Bicycle seatpost. Choosing the right bike size Bicycle with the saddle moved back

Owners of hardtails have probably more than once encountered the problem of excessive frame rigidity. If vibrations on the handlebars can still be dampened with the help of gloves and soft grips, then installing large, heavy saddles on springs is not the best option. But you can still solve the problem of rigidity using a seatpost with a shock absorber.

Standards: length and width

At first glance, the seatpost is a very simple spare part that does not have any properties, but this is not so. The fact is that during active riding, the seatpost experiences quite large loads, so both the tube itself and the mount must be designed in such a way as to compensate for at least part of such loads.

Seatposts are available in different diameters and lengths for all types of frames. They can also be classified by purpose. Often, the greater the expected load on the seatpost, the larger its diameter.

Seatposts are made primarily from 6061 aluminum, but there are also extra strong 7xxx series or carbon fiber seatposts. Among other things, carbon fiber also dampens vibrations quite well, unlike metals, but this will only be noticeable for advanced riders. Those who simply want to improve their bike and have a softer riding position can use a shock absorber seatpost.

Pins with built-in shock absorber

Unlike rigid seatposts, they have a built-in damping system. Shock absorber seatposts are in great demand on touring bikes, where weight and high reliability are not important. With the help of such a seatpost, you can easily turn your hardtail into a full-fledged dual-suspension bike without losing much in weight or money.

There are several types of shock absorber seatposts:

Telescopic. The design is quite simple and unreliable. Resembles the severed leg of a regular spring fork. Despite the existing adjustments, the spring will immediately sag under your weight and the useful stroke will decrease.
Parallelogram type. Under the seat there is a mechanism that operates on a system of levers and presses the central piston. The design is more advanced, dampens vibrations better, does not sag as much when free, is significantly more expensive and is just as unreliable as the telescopic one.

The seatpost and shock absorber are adjusted using a hexagon. At the end there is a plug, which, when rotated, regulates the compression of the spring in exactly the same way as on spring forks. But there are pins that can be adjusted manually.

Mounting types

Almost all telescopic seatposts use a single hex bolt mount, as on conventional systems; this is somewhat lighter and simplifies the design.

Typically, parallelogram bicycle seatposts with a shock absorber have a through-bolt hex mount that tightens the saddle frame. This system is more reliable, since the moving mechanism is located directly under the slats, and the bolt protruding from below slightly interferes with its operation.

Classic pipes

Conventional rigid seatposts come in not only straight shapes, but also curved backwards at various angles. This helps you fine-tune your riding position even more precisely, just like with the stem. The clamp is often compatible with several saddle rail standards.

All seatposts have a diameter ranging from 26-31.8 mm, and a length from 150-450 mm. Longer models are suitable for tall people. Remember: the more the post protrudes from the frame, the easier it is to break both it and the frame seat tube.

How to install?

This miracle of technology is mounted in the same way as a regular pin, and the only tools you need are a 6 or 5 mm hexagon. It should be said that the final set of tools and the complexity of the work performed depend on the manufacturer of the pin and frame.

For example, on some Compagnolo saddles, the clamp is tightened with two 5 mm hex bolts, and on old-style, children's and modern cheap bicycles with steel pins, there is a fastening in the form of a pin and a set of special toothed washers, which attract the saddle frame on both sides. The structure is tightened on both sides with 13 mm nuts and does not use hex bolts.

The replacement instructions themselves look like this:

Loosen the saddle frame fastener a little while the pin is in the frame and clamped tightly.
Open the seat clamp and remove the post.
Unscrew the seat completely.
Take your shock absorber seatpost and install the saddle on it.
Adjust the spring stiffness at the end of the seatpost.
Insert the pin into the frame, adjust the height, and then tighten the eccentric.
Tighten the bolt securing the saddle.

You should not install a seatpost with a shock absorber as a means of softening shocks in the saddle. It will not provide a good effect, but an extra squeak under the saddle, plus a few grams of the weight of the bike and extra costs - easily.

Do you need it?

Installing a seatpost and shock absorber is adding another complex mechanical component to the bike, which means it needs to be looked after in the same way as, say, a fork. The design needs constant rebuilding, lubrication, and perhaps even replacement of springs.

