Bicycle Hub A to Z
Is a bicycle a simple or complex mechanism? It all depends on which side to look at and which one is big before our eyes. For example, an MTB device can be called complex compared to a city bike, but simple relative to a car. Nevertheless, even the most ordinary model is a system of interconnected nodes. It will not be possible to single out any one of them. the operation is ensured by the well-coordinated work of all mechanisms. These are the wheel hubs.
Bicycle hubs are responsible for the distribution of circular and radial loads, uniform wheel rotation, rolling, and in some cases. for shifting gears and stopping the bike. Based on this, we understand that the condition of the bushings directly affects the ride quality. And if so, let’s dwell on this mechanism in more detail: how it works, how the bushings differ from each other, how to service this unit.
Rear hubs. varieties and fundamental differences
The arrangement of axle assemblies for the rear wheels is more complicated than for the front wheels. we have already mentioned the built-in freewheel mechanism above. In addition, the bushings are supplied with special inserts for the cassette, ratchet, brake discs. On planetary shift models, the rear hubs are complex gear systems.
And of course, on classic Soviet bicycles and modern city bikes, they are equipped with a braking mechanism:
By design, rear bicycle hubs are divided into types:
- classic, without brakes, with mounting for a cassette and / or disc;
- brake with an internal drum-shoe mechanism;
- without freewheel.
Classic narrow bushings are similar in appearance to the front ones. Installed on high-speed models, they have a built-in freewheel mechanism. The principle of operation consists only in the direct transfer of forces from the pedals through the transmission to the axle. Fixation of the bushing is provided by pawls, which, in the absence of applied forces, hold the body, due to which the wheel spins independently by inertia.
The planetary model is a model that arouses keen interest among cyclists. The entire multi-stage transmission is hidden in the hub housing, so it does not require adjustment, it is 100% protected from harmful weather conditions and has a very high running life.
The classic planetary system. three gears: standard, high and low. The picture shows a model with a foot brake, as on Soviet city bikes, but there are also planetary without brakes. High-speed transmissions are available in five, seven and eight gears. In terms of the number of gear ratios, they are comparable to 24-speed cassette systems.
Repair of planetary gears is not provided, they serve only once. Difficulties can arise with the maintenance of the axle assembly and bearings if they wear out before the gearshift mechanism. There are also a couple of other disadvantages. high weight and relatively low impact strength. Planet cars are installed on urban models, as they wear out quickly in aggressive conditions.
Worm and drum brake hubs are mounted on the rear wheels of single speed bicycles. Braking occurs when pedaling backward. The mechanism works according to the following algorithm:
- When the driven sprocket moves backward, the freewheel mechanism is activated. All foot brake systems have some margin where the sprocket can turn back 1/8 of a turn. This, in turn, reduces braking performance.
- Stopping the body.
- Drum rotation and brake pad spreading, wheel stop.
- In the absence of applied forces on the pedal, the spring of the drum should instantly rebound. If this does not happen (indicates wear of the mechanism), the wheel must be released by scrolling the pedals forward.
The worm brake mechanism differs from the drum brake in that a threaded auger is applied to the inner wall of the housing when the star rotates in the opposite direction. Benefits of brake bushings:
- does not require frequent maintenance. this is facilitated by a sealed housing and a large amount of lubricant;
- if necessary, it is easy to remove and lubricate the bearing-axle part without touching the brakes;
- relatively light weight, good strength.
Flip-flop, or two-star hub, is a system that allows the wheel to flip 180 degrees. At both ends there are two stars of different diameters, depending on the intended driving conditions, turn the wheel with a large or small sprocket.
The two-star model does not have a built-in braking mechanism or even a free wheel. The non-free wheel rear hub transmits forces in both directions. from pedals to wheel and from wheels to pedals. Thanks to this, the dynamics of the bike is noticeably increased compared to free-wheeling models.
Service A Bike Wheel’s Cup And Cone Front Hub
Bushings are a relatively new and little-known variety. It is installed on the front axle and serves as a wheel vibration damper. When the bike moves, it reciprocates up and down along the guide bracket. To achieve a shock-absorbing effect, the outside is bordered by elastic elastic inserts.
