The rear hub device of a mountain bike has some differences from the design of the undercarriage for road bikes.
Bushings for road and road bike models have oil seals. special seals designed to protect bearings from contamination. Often glands are integrated into a single piece with tapered elements.
Rear wheel bearing replacement
The rear hub of the “Stealth” bicycle, as well as of other common models of mountain and off-road bikes, in addition to the oil seals connected to the cones, often has rubber anthers. The presence of such elements helps to increase the protection of the chassis from dirt, all kinds of debris and dust.
Unlike the road bike category, mountain bikes are designed to ride in the most rugged terrain. Naturally, the use of additional protection for the rear hub mechanism proportionally increases the weight of the two-wheeled vehicle and reduces the ease of movement. That is why the assembly of the rear hub of a road bike is carried out by most manufacturers without installing these elements.
Separately, it is worth considering the design features of bicycles with disc brakes. Here mechanisms are used, the flanges of which are connected to the brake discs.
Differences are also present in the methods of connecting the ratchets to the hub with the cassette mounts. Most common domestic bike models contain hubs with built-in ratchets. In contrast, the rear hub of a speed bike is usually a screw-on type of ratchet.
This component of the rear hub design acts as a connecting shell for other functional mechanisms. The main requirement for the body is a high degree of rigidity, since during the ride the hub is subjected to significant torsional loads.
The rear wheel hub of a bicycle can be protected by a stamped or cast body. The most reliable high-strength housings are produced in the first way.
How to Assemble the Rear Bicycle Hub?
When assembling the mechanism, you need to take into account the fact that the left and right ends of the axis have some differences. The right cone is firmly connected to the axle, is additionally secured with a lock nut and therefore is never dismantled. The system is adjusted by changing the position of the left cone.
When trying to figure out how to assemble the rear hub of a bicycle, the main thing is not to confuse the side on which the axle with the right taper should be installed. It is much easier to make a mistake here than in the case of a front wheel assembly, where both sides of the mechanism look identical.
To avoid trouble by connecting the elements of the rear hub into a single whole during installation, the following sequence of actions will allow:
- To begin with, the bushing body, ratchets and the surface of the cups for mounting the system are cleaned of dirt, remnants of old grease, after which a new grease base with a thick consistency is applied.
- Using tweezers, the balls of the bearings are placed in the right place and pressed into a layer of grease, the amount of which should be sufficient so that the balls do not roll back.
- On the side of the ratchet, an axle with a right taper is installed. The operation is carried out carefully, as there is a high risk of pushing the bearing balls out of the bowl.
- Finally, the left cone is screwed onto the axle almost to the stop, but not tightened. Washers are screwed on in the correct sequence and then the locknuts are secured.
On this, the rear hub is considered to be practically assembled. The only moment is the installation of rubber boots. However, it is advisable to do this only after the final adjustment of the chassis.
These are specific annular protrusions that are contained on the rear hub body. This element is used to connect with the spokes of the wheel. Flanges contain special holes where spokes are inserted when dialing.
The main requirement for flanges is a high strength index. Based on the small size of the part, it is enough just to imagine how much increased loads fall on its share. After all, a third of the bike structure, together with the cyclist, is located just above the area where the rear flanges are.
The rear hub of a bicycle includes the following structural elements:
In the overwhelming majority, the rear bushings are asymmetric, since a cassette or a rear sprocket should be located on the right side of the mechanism. Compared to the left flange, the right flange is closer to the center of the axis. As a result, on the right side of the spoke is slightly shorter.
There is a special type of planetary bushings. The internal structure of such products contains a mechanism for gear shifting. Only one star is installed on such systems. The bushings of this plan can be operated without installing a chain tensioner.
Having studied the internal and external design of the rear bicycle hub, it is recommended to pay attention to the wide range of standard sizes of this system. The presence of some differences in parameters is due to the use of hubs on various types of bicycles:
- track models. 10×120 mm;
- road bikes. 10×130 mm;
- the bulk of common mountain models. 10×135 mm;
- downhill bicycles. 12×135 mm;
- professional models of the “cross-country” class. 12×142 mm;
- models of bicycles for freestyle, extreme sports. 12×150 mm;
- BMX bikes. 14×110 mm.