You should not install pins with a shock absorber if your weight is more than 100 kg. Although some of them are able to withstand such loads, you will not get long and smooth operation. Reviews of seatposts with a shock absorber from real owners of such a device do not call for immediate purchase, which means that such a system is not reliable enough for active riding.

A seatpost is a part of a bicycle that serves as a connection between the saddle and the bicycle frame. In addition, the seatpost allows you to adjust the height of the saddle, and with the help of a lock on the end of the pin you can adjust the angle of the saddle and the length of the runners (rails) of the saddle frame. Some call this part a seat tube, but this is not correct. The seat tube is the part of the bicycle frame into which the seat post, also called the saddle stem, is inserted.

The seatpost is inserted into the seat tube and secured with a bolt or cam clamp. If the clamp is loosened, the pin will move freely inside the tube, which allows you to adjust the height of the saddle to suit the height of the cyclist. Despite the fact that the design of the seatpost is quite simple, there are still design features by which several types of posts can be distinguished. In addition, the posts differ in the materials from which they are made and the types of locks - securing the saddle to the end of the seatpost.

Manufacturing materials

The seatpost should be strong, lightweight and durable. All these parameters depend on what material they are made of. The seat stem can be made from the following metals:

Steel - pins made of steel alloys are now found only on old and very cheap bicycles. Such pins are the heaviest and short-lived; in addition, steel is a soft metal and can be easily deformed.
Aluminum - Aluminum alloy is the most popular material for seat stems. It is popular because I use it to make pins of both the lowest and highest levels. Aluminum pins are strong, rigid, durable and lightweight.
Carbon - carbon fiber is mainly used to make stems for racing road bikes. The carbon seatpost is the lightest.
Titanium is a good, but expensive material, so it is rarely used.
Scandium - only the highest level pins are made from this material.

Seatpost types - adjustable, telescopic and shock absorber

- is an ordinary pipe with a lock at the end and has no additional adjustments. This design is the most popular and does not have much comfort, but such stems are the cheapest, lightest, most reliable and durable.

Telescopic- such pins consist of two pipes that are inserted into each other and fixed with an additional clamp. These stems are good for bikes with a short seat tube, such as dual suspension bikes.

With height adjustment- this is the same telescopic rod, only the height can be changed using a switch on the steering wheel. That is, you can change the height right on the fly, which is very convenient when going up and down the mountains. It is worth noting the very high cost of such removals.

Integrated- such pins are very rare, since they cannot be adjusted. The integrated pin is an extension of the frame and is made to order for individual orders. An integrated saddle stem is also used on BMX bicycles.

Depreciation- These are seatposts with increased comfort. Thanks to the built-in shock absorber, they can smooth out impacts on uneven surfaces. There are two types of shock-absorbing seatposts - telescopic and lever. Telescopic shock absorber pins have a very short lifespan due to the high friction within the mechanism, but they are relatively cheap. The linkage pins have a parallelogram mechanism and elastomer that provide excellent shock absorber performance. The only drawback of such a shock absorber is the change in the distance to the steering wheel during operation of this mechanism.

Bicycle seatpost lock - mount to saddle

The lock is designed to connect the saddle and seatpost; the lock also allows you to adjust the level of inclination of the saddle in the longitudinal direction by moving the lock along the rails of the saddle frame. The lock can be integrated into the seatpost or attached to it. According to their design features, locks can be divided into the following types:

Removable lock - the lock is not integrated into the seatpost and is attached to it using a clamp. There are grooved flanges on the outside of this clamp. The support washers also have notches and fastenings for the saddle runners. This entire structure is tightened with a special pin with two nuts on the edges, thereby ensuring that the saddle is securely fastened to the saddle stem. This is a rather outdated type of lock. Currently widely used on children's, road and entry-level sports bikes.

Single bolt lock- provides fairly reliable fastening, but has rather rough adjustments.

Double bolt lock- provides reliable fastening and at the same time allows you to smoothly adjust the angle of the saddle.

Original locks- in addition to the three aforementioned locks, there are many other types developed and patented by various manufacturers.

Locks may also differ in location relative to the seatpost. Locks can be offset back or without offset, the former are much more popular.

Edited: 03/27/2019

Seatpost(also called " verb") is the tube that connects the saddle and the bicycle frame.