Bicycle hub device
Mechanisms of this type first appeared on bicycles. The operation of the bushing is based on rolling bearings. ball parts for transferring torque from the axle to the bushing housing and rotating the wheel. Three main types of rolling bearings have become widespread. ball embankment, separator and closed (industrial).
The front hub has a classic and versatile design:
- wheel axle with attachments to dropouts;
- protective inserts. anthers;
- external spokes.
The design is identical on any type of bike, from standard road bikes to special-purpose high-speed bikes. Of course, with the similarity of the general structure of the bushings, they will differ in material, weight, strength, degree of protection and running resource.
Front hubs are lighter and simpler than rear hubs. This is due to the lower dynamic load on the front of the bike. In addition, the complexity of the rear mechanism in comparison with the front is associated with the presence of free wheeling. It is installed on all bikes except fix bikes. It is also easier to do it yourself before.
What are bike hub bodies? By the type of production, they are divided into:
Compared to turned and stamped (rolled) bushings, cast bushings have a low margin of safety, and are also slightly inferior in weight. However, with proper operation and timely maintenance, they can also serve for a long time without wheel alignment. The materials used are aluminum alloys for casting and dots, steel is used in stamping. The axle is made of steel, aluminum and less often titanium.
Most bicycle hubs are fitted with radial thrust tapered bearings. The part is attached in this way:
- A cone is screwed onto the axle.
- A bearing is mounted on top of the housing.
- Outside fits snugly against the hub body.
Bearings of this type have become widespread due to their high travel resource, the ability to sort out and adjust as they wear out. Some mountain and road bikes are equipped with industrial radial bearings. Compared to classic open ball flush systems, they do not require disassembly and are easy to install. With lower rolling resistance and higher efficiency, these bearings significantly increase the running life of the bushing.
Types of bike frame mounts
Consider what mounts are on the wheel axles. Traditionally, they are presented in three types:
- nut. on budget road and high-speed models, the axle is fixed to the dropouts with two nuts;
- splined. have an analogy with nuts, instead of them flat splined linings are superimposed on the axis;
- eccentrics. a common mount on speed bikes, the spring is fixed with a clamping nut and a lever.
From the standpoint of convenience, eccentrics are better than nuts and splines. the wheels are removed and put in half a minute, the mechanism is simple and relatively durable. However, the fastening force does not correspond to aggressive driving conditions. too high loads on the fasteners.
Hybrid eccentric-nut fasteners have been invented especially for these purposes. On the right side, the axle is attached to the dropout through a regular nut, and on the left it is clamped with a lever. The installation of such an eccentric looks like this:
- The axle is threaded through the linkage through the entire hub body.
- The thread is screwed onto the dropout of the fork or stays.
- A nut is thrown from above.
- The eccentric fixed on the right side is clamped with a conventional lever.
This way, the wheel will not loosen at high speed off-road. If an ordinary eccentric no longer rescues, it makes sense to choose just this type of attachment.
Bulkhead bushing. simple, fast, high quality
Sooner or later, the need to get into the axle system of the wheel and repair it arises for any cyclist, even the owner of a standard city bike. Over time, the grease ages, the bearings wear out, washers may break, and the axle is not eternal.
Bushing malfunctions are determined very simply:
- deterioration of the roll, the average speed of the bike decreases;
- crunch of bearings;
- leakage of grease;
- crack in the case.
To eliminate the last problem, disassembly of the wheel will be required; in other cases, you can do without spacing. In general, it is better to entrust the operation to remove the case to the master. it will be easy to remove the knitting needles, but putting it back on and correctly adjusting it will not always work.
The procedure for disassembling the bushings yourself:
How to Install a Nutted Hub front wheel
- Remove wheels from dropouts.
- Loosen the fixing nuts on the axle using suitable spanners. It is necessary to remove the cassette from the rear wheel using a puller.
- The bearings can be locked with rings. Use a thin screwdriver to gently pry them.
- We now have access to the bearings. We take them out and carefully set them aside. It is undesirable for the balls to crumble.
- Pull the axle out of the body cavity.
- Wipe the interior space and parts from old grease. Place the parts neatly on a clean cloth.
During preventive overhaul, the parts and the body are lubricated, and then the assembly is assembled in the reverse order. As you can see, making a bulkhead is very simple, half an hour at most.
Note: it is better to purchase a special lubricant for the bushings, and separately on the bearings, you can apply thick grease.