Bicycle rear hub: device and assembly instructions
The rear hub of a bicycle must always be in good condition, because it is it that determines the smooth running of a two-wheeled vehicle. According to many cyclists, the ride quality of a bike depends largely on the type and mechanical performance of the frame. However, in practice, the defining moment here is the state of the undercarriage. bushings, carriages, chains, and other systems.
Shimano XT rear hub service
According to compatibility with different types of brake systems, there are several distinct types of rear hubs:
- for disc brakes;
- for roller brakes;
- for rim brakes.
Of course, the more complex rear hub of a bicycle, designed to be connected to a disc brake system, can easily be used when assembling a wheel with rim brakes, but not vice versa.
Replacing the bearings in the carriage
The most susceptible to damage is the crank and pedal assembly. It is called a carriage, and the bearings that are located in it can accommodate pedaling if they no longer meet the requirements.
The carriage of a bicycle can be open or closed; the operation of the bearings depends on its type. For example, the open one rotates thanks to the bearings in the cups installed in the bottom bracket and built into the frame tube. This is a complex unit, since it is subject to external influences more than other parts of the bicycle, which means that they need to be changed often. The carriage cup can have different sizes and threads depending on the type and model of the bike.
In closed carriages, the bearings are protected, so dirt from the street cannot spoil them.
Disassembly and assembly of the carriage
Sometimes you have to disassemble the open carriage in order to clean it, lubricate it and change the bearings in the bike. This is due to dirt on the cartridge, as well as due to wear, which can cause accidents while riding a bicycle.
To replace the cartridge, you need to bring the bike upside down and remove the cranks. Start with the nuts, unscrew them with a wrench and fold them neatly in one place. Do not press hard or use tools that could damage the bike, even if the nuts become tight. You need to act gradually and carefully. To remove the connecting rods, a squeeze and a puller are used. A special puller is also used to remove the carriage, but it must be removed strictly from the left side, away from the stars of the connecting rods.
Then you need to clean the carriage glass, in the future this will save the bearings from the harmful effects of dust and moisture. Next, get down to the cups, they need to be pulled out using the keys inserted into the grooves of the carriage, then take out the bearings and replace them. Assemble the knot in the same way as you took it apart.
After assembly, check that the assembly is functioning properly, the connecting rods rotate without effort, and the axle is not misaligned. If problems arise, you need to disassemble everything again to rule out the possibility of a serious error.
How to change bearings on a bicycle
All decent bikes must have quality bearings. They are located in several nodes and may differ from each other. So, some of them are designed for a fork, others for pedals, so both the carriage and the wheel can be disassembled. So that the products do not deteriorate ahead of time, you need to regularly lubricate them, as well as replace them. over, install exactly those bearings that are needed in this unit.
It is important to pay attention to quality, appearance and other characteristics. If you make a mistake by installing the wrong device, the entire bike may break down, and this is a direct threat not only to the vehicle, but also to your safety.
Bearings are support devices for the moving parts of a bicycle. They hold the parts in place and help the mechanism to function properly, making the pedals rotate smoothly, for example. The rest of the components of the bicycle structure work in the same way.
Since bearings on a bicycle can be in different places, the principle of their operation is different, which means that before changing them, you need to know what types of this product are. They are divided into three types:
Let’s dwell on the extreme option. In total, two types of rolling bearings are used for a bicycle: a cone-cup (or bulk) and non-separable, which are called “cartridge”.
Bulk consists of a set of balls and a cup built into the bike. Cartridge are two rings with balls. They do not need adjustment, since such bearings just need to be changed if the need arises.
Replacing the bearings in the front fork
Loose bearings look like balls moving in a wheel hub. They roll along the groove and provide support. The number of such balls is always certain, therefore, during their replacement, it is important not to lose a single one, and also to change the entire set if at least one of them has worn out ahead of time. If you don’t know how to change bearings on a bike but would like to do it yourself, take note of the following advice:
After carefully pouring them out of the cups into the glass so as not to get lost, remove the plug. The cups should be rinsed well to remove dirt, just like the balls. Be sure to dry them or wipe them dry, as moisture affects the device negatively. The balls may rust or deform and will need to be replaced. You cannot use them even if only one is damaged. In this case, you will need to replace everything with new ones. Use grease for the cups, grease the axle as well. Only then reassemble the structure in exactly the same way as it was disassembled.