What is it
Bicycle rear shock absorber. it is a device that serves to eliminate and absorb shocks, vibrations, shocks when driving on uneven roads. Off-road conditions negatively affect the bike frame and the entire structure, therefore, if a cyclist uses a bike for long trips not only on asphalt, it is advisable to additionally purchase a rear shock absorber. Bicycles are equipped with spring or air shock absorbers. The spring has a fairly large weight and a stiff stroke. Air-oil are lightweight and smooth running.
Full suspension bicycles. it is a design with two shock absorbers, front and rear. The front fork is standard and the rear. additional. This part makes cycling more comfortable. If you add a rear shock to the structure, it will become heavier, and the operating conditions will change. This detail fits perfectly into mountain bikes, suitable for a sporty riding style.
Do you need a rear shock on a bike? In most cases, suspension systems are installed in the front end, they are also called “fork”. Such a device dampens shocks and vibrations in the part of the frame on which the front wheel is mounted. The rear shock absorber is considered optional and is installed primarily in mountain models. Most of the load falls on the front wheel. A bike with two shock absorbers is called two-suspension. By type, these elements are spring, spring-elastomeric, air, oil-air and oil-spring. The spring of a part has characteristics such as stiffness, recommended stroke, inner and outer diameters and lengths.
Bicycle shock absorber rear: functions, settings
Bicycle rear shock absorber. one of the suspension elements of the bike. This part can be spring or air, with or without a stable platform. Ride safety, ride smoothness, obstacle avoidance. it all depends on the correctly selected and tuned shock absorber.
How to choose
The modern rear shock absorber of a bicycle has a large number of settings. This component is selected taking into account the transport model. It is most commonly used in mountain biking. The shock absorber can be linear, which means that it takes a lot of effort to compress it. All spring models work according to this principle. Comfort of movement depends on the quality of the shock absorber, so the stronger the structure, the better for the bike.
The load on the rear shock is always heavy, so don’t skimp on this part of the bike, especially if you’re cycling. Select the rear shock absorber lengthwise. It ranges from 125 mm to 220 mm. For fastening the elements, special caps and bushings are used. In progressive (air) dampers, increasing force will be required to compress.
When compressed, the volume of the air chamber decreases and the pressure increases. Knowing the difference between linear and progressive elements, you can choose the right option for your bike. It is important to consider the frame design when choosing a shock absorber. The best option. it is a spring type. It works linearly, doesn’t weigh it down too much or make it stiff.
What is it needed for
The design of the bicycle includes an element such as a shock absorber. Thanks to him, you can operate the bike for a long period of time and not feel discomfort while driving. The rear shock absorber of a bicycle consists of a spring and a damper. Springs reduce shock load on the frame when driving on uneven roads at high speeds.
Consequently, the cyclist also does not experience a strong load while riding. Dampers dampen vibrations and stabilize the bike’s position. This system is optional, so it is not available on some types of shock absorbers. Rear springs are fitted to sports models and are not used on road or road bikes. Sometimes they are mounted on regular bikes to increase ride comfort.
What to do if the bike’s rear shock squeaks? This element is a complex structure, so it’s not quite easy to figure it out the first time. The most common causes are lack of lubrication, mismatched parts and poorly tightened bolts. During adjustment, it is important to consider such a concept as shog. This is the difference in length between the compressed shock absorber under the rider’s weight. Seg should be set correctly, otherwise the part will not work fully. Expose it in the range from 23 to 33% of the stroke. If the shog is large, the suspension works softly, and if it is small. hard.
Several factors affect the adjustment of a bicycle’s rear shock: preload, rebound, and compression. In the first phase, the suspension fork will resist the rider’s weight. First, change the percentage of the element’s subsidence. The best option. 25%. If the bike is designed for fast riding and descents from the mountain. thirty %. Most rear shock models have a retaining ring that measures the level of sagging.
Adjustment of the rear shock absorber of a bicycle is carried out independently or with the help of a specialist, regardless of the bike model and the cost of the element. The spring of the shock absorber is sufficiently resilient and durable. Sports models use expensive rear shock absorbers and above. The simplest elements cost about 400 rubles. Despite their budget price, they are made of steel and can withstand pressure up to two thousand kilograms.
Bicycle Shock Absorbers: Varieties and Adjustments
The popularity of two-wheeled vehicles continues to grow steadily every year. New models appear and existing ones are improved. Bicycles began to be in great demand for use in specific conditions: riding without a road, rough terrain, jumping over obstacles. The design includes special elements. shock absorbers, which allow you to repeatedly operate the bike and not experience discomfort when moving.
Adjusting Rear Shock Air Pressure on a Bicycle
In most cases, the systems are installed at the front of the bike and are called suspension forks. The name speaks for itself: the shock and vibration damping device is located in the part of the frame to which the front wheel is attached. There are several types of front shock absorbers:
- Rigid spring.
- Spring loaded with elastomeric damper.
