Frame materials

Bicycle frames are made from the following materials:

Hi Ten(Hi Tensile Steel) - high-strength steel, this is the cheapest material. In common parlance - a water pipe. The frame is heavy and does not roll. Doesn't cost anything at all. Bicycles with steel frames cost no more than $300.

Cro Mo(cromomolibden) - chromomolybdenum alloys. Frames made from this material are lighter than those made from Hi-Ten, more rigid, but also more expensive. A good chrome frame costs from $500. Cheap varieties of chromium-molybdenum alloys are no different from hi-ten, well, they roll a little better, weigh a little less. At one time, manufacturers took such a bad fashion: they put only one chrome pipe, and all the rest are hi-ten and proudly write that the frame is made of chrome-molybdenum pipes. If the price tag is below $500, they are lying. Bikes with chromoly frames start at $1,000.

Alu(Aluminum) - aluminum alloys. This material allows for an even stiffer and in many cases lighter frame than chromoly. Commonly used alloys 6061 ,7005 , less often Altec-2, Magnesium, Scandium, and the latter is insanely expensive. The range of frames is very wide, from "stools" that are terrible in terms of rigidity, to full "sausages", from non-rolling graves to downright rockets. A good training KK frame costs $300-500. Sports frames - over $500. On bikes in the sub-$700 price range, the frame costs next to nothing, with the rare exception of custom builds. Cheap aluminum frames (on bikes up to $500) for a similar application do not differ from each other in anything other than size, length and color. Small frame differences start at over $700, and noticeable differences start at $1200.

Ti(Titanium) - Titanium. A very durable material, but at the same time soft (compared to Alu frames, for example), which not everyone likes. Before buying a titanium frame, it makes sense to ride it first and understand for yourself whether it is necessary. Titanium frames start at $400.

Carbon(carbon fiber). These are ultra-light frames, but extremely unstable to shock loads. They cost a lot, so they are used either by the pros or by those who can afford it. Technologies do not stand still, so they learned to bypass instability to shock loads in critical places with purely constructive solutions. And the carbon components themselves are becoming stronger and longer lasting, and prices are dropping. For example, at the Taiwanese factory, a fully carbon frame with at least some calculated geometry, the frame costs ~ $ 150; an aluminum frame with "standard" geometry carbon rear stays costs $20-$30. The quality, you know, is killer.. When choosing a carbon frame, it makes sense to focus ONLY on the name of the manufacturer, it must be a serious brand.

Steering column

The 1 1/8" size has become the current headset standard. There are other sizes, such as 1 1/4", but this is rare.

Regular and semi-integrated steering columns are now standard. There is no functional difference between them, but the semi-integrated one is a bit lighter. Therefore, do not bother.

If we consider the long-term perspective of the operation of an aluminum frame, about eight years, with runs over 5000 km per year and year-round use, then we should prefer the "normal" steering column, because the head tube of the frame under the semi-integrated steering column will break faster than the standard one. Naturally, if this frame is able to live so long.

Rooster

The cock is a metal bracket on which the rear derailleur is attached. It is removable and non-removable. It is preferable that it be removable, because. in the event of a breakdown, you simply put a new one, and the fixed one will have to be welded to the frame. On the vast majority of bikes over $300, the cock is removable.

frame metal structures are distinguished by a wide variety of static schemes, the number of spans, configuration, etc., which makes it possible to build buildings of various purposes and sizes.

Figure 3.2.1 shows some types of flat and spatial steel frame structures. Static schemes of frame structures are shown in Figure 3.2.2.

Most often, the sections of frame structures are made of solid I-beam or box section. Some possible options for solid sections of steel frames are shown in Figure 3.2.3.

The use of one or another type of frames, their static scheme and type of section is determined by the size and configuration of the building being designed, the availability of appropriate technological equipment for the manufacture of structures, and other factors.

Depending on the calculation scheme of the frame, the crossbars are of constant or variable section. In double-hinged frames (Fig. 3.2.2 c), the height of the crossbar of constant height is taken equal to 1/30-1/40 of the span. Racks usually have a variable section, decreasing towards the supports.