The upper part of the post contains a lock to which the saddle is attached, and the lower part is inserted into the frame's seat tube. The pin is clamped in the pipe using a special seat clamp with bolts or an eccentric. Clamps with an eccentric are much more convenient; you can open the pin with one movement and set the desired height. For clamps with bolts, you need either hexagons or a screwdriver with keys. By the way, it is very convenient when all the necessary cycling tools: hex wrenches, screwdrivers and others are collected in one compact multitool, which the cyclist can put either in or in his pocket.

Seatpost Types

Hard seatposts

It is simply a pipe with a saddle lock on one end. The most common type today. They are quite easy to use, do not require any maintenance, are strong, lightweight, reliable, and durable. Their only drawback is limited comfort, which, however, is enough for 90% of cyclists. After all, if you install a correctly selected and adjusted saddle, correctly, then the ride will be quite comfortable.

Hard seatposts are made from:

Become- the cheapest, fairly common and reliable option.
Aluminum alloys- also quite common. Such pins are lighter than steel ones, but more expensive. Naturally, like all products made of aluminum alloys, they are much less susceptible to corrosion.
Carbona. Lightweight and durable. On average, they are 2 times lighter than aluminum ones, but more expensive. Although recently there has been a tendency towards a decrease in the price of carbon products, so evaluate your finances and choose.
Titanium, scandium- very light, durable, but also very expensive. They are used only by athletes or wealthy connoisseurs of “art”.

Sometimes butted tubing is used to reduce weight. These are pipes whose wall thickness varies in different places.

Typically, such pins have thicker walls where the pin enters the seat tube (where the loads are heaviest), and thinner walls closer to the top.

Butted seatposts are more expensive than their standard counterparts, but lighter, so if weight is critical for you, look for these models.

Durability and reliability of the seatpost

Your health directly depends on its strength and reliability. Imagine how you will feel if it breaks during a trip? Introduced. Agree, not very good, to say the least.

The strongest, lightest and most reliable are titanium ones - they are unlikely to ever break, but for the average cyclist they are too expensive.

Next come the steel ones - these also very rarely break. In addition, unlike aluminum ones, they do not break immediately. Aluminum tends to “accumulate fatigue.” It breaks immediately, but the steel will first crack, and only then, in this place, will break. It is precisely this property of steel as a metal that allows you to notice the crack in advance and replace the pin. Of course, if the bike is not inspected from time to time, then the steel pin will break on the next bump.

In addition, I personally do not consider the argument that an aluminum pin is lighter than a steel one to be very compelling. An extra hundred or two hundred grams will not save you.

Carbon pins stand apart. Carbon itself is a very strong and durable material. The peculiarity of these pins is that what to buy real carbon pin, and not a fake from a Chinese garage at a “promotional price”. Otherwise, you will get one of the situations like in the photos below.

Carbon is also a fairly fragile material, so when clamping the pin in the seat tube, do not overdo it with the “heroic strength”. Otherwise, it will crack at the clamping point, and then break at the most inopportune moment.

I would advise purchasing a carbon pin only for bicycles with . And most likely, anyone who has enough money for a real carbon frame will also have enough money for a high-quality carbon post.

For all other lovers of riding, I would advise purchasing a regular steel pin as the best value for money. It will serve faithfully for decades, and you are unlikely to feel it as your underside.

It differs from hard ones by a special mechanism that softens shocks and shocks that occur during a trip.

Depreciation systems are very diverse and some examples are presented in the picture below. We will not describe them all. Some models compensate for shock by moving only up and down. Others, receiving a push from below, swing the saddle down and back, which provides more effective shock absorption. On the other hand, this increases the distance to the handlebars, which is not very convenient for some cyclists.

When choosing them, keep in mind that they are quite expensive, weigh more than rigid ones, and some models require regular maintenance.

The following can be noted as a disadvantage of shock-absorbing pins:

When adjusting the height of the saddle, you need to take into account the slight subsidence of the post when the cyclist sits on it. Moreover, over time it can increase. But bikers quickly get used to this.
Shock absorption most often works in the direction of the pin axis. Note that it is installed in a bicycle with a tilt back, and the direction of shocks when riding is mainly vertical and to the left, to the right of the handlebar. In such cases, depreciation helps little. Those. the opinion that the shock-absorbing pin protects the fifth point from all impacts is not correct.
If the shock-absorbing mechanism itself is very rigid, then it will be weak in absorbing small shocks.