The first type includes the simplest and cheapest devices. They consist of rigid metal springs embedded in the legs of a bicycle fork. The springs of such shock absorbers are not supplemented with a damper, which makes them ineffective when driving over rough terrain. But they are actively used on road bikes for comfort.
The elastomer springs include a rigid metal spring and a rubber damper located in the center of the fork tube. This type dampens vibrations much better than the previous one, and can be actively used when driving on small and medium bumps. A significant disadvantage of elastomeric shock absorbers is the low cold resistance of the rubber damping pin: with a decrease in temperature, the ability to damp vibrations is significantly reduced.
Air shock absorbers have high efficiency compared to spring-loaded ones. Air pumped into the fork is used as a shock absorber and vibration damper. Disadvantages: deterioration of the sealing properties of the cuffs and air permeability, as well as the high price of forks.
Oil shock absorbers are divided into two subgroups: oil-air and oil-spring. The “spring” on them is the air pumped into the bicycle fork and the steel spring, respectively. A cartridge filled with oil is used as a damper.
Another type of shock absorbers is also widespread. rear, which eliminates the residual force effects of the drive wheel. Most of the shock loads still fall on the front wheel, so rear damping systems are used as additional ones. They are similar in design to the front ones. A bike with two shocks is called two-suspension.
Methods for setting up a depreciation system
Shock absorbers can be adjusted in several ways:
- Spring Flexibility Setting.
- Changing the speed of compression and return of the spring to its original position.
- Travel blocking.
- Adjusting the travel distance of the bicycle fork spring.
Adjusting the stiffness and mobility of the shock absorber spring involves changing the resistance to external influences and the selection of the optimal characteristics. So, the stiffer the spring, the worse it resists impacts during movement. In a weakened state, the shock absorber will constantly “jump”, and on serious obstacles it can even break through.
The selection of the rebound and compression speed allows you to adjust the shock absorption system for specific travel conditions: mountain trail, forest road, complete off-road with stones and holes. Along with setting the speed, leveling of the stroke length of the bicycle shock absorber is also applied: this adds or removes a margin of distance within which the spring can move. This is done in order to reduce spring wear during long-term operation.
Blocking the stroke is “disabling” the softening ability. The spring is made rigid and incapable of deformation. It is advisable to use on smooth asphalt where there is no need to damp shocks.
Self-assembly and repair of shock absorbers
The damping system requires periodic maintenance, and in case of deterioration in performance, inspection and repair. In either case, you will need to remove the fork from the bike. But, before proceeding with the description of this process (and, by the way, it is simple), we note some features of the service.
Oil and air plugs require special attention:
- Changing the oil in the cartridges after 4-5 thousand km of run.
- Cleaning, lubricating and checking oil seals for leaks after 100-150 km.
- Weekly check of cuffs on air forks.
- Examination of the external surface for chips and cracks.
The last point applies to conventional spring or elastomer suspension forks. Also, from time to time, you will need to change the polymer damper.
To remove and disassemble the fork, turn the bike upside down, dismantle the rim brake and remove the front wheel. Next, the steering stem and pipe are pulled out. After that, the support ring is carefully removed and the fork itself is removed. To remove the spring, you will need to unscrew the force adjustment bolts, and then remove the damper.
Using an ordinary screwdriver, remove the seals (anthers or oil seals), then pull out the entire shock absorber completely. The overhaul of parts consists in a thorough inspection, cleaning, lubrication and replacement of some elements. On average, fork disassembly should be done once a season. Installing the front shock absorber and fork on the bike is done in reverse order.
The rear shock absorber also requires periodic inspection. Standard maintenance consists of periodic lubrication and cleaning of components. It is recommended to use heavy high-temperature greases for the suspension. Clean the surface of the springs and damping element as needed.
Long-term operation knocks down the travel distance of the shock absorbers, so it is necessary to periodically tighten the springs, adjust the compression and rebound speeds. To avoid a decrease in the spring’s sensitivity to shocks, it is recommended to adjust the settings in stages: first select the compression speed, check while driving, and then adjust the rebound speed.
Do not neglect the shock-absorbing system in a faulty condition. This will not only cause inconvenience when driving, but will also contribute to a deterioration in the bike’s running characteristics. there is a risk of bending the wheels or damaging the frame. Self-disassembly of suspensions should be carried out if there is confidence in their subsequent assembly. Otherwise, it will be better not to touch anything, but contact a specialist for repairs.
What are shock absorbers for?
Traditionally, shock absorbers for bicycles consist of leaf springs (springs) and a damper. The springs, as a more powerful element, help to reduce shock loads on the frame and the cyclist when driving over bumps at high speed. The damper functions include vibration damping and position stabilization. It should be noted that the damping system acts as an additional one and is not installed on all types of shock absorbers.
Initial installation is for mountain bikes and sport bikes. For example, in downhill competitions, a cyclist is required to quickly drive a track strewn with stones, bumps and holes. Often you have to jump into the air to jump a high obstacle.
