Rear bicycle hub: device and assembly instruction

The rear bushing of a bicycle should always be in good condition, because it determines the smoothness of the two-wheeled transport. According to many cyclists, the running qualities of the bike depend largely on the type and mechanical characteristics of the frame. However, in practice, the determining moment here is the state of the running gear - bushings, carriages, chains, and other systems.

Types

According to compatibility with different types of brake systems, several separate types of rear bushings are distinguished:

• For disc brakes;
• For roller brakes;
• For rim brakes.

Of course, the more complex rear bushing of the bicycle, designed to be connected to the disc brake system, can easily be used when assembling a wheel with rim brakes, but not the other way around.

Design

The rear bushing of the bicycle includes the following structural elements:

• The body;
• Flanges;
• axis;
• Bearings.

Housing

This component of the design of the rear hub acts as a connecting sheath for other functional mechanisms. The main requirement for the hull is a high index of rigidity, since during the ride the bushing undergoes significant twisting loads.

The bushing of the rear wheel of the bicycle can be protected by a body made by stamping or casting. The most reliable high-strength casings are manufactured in the first way.

Flanges

They are specific ring protrusions that are contained on the hull of the rear hub. This element serves to connect with the spokes of the wheel. Flanges contain special holes, where the needles are inserted when typing.

The main requirement for flanges is a high index of strength. Proceeding from the insignificant size of the detail, it is enough only to imagine how much the increased loads fall on its share. After all, a third of the design of the bicycle, together with the bicyclist, is just above the area of the rear flange.

Bearings

The rear bushing must be equipped with bearings with a dirt barrier. Only in this case it will be possible to forget about their maintenance and replacement, having rolled on a bike more than 10 000 km. Frankly, low-quality bearings will make you endure unpleasant sounds and suffer wheel play after the first trip in rainy weather, not to mention winter. Reliable mud protection is represented by various seals, which prevent contact of lubricant with the external environment.

At present, loose and industrial bearings for the rear bushings are isolated. The difference is that you can remove the backlash in the wheel by performing the normal adjustment of the loose bearings. If there is a similar problem in the case of industrial bearings, they will most likely have to be replaced. Therefore, the bushing of the rear wheel of the bicycle must be selected based on the type and reliability of the bearings.

Axis

The main parameter of the axis of the rear bushing is its length. To select a bushing according to the length indicator of the axis, it is sufficient to only measure the distance between the opposite outer nuts on the respective bicycle frame mounts.

Standards

Having studied the internal and external device of the rear hub bike, it is recommended to pay attention to a wide range of sizes of this system. The presence of some differences in the parameters is due to the use of bushes on various types of bicycles :

• Track models - 10x120 mm;
• Road bicycles - 10x130 mm;
• The bulk of the popular mountain models -10x135 mm;
• Bicycles for downhill - 12x135 mm;
• Professional models of the class "cross-country" - 12x142 mm;
• Models of bicycles for practicing freestyle, extreme sports - 12x150 mm;
• Bicycles class BMX - 14x110 mm.

Constructive differences

The device of the rear hub bike of the mountain group has some differences from the construction of the running parts for the bikes of the road category.

The bushings of road and highway bicycle models have seals - special seals designed to protect the bearings from penetration of contaminants. Omentums are often combined in a single unit with conical elements.

The rear bushing of the bicycle "Stealth", as well as other common models of mountain and off-road bikes, in addition to joints with cones of oil seals, often has rubber anthers. The presence of such elements helps to increase the protection of the running gear from dirt, all sorts of debris and dust.

In contrast to the highway category of bikes, mountain models are designed for driving on the most impassable terrain. Naturally, the use of additional protection of the rear hub mechanism proportionally leads to an increase in the weight of two-wheeled vehicles and a reduction in the ease of travel. That is why the assembly of the rear bushing of a highway class bike is made by most manufacturers without the installation of these elements.

Separately, it is worth considering the features of the design 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 ways of connecting ratchet to the hub with the cassette mounts. Most common domestic bicycle models contain bushings with built-in ratchets. On the contrary, the rear bushing of a high-speed bicycle usually has a pinched type of ratchet.

Specific features

In the majority of cases, the rear bushings are characterized by an asymmetric design, since a cassette or a rear sprocket must be located on the right side of the mechanism. In comparison with the left, the right flange is closer to the center of the axis. As a result, the right side of the knitting needle is somewhat shorter.

There is a special type of planetary bushings. The internal design of such products contains a gearshift mechanism. Only one star is installed on such systems. The sleeves of this plan can be operated without the installation of a chain tensioner.

How do I assemble the rear bushing of a bicycle?

When assembling the mechanism, it is necessary to take into account the fact that the left and right end of the axis have some differences. The right cone tightly joins the axis, is additionally strengthened by a lock nut and therefore never dismantled. The system is adjusted by changing the position of the left cone.

Trying to figure out how to assemble the rear bushing of a bicycle, the main thing is not to confuse the side with which the axis with the right cone should be installed. Admit the mistake here is much easier than in the case of assembling the front wheel, where both sides of the mechanism look identical.

Avoiding trouble, connecting the elements of the rear hub into a single unit during installation, will allow the following sequence of actions:

1. For starters, the sleeve body, ratchets and the surface of the cups for system mounting are cleaned of dirt, old grease residues, after which a new lubricating base of a thick consistency is applied.
2. Using tweezers, the bearing balls are placed in the desired place and pressed into the layer of lubricant, the amount of which should be enough to keep the balls from rolling back.
3. On the side of the ratchet, an axis with a right cone is installed. The operation is carried out carefully, since there is a high risk of pushing the bearing balls out of the bowl.
4. In the end, the left cone is practically pushed to the axis almost to the stop, but it does not tighten. The washers are screwed in the correct sequence, after which the locknuts are fastened.

On this rear hub is almost assembled. The only thing left is the installation of rubber anthers. However, it is advisable to do this only after the final adjustment of the running system.

Rear Bicycle Sleeve - Repair

As practice shows, the most common and typical for the rear bushing fault is excessive tightening or loosening of the cone. In the latter case, you will have to tolerate a noticeable backlash play. On the contrary, the tightening of the cone mechanism will lead to a more tense, difficult walk of the two-wheeled vehicle. In addition, there may be a crunch in the bearings.

What should I do when the cause of the backlash is the frustrated rear bumper bushing? Repair in this case will consist in tightening the cones with the help of special wrenches. Suitable for this are carabiners keys 15 and 20 mm, by means of which the locknuts are first unscrewed, and then the cones are clamped or loosened to the desired limit.

Ideally, the effect of backlash when driving a bicycle should be completely absent. If the adjustment of the cone mechanisms of the rear hub has been made correctly, the wheel will easily rotate without additional impulse, only under the influence of the force of attraction on the cataphytes.

Often the cause of breakage is the bending of the bushing. Most often, this happens when low-quality, inexpensive parts are used. If this happens, only the complete replacement of the axis with a new, more reliable one will solve the problem.

To perform repairs or routine maintenance of the rear wheel hub was more convenient, it is recommended to dismantle the ratchets in advance. However, when the whole point of repair lies in the usual tightening or weakening of cones, it is not necessary to resort to such an action.

In the end, in order to avoid unnecessary problems in the form of a long idle time of the bike and waste on expensive repairs, it is enough to pass a routine maintenance. Most often, the essence of maintenance is reduced to the bulk of the mechanisms, their cleaning, lubrication and installation in the reverse order.