If necessary, you can find more detailed information about them on the Internet.

Height-adjustable seatposts

Their distinctive feature is that the seat height can be changed during the trip. This may be necessary, for example, when climbing a mountain - when you need to sit higher, but on a flat section of the road or going down a mountain you can sit lower to reduce resistance to air flow.

They come in the form of two pipes inserted into each other with a clamp - the so-called telescopic pins. It is impossible to say that they are very comfortable, since to change the height of the saddle you need to stop, get off the bike and adjust the height. They are usually installed on bicycles with a frame that has restrictions on the length of the post, but when the saddle needs to be raised high. Although there are models in which the height change lever is located directly under the saddle, which allows you to change the height on the go, but how convenient it is - everyone decides for themselves.

Hydraulic seatposts do not have this drawback; they can be smoothly adjusted during a trip using a special lever or shifter mounted on the steering wheel. Then the height of the saddle changes “with a slight movement of the finger.” They are, of course, convenient for cycling in mountainous areas, but they are very expensive, heavy and require regular maintenance.

Disadvantages of height-adjustable seatposts

Just like shock-absorbing pins, telescopic ones can sag a little under the biker during trips.
The strength of such pins is lower than that of rigid ones. And sometimes, in not very high-quality models, play appears between the pipes, which leads to rattling during the trip.

Seatposts integrated with frame

Quite rare and too specific type. They are made almost individually for the height of a particular athlete. It is cast together with the frame and, of course, is not adjustable in any way. The purpose of all this is to lighten the entire bike. This is most often done with carbon bicycle frames.

How to insert a seatpost into a frame's seat tube

When adjusting the height of the saddle, it is very important not to insert it into the frame above the special mark marked on the pin. It must remain inside the tube by at least 10-15 centimeters, otherwise the seat tube of the frame will simply break over time from constant heavy loads on its upper part.

Serious manufacturers usually apply special depth marks to their products.

Second point. If the pin does not go down and you feel that something is blocking it in the pipe, there is no need to hammer it in there.

Firstly, You can break both the pin itself and the frame.

Secondly, it is quite possible that during the manufacture of the frame there was a drop of metal left from welding or the seam was not welded carefully. With these blows you will not cut down a drop, but this very place in the frame will become a point of tension and it is here that the frame can burst over time.

There are different diameters of both the pins themselves and the seat tubes on the frame. Of course, before purchasing a post, you need to check whether it matches the diameter of the seat tube on the frame. If it’s more, then you definitely won’t be able to fit it into the frame. But if the diameter of the pin is smaller than the pipe, then for its reliable fastening you can use special adapters for different diameters.

There are several diameters of seatposts.

The most common diameters:

25.0 mm. - for one inch (25.4mm) seat tubes. It is also called the Soviet diameter. It was very often, but not in all models, used in bicycles produced in the USSR.
27.2 mm for 1.1 inch pipe
31.6 mm for 1.25 inch pipe

Some manufacturers produce frames with their own seat tube diameters and, accordingly, you need to look for pins that match the diameter. These are, for example, diameters such as (in mm): 26.0; 26.8; 29.2 (Trek, Stels steel); 29.6; 30.8 (Giant); 30.9 (Specialized); 31.2 (Atom fxc); 31.4; 31.8; 33.9 (Shulz)

In general, almost complete list of seatpost diameters in mm looks something like this: 25.0 / 25.4 / 26.0 / 26.4 / 26.6 / 26.8 / 27.0 / 27.2 / 28.6 / 29.0 / 29.2 / 29.4 / 29.6 / 29.8 / 30.0 / 30.2 / 30.4 / 30.8 / 30.9 / 31 .2 / 31.4 / 31.6 / 31.8 / 32.4 / 33.9 / 34.9

When selecting an adapter, carefully ensure that the pin sits tightly in the frame seat tube and does not wobble. Even a small gap of half a millimeter, in which the seatpost swings, will eventually lead to the destruction of the seat tube. And riding on a swinging saddle is not comfortable. If it is difficult to find such an adapter, try simply wrapping the pin with electrical tape or use thin metal plates to close the gap between the pin and the pipe.

How to determine seatpost diameter

There are several options:

If you have an old one, you need to find out its diameter. How?