Conversely, shock absorbers are not fitted to road and road bikes as they are designed to be driven on tarmac and not suitable for cross-country riding. Although cyclists can sometimes set them up on their own to increase comfort when riding on uneven roads.
Types of shock absorbers
often than not, a suspension fork can only be found at the front of the bike, so manufacturers take care of reducing the force of impacts on the front wheel. Rear detail eliminates the drive wheel force that the front fork could not hide.
Spring-loaded, characterized by special rigidity. do not provide dampers.
With spring and elastomer. they consist of a metal spring and a rubber damper in the center of the fork. The forks are used in bicycles for traversing moderate to fine terrain. Significant disadvantages include the low resistance of the pin to cold temperatures.
Air. air is pumped into the plug, it just dampens the vibrations. However, over time, air penetrates through the smallest holes, how long such a shock absorber will last depends on the sealing characteristics of the cuffs.
Oil-filled. instead of a damper, the front and rear forks include an oil cartridge.
How to properly adjust a bike’s rear shock
There are three main controls: preload, rebound, and compression. The latter is sometimes divided into slow and fast compression at the upper ends of the shock absorber.
Preload is the resistance the fork gives against your weight. The more your weight, the more preload you need. For coil spring shocks, this means more or less spring, but for air shocks, this means more pressure.
Compression damping emerges from the inside of the shock and regulates the flow of lubricant through the small holes. Compression damping only affects the shock absorber when compression occurs. it does not affect preload, but can have a similar effect on the rear suspension.
The more pressure is applied, the more difficult it will be to steer. This is fine if you want the bike to ride smoothly, without bouncing, but the negative effect will be limited movement (see below). In fact, suspension lockout is just an extremely high amount of compression damping.
Shock Pump: How to use a PRO BIKE TOOL Shock Pump
Recoil Damping. Similar to an internal compression system and affects the shock absorber when it returns to its natural position.
When you apply more recoil damping. the fork will return to its natural position more slowly. Slower return. or more compression on rebound. is required if you feel resistance from the bike, especially around corners or bumps, but if repetitive bounces feel “tight”. less damping is needed.
Lockout is the most common and uses the compression damping system extensively to effectively lock out the fork.
Lockout is useful when you are faced with long climbs or flat surfaces where you might want to put more effort into the ride. CTD or Climb, Route, Descent is a slightly more advanced form of lockout that is set for the type of terrain you are driving. CTD. Fox specific term, but other manufacturers have comparable systems.
The climb mode acts much like a lockout, although it usually gives a lot of freedom of movement; Route or Ride Mode is a movement with a lot of resistance, for convenience when driving with a tighter compression; while downhill means the lock is fully active and will require less compression damping during use.
Why you need rear bike shocks
Cyclists are divided into two types: hardtail riders and those who love comfort and safety. Lovers of a quiet ride must install a rear bicycle shock absorber. It is he who is considered the heart of the entire suspension of the bicycle, its correct selection and installation will significantly improve comfort and speed of movement on rough terrain.
How to adjust the rear suspension
Before starting the installation, you need to make sure. that you have all the tools you need.
It is best to make adjustments before riding, but carry tools for additional adjustments during the trip.
It’s good if you have an assistant. but you can install yourself on a wall or a hard surface.
Measure the inside first. the shiny part that moves inside the case. Divide its value by four to get the best result.
For optimal performance, you need 25 percent drawdown. However, some more aggressive shocks, like those on downhill bikes, can be fitted with a maximum of 30 percent.
Most shocks have a small inflatable ring or stop to measure sag. if your bike doesn’t have one, you can tie an elastic band. Don’t use a cable and of course don’t leave it there; the dirt it collects in combination with hard plastic will scratch the surface and be expensive to fix.
Set the compression damping switch to “down” or open, remove the ring, gently place the bike and enter the riding position. Try not to shake the bike. you are picking up a constant weight.
Carefully check the level of subsidence. how far the ring has moved. If the sag is more or less than a quarter of the length, adjust the psi. For most cyclists using air shocks, 150 to 200 psi will give 25 percent sag, so if you don’t know how much pressure you have, reduce it to 150 psi. Then add or subtract 25 to 50 psi at a time until you reach 25 percent subsidence.
2.Adjust compression and damping
Depending on your shock model, you will have a CTD switch or suspension settings as well as damping settings. If you have a CTD, then just tweak it according to your current terrain; if you have settings, proceed as follows:
If you are unsure of the value you want, set the disks to medium. You can experiment to find the value you want.
Setting extreme values is rarely suitable for cyclists. so most of them set an intermediate value.
Memorize the route and the necessary settings, you will have a feeling of understanding the process of the suspension.
Good bike shock absorbers not only keep the vehicle parts intact, but also contribute to a comfortable ride. When faced with poor amortization on a two-wheeled bike, don’t panic as you can repair the front and rear forks with your own hands. Clean, lubricate and replace the anthers, seals, bushings and feet of the shock absorption system in time, and then the bike will enjoy long-term use.
