DIY Bicycle Repair - Detailed Guide

Hello dear readers! As I noticed, there are a lot of articles on the Internet about how to take care of your bike, where to start repairs, and so on. I would like to deviate a little from the formed concept of advisers regarding the general, basic rules for carrying out repair work, and pay attention to all components and mechanisms, without exception. Of course, such an undertaking forces you to create quite a lot of material, but having it at hand, you do not have to look for additional information in other sources. After reading this guide, you will get the basic knowledge, and to learn how to repair a bicycle yourself, you will have to go deeper and study more articles, since it is very difficult to fit everything here. So let's get started!

During operation, the bicycle undergoes wear and tear of almost all components, therefore, it requires periodic maintenance by specialists. But it is far from always necessary to take your iron horse to a specialized workshop. As practice shows, in 80% of cases you can get by with self-repair of certain parts of the bike.

After buying a bike and, accordingly, the start of operation, there is such a thing as primary running-in. This concerns, first of all, rubbing nodes. The oil or grease that such places are crammed with accumulates a large amount of microchips in its structure. It would seem that there is nothing wrong with this - the oil works as a "cleaner".

But in fact, the untimely maintenance leads to the fact that the oil or grease acts as an abrasive paste. Accordingly, a dangerous mixture leads to accelerated wear due to an increase in the coefficient of friction. This coefficient can increase several times; it all depends on when the scheduled service work was last performed.

After the first service, the frequency of repair work can be extended. And all due to the fact that the coefficient of friction will increase significantly, the suspension will better swallow any bumps (even if they are minor), the brakes will work like stop cranes on a train, and the bike runout will increase.

List of tools and materials that you can not do without

It is impossible to carry out maintenance work on an iron horse without tools. Here is a basic set of tools that all cyclists must have. This set is almost impossible to replace with other analogues.

Set of wrenches.
A set of hex keys.
Kiyanka
A set of pliers (for retaining rings, even the most common ones will do);
Set of Phillips, slotted and Phillips screwdrivers;
Clamps and scissors (for tying hydraulic lines and landing in appropriate places on the frame, fastening wires and other important elements);
Tweezers;
A set of end nozzles with special levers.

List of additional tools

If the list above was basic, that is, you cannot do without it in any case, you can refuse some of the tools in the list below. But this does not mean that, having abandoned these tools, you will not have to deal with them in the future. With the help of these keys, a full service is carried out, when the bike is disassembled down to the bare frame without hitch.

Chain squeezing.
Carriage remover.
Ratchet and socket wrenches.
Cassette remover with Center Lock brake discs (Shimano).
Spoke wrench to eliminate wheel defects.
High pressure pump.
Crank puller.
Transparent hydraulic brake bleed kit.
Chain cleaning brush.
Syringe for dispensing oil.
Beaker.
Repair kit for broken cameras.

Consumables List

When operating a bicycle, you will have to deal with consumables more than once. Typically, this includes synthetic-based oils, solvents, and other materials. So, the list of materials is below.

Oil for lubricating shifter springs, chain and clipless pedals (if dirty conditions occur).
Oil for lubricating fork legs, impregnating oil seals and lubricating pneumatic suspension chambers.
Fork oil (note - only fork!) for damping.
Brake fluid for bicycle brakes type DOT or hydraulic oil. The choice of a particular fluid depends on the specific type of brakes installed on the bike.
Cleaner for transmission and brake parts.
Grease for fork springs, bearings, ratchet, suspension o-rings and shifter springs.
Solvent for complex cleaning of sprockets and chains.

A little about lubricants

Like any other working mechanism, a bicycle needs periodic lubrication. Gentle lubrication is required from the owner. It should be noted that the lubrication of a particular bicycle assembly is carried out at a certain time. It is unacceptable to use lubricants that are not intended for working with one or another rubbing mechanism.

Bicycle transport needs periodic lubrication of hinge and bearing assemblies, including tensioner or chain damper rollers, bushings, steering column, carriage, pedals. In addition, it is imperative to lubricate the shifter cables and the switches themselves.

Before tightening, it does not hurt to lubricate the threaded connections so that in the future they unscrew easily enough. But here you need to remember: excessive lubrication of threaded connections will lead to the risk of losing certain components.

Those components that the manufacturer defines as hydraulic - brakes / shock absorbers - it is extremely important to service with exactly the oil that is declared by the manufacturer.

There are places that do not need, or even recommended, to be lubricated. These are brake pads, rotor and rim. If oil accidentally gets on the surface or working part of these brakes, you must immediately clean them with a clean cloth. Otherwise, oil residues will interfere with the correct operation of the brake mechanism.