The most accurate and reliable way is to measure the diameter with a caliper.
Measure with a simple ruler - a school or construction ruler. The method is not very accurate, but it is suitable for the main diameters.
Another method for those who are not looking for easy ways in life or if there is no caliper. We take a thin thread (the thinner, the more accurate the result) and wind 10 turns around the old pin. After this, measure the exact length of the thread, divide by 10 and 3.14. Why 10 turns? To more accurately measure tenths of a mm of pin diameter. Why do we divide by 3.14? This is a school geometry course: circumference = diameter times Pi.
A couple more popular ways to measure seat diameters using a construction angle and a school triangle or using an adjustable wrench are described in the article and we will not repeat them here.

If you are buying a seatpost for a new frame, you need to measure the inner diameter of the seat tube. There is only the option of a caliper or ruler.

Seatpost Length

Compared to the diameters of the pin, choosing its length is much easier. Typically, pins with a length of 350 to 400 mm are installed. On and road models from 270 to 300 mm

Attaching the seat to the post

There are different designs for attaching the saddle to the seatpost:

The easiest way. The pin itself has a narrowing on top into which the seat fastener is inserted and clamped with special bolts and secured to the pin.
Single bolt. A three-piece structure that clamps the frame between two semicircular parts with a grooved surface and holds the entire structure with a special bolt.
Double bolt. The next option is used on expensive models, since it is quite expensive. It is similar to the previous design, but there are two bolts. They are screwed into special inserts directly into the saddle mount. The advantages of this design are very smooth adjustment, allowing you to set any angle, independent of the location and pitch of the notch, as in the second option.
There are also all sorts of complex patented designs from individual manufacturers, but we will not consider them.

There are models of curved pins (for example, as in the figure on the right), which are used if necessary to change the position of the cyclist's body, moving it a little back. The size of the rear stem is selected individually to obtain a comfortable riding position for the cyclist.

conclusions

So, when choosing a seatpost, consider a few points:

Their financial opportunities. A shock-absorbing hydraulic pin will cost significantly more than a regular steel one.
Comfort level, which you want to receive. A steel pipe is one thing, but well-chosen wheels will suit 90 percent of bikers. Or you want to spend the money and buy a shock-absorbing post with variable height and provide your spine and butt with more comfortable conditions.
Are you ready to study technical maintenance hydraulic pin or do nothing with regular steel pipe.

The most frequently asked question from beginners: choosing a bike by size. Often people who ski only a few times throughout the summer give a completely wrong answer. As a result, beginners will buy a bicycle that has a frame that is not suitable for their height, which will cause problems with their knees and affect their back. The wrong frame size always leads to discomfort while riding.

This feeling occurs when the mileage traveled per day increases to 30-50 km. Therefore, novice cyclists should listen to a few tips:

Please note that frame size (ST) is designated by the length of the seat tube.
Dimensional parameters of road, hybrid, and city bikes are presented in centimeters, mountain bikes - in inches. Since road bikes became popular primarily in southern Europe, and mountain bikes were invented in the USA.
If someone says that, for example, an 18" frame is suitable for you, this is not a complete answer. Gone are the days when a tube length of 18" meant that a frame was suitable for a person with a height of 1.75 meters. Now they produce frames with a variety of geometries for different riding directions.

Now about the parameters. Below are drawings of mountain and road frames. Look at the following dimensions: ST - the length of the seat tube, ETT (T/Th,L) - an imaginary line laid from the center of the steering tube to the intersection with the imaginary axis (passes through the seat tube). In general, ETT corresponds to the length of the bike, the main parameter when selecting a bike. Newbies usually don't look at him.
It is worth noting that both frames are intended for the same person. Although the ST parameter (frame size) is different. Therefore, a beginner who was advised to use an 18" frame may be mistaken.
The example clearly showed the existing differences in geometry between the mountain and road frames. However, it is a mistake to think that frames belonging to the same class are the same. For example, a 21" MTB bike can be shorter, and a 19" bike can be longer.
When choosing a bike by height, first of all you should look at its length, since the inscription on the frame indicates the size of the seat tube, which is a secondary parameter.
The designation of bicycle sizes (18", 20", L, etc.) is misleading, because frames have different geometries.

