How to sort out a hub with a coaster brake
Bicycles with one gear and foot brake are still popular today, because many people simply do not need a bicycle with gears for their purposes. Also, single-speed hubs are available on all children’s bicycles up to 20 inches. They are reliable, simple in design, but the problem is that if a low-quality lubricant is used in the hub, it will strongly resist rotation and it will be frankly difficult to ride a bicycle. And if an adult can resist this resistance, then the child after a short period of time simply will not want to get on the bike anymore. Therefore, take care of changing the grease in the rear hub.
We’ll be looking at the rear wheel bulkhead for an adult bike, but keep in mind that the construction is exactly the same on kids’ bikes. For the purity of the experiment, we took a new wheel, weakened the cones so that it spins easily, but also does not play. This is how it spins
Bearing grease. We will use Mobil XHP 222 multifunctional grease. You can get by with cheaper greases such as lithol.
!Important. The lubricant must be plastic (not liquid).
We start work on the right side (where the asterisk is located).
Remove the retaining ring holding the star with a screwdriver
Remove the star and the metal boot, then grab the 15 mm cone with a cone wrench and loosen the lock nut with a 17 mm wrench
Unscrew and take out the right side of the coupling together with the bearings
We take out the left part of the clutch together with the brake lever
As you can see, this is not the worst option for lubrication. Despite its overly viscous consistency, judging by the flash photo, the grease is similar to graphite. But this happens on adult bicycles. Unfortunately, for children, either a drying paste or “Moment” glue is laid, which simply do not allow the wheel to spin normally. It’s good if the bushing manufacturer regrets the lubrication. then your child will be able to ride more or less normally. Otherwise, cycling will take place with a great deal of suffering.
First, remove as much of the grease as possible with rags or toilet paper. Take some kind of cleaner (we used a pressure cylinder carburetor cleaner) or solvent and clean as much of the inside of the bushing as possible. By the way, the beloved WD-40 is also suitable.
Wipe clean the parts. If you don’t have a cleaner, you can simply wipe it down more thoroughly with rags.
Apply grease to the inside of the bushing housing, including the surfaces that the bearing interacts with
The main task is to assemble the left side of the clutch and completely install it into the bushing together with the pads.
We install a washer in part of the coupling, behind it a spring so that the antennae are directed outward
Lubricate the cone next to the brake lever, install a bearing on it
!The bearing should rest against the bushing cup with balls, and on the other side should be supported by a cone.
We fall with antennae into special holes made in the cone. For clarity, the photo without lubrication
Lubricate part of the coupling, put pads on it. The protrusions on the pads must lie on the cone between its protrusions
In this form, we install the resulting structure into the sleeve body.
We install a bearing of a larger diameter into the bushing housing with balls inward, and a bearing of a smaller diameter into the right side of the coupling, after having lubricated all surfaces
We tighten the coupling, fasten the cone and locknut, then grab the cone and tighten the locknut. It is important to choose a moment when the wheel turns easily, but does not have any backlash.
We install the boot, the asterisk, and then put the retaining ring in the groove specially designed for it
The video shows a visual result of changing the lubricant (compare with the video at the beginning of the article)
An hour-long video of single speed hub with coaster brake overhaul will perfectly complement our article.
Speed bike rear hub device
Rear hub device for sport and mountain bikes
The hub device of the rear wheel of a high-speed bicycle provides for a set of driven stars through which torque is transmitted to the wheel. There are two types of chainring set. cassette and ratchet. If the hub is designed for a ratchet, then the drum (nut) is located outside the hub and integrated into the set of stars. The ratchet itself is attached to the fork with a special thread. If the sleeve is for the cassette, then the drum is located on the sleeve itself and is attached to it using a special hollow bolt (see diagram). The cassette, in turn, is attached to the drum through a spline connection and secured with a special nut.
Rear ratchet thread hub
Splined and threaded hubs, cassette and ratchet
It is worth adding about the mounting of the disc brake rotor. Here, like the front hubs, there are two standards. CenterLock and 6 Bolt. The CL standard provides for spline fastening and tightening with a special nut. This standard is patented by Shimano. The six-bolt mount is more popular and is used by all rear hub and brake manufacturers.