Three types of oils are used for a bicycle.

Aerosol lubricants. Suitable for lubricating swivel joints, for the trouble-free removal of stuck and rusted threaded connections, lubricating the chain and cable switches in the event that at the time of maintenance there are no materials for more thorough lubrication at hand.

Liquid lubricants. Supplied in special bottles-oilers. A striking example is type I5A oil, which is often used to lubricate the working areas of sewing machines. In general, I think everyone is familiar with this oil.

Modern sport bikes "accept" these lubricants to lubricate the rear hub drum and chain. Liquid lubricant is applied pointwise, so it does not get into unwanted places, as is the case with aerosol lubricants. The only downside is the cold weather. Such oil tends to thicken, as a result of which the work may deteriorate.

Greases or greases. Supplied in tubes or jars. It is these lubricants that are used to lubricate bicycle bearing assemblies, as well as threaded connections.

Grease is based on calcium, lithium or graphite. Therefore, such substances are divided into three categories - calcium, lithium and graphite.

Anyway, let's get back to consumables. When repairing a bicycle, as practice shows, the above list of tools and materials is not enough in the conditions of the modern riding style and design features of bicycles.

When traveling, cycling long distances (which is especially important), you need to have a set of tools and essential spare parts with you. They will help to eliminate problems right on the spot, making it possible to continue the trip.

Chain wringer, quick-release lock and connecting pin.
A set of screwdrivers and hexagon pen type.
Speed switch cable.
Rooster (rear derailleur holder).
Pump.
Camera patches.
Spare camera.

With this list of tools available, you can not be afraid of any minor breakdowns.

Bicycle wear

Bicycle wear problems have always been, are and will remain. It is important to understand that each bike node wears out specifically, and this should be discussed in more detail.

Drop in frame stiffness

After some time, the frame inevitably accumulates fatigue stress, which leads to a drop in stiffness. A particularly noticeable drop in stiffness is considered to be among hardtails, since the rear axle does not have any shock absorbers.

Accordingly, all vibrations that occur directly during the ride are directly transmitted to the bicycle frame. Metal here gets tired much faster. As for double suspensions, they are subject to this phenomenon to a slightly different extent. Stresses are predominantly accumulated in the region of the rear suspension pivot, which acts as a stress concentrator.

What is the risk of changing the stiffness parameters of the frame? First of all, as a result of excessive accumulation of fatigue stress, the geometry of the frame is distorted. The deformed frame geometry does not correctly perceive the loads from unevenness, therefore, the risk of cracks and breaks at the junctions of the frame nodes increases.

Most often, cracks appear on the feathers, dropouts (the landing sites of the front or rear wheel hub shaft), in the area where the weld passes on the bottom bracket and head tube.

There is no escape from the drop in frame stiffness, except to keep the bike on your balcony and not ride anywhere. Accurate driving will help prevent too rapid accumulation of fatigue stresses.

Drop in wheel stiffness

Wheels are the busiest part of a bike. Initially, the rims are devoid of beats, being a perfectly flat disc with correctly tensioned spokes. During operation, the wheels have to withstand impact loads of various sizes, as a result of which the rim profile may have dents and other deformations.

The new wheels, centered by robots at the factory, have residual spoke stresses, but after a short run on the street, they stretch. With a strong impact, the hub axle can be deformed, due to which the wheel will become eight even if there is a perfectly even rim.

Very often, overtightening the spokes results in a drop in the correct stiffness of the wheel. The operation of the disc brake contributes to the development of the umbrella, when the spokes on the side of the rotor mount slowly weaken. As in the case of a drop in frame stiffness, all this leads to an increase in the likelihood of breakage and more noticeable deformations in the future.

Bearing wear

Of course, the wear of bearing mechanisms occurs along with a number of other parts. According to research conducted by Specialized, the most noticeable wear in bearing arrangements occurs in the bushings. Bearings in the ratchet (the ratchet also wears out), bottom bracket, pedals and rear derailleur rollers are subject to wear to a slightly lesser extent.

The least loaded were the bearings located in the rear suspension pivot and the steering column bearings. To ensure smooth operation of rotating mechanisms and reduce contact wear, all bearings must be rebuilt using new grease. All balls and the body are pre-cleaned from the remnants of the old grease. Why exactly - it was described above (abrasive properties).