Mountain bike

Road bike
Beginners can shrug off such subtleties, but it’s still better to take a closer look at choosing the size of the bike. (Better sooner than later!) If you like this hobby, the wrong frame length will force you to buy a new bike.
Modern bicycles do not have handlebar height adjustment without additional steps. (exception - city bikes). You can't "outplay the geometry" if the size is wrong.

Read these tips to help you choose a mountain bike or hybrid:
1. Be sure to try the bike yourself. If you don’t have the opportunity to go for a ride, then at least sit;
2. When standing with both feet on the ground (the bike between them), there should be a distance of at least 10 cm from the crotch to the top tube. An underestimated distance threatens injury in case of falls or during an emergency stop;
3. The longest bike creates a sportier riding position. To obtain high speeds and effectively climb a slope, you need to “spread out” over the frame. If you need a bike for sporting purposes, get one with long and low frames. Marathon runners use such bikes for long distances, although ordinary people's arms soon begin to fall off due to the serious load on them;
4. When you need a leisurely, comfortable ride, short frames are suitable. For example, a city bike: the seating position is almost vertical, you sit as if on a stool, just holding the handlebars. It is not so comfortable to travel long distances: the weight of the body rests on the spine. For serious riders, long frames are preferred;
5. The frame has a medium length and is ideal for an advanced cyclist without a penchant for sports. He will not need to “spread out”, transfer weight to his hands, and will not have to sit on his tailbone. Having such a bicycle, you can travel tens of kilometers without any discomfort from landing.
Let's say, having bought a bike, you decide that it is not completely suitable in size. There is a possibility that you incorrectly adjusted it to your own height. How to customize your bike - below!

Handlebar and stem
Modern bicycles do not have handlebar height adjustment. The stem (this is a short stick designed to secure the steering wheel) has a length and angle. There are stems of various sizes. By purchasing the right one, you will improve your riding experience. Also, spacer rings on the fork rod will help raise the stem relative to the frame (if the fork rod is long enough for this)
It is possible to install the stem with ascent, as well as with descent. There are adjustable stems, handlebars with or without lift. This will help change the height of the handlebars.

Horns
An important element at significant distances, it allows you to change the positions of your arms and body. They are placed almost parallel to the ground, with a very slight rise. It should be possible to lie on them with your palms with the center of gravity moving forward.
This position will add aerodynamics; cyclists often use this technique when moving against the wind. A good addition is the grips, which have flat areas so you can rest your palms on them.

The saddle needs to be adjusted horizontally
The saddle should be parallel to the ground. Some people tilt the saddle forward or backward for convenience. This is fine tuning! In case of excessive bending, pressure on the hands may increase (numbness, cramps), and pressure on the perineum - discomfort is guaranteed.
A perfect fit is essential. Lowering the seatpost slightly (a centimeter) may allow the saddle to be leveled.
If the frame does not quite fit, the position can be corrected by a longer stem, offset seatpost, and horns.

The saddle height will need to be adjusted.

Many beginner cyclists set their saddle at a low level. The result is the so-called “knees above ears” fit. Which looks funny and poses a danger to the knee joints.
The height of the saddle is such that the leg standing at the lowest point of the pedal (with the toe positioned) is slightly bent or completely straightened when the pedal is lifted from below.
Place your foot on the pedal with your heel, it should be fully straightened. The most important moment! It may seem inconvenient that if you need to stop suddenly, you cannot touch the ground with your feet unless you get off the seat. However, the well-being of your knee joints is more important than comfort.

Longitudinal saddle adjustment
Ideally: the foot rests on the pedal in such a position that the pedal axis is located under the knee joint. This is achieved by moving the saddle along the longitudinal direction.

Offset seatpost
The detail will be useful when, having completed the maximum longitudinal adjustment of the saddle back, you still feel that the seat is a little short. The pin can provide an additional three to five centimeters.

These simple tips will help you find the right bike size for you. Remember that the size and adjustment of the seat on a bicycle are very important things; not only the rider’s mood, but also his health depends on them!

The seatpost is the tube on which the bicycle seat rests. It merges the saddle with the frame into a single system and allows the two parts to interact.

Why do you need a seatpost?

The main function of the seatpost is to adjust the height of the saddle. Also, using special locks, the pipe adjusts the angle of the seat. The correctness and comfort of seating a person on a bike and obtaining the maximum efficiency from the efforts of the cyclist depend on these parameters.