If you need to change the shock absorber
Determining the best part is tricky, so be guided by the bike manufacturer. As a last resort, experts advise to be guided by the following rule: the length along the axes should approach the value of /. 5 mm, and the movement of the stem should be no more than 3-5 mm.
How to lubricate shock absorbers on a bicycle
The most popular and cheapest shock absorber is spring-elastomeric. This shock absorber is very simple in design: a polymer rod is inserted inside the steel spring, which dampens vibrations.
The second type is oil-spring, more modern and reliable. Due to its relative cheapness and simplicity of construction, it has become one of the most common in cycling.
And the third type is oil-air. It uses a compressed air cylinder instead of a spring. Due to the complexity of the design, it is better to repair them in specialized workshops, where they know exactly how to lubricate shock absorbers on a bicycle.
Lubrication of shock absorbers
A poorly lubricated and misaligned mechanism can not only make an unpleasant sound, but also make it difficult to control the bike, spoiling all the enjoyment of sports. The ideal option is to externally clean the bike fork after each ride, and at least once a season to lubricate the internal parts of the mechanism. The easiest way is to take the bike to a workshop, whose master knows exactly what to do, but experienced cyclists can try it themselves.
Springs and Elastomer Springs can be lubricated without disassembling the fork. For this, the grease is drawn into a syringe and poured under the boot. After that, the bike should be “rocked” and the excess oil removed with a napkin. But! This is a quick, hiking option used when the bike cannot be disassembled even partially. According to the rules, you should first unscrew the mounting bolts from the bottom, then unscrew the Preload bolt, get the elastomer and the spring, unscrew the mounting bolts and remove the “pants”, that is, the part of the bicycle fork to which the wheel is attached. It is here that the most dirt is found and it is this part that most often needs repairs. Anthers are taken from the last part (they can be easily picked up with a screwdriver).
All parts must be cleaned of road dirt and oil residues. Masters recommend using exclusively branded lubricant or taking universal Teflon. After that, you should lubricate the parts, and assemble the plug back.
Maintenance of the oil spring design is also simple. If the open oil bath method is used, then the oil is simply drained and the parts cleaned. This system is perhaps the easiest to maintain, and inspection and minor repairs can be performed even at home. Things are a little more complicated with a closed oil bath. The oil in this design is in the capsule and changes with the entire capsule. In contrast to the first option, a closed oil bath often requires more maintenance.
The most whimsical service is considered to be an oil-air shock absorber. To clean and lubricate it, you must:
- Unscrew and clean the shock absorber. This will prevent debris from entering the air chamber;
- Open valves and relieve pressure. If done correctly, the mechanism will be easy to compress and unclench;
- Further, the mounting parts are removed from the shock absorber, and the air chamber itself is disassembled;
- Then the oil seal should be removed. If any parts are damaged, it’s time to replace them or perform other repairs. If everything is intact, then old grease and mechanical impurities are removed, and you can start assembling the bicycle fork;
- Fork oil is poured onto the shock absorber body, placed vertically. Gaskets and seals are installed in place. The air chamber is pushed all the way so that no air escapes from it. It is better to add a little more oil, and only then screw it back to the shock absorber body;
- Next, the shock absorber is inflated to the desired pressure and installed in place.
Motorists have a saying: “The car loves affection, cleanliness and lubrication.” The same can be said for a bicycle, although it requires much less maintenance. If you know how to lubricate shock absorbers on a bicycle, then this procedure will not seem long or laborious at all, and the iron horse runs without repair for more than one season.
Making a bike without shock absorbers softer / About mountain bike
If the cyclist sits too upright in the saddle, then each blow hits the spine. With a strong forward bend, the entire load is transferred to the hands. Each blow is transmitted through the steering wheel, which makes the hands go numb and pain appears. The first situation is solved by slightly moving the rudder down and setting the stem longer. A more stretched stance will help distribute body weight evenly around the bike.
The handlebars should be raised if the fit is too low and the stem should be shorter. To determine the ideal handlebar height, you have to constantly try different positions to find the right one. In some cases, adjusting the fit is sufficient. But this is only in the case of a suitable frame size.
The most balanced riding position on a road bike is the hand grip position. In this position, the owner is comfortable enough to sit on the bike. The body is bent at the lower back, and the hands are on the handlebars, but the weight is not completely distributed on it. It turns out an excellent natural shock absorber. With it, each part of the body is in balance, supporting each other. Therefore, on a highway it is much more convenient to ride on rough roads than on a hybrid.
If the weight is distributed normally during landing, the steering wheel should be softened. Neoprene grips can be used when the handlebars are straight, such as on a mountain bike or hybrid. Ergonomic cork grips do a good job, as they absorb vibration. Road windings come in a variety of thicknesses, so a thicker, softer winding is enough for these bikes. Sometimes two layers are used, as one does not cope with vibration absorption. After such a procedure, even the smallest vibrations almost completely disappear, and noticeable irregularities on the road cause a minimum of pain.