As for industrial bearings, they need service much less frequently. You can determine the need for a bulkhead by reducing the smoothness of operation and the appearance of third-party noise. Replacement is carried out as the resource is developed. You can determine the end of the service life by jamming. Landing cups, trunnions of bearing shafts and bearing rings are subject to processing.

Transmission wear

Any bicycle is driven by a gear chain drive. After a certain time, the chain can stretch, grinding down the stars. The result of such changes is a breakdown or periodic overshoot of the chain, as well as breaks. Dirt and dust, the source of which is the road surface, enters the inner space of the rollers. And this is the cause of the jamming of the links and the drop in the longitudinal flexibility of the chain.

The chain needs periodic cleaning and lubrication. After a complete failure, it is replaced. Not replacing the chain time, it grinds the teeth of the gears. Even if you put in a new chain, it will not be able to work as it should because of the link pitch mismatch. As you can see, just one chain can cause the entire transmission to be replaced without exception.

The shifter settings also change as a result of tension cable stretching. As problems arise, you need to adjust the switch by tightening the cable. Unweaving the working part is a sure sign of complete wear of the cable. The derailleur spring and shifter ratchet also need maintenance, which consists of adjustment and lubrication. The cock (rear derailleur holder) can also be replaced as a result of fall damage.

Suspension wear

The fork and shock absorber are used to minimize shock loads, thereby increasing ride comfort. Pneumatic chambers or compression springs act as elastic suspension elements, and closed-type cartridges or open oil baths act as damping elements.

Springs tend to lose their elasticity, sagging more and more. Pneumatic chambers are sealed with special rings, which also wear out a lot, starting to let air through.

The oil collects wear products and loses damping properties, and the o-rings and fork seals leak, leaving marks on the legs and letting air through. Ignoring the need to replace oil seals, anthers and o-rings will inevitably lead to backlash due to problematic bushings (guides in the fork). The diameter of the legs of the fork ranges from 28-40 mm.

Most often the diameter is 32mm (my Demo 8 has 40mm fork legs, Fox 40 2008 World Cup Edition). Increasing the diameter of the legs automatically increases the reliability of the fork by increasing torsional stiffness. Suspension wear also manifests itself in a change in color and texture of the special coating of rubbing parts - legs. Different forks use different spraying methods - Teflon, anodizing, chrome plating, polishing. The main cause of fork leg cover wear is the complete wear of the bushings that guide the legs straight into the inside of the fork, preventing trouser play.

Brake wear

Brake pads wear out the most. This leads to a decrease in braking force on any section of the road. The pads are replaced as they wear out. Brake caliper pistons (often referred to as calipers, although this is a misnomer) accumulate dirt, resulting in a change in the quality of transmission of braking power.

Wear can also show up as air in the hydraulic system that is drawn through micro-scratches in the caliper or brake lever pistons. The problem is periodically solved by pumping with a special kit.

Complete bike overhaul

So let's go over the basics of bike bulkheading. As with the basics of wear, here we will also look at each mechanism.

Frame

Before the bulkhead, the frame is completely cleaned of dirt. Ignoring this requirement can lead to various problems. It is possible that the dirt will not get into the working part along with the oil, and will not act as an abrasive.

On a dirty bike it is difficult to evaluate the scope of work. The best washing option is under low pressure, or with a brush and a damp cloth.

After completely cleaning the frame, it is necessary to inspect each part and make sure that there is no damage. The most problematic areas of any frame, without exception, are such as the bottom bracket tube, head tube, chainstays of the rear triangle, rear suspension pivots and dropouts. Even if the most minimal damage in the area of welds is found, the frame will have to be replaced.

If there are scuffs on the frame, it is recommended to paint over them. If the frame is white or black, it will not be problematic to choose the color. In other cases, you will need to make efforts to search. All you need to remove scuffs is masking tape and a spray can of paint. For better adhesion of the paint to the surface, it is highly recommended to use an alcohol solution.

Painting the frame with enamel

Suspension

The essence of service work with a suspension fork is the need to change the oil, replace or lubricate the sealing rings of the seals, pistons and springs, clean the legs and anthers from dirt. In some cases, you have to change the springs or cartridges, but it almost never comes to this.

It is extremely important not to lose or damage the compression ring springs, which protect the inside of the fork from the sudden penetration of dirt. The maintenance of fork cartridges is to improve their performance when a particular mode is selected (compression, rebound, travel). Cartridge reassembly is a tricky business, so it's best to leave it to the professionals.

For all rear shock absorbers, the requirements are the same as those for forks.