What material should the seat tube be made of?
Nowadays, approximately 90% of bicycle seatposts are made from aluminum. This metal is very light, but has enough strength to withstand significant loads. Seat tubes for bicycles of very cheap series, for example, “Ukraine”, are made of steel. These pins are very rigid and durable, but much heavier than aluminum ones.

Bicycles used in sports competitions are equipped with carbon seat tubes. Such parts are lighter than aluminum and can reduce the weight of the bike by 100-200 grams. At the same time, carbon pipes are not inferior to aluminum pipes in terms of strength. This is why athletes love them.

The most expensive and prestigious bike models are equipped with scandium seatposts. They are even lighter than carbon ones, but have a very high cost.

How long should the seatpost be?

The length of the seatpost must be at least 30 cm. Most modern bicycles use tubes 30-40 cm long. Some models of economy class bikes have very short seatposts (up to 15 cm). This feature does not allow you to extend the tube higher and maintain the correct position on the bicycle.

Checking the seatpost length when buying a bike is very easy. You just need to open the eccentric (lamb), which is located at the base of the pipe, and pull the tube up a little. If this part is short, it will slip out easily; if it is long, it will pull out slowly and require effort.

Determining the correct seatpost length for a specific bike is very easy. To do this, you need to extend it to the maximum possible mark, which is indicated by a long white line. After this procedure, you need to get on the bike. If, when sitting down, your legs do not touch the asphalt, but reach the pedals at the lowest point of their rotation, then the seat tube is long enough. If the lower limbs reach the asphalt, you need to change the device or bike.
In good bicycle shops, the bikes that are on display have the saddle raised to the maximum and no additional manipulations are needed with them. It's enough just to ride the iron horse.

What should the seat tube diameter be?

There are 3 main diameters of bicycle seat tubes:

25 mm,
27.2 mm,
31.6 mm.

The 25mm diameter was used in Soviet bicycles. Currently, bikes with this pin width are not produced, but frames with it are actively used. Diameters 27.2 and 31.6 mm are used on all modern bicycles, regardless of class and purpose.

Some manufacturers make frames with a different width seatpost hole. Pipes for them must be selected individually. You can find out the diameter of the seatpost on the specifications plate, which is attached to the bike in the display case or posted on the store’s website.

What types of locks are installed on seatposts?

There are 3 types of locks that are placed on seatposts:

Single bolt. Such devices roughly adjust the tilt of the saddle.
Double bolt. These mechanisms allow you to fine-tune the seat position.
Original. Some manufacturers install very complex locks of patented designs on their premium bikes. The high cost of pins with them is not always justified when using a bicycle.

Depending on the position in relation to the seatpost tube, locks are of the following types:

With a backward shift is the most common type.
No offset. Devices of this type provide a slightly forward seating position.

What additional devices are equipped with seat tubes?

Shock absorber

Until the early 21st century, a seatpost was simply a hollow tube with a saddle mount at one end. But since the early 2000s, pins with shock absorbers began to gain popularity. Such devices significantly soften the load and impact of the saddle on the gluteal muscles when riding on rough terrain or on dirt roads.

All shock-absorbing mechanisms for seatposts are divided into 2 types:

telescopic,
lever

Pipes equipped with the first type of device are relatively cheap, but have a short service life, especially if the bike is used by a person weighing more than 90 kg.

Pins equipped with mechanisms of the second type cost several times more, but provide maximum reduction of load on the gluteal muscles.

Telescopic device

Also, telescopic seatposts are sometimes installed on bicycles that are designed for off-road riding (double suspension). They consist of two pipes. The upper one is pulled into the lower one. This feature allows you to extend the saddle as far up as possible when riding on the highway and reduce its height when walking off-road.

Height adjuster

A subtype of telescopic seatposts are tubes with a height adjuster. In them, the cable from the guide device is pulled to a special button mounted on the steering wheel. With the help of the latter, the cyclist can change the height of the saddle without getting up from the bike. Regulator tubes are rarely factory installed on bicycles. They can only be purchased in stores for professional riders.

The final choice of seatpost depends only on the preferences and financial capabilities of the bicycle owner. For walking around the city, a simple pipe with a single-bolt lock offset to the rear will suffice. Only extreme off-road racing requires complex seat tubes equipped with various bells and whistles.