Any rigid fork is capable of shock absorption, but with a small amplitude. The math is simple: the farther the wheel axle is from the represented mowing line through the steering tube downward from the steering wheel, the less bumpy roads are felt. Therefore, bent rigid forks should be used for better cushioning.
No less important in this matter is the material of the fork. Aluminum absorbs the least amount of vibration. Things are much better with carbon and steel. Titanium claims to be a very good vibration damper.
The next step could be replacing the aluminum components with carbon ones. Replacing the handlebars, stem and seatpost will create a distinct sense of change. By purchasing carbon components, you can count on the subsequent replacement of the frame and the installation of these to assemble an already new bike.
There is little choice in the road bike situation, but much more cloudless for mountain bikes and many other models. Ideal for asphalt roads and a small part of rough terrain near a mountain bike. tires with soft side spikes and a hard center section. Tires are a very important factor. Rolling will be most likely to soften a decrease in pressure and an increase in tire width.
You can transfer to a hardtail with a suspension fork. However, if someone has purchased a rig, then the person needs it and this cyclist is unlikely to want to change to a bike with shock absorbers. Another option is to use a shock absorbing seat post. There are pins with parallelogram designs, or a simpler option for unsportsmanlike riding. spring saddles.
Original publication. on cortobike.ru
How-To: Tuning Mountain Bike Suspension With Art’s Cyclery
Aside from inflated wheels, nothing is more important to cycling enjoyment than having the right suspension setup.
To begin with, let’s define what a “sag” is: this is the travel that the suspension sags under the rider’s weight (usually measured as a percentage of the total travel of the fork or shock). Make sure your fork and rear shock have travel indicators or rubber bands on the fork leg and shock stem. If none of this, then put plastic ties on the fork and shock absorber, just do not tighten them too much.
Let’s start with the shock absorber and rear suspension. Place the bike next to a wall, or have a friend hold the bike while you sit on it. Put on everything you normally ride in, including a water-filled hydropack, protection, and so on. Step on the pedals with your center of gravity roughly midway over the bike. Gently squeeze the suspension several times, then slowly sit on the saddle and pull the travel indicator (rubber o-ring or zip tie) to the shock absorber boot, being careful not to compress the shock absorber further. Now slowly dismount from the bike, transferring your weight forward onto the fork, so as not to further squeeze the shock absorber. If you have inflated the shock absorber correctly, the travel indicator will be located from the boot at a distance of approximately 20-30% of the stroke length of the shock absorber rod (that is, from the visible length of the rod). Longer travel bikes have a slightly higher sag, usually around 35%. Add or release shock pressure in 5 psi increments until required sg is achieved. Record Shock Pressure Values for Different SEGs.
If you have a spring damper, completely unscrew the spring preload nut, then tighten it again to the point where spring resistance begins to be felt. Now measure the axial distance (center to center of the ears) of the uncompressed shock. Then measure the lengths along the axes of the compressed shock, and you can calculate the suspension sag in millimeters. An assistant is required to measure the shock absorber in the compressed position. Divide the shock absorber sag in millimeters by the stroke length of the shock absorber, and you get the suspension sag as a percentage. If the sag is not enough for you, you need to replace the spring with a softer one. If the sag is too large, tighten the spring preload nut on the shock absorber and repeat the measurements. If you have to tighten the nut more than 2-3 full turns to achieve the required sag (depending on the manufacturer of the shock absorber), then you need a stiffer spring.
Adjusting the fork sag is almost the same as the procedure described above for the shock absorber, to calculate the sag as a percentage, you need to divide the distance by which the travel indicator on the fork leg moves by the full travel of the fork (for some forks, the full travel differs from the length of the visible part of the fork legs). Be sure to get off the bike by sliding backwards so as not to squeeze the fork further.
The springs in our suspension are tuned, so let’s move on to adjusting the rebound damping. The lower the rebound damping (rotate the rebound adjustment counterclockwise), the faster the shock or fork will expand from the compressed position, and vice versa. If the rebound is too fast, then the suspension will “goat” and bounce on bumps, if too slow. the suspension will not have time to unclench before the next impact, it will seem more rigid.
The easiest way to roughly get into the desired bounce setting. this is to run a full extension test, which can be done with both a fork and a shock absorber. Unscrew the rebound adjustment all the way (to the “fastest” position). Then squeeze the shock absorber as much as possible, leaning against the saddle, and release abruptly. If the shock is expanding too quickly, with a sudden stop at the end of the expansion, you will need to increase the rebound damping (tighten the rebound adjustment). Too abrupt stop of the shock absorber at the end of the release can even be felt or heard with your hands. Repeat the process several times until the shock absorber begins to expand at the desired speed.