Rear hub for six-bolt rotor mounting
Rear hub with CenterLock for rotor
6-bolt rotor with CL mount
How to disassemble, lubricate and reassemble the rear and front bicycle hubs
Over time, everything breaks down or gets damaged, as every bike owner expects. In case of damage to the axle system of the wheels, you can handle it yourself. But how to identify a broken or damaged bushing?
- The bike does not go as fast as it used to;
- The characteristic crisp bearing sound is heard;
- Grease is leaking;
- Got a crack in the case.
To get rid of the crack, you need to disassemble the wheel, all other problems can be solved without this. Not every cyclist can handle this, so in order to avoid trouble, it is better to entrust this matter to a specialist. Dismantling of the spokes is carried out once or twice, but it is not a fact that it will turn out to be installed back. For self-confident cyclists, we have provided an algorithm of actions for self-disassembly of the bicycle hub:
- Dismantling of wheels;
- Select the correct spanner and loosen the axle nuts. Using the puller, you can easily remove the cassette on the rear wheel;
- Using a screwdriver, you need to pry the bearings and remove so as not to lose the balls;
- Remove the axle from the body;
- Wipe all elements thoroughly and put on a clean cloth.
Types of bicycle hubs and their differences
Manufacturing firms make them cast, turned and stamped. Unlike stamped and chiseled ones, cast ones are not as strong, and they are also lighter in weight.
But with careful use, such a case can also last a long time.
- Cast and turned bodies are made of aluminum;
- Stamped, as a rule, steel;
What Is Inside A Bike Freewheel/How Does It Work?
- For the manufacture of the axle, aluminum, metal and, in rare cases, titanium are used.
Almost all bushings are fitted with tapered bearings with a radial stop. Let’s see how the installation works:
- The cone is twisted onto the axle;
- Bearings are installed on the housing;
- The outer part should fit snugly against the hub body.
Due to the high level of operation and the ability to replace, these bearings have become the most common.
Rear Hub Types
By application, the rear bushings can be used for road bikes, high-speed bikes (mountain, touring and road). Road bikes are usually fitted with single-sprocket hubs and a freewheel mechanism. Also bushings for road workers are equipped with a drum brake, i.e. hub with foot brake. The rear hubs for sports bikes do not have a brake mechanism, but they have a free wheeling system. In addition, the sports rear hubs are divided into cassette and ratchet.
Rear hub materials and manufacturing technologies
The rear hubs do not differ from the front hubs in manufacturing methods and materials. Bushings are produced by casting, turning or stamping. Cast bushings are the cheapest to manufacture, but also the least durable and heaviest. The most optimal metal for the bushings is an aluminum alloy. Bushings for the simplest and cheapest bicycles are made from steel. The lightest and strongest hubs are made from titanium alloy, but they are so expensive that they are used only in professional sports bikes.
We work with the inner space of the bushing
After the axle has been removed, you need to carefully inspect it. As a rule, this part of a bicycle wears out very rarely, but in any case, you will need to thoroughly wipe it off from dirt and dust. This is done with a dry cloth, but in some cases (with heavy pollution), you can use gasoline. So, we wipe the left cone and examine the right one for fastening strength. Only after the axle walls are completely dry (if gasoline was used for processing), can new grease be applied to it.
Note: in no case should you use chain lubricant or some other lubricant for the rear hub of the bicycle. you will need to purchase a special tool. Bearings are often used for bearings. this lubricant will be the most suitable. Too thick a layer of grease should not be applied. during the operation of the bike, it will be squeezed out and actively absorb dirt, which leads to rapid wear of the part.
How the rear hub of a bicycle works
Spoke is the order in which the hub, spokes, and rim are fastened together. There are two main types of wheel lacing: “radial” and “cross”.
In the “Radial” view, the spoke does not intersect with the others. When assembling “crosswise”, a knitting needle is crossed with the rest of the knitting needles several times, depending on the selected spoke method. On widespread 26-inch wheels, three-cross lacing is more commonly used.
Control system and depreciation
The main element of the bicycle device is the steering unit. It includes several components:
- steering column;
- steering part.
The bike fork serves as a connecting point for the handlebar and front wheel. It is installed in the front glass of the frame using a rod. The handlebar is inserted directly into the fork, and the wheel is attached to the ears of the legs. dropouts.