But what if you need to replace bearings, axles, washers, or even the entire bushing? It is better to contact a workshop to replace the entire unit. To be more precise, it is necessary to remap the wheel. Otherwise, it will not be difficult to repair the internal mechanism on your own:
- We select bearings by standard size. They are installed on one side with the outside, on the other. with the inside, the main thing is not to confuse.
- After disassembly, it is better to fold all the parts in the order in which they were installed on the bushing. it is easier to assemble later.
- It is necessary to lubricate the inner cavity first, then the axle and only the bearings last.
- After the assembly is complete, we install the wheels on the bike and check the operation of the bushings. Backlash, braking, grease leakage. all these are signs of an incorrect bulkhead.
The retaining nuts must be tight but must not interfere with the rotation of the axle. A weak tightening will cause play, and too strong an additional load on the bearings and difficult rotation. It is easy to disassemble and assemble the hub, from the rear everything is complicated by removing the cassette and brake disc. In addition, its device due to the built-in freewheel mechanism is (at least) more complicated than that of the front one, so it should be sorted out with special care.
Types and arrangement of the rear / front hub of a mountain bike
In the MTB class, only two types of sleeve mechanisms are common: axle-cone-ball bearing and axle-industrial bearing. By the name of the classes, it is clear that the difference between them lies in the structure of the supports.
How to change the rear or front hub on a speed bike
When it comes to tapered bushing mechanisms, then only products with worn cups need to be replaced. In this case, an analog is selected that is suitable for the distance between the dropouts and the number of holes for the knitting needles. It is better to entrust the work of re-spacing the wheel to an experienced master, as well as the selection of new spokes.
The most common type. Particularly in the Shimano range, you will not see a knot on the “slip”. The company explains this by the fact that the design based on cone-nuts has better reel. The configuration elements of such a product are shown in the figure:
How to disassemble
Initially, it is necessary to provide unhindered access to the flare nuts. For this, they usually remove:
- Disc brake rotor. Not in all cases can be dismantled. Make sure that the bolts do not interfere with the installation and rotation of the tapered (thin) wrench. If there is a gap between the key and the disc, it is not necessary to remove the latter. There are situations when the tool fits freely in the back, and on the front hub it is impossible to do without removing the rotor.
- Cassette / ratchet. It is imperative to remove, otherwise you cannot reach the second cone, and the axle cannot be removed. The process of dismantling the cassette is shown in the photo.
When the flare nuts are accessible, you can unlock one of them. In this case, it is important to observe two rules:
- Only one side is allowed to unlock! The second must be locked to failure even from the factory and it is forbidden to touch it.
- You can only unlock the cone located on the side of the rotor mounting (if there is no disc brake, then focus on the side opposite to the cassette). The fact is that the cone nut, weakened from the side of the sprockets, self-tightens upon impacts or collisions with an obstacle, which is why the free movement of the sleeve is disturbed. And this reduces the resource and worsens the roll-forward. This does not happen with the left side, since there the cone-nut tends to unscrew, and the lock nut and eccentric prevent this. In total, such a scheme maintains a balance and you can choose a gap without prejudice to the roll.
The deconstructing procedure is shown in the photographic material. A thin cone wrench adheres to a cone-nut, and with another wrench (for convenience, it is advisable to take a more massive tool) unscrew the locknut. After that, the threaded parts are completely twisted, and the axle is removed. Next, you need to remove the anthers and remove the balls from the cups.
Attention! When disassembling, note the order in which the components are located. The ideal option is to take a photo of the placement of anthers, nuts and washers on fresh tracks, as shown in the image.
When dismantling the balls from the seats, it is important to separate them into two groups. Those on the right must be folded in one place, those on the left in another. Do not mix or confuse these groups with each other, otherwise, after assembling the perfect reel without backlash, you will not get.
Important! When removing the axle on the front wheel of a bicycle without disc brakes, mark the side of the non-rolled cone on the tire. Another landmark on this type of bike is the direction of rotation of the rubber shown on the side.
Hub maintenance, general bike wheel arrangement
One of the most important parts of a bike is the wheels, as they determine the smoothness and speed of the ride. They come in the following sizes (bicycle rim diameters). 20 (children), 24 (teenage bicycles for boys and girls and for extreme disciplines), 26 (mountain, city and recreational), 27 (road), 28 (hybrid and road) and 29 inch bicycles (new standard mountain bikes).