Another way to tune the rebound is to ride off the curb while standing on the pedals, gradually slowing down the rebound until the shock begins to compress and expand without swinging. Repeat the full compression test with your fork, pushing all your weight down on the handlebars. You will most likely need more fine tuning of the bounce on the trail you are riding. If the front or rear of the bike seems to bounce too much from the bumps while riding, twist the rebound on the shock absorber or fork 1-2 clicks. If the suspension starts to clog and becomes stiffer on a series of irregularities, unscrew the rebound 1-2 clicks so that the suspension has time to unclench before the next hit. When adjusting the rebound of the shock, it’s best to err on the side of slow rebound so the rear suspension doesn’t kick you out of the saddle, and quick rebound in the case of a fork so it doesn’t collapse over a series of obstacles. As a general rule of thumb, adjust your rebound 1-2 clicks faster on trails with small, frequent bumps, and 1-2 clicks slower on trails with large obstacles.
Compression (compression) damping is more complex, it will take a little more time on the trail to properly adjust the suspension compression damping. The compression setting is not present on all suspension components. Most trail forks and shocks have a low speed compression (LSC) setting, and downhill components often allow for a high speed compression (HSC) setting. Compression speed is related to the speed of movement of the damper rod, high speed compression is associated with large, sharp obstacles and fork action at full travel. Low-speed compression is involved in damping small bumps and in the platform when pedaling, as well as compressing the suspension during braking and counter-slopes. It is useful to think of the NSC as some kind of safety valve before the VSK.
My favorite way to tune compression damping is to completely unscrew all the adjustments, hit the Trail, and watch some of the shock and fork performance. First, if you hit the suspension frequently or hard while riding, increase the high speed compression by turning the appropriate adjustment. Also, to prevent suspension breakdown, spacers can be used to reduce the volume of the positive chamber of the air spring of the fork or shock absorber. Adding spacers increases the progression of the spring, adding stiffness at the end of the travel. If during the test the suspension stopped working for the entire stroke and became stiff, gradually reduce the damping of the VSK.
For low speed compression adjustments, focus on suspension response during braking and cornering. If the fork compresses too much during braking or counter-angle, increase the NSC damping until the suspension compression during rolling and braking is under control. For the rear shock absorber, the determining factors when adjusting the NSK are the sensitivity to small bumps and the buildup from pedaling. If the shock absorber does not work out a trifle, reduce the low-speed compression damping. Twisting (increasing) the NSC can reduce the swing of the suspension from pedaling in the saddle and in a standing position on the pedals.
It is very important to write down all your harness settings. This will allow you to get a feel for how changing the settings affects the behavior of your bike, and then quickly return to the optimal settings. Once you’re done setting up your suspension, you can write down all the values on the shock and fork decals so you can always tune your bike quickly and correctly.
How the bike works. Shock absorbers.
The rear shock absorber absorbs the kinetic energy transmitted through the impact of the rear wheel when jumping, hitting a curb. According to the principle of depreciation, there are: pneumatic, hydraulic, elastomeric and spring.
In a two-suspension bike, the shock absorber works as a damping element on the rear suspension. In the figure, it is presented in section with a compensation chamber.
The principle of operation of the rear shock absorber is not significantly different from the fork shock absorber, but there is a caveat: the shock absorber does not have to turn, assigning the wheel trajectory. Consequently, its installation is more convenient, and, importantly, the manufacturer can reduce the effect of lateral forces on the shock absorber rod.
The main task of the shock absorber. development of irregularities, the difference between high and low frequency suspension vibrations. Consider the structure of a conventional rear shock absorber.
A twisted metal spring (as in the figure) or a sealed air chamber serves as an elastic element, in this case the shock absorber is called “air”.
Using the mounting holes, the shock absorber is mounted to the frame and attached to the rear suspension arm. Shock settings are the same as forks. For example, the shock absorber of the “DNM Burner-RC” model has three independent adjustments: rebound speed, compressed speed and spring preload (fine adjustment of the spring stiffness to the cyclist’s weight).
advanced designs provide for other adjustments. For example, a dual-range rebound and / or compression setting that controls these parameters separately at the start or end of the shock absorber’s compression stroke. There is also a setting of the progressiveness of compression by changing the pressure in the compensation chamber or changing its volume. The compensation chamber in the shock absorber is designed to reduce the overall dimensions of the main body, control the compression progression, and better cool the shock absorber.
|Drawing “Cane Creek” Rear Shock||Figure PuLl-Stroke Scott Genius Shock|
1.upper attachment point, 2.lower attachment point (not shown), 3.positive air chamber, 4.negative air chamber, 5- rebound adjustment, 6. positive chamber air valve, 7.negative chamber air valve, 8- attachment the operating mode cable to the damper blocking valve, 9.the damper blocking valve drive, 10.the operating mode cable fastening to the positive chamber shutoff valve, 11.the positive chamber shutoff valve drive, 12. stem, V. air, M. oil
During standard operation of the shock absorber, a pressure balance is created in the positive chamber 3 and the negative chamber 4. When the suspension is compressed, the shock absorber expands, and the rod 12 moves downward, creating an increased pressure in the positive chamber 3. Therefore, the pressure in the negative chamber 4 decreases. The throttling holes in the piston provide the desired level of damping. Shock absorber mode control (traction control) has three stages.
