ISO MTB Hub Assembly and Disassembly
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 the bike hub bodies? By the type of production, they are divided into:
Service A Bike Wheel’s Cup And Cone Front Hub
Compared to turned and stamped (rolled) bushings, cast bushings have a low margin of safety, and are also slightly inferior to them 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 running 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;
- cams. 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 mountings have been invented specifically 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.
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 equipped with special inserts for a 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 rotates 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 put 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.
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 bicycle moves, it reciprocates up and down along the guide bracket. To achieve a shock-absorbing effect, the outside is bordered by elastic elastic inserts.
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:
- 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 a 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 reassemble 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 fastening 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.
How to repair the front wheel hub of a bicycle with your own hands
Before taking on the repair of the hub on a bicycle wheel, you need to determine exactly where this part is located, without which the rotation of the front wheel is impossible. The front hub of the bike is located in the center of the wheel and is connected to the rim using spokes, this part determines how easy your favorite vehicle will be to move.
When to repair the bushing
Do-it-yourself repair of the front wheel hub of a bicycle involves dismantling the structure and sequential installation. When repairs are indispensable?
- If the front wheel rotates worse than before.
- Gone are the speed and ease of movement.
Repair work includes, among other things, lubricating the bearing cage, even a beginner can handle this.
Assembling a part
If you were able to disassemble the sleeve, then you will be able to assemble it. you just need to follow the reverse order of the above instructions. Remember an important rule: one side of the part is made stationary by tightening the nut until it stops. Next, position the axle so that the front hub is connected to it. Experts do not recommend over-tightening the cone, this is fraught with the fact that the wheel will not rotate. Weak tightening, in turn, leads to oscillations of the link in different directions.
Now you can put the vehicle in its normal position and finally adjust its operation. What characteristics need to be checked before driving a repaired vehicle?
- Correct disassembly of the front hub of the bike, lubrication and assembly solves the issue of heavy transport movement.
- The front hub, which makes the bike easy to ride, is believed to also ensure that there is no backlash.
- Thoroughly lubricated front wheel hub removes noise, friction and crackling noise while cycling.
How to repair the front hub with your own hands
Varieties of front bushings
Turned and stamped models are in less demand. They are considered more reliable devices and have an important advantage. the minimum weight, but it is not so easy to find them, and the cost of the elements goes off scale.
The front wheel hub of a bicycle can be different according to the following criteria:
- the material from which the part is made;
- the purpose of the part;
- what is inside. a hollow component or one-piece.
Bicycles designed for tourism, pleasant city driving or mountain climbing determine in what quality, strength and degree of protection the sample will be made. The best modification of the part is considered to be fasteners with eccentric clamps, which provide both easy removal and installation of the wheel in its original place. In vehicles intended for use in extreme sports, the fixing of the element implies the use of bolts.
How to disassemble
Do-it-yourself disassembly of the front bushing of a bicycle is as follows:
- Place the vehicle in front of you in such a position that it is convenient for you to repair the structure, preferably on top of the goat.
- If there are disc brakes, disconnect them.
- Armed with two keys, unscrew the bushing. It is important not to lose the bearings, which will immediately begin to fall out of the cage, collect them and put them aside. Even with a separator, the balls can still fall out, it all depends on the degree of wear of the separator.
- Experts recommend remembering the sequence of unscrewing each part; in the same order, the assembly of the functional component of the vehicle is to be done later.
- Inspect and assess the condition of the part cup. The presence of mechanical damage, chips and scratches is unacceptable, the trace of the balls should ideally be even and smooth. If damaged, while driving, the bearing will cause an alarming crackle and seizure of the rotation of the front wheel, which is difficult to ignore.
The front hub of a bicycle, which can be repaired by hand, after disassembly involves thorough wiping of the dust from the components, as well as lubricating the cup. It is better to use a lithol-like lubricant as a lubricant.
How to disassemble the front bike hub
Front Wheel Hub Service
The condition of the bike’s front and rear hubs affects the ease of travel. In my humble opinion (which I do not want to impose on anyone), the concept of “a bicycle rolls” or “does not roll” depends not so much on the geometric and mechanical properties of the frame, as many believe, but on the state. bushings, chains, systems, carriages. Although, of course, the properties of the frame should not be neglected either.
A well-adjusted and lubricated bushing should rotate easily and quietly without jamming. If the bushing starts to make strange sounds, or the wheel becomes difficult to rotate, then it is time to wash the bushing, lubricate it, or at least adjust it. With proper care, the bushings can work 10.20 thousand km or more, and it is better to monitor their condition. Replacing the bushing. the operation is quite time-consuming, because in this case you will have to remove all the spokes from the rim.
Maintenance of the front hub is easy. At the beginning of the season, it is necessary to check it for play or excessive tightening of the bearings, and, if necessary, adjust everything. And after 1000-2000 km it is not bad to change the lubricant. If you ride on muddy dirt roads, you can lubricate more often.
That, in fact, is all that needs to be done. It can be added that before a long trip, it is also worth checking the condition of the bushing, because it is inconvenient to adjust and lubricate the bushings in the field.
Almost all front hubs that are found on modern bicycles are similar in design. The differences can be mainly only in the way the wheel is attached to the fork. Some wheels are attached to the fork with nuts, and some. quick-acting eccentric clamp. But this difference practically affects only the way of removing the wheel, and the sequence of disassembly. assembly. adjustment remains the same for all types of bushings.
Some design differences have bushings related to mountain and road groups.
Road and road bike hubs have seals (oil seals) that keep dirt out of the bearings. Usually they are structurally combined with bearing cones.
Mountain and off-road bike hubs, in addition to taper seals, often have rubber boots that provide extra protection from dirt. After all, such bicycles, unlike road bicycles, must be able to ride on muddy terrain. This extra dirt protection increases the weight of the bike and reduces ease of movement, so anthers are not used on racing and road bikes.
How To Replace A Bent Axle On A Bike Wheel
Bicycles equipped with disc brakes have special bushings to which a brake disc can be attached.
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 bushing 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 using 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.
Ball bearings are composed of a cup recess, balls and a 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 screw 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.
Disassembling the bushing
We remove the eccentric (if any) (in the figure). To do this, unscrew the cap nut to the end, remove the spring, take out the clamping axis;
Remove the boot on the left side (if any). Next comes the lock nut (in the figure), the washer (in the figure) and the cone (in the figure) with edges for the key;
Next, take a taper wrench (usually 13 mm) and a lock nut wrench (usually 17 mm).
With one key we hold the cone, and with the other we unscrew the lock nut, remove it and the washer;
Next, unscrew and remove the cone. We take out the axle with the second cone, be careful, there may be bearing balls inside and they may wake up.
Remove the bearing balls from the bushing housing. In some bushings, the balls can be combined into one industrial bearing, in this case you just need to remove it;
Remove old grease from balls and bushing body. This can be done with a cloth dipped in kerosene, and then dried on a clean cloth.
Bushing assembly and lubrication
Remember that the right and left ends of the axle are different. The right cone is screwed onto the axle tightly and is fixed with a lock nut, it is never removed from the axle, and adjustments are made using the left cone. Do not confuse which side you insert the right cone.
Apply new grease (thick) to the surface of the ball cups;
Next, take the balls with tweezers and put them in a layer of this grease, if the balls roll out, then you can add more grease;
Insert the axle on the right side. When installing, do not push the balls out from the opposite side of the sleeve;
Screw the left cone onto the axle, screw it almost all the way, but do not tighten. If you tighten the cone too much, then the axle will not spin, and if it is too weak, then the wheel will move from side to side. Put on the washer and lock nut, and remember to put on the rubber boot at the end.