Bicycle fork structure: shock absorbing (left) and rigid (right)
In order for the fork to rotate freely when turning, a steering column is installed inside the glass. It consists of upper and lower cups, bearings and locating rings. Cups can be pressed or screwed onto the internal thread of the glass (on expensive professional models). Bearings are divided into closed industrial and bulk ball bearings. The rings are put on the fork rod, which is fixed in the steering column.
The handlebar of a bicycle consists of a horizontal curved tube and a vertical rod. In terms of shape, the rudders are divided into:
- straight (for MTB and hybrids);
- curved upward (road);
- curved downward;
- rams (for road bikes).
The vertical stem of the steering wheel has a wedge at the end, which fixes the pipe in the fork when the nut is tightened.
The stem is a part that determines the distance of the rudder from the frame and is attached to the adjusting tube. Rigid and adjustable stems are installed on different models. Simple road-type bicycles are not equipped with a stem. The distance of the steering wheel affects the fit: the further it is, the more the cyclist takes a horizontal position.
The saddle is secured to the center tube of the frame by a seat post. The height adjustment will allow you to find the optimal fit. Saddle widths differ depending on the type of bike: on road models they are wider than on MTB and road models. Saddles can vary in shape and length. They are spring-loaded from below or equipped with dampers.
How Do Rear Mountain Bike Hubs Work? | #AskGMBNTech
Damping is the ability to damp vibrations and cushion shock loads. Traditionally, the suspension system is located in the front fork, and these bicycles are called hardtails.
The damping consists of a spring and a damper. Depending on the components used, forks are divided into several types (spring / damper):
- spring (without damper);
- spring oil;
Adjustment of fork parameters: stroke length (Preload), rebound speed (Rebound) and lock. Forks without shock absorption are called rigid forks and are used on road and on-road models.
In addition to standard cushioning, mountain bikes are fitted with a rear shock absorber that dampens frame vibrations. Bicycles with two shocks are called double suspension.
The drivetrain is something a bike won’t run without. A fairly complex unit, it includes most of the mechanisms:
- leading stars;
- connecting rods and pedals;
- rear stars;
- speed switches and coins.
The carriage assembly is located in the lower frame glass and serves as a connecting unit for the connecting rod pair and chainrings. The carriage provides free rotation without turning due to the fixed bearings and the through axis on them. It is divided into two types: with open bearings and cartridge, where the entire mechanism is hidden inside the case.
Connecting rods. parts for connecting the carriage to the pedals. They can have two mounting options: slotted and square. Two-piece, or twin, connecting rods come with a chainring (stars on high-speed models) attached to the right connecting rod.
Twin cranks with square mount
Pedals are leg supports through which forces are transmitted to the cranks, carriage and chainrings. Depending on the scope of application, several types are distinguished:
- classic, or platforms. put on entry-level bicycles, you can use any shoes, engaging on the pedals due to friction forces;
- contact. with special inserts, designed only for cycling shoes, improved grip of surfaces;
- extreme. for a sports bike, wide surface, thickness, fixing inserts;
- pedals with straps;
The speed bike rear transmission chainrings attach to the rear wheel hub. There are 2-3 rear sprockets per one chainring. Small stars are responsible for high gears, and large stars are responsible for low gears.
The connecting link between the front and rear sprockets is a chain: the Gall block model is used on the bike. The chain transfer is carried out using switches that are controlled by shifters on the handlebars. Shifters are divided into two types. drum and lever. Driving cables connect them to the switches.
There are no derailleurs on the singlespeed, the front and rear sprocket in a single copy, the chain is shorter.
Brakes are the most important system, without which it is strictly forbidden to roll out the bike. Modern brake systems for bicycles of various classes:
- rim. pliers, V-brake;
Rim brakes are clamping devices with pads that act on the rims of the wheels, slowing down their rotation. Plier models have one fastening, due to the movement of the lever, the staples come closer together, and when they are loosened, they move back. Pliers are placed in place of the wing attachment. Used as additional brakes on singlespeeds and road bikes.
V-brake works on the same principle, but the calipers are fixed: to the fork for the front brake, to the stays for the rear brake. V-brakes have more precision and braking power than crimped.