- 1. The shock absorber is completely “open”, that is, the entire active stroke is available. The check valve 11 in this case is completely open, connecting the sub-piston space with the positive chamber 3.
- 2. The shock absorber operates in a “covered” mode, with a travel reduced to 1/3. In this case, the check valve 11 is closed and the positive chamber is separated from the sub-piston space. Since the volume of the sub-piston space is much less than its total volume with the positive chamber, the shock absorber stroke (downward movement of the piston) becomes significantly less.
- 3. The shock absorber is locked. In this case, together with the closing of the shut-off valve 11, the throttle holes d are also blocked by the valve 9. Consequently, the rod 12 becomes stationary relative to the shock absorber body.
The principle of operation of the rear suspension of a bicycle differs from the front only in that the rear wheel is not a steering wheel, it does not turn. But the rear suspension has a number of features:
- it is loaded much more than the anterior one, which partly removes the question of its sensitivity. However, another problem immediately arises: the loads applied to the suspension arms and the rear shock absorber are very significant, and require increased attention to their design. In this case, the bicycle should remain as light as possible, that is, elementary reinforcement with additional metal is contraindicated;
- the suspension must effectively handle bumps without swaying to the beat of pedaling. And if the fork sways, mainly when the biker raises the saddle and pedals while standing, then the rear shock absorber is prone to swing, even when the cyclist is sitting quietly in the saddle and pedaling evenly;
- the design of the rear suspension should, if possible, exclude lateral deformation, that is, have significant lateral (lateral) rigidity. At first, this factor was not particularly taken into account, but with the spread of double suspension for competitive disciplines, it became important.
Today, the development of the rear suspension is carried out in three directions.
- First, the suspension kinematics is improved, namely the relative position of the levers and hinges.
- Second, the use of platform technology in the rear suspension.
- Third, the development of both a technically and aesthetically improved design.
Suspension: 1. main lever (swingarm), 2. additional lever, 3. link arm Example of a “Specialized Epic” suspension system “GT I-Drive 4” design with 100 mm travel.
The front shock absorber is integrated into the fork. The fork holds the front wheel and brake components. Usually, forks have a shock absorber, but they are also available without shock absorption. The fork body, like the frames, is made of various materials: aluminum, steel, carbon, titanium, magnesium. Spring, elastomer, oil and air systems are used for shock absorption.
How to inflate a bike shock (easy)
Forks are produced in two types: “hard” without a shock absorber and “soft”. with shock absorber. Use a hard plug. justified for road riding if the track is flat and smooth like a track.
For driving on a not very good road, it is better to choose a fork with at least curved stays, since straight stays transmit all shocks and vibrations directly to the hands. What is unpleasant, sometimes painful and definitely harmful to health.
Bicycle classification by the number of suspensions.
The diagram shows the types of suspension depending on the number of sprung wheels:
“Rigid”. a bike that does not have a suspension. The advantage is lightness and reliability. Disadvantages. uncomfortable comfort and controllability worsens on uneven surfaces. You can reduce shaking by using wide, up to 2.3-2.5 inches tires or a slightly springy “titanium”, carbon fiber (carbon) fork;
“Hardtail” (hard tail. English “hard tail”). this bike has fork cushioning but no rear suspension. Hardtail today. the most popular type of mountain bike. In addition to improved comfort, the shock absorber makes the bike more manageable, since the wheel bounces noticeably less on a dirt road. which means it is in the best grip;
“Double suspension”. a bicycle with a shock-absorbing suspension of both wheels. This is the most comfortable option, but they are usually heavier than hardtails of the same level, and are significantly more expensive in price. Full suspension, thanks to the simultaneous operation of both shock absorbers faster than hardtails on rough terrain.
Mountain bikes are mainly equipped with shock absorber forks. Let’s take a closer look at the main pros and cons of depreciation forks.
- 1. Increased contact with the surface, improved control and handling. If the wheel is moving at a sufficient speed on an uneven surface, there is a force that tends to pull it off the road. This is what happens with a rigid fork (suspension), and the speed must be reduced. But thanks to the shock absorber, the front wheel rolls over irregularities smoothly, without impacts.
- 2. Increased cross-country ability. This is a subjective feeling of a cyclist, in reducing vibrations from the steering wheel, and reducing efforts when jerking the steering wheel towards himself in order to overcome another obstacle.