- Read also how to choose your bicycle tires.
- You can also find out more information about bicycle rims here.
Bicycle wheel device, its main components
Bushings are the most important part of a wheel, since the quality of its rotation depends on the hub. Consists of an axis, balls, drum. The bushings are clamped in the frame dropouts using an eccentric (a special clamp that can be easily removed without tools) or two nuts at the ends of the axle (you can remove it with a wrench). Hubs for disc and rim brakes are different.
The strength of the wheel depends on the following factors:
- uniform spoke tension;
- the quality of the rim;
- wheel assembly quality;
- stability of the wheel under impacts (profile);
- the number of spokes, as well as the material from which they are made.
Bicycle wheel repair is most often necessary in two cases, not counting wheel punctures:
- alignment of wheels (eights, eggs);
- bulkhead and bushing relubrication.
When assembling the wheel, you will need the following tools:
wheel machine. a special machine that will help you assemble a wheel with precision;
When assembling the wheel, it is important to select the correct spoke length. In order to accurately select a spoke of the desired length, you can use a special calculator, you just need to make a few measurements. An example of a calculator for calculating the length of the needles: http://www.velostyle.com.ua/spcalc.php http://upbikes.com.ua/calculator.php
Based on the calculations, you can start assembling the wheels.
Correction of “eight” on the rim
If a figure eight appears on the rim, then it is easy to fix it with a spoke wrench. An 8 on the rim may mean some of the spokes are loose and need to be re-tightened periodically. In order to tighten the weakened knitting needle, pull the knitting needle clockwise, to loosen the knitting needle. counterclockwise. Recall that the spoke wrench only rotates the nipple, the spoke remains stationary. We find the place on the rim where the rim wags, you can do this using chalk and rotating the tire. After finding the place of deformation of the rim, we tighten one side, weaken the other, while the tightening is proportional to the weakening.
Bushing lubrication (maintenance)
As you know, bushings are available on bulk bearings and on industrial bearings. The hub should be serviced as soon as you notice extraneous sounds, tire rotation, etc.
Maintenance of the sleeve on bulk bearings. It is recommended to change the lubricant every 1000-2000 km. In order to lubricate the wheel hub, it is necessary to remove the wheel from the bike drop points, the camera and tire do not need to be removed, they will not interfere. If you carry out maintenance repair of the rear wheel hub of a bicycle, you will additionally need a whip for removing the cassette and a cassette remover.
bicycle rear wheel hub removal tool.
- What to do if the bike squeaks when riding. Discover.
- Find out in this article //velosipedinfo.ru/kak-pravilno-nakachat-koleso-na-velosipede what pressure should be in bicycle tires.
Watch another video on how to do full maintenance of the rear wheel of a bicycle. Disassembly, assembly of all its parts, with their mandatory subsequent lubrication.
What is the front wheel hub?
There are many hubs throughout the bike design, but today it’s worth talking about this front wheel mounted part.
The front wheel hub, in contrast to the rear, is of a simpler design, since it is not subjected to heavy loads.
Depending on the type of bike, parts are installed on it, which differ from each other:
- by size;
- by weight;
- by strength.
On sale most often you can find solid aluminum bushings, but there are also chiseled and stamped variations. The latter are extremely difficult to meet, due to their rather high cost.
Although they have several advantages over solid parts:
Front wheel hubs may vary depending on:
- From production material.
- From destination.
- From structure. hollow or solid.
How to repair the front wheel hub?
To repair the hub installed on the front wheel, you will need to dismantle the structure followed by step-by-step installation.
Disassembly and repair
Step-by-step guide to disassemble and repair the front wheel hub:
- The vehicle must be installed in a position in which repairs to the structure will be carried out without additional difficulties.
- If there are disc brakes in the design, it becomes necessary to remove them.
- Using two keys, you need to unscrew the bushing, while preventing the loss of bearings, which can instantly jump out of the cage. Don’t rely on a separator as it also has a degree of wear resistance.
- Inspection and assessment of the condition of the cup. We admit only an even and smooth trail of balls, but the presence of damage (chips and scratches) will indicate the subsequent possibility of a wedge on the front wheel.
