted on the frame or fork either with nuts - only on inexpensive bicycles, or using an eccentric mechanism ( quick release). The convenience of using an eccentric coupler lies in the ability to quickly remove and install the wheel without the use of tools. The 20mm DH axles are secured using a cam and fork leg bolts.

Modern mountain bike hubs from mid-level up have a double contact seal. Expensive hubs, such as DT Swiss, and road bike hubs use a labyrinth seal, which creates less resistance to wheel rotation than a contact seal, but is somewhat less protective against dirt and water.

Bearing types

To date, bushings with angular contact cone rolling bearings. For example, all Shimano hubs use these bearings. Bearings consist of an outer and inner race, a set of balls and, sometimes, a cage. The inner race is a cone that is screwed onto the bushing axis, and the outer race is pressed into the bushing body. The main advantages of bearings of this type are: maintainability And possibility of adjustment as it wears out. Among the shortcomings - difficulty of assembly(lots of details) and need for adjustment.

Another type of bearing previously found only in road bike hubs is radial cage (industrial) bearings. Now they have spread to mountain bike hubs. The advantages include lower friction losses, ease of assembly bushings, no need for adjustment. Taking into account the easy replacement of the bearing, the life of the bushing increases many times. But radial bearings do not tolerate axial loads well, sometimes occurring in bicycle wheels. An interesting feature of some of these high-end bushings is that they can be disassembled with just one hex key.

About replacing spokes

For a front hub that does not have a disc brake, replacing broken spokes does not present any problem, since the spoke can be easily inserted into the hub flange from the side. But this option is of little use if a disc brake hub or rear hub is being considered. To install the spoke into the flange, you will have to remove the brake rotor and cassette, which greatly complicates the work and requires the use of special tools. To simplify these operations, Mavic developed hubs with a non-traditional spoke mounting method.

Mavic uses segmented flange hubs for special straight spokes. Replacing a spoke in a wheel assembled on such hubs is very simple. Shimano tried a different route by creating wafer hubs DDH(directional design hub) and hubs with a small number of spokes placed with nipples to the hub (stepped flanges) with fastening not in the center of the rim, as is usually the case, but on its sides. Now, however, they have gone the way of Mavic.

Manufacturers

The most widely used hubs at the moment are Shimano. On inexpensive bicycles - from various Chinese manufacturers, supplying them only to assembly lines.

Expensive and high-quality bushings are produced by companies such as DT Swiss, Hope, Hayes, American Classic, Tune, Chris King and some others. Shimano XTR hubs can also be considered high-level hubs. Their cost can range from $100 to $300.

Results

In conclusion, it is worth mentioning that the quality of the bushing very much depends on the type of bearings, the quality of their processing, as well as the quality of the seals. The softness and ease of rotation of bearings is determined by the precision of manufacturing of parts, the type of polishing of the raceways and bearing balls, their surface hardening and compliance with tolerances. But remember that no matter how high the level of bushings on your bike are, you still shouldn’t dip them in water again, it won’t do any good.

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