Transmission Service

Chain

The chain is the second component of the bike that needs to be replaced most often. High-quality models of chains can withstand several thousand kilometers, only some can withstand tens of thousands of kilometers. Naturally, subject to timely service.

Most manufacturers complete their chains with special locks, with which you can quickly remove the part from the bike and repair it. If there is no such lock, you need to use a special squeeze. The essence of chain maintenance is periodic cleaning of accumulated dirt and lubrication with liquid lubricant into the inner space of the rollers. It is also important to check the tension.

System

In the same way as in the case of other transmission elements, the system must be periodically cleaned with a solvent. During assembly, the stars must be placed relative to each other. The fact is that on a large star, its outer side contains a special pin. It is placed opposite the crank.

The essence of the pin is to prevent the chain from flying out of the star. Small and medium stars look with internal teeth opposite the crank. The pin on the middle chainring "looks" at the bottom bracket. This sequence is extremely important.

Cassette

A cassette is a set of stars, each of which is mounted on a bushing drum, made in the form of splined protrusions. As a rule, it consists of 7 gears mounted on a spider. Additionally, this may include another 1-4 stars. The life of a cassette is much longer than a chain, but less than a system. Service consists of solvent cleaning from accumulated dirt. A special puller is used for installation and uninstallation - so do-it-yourself repairs will not be difficult.

Carriage

At the moment, there are at least two types of carriages - integrated (GXP and Hollowtech II models) and cartridge (ISIS, Octalink, Howitzer). All of them are assembled on industrial bearings and connect the shaft with the rods of the connecting rods with a spline connection. Formally, the design is non-separable, but the integrated carriages, nevertheless, can be disassembled.

Technically, they consist of two cups, each with its own industrial bearing. Please note: it is important to remember exactly where this or that cup is located - on the right or left side of the bottom bracket tube of the frame. The reason is that the threads in the glass are not the same.

ratchet

The ratchet is a ratchet type mechanism in which there are lamellar or cylindrical compression plates. The ratchet has at least three rows of bearings, two of which are mounted in the housing and the third on the drum.

All bearings need to be lubricated and cleaned of old grease. If the bearings are ball bearings, you need to inspect them for wear. It is recommended to lubricate industrial bearings, after getting rid of the old grease and drying them to a dry state. Carrying out service maintenance of ratchets leads to an increase in rolling and a decrease in wear of the pawls on crackers.

Pedals

Pedals are one of the most wear-sensitive mechanisms. It is very simple to make sure that service is necessary - you just need to scroll the pedals. Stopping too quickly is a sign of lack of lubrication or insufficient lubrication. Disassembly is carried out from the side of the end or crank. As in other mechanisms, either ball or industrial bearings can be used here. The principle of their bulkhead does not differ from the generally accepted one.

When it comes to clipless pedals, it is important to remember that the cylindrical torsion springs also need to be lubricated. You can check the status by the behavior of the mechanism during the snapping of contact shoes. If the shoes are tight, it is necessary to lubricate the springs with liquid lubricant.

gear shifters

The essence of the service of the speed switch is to position the position of these mechanisms relative to the stars of the system and the frame, setting the screws H and L, with which the stroke of the foot is limited. In addition, the task of the cyclist when repairing gear shifters with his own hands is to lubricate and clean the cylindrical torsion springs and tension rollers, and check the cable tension. It must be remembered that the algorithms for setting the rear and front (if any) switch differ from each other.

Shifters, cables

The shifters contain a ratchet mechanism with helical torsion springs. Servicing the shifters consists of cleaning and changing the lubricant. Since the shifter is considered the least loaded node, an oil change can be carried out once a season. In this case, you should make sure that the cable is well tensioned and that it moves freely along the inside of the shirt. If necessary, you can remove the cable from the shirt and treat the interior with liquid oil.

Steering column

There are two types of steering columns - integrated and semi-integrated. In the first, industrial bearings are used, in the second - ball bearings (separator or bulk). Carrying out service maintenance of integrated columns with industrial bearings is a lubricant change.

In a steering column with ball bearings, the working mechanism takes on increased loads, because. they are distributed unevenly in relation to the fork stem. Therefore, there is a possibility of severe wear of the bearing balls. If necessary, they must be replaced. A sign of a problem with the steering mechanism may be a creaking in the head tube area, steering column play or difficult turning of the wheel.

Brake system

The safety of the cyclist depends on the operation of the brake system, so its normal condition is a prerequisite before setting out on the road. Modern bicycle brake systems are conditionally divided into three parts - brake calipers (calipers), hydraulic lines and handles.