The sleeve needs a large and thick layer of lubricant and, only after applying it, balls are distributed from above, in increments of no more than two millimeters.
The bushing must have the same number of balls on both sides!
For convenience, cage bearings can be used to shorten repair times.
When repairs are needed?
Repair cannot be avoided if the following problems appear:
- deterioration of the degree and speed of rotation of the front wheel;
- lack of speed and lightness while driving.
Disc brake mounts
If the front wheel design is equipped with a disc brake, then two types of fasteners have been developed for the hubs:
- ISO standard. Fastening with six bolts.
- The Japanese concern Shimano has developed its own standard for spline fasteners.
Front hub types
The front hub of a bicycle, in contrast to the rear, has a fairly simple device. For different types of bicycles, its design may vary in size, weight and strength. Currently, the front hubs are mostly made from die-cast aluminum. There are also turned and stamped models, which are more durable and lightweight.
There are many features that distinguish the front hubs: material of manufacture, purpose, interior. For touring, mountain, city or road bikes, hubs can vary in protection, strength and weight.
Nowadays, more and more often, the sleeve is fastened using eccentric clamps. These modifications allow you to quickly remove and put the wheel on the bike. For bikes used in extreme sports, the bolt-on option is used.
Bicycle front hub: assembly and repair
The front wheel is one of the main components of the bike. The way it rotates and takes the load from the total mass depends on the convenience and comfort while driving. The rotational ability of the wheel is directly related to the hub, which is its connecting element to the frame. The front hub is the part of the bicycle wheel located in the very center of the wheel and connected to the rim by means of spokes.
Front hub device
The most massive part of the front hub is its body, which can be made in many different ways. In the first case, it is one piece with the cups, in the second. the central tube and two cups are the integral parts of the sleeve. Flanges with holes are pressed on top of the cups on each side, where the knitting needles are inserted.
The inner part of the hub consists of an axle, ball bearings located on both sides, cones, safety caps, washers, locknuts and nuts with which the axle is attached to the bicycle fork.
The component parts of ball bearings are cup recess, balls and cone. The balls can be placed one at a time, and in some cases they are in special clips called separators.
The cones are screwed onto the axle, and one of them must remain motionless, for which it is screwed on until it stops. The other is screwed on until the bearing clearance is adjusted. The clearance is adjusted by rotating the cone. Both cones have a right-hand thread and are additionally secured with locknuts.
Cup recesses and cone made of high strength heat treated steels.
DIY disassembly and repair of the front hub
If you notice that the front wheel has become worse to rotate, there is no such speed and lightness as after purchase, it means that it is time to disassemble and lubricate the hub. Its design is quite simple, so small repairs can be done by hand. The main thing is to follow the order of disassembly and assemble everything in reverse order.
- We put the bike in a position convenient for repair, that is, “on the goat”.
- If equipped with disc brakes, unfasten them.
- We take two suitable keys and unscrew the sleeve. Be careful not to lose the bearings, which will start to fall out from there, carefully assemble them. Even if a cage is installed, be careful: if it is worn out, it will not hold the balls. Fold up all the parts in the order in which you shoot, so that later it will be easier to assemble.
- We carry out a thorough inspection of the sleeve cup. The presence of mechanical defects on it is unacceptable, only an even smooth trace of the balls. If damaged, your bushing bearing will crack and wedge.
- We carefully wipe all the details.
- We lubricate the components, including the sleeve cup, with a lithol-type grease.
- Apply grease to the cup of the sleeve with a grease layer and stick balls evenly in a circle around it, or put a bearing with a cage. When installing balls, distribute them evenly, the distance between them can reach 1-2 mm. There must be an equal number of balls on both sides of the sleeve.
- Checking the surface of the cone. It should also be undamaged. Lubricate the cone and axis.
- Be careful in the next step. We make one side “dead”. To do this, on one side, tighten the nut until it stops. Then we insert the axle into the bushing and twist it on the other side. Do not overdo it by tightening the cone, otherwise your wheel will not spin. With a slight tightening, it will dangle from side to side. So look for a middle ground.
- We put the wheel on the bike and adjust its position. We check the ease of rotation and the absence of backlash. There should be no extraneous noise, friction and crackling.