The disc brake consists of a disc (brake surface) fixed to the hub, a caliper and a drive. a lever and a cable. The brake pads are attached to the calipers, which are pressed against the disc when the handle is pressed. The disc accuracy is higher than that of the V-brake due to the larger braking surface, less pad travel and independence from the rim geometry. By the type of drive, disc brakes are divided into mechanical and hydraulic.
Drum-hub brakes are outdated, but they continue to be actively installed on road models. The drum is hidden in the rear hub and is brought into contact with the pads by depressing the pedals backward. To prevent the sleeve from spinning, a special locking mechanism is built in. Braking efficiency is low in comparison with rim and disc counterparts, but for single-speed road workers there is no better option.
Varieties of rear bicycle hubs, how they differ from each other
The hub is the base of the wheel. The quality of manufacture of the hub, its weight and size determines the roll of the bike and the energy consumption of the cyclist during the ride. Bicycle hubs differ from each other in strength, the presence of additional elements and the level of protection from external climatic factors.
The hub is located in the center of the wheel and rotates on bearings. Collapsible balls or factory-made universal sealed bearings are used as bearings. The bearing carries all the pressure of the bike while riding, so its quality must be high.
The hub is spoked to the wheel rim. Outdated Torpedo bushings contain a brake drum inside the structure, with the help of which the cyclist brakes by reverse pedaling.
The modern rear bicycle hub features a ratchet mechanism and a cassette star cassette slips over the drum. On the ratchet hub, the bearings are closer to the center, so the load is not evenly distributed. Hubs of this type are installed on teenage or budget adult bikes.
The cassette hub is another popular type of rear hub. It has slots on which a cassette with stars is fitted and is fixed with a cassette nut. These bushings are more reliable, the bearings are further from the center of the hub, so the bike can support up to 120 kg.
The third type of rear hubs is a hub with a planetary gearshift system. It combines the functions of the hub and the gearshift mechanism of the bicycle.
The entire mechanism is located inside the hub and is protected from dust and moisture. The chain on a bicycle with such a hub lasts longer, since it does not change its position. The planetary hub has a high degree of reliability.
SRAM’s 3-speed planetary hub is very simple in design. But it is better not to disassemble the 5 and 7-speed ones. Planetary gears are installed in a special position. this requires a special tool.
What holds the bike
The structure of a bicycle is similar to that of a car: there is a supporting structure on which all working units are attached. For a passenger car, this is a body, and for a bicycle, a frame. The type of frame largely determines the purpose, and its quality is responsible for the life of the bike.
The bicycle frame is represented by a diamond-shaped frame, welded from the elements:
- main front tubes. top and bottom (closed), curved front tube (open);
- seat tube;
- top feathers;
The front tubes are “stitched” together into the head tube, the down tube and seatstays from the seatpost. into the bottom bracket, and the feathers between themselves. into the rear wheel dropouts. Front tubes and stays are welded to the top of the seat tube on both sides.
In relation to the seat tube, the front and rear are represented by two unequal triangles, the dimensions and geometry of which depend on the type and purpose of the bike. For the modern assortment, there are a large number of frame options, but they are all divided into classes:
- urban. tough, durable and heavy;
- mountain. resistant to loads, mobile, durable;
- road. light;
- sports. resistant to high loads, durable, shock-resistant;
- stunt. used for BMX bikes.
Mountain bike device in picture
Bicycles are divided into full-size and foldable. The first ones do not have a folding mechanism, and they must be disassembled for transportation in the subway, public transport and the trunk of a car. Folding ones have at least one joint along which the frame is folded. They are more convenient in transportation and storage, but inferior to full-size ones in terms of running performance.
The material of the supporting frame has a great influence on the operation of the bicycle. Modern bicycles are available on steel, aluminum and carbon frames.
Steel is used on city bikes. The material has high strength and shock resistance, and its disadvantages are heaviness and low flexibility, which is why the frame does not smooth out shocks well. All this does not have the best effect on the dynamics of the bike.
Aluminum is lightweight, durable and flexible. Compared to steel counterparts, frames made of it have better maneuverability and passive damping. Lightness and strength improve dynamics and do not create significant resistance to movement. Of course, their cost will be higher.
The most expensive frames are carbon fiber-based frames. This material is used on high-end road, mountain and sport bikes. Among the advantages compared to metal competitors are durability, strength, shock resistance and lightness. Plus, carbon-based bikes have better maneuverability compared to aluminum.