- 3. Speed and energy. A soft fork will not only allow you to traverse bumps at high speed, but also use less energy. The shock absorber “swallows” not only the vertical component of the force, which tends to throw the front wheel up, but also partially the horizontal component that slows down the bike. The sharper the angle of inclination of the fork to the plane of the road surface, the more effectively the horizontal component is worked out, the higher the speed in strong off-road conditions. Although this slightly deteriorates dynamics and maneuverability, since at the same time the wheel rollout (the distance from its axis to the steering column) and the length of the bike base increase. If the angle of inclination of the fork tends to 90 degrees, the fork better responds to small “bumps” on a paved road, the bike accelerates faster in acceleration, turns easier, but directional stability decreases.
- 4. Improved braking. In the event of a sharp operation of the front brake, the chance of rolling over the handlebars is reduced. The inertial force that tends to flip the bike over the handlebars is partially offset by the action of the shock absorber. Important! A long-travel fork has a dramatic change in the angle of the head tube when compressed, so you are more likely to roll over the handlebars on steep slopes and / or brake your front wheel sharply.
- 5. Riding comfort and durability. The front suspension (shock absorber) reduces shock loads on the frame in the places of the steering column, handlebar, stem, seatpost, thereby increasing their service life. The hands of the cyclist, the shoulder girdle and the upper spine, without shock absorption, are the first to suffer.
It should be noted that the quality of depreciation is affected by the ratio of sprung and unsprung masses.
The sprung mass. it is the mass of the units supported by the shock-absorbing suspension. In the case of a bicycle, this is the combined frame, saddle, handlebar, biker, payload.
Unsprung weight. mass of bicycle assemblies not supported by the suspension. These are the combined wheels, movable fork tubes, rear suspension arms. The lower the unsprung mass, the better the damping.
To determine the ratio, sit on your bike and see which parts move under your weight. The handlebar, frame, saddle, trunk, all attachments and the cyclist will be sprung masses. And the wheels, brakes, forks, levers of the rear suspension remaining in the “stationary state” are unsprung masses. If the bike does not have any suspension, then the shock absorber can only be used on pneumatic tires. When a wheel hits a road unevenness, the unsprung parts receive an impulse proportional to their mass, which, when loading the suspension, is transmitted to the sprung parts. This causes “harmful shocks” and vibrations. It is impossible to completely eliminate the unsprung mass, therefore, their weight is minimized as much as possible. The test shows that a rider on a bike with two suspensions (which are usually heavier than hardtails) on a difficult track performs better and uses less energy than an athlete on a bike with one suspension. And a bicycle without a suspension (rigid) has not been used for several years, even in amateur sports.
- 1. The suspension fork is noticeably heavier, stiffer.
- 2. When driving on a smooth highway or going uphill, extra effort is expended as the bike sways on the suspension. and some of the energy transmitted from the transmission to the wheels is dissipated, the dynamics deteriorate. This is especially noticeable on long-travel (over 100 mm) forks that do not have a stable platform. On a flat road and uphill, it is more profitable to make the suspension fork as stiff and short as possible. If the travel depth of the fork is less than 80 mm, then the losses are hardly noticeable.
Adjusting bike shock absorbers
Bicyclenbsp | nbspRepair
Now we are going to talk with you about setting up bike shock absorbers. Almost all bicycle shock absorbers consist of a spring (called a spring) and a damper. A conventional spring made of steel or other materials is used as a spring. A metal spring is best mounted on a bike that is designed for fast driving on rough roads, where it will quickly compress and expand. For more efficient operation of the shock absorber, it must be adjusted for yourself. This is done like this: you need to sit on the bike and put your feet on the pedals. Then fix the spring with the fixing nut a few turns. As a result, the spring should be fixed, but not compressed. In this case, the shock absorber should be compressed by about ¼ of the rod (the central axis of the shock absorber).
If you install a very stiff spring, then the entire suspension of the bicycle will not work completely, and if you install a very soft spring, breakdown is possible after jumping from a great height.
The damper has the function of slowing down the compression and expansion of the shock absorber. Dampers can be air or oil. It is how well the damper itself is made that determines the quality of the entire shock absorber. To fine tune the shock absorbers of a bicycle, spring compression / expansion speed regulators can be used. When driving on a highway, the need for a rear shock absorber is almost zero.
Therefore, it can be made more rigid. And when driving off-road (mountains, bumps, forests), the need for a rear shock absorber increases and it is better to make it a little softer. With such a ride, the shock absorber significantly reduces the load on your spine.
If the bike is designed for extreme riding, then the role of the shock absorber is to extinguish all vibrations after jumping from a great height. The maximum downhill speed will depend on the travel of the shock absorber. the greater it is, the higher the speed. But at the same time, you need to take into account the fact that too long a shock absorber will interfere with acceleration on a flat road and when climbing up. Therefore, it is advisable to find out in advance whether your driving will be extreme and by how much. And then buy a shock absorber of the desired length. That is, if you do not plan to go down steep mountain paths, then a shock absorber about 10 centimeters long should be enough for a comfortable ride. If you have opposite plans, then you need to take something longer.
These were the main features of the bike shock absorber tuning.