Calipers

The caliper is an aluminum body divided into two parts, inside of which the pistons and brake pads are located. The number of pistons is usually 2, in some models there are 4. The number of pistons has a direct effect on the braking force and the comfort of pressing the handle. The caliper is mistakenly called a caliper.

The essence of caliper service is to replace worn brake pads with new ones, as well as to check the condition of the pistons. The caliper must remain sealed. Air ingress or loss of oil on the road can lead to total brake failure, increasing the risk of falls and injury.

During the operation of the bicycle, the following problems with the caliper are possible:

Braking is not strong enough, the handle falls through. Cause: air in the hydraulic line or pads worn out. It is necessary to replace the pads with new ones or re-bleed the brakes.
Prolonged braking causes the handle to fail, resulting in complete brake failure. In this case, the brake fluid boils. Wait a few minutes and let the liquid cool down.
Braking is not strong enough, the handle does not fall through. There are many reasons for this problem. There is dirt or oil on the pads or rotors. Degrease the surface. If you put in new pads, they most likely did not have time to get used to the rotor. Over time, the braking force will increase. Also, the cause of weak braking without the failure of the handle may be the presence of air in the hydraulic line.

Pads. Left is normal, right is worn.

brake levers

Structurally, the brake lever of a hydraulic brake consists of a body, a handle and a piston. Check if the handle is leaking, if everything is in order with the o-rings. Consumables are changed as necessary - the sealing ring and the piston.

hydraulic lines

With each season, the brake fluid in the hydraulic line loses its homogeneity, as a result of which the handle fails, and the braking power decreases. Therefore, re-bleeding the brake is a mandatory event, which is enough to perform once a season. Tektro, Shimano and Magura brakes use semi-synthetic or mineral oil. Everyone else (Avid, Formula, Hope Inc., etc.) has a special fluid DOT 3, 4 or 5.1 (depending on the force of compression). Re-pumping is carried out using special syringes. For some models, you need to purchase a special set of M5x0.8 fittings.

Before pumping, it is necessary to protect yourself from getting liquid on your hands and a number of plastic / metal surfaces. The liquid is highly reactive (mineral oil is an exception) and can cause serious harm.

When re-pumping, they completely get rid of the old fluid and slowly add a new one. To ensure that no bubbles remain in the system, excess air goes back into the syringe or into a special air valve.

wheels

The wheels are the most loaded part of the bike, which takes on all the bumps and bumps in the road. Timely service not only increases the comfort of the rider during the movement, but also increases the speed.

bushings

The bushing bearings bear the greatest load. They work in harsh environments. For every two thousand kilometers, there are 1 million revolutions of the axle (wheel 26x2.0). If industrial bearings are installed in the hub, service should be carried out no more than once every two seasons. This is because the bearings of this assembly have a very large operating margin.

Maintenance of ball bearings or loose bearings should be carried out once a season. Do not forget to monitor the condition of the balls - if they have dents or severe abrasions, it is better to replace them with new ones.

Rims and spokes

Reducing the weight of the wheels is considered one of the most important factors in facilitating cycling. Less weight reduces unsprung mass and thrust when subjected to inertia. Consequently, the ride will become more comfortable, and acceleration - instantaneous. But weight loss provokes a drop in strength. Thus, excessive weight loss can lead to different consequences.

During the movement, the rims take strong impacts from the side of the road surface. The strength of the wheels is affected by the presence of pistoning and the type of joining of the rims (riveted or welded). Of great importance is also the weight of the cyclist and riding technique.

The risk of rim runout is almost always present. There are three types of beats:

axial (figure eight);
an umbrella (the wheel resembles an oval, it is almost impossible to restore it);
radial (egg, small dent along the radius).

You can correct the deformation of the rim using a special key for the spokes and the stand. You can improvise by placing two ear cleaning sticks near the rim (I believe everyone has them). It is necessary to edit the wheel without tires, because. they may not sit properly on the rim, giving the illusion of an uneven wheel.

In the presence of a stand, the measuring probe is installed perpendicular to the axis directly to the rim, so there is no way to do without removing the tire. If the rim is bent to the left side, it is necessary to tighten the spokes of the right side of the rim, and loosen the spokes of the left side accordingly. Both tightening and loosening are performed with the same number of turns of the wrench, this is extremely important for torsional rigidity.

As you can see, service maintenance is not as difficult as it seems. After completing all these steps, you can be confident in your safety and reliability of the iron horse.

Author Arseny. RockShox Inc.