With spans of more than 50-60 m, through (lattice) frames are economical (Fig. 3.2.4). In double-hinged through frames with hinged pairing of racks and foundations, the height of the crossbar of the frame is taken within 1/8-1/15 of the span.

Hingeless through frames, usually used in hangar covers, have very large spans (120-150 m). The height of the crossbar in such frames is taken equal to 1/12-1/20 of the span. In hangar construction, double-console and single-console frames are also used. Single-console frames are suitable for sheds sports facilities. In buildings with a span of 40–50 m and a height of 16–20 m, it is possible to use through double-hinged frames with a broken crossbar (Fig. 3.2.1 h) of a constant height equal to 1/15-1/25 of the span.

The lattice of crossbars of through frames is usually taken triangular. Racks of frames can be designed solid (Fig. 3.2.4 a) or lattice (Fig. 3.2.4 b). Lattice racks can have a triangular or diagonal lattice. The sections of the rods and the nodes of the through frames are designed similarly to the trusses of large spans. However, it is most expedient to use bent profiles of rectangular section.

Below are examples of typical frame structures used in industrial buildings.

Fig.3.2.1. Types of frame structures

a - a frame made of flat frames; b - from spatial frames; c - a spatial frame of flat frames and power spatial connections; g - single-span frame; e - multi-span frame; e - U-shaped frame; g - a frame with a slope of racks and crossbars; h - polygonal outline frame

Fig.3.2.2. Static schemes of frame structures.

a - double-hinged frame; b - three-hinged frame; c - a frame with rigid support of the posts on the foundations and rigid junctions of the crossbar with the posts; g - a frame with rigid support of the racks on the foundations and hinged joints of the crossbar-rack; e - a frame with hinged end and intermediate posts, rigid junctions of the crossbars with the end posts and a hinged connection with the middle ones; f, g - frames with split or continuous crossbars hinged on pinched posts; h - a frame with a developed middle stance, which acts as a core of stiffness; and -, k - mixed schemes.

Fig.3.2.3. Types of sections of frame structures.

a - from welded I-beams of constant or variable section with flat walls; b - from rolled I-beams of variable height, formed from ordinary ones by diagonal dissolution and welding; c - from rolled I-beams without reinforcement and with reinforcement with haunches; g - from welded I-beams with a corrugated wall; e - box-section (type "PLAUEN" or "ORSK").

Rice. 3.2.4. Lattice frame types

a - with solid racks; b - with lattice racks

Frame structures according to series 1.420.3-15 "Steel frame structures of frames of the Kansk type" of one-story industrial buildings using load-bearing frames made of rolled wide-shelf and welded thin-walled I-beams "are designed for one-story buildings with spans of 18 and 24 m, the number of spans from one to five and a height to the lower beam of the crossbar of 4.8 - 10.8 m. Frame spacing for single-span buildings, 6 m is adopted, and for multi-span buildings - 6 and 12 m.

The building can be equipped with overhead cranes with a lifting capacity of 1 to 3.2 tons or overhead cranes of light and medium duty with a lifting capacity of 5 to 32 tons.

For structures of the Kansk type, two options for solving the ends have been developed:

With the presence of frames at the end, offset by 500 mm inward, and a non-bearing fachwerk;

Instead of frames, an end-bearing fachwerk is installed at the end, including racks, horizontal beams and vertical ties.

The option with non-bearing fachwerk is used in cases where it is planned to expand the building in the future, while the end frames will serve as twin frames of the expansion joint. The second option is appropriate if further construction is not provided.

The crossbars of the frames are designed from thin-walled welded beams, and the posts are made from rolled wide-shelf I-beams. The coupling of crossbars and racks of single-span frames is rigid. The crossbars of the multi-span frames are hingedly connected to the columns of the outer rows, and rigidly to the columns of the middle rows.

The racks of the supporting fachwerk are designed from cold-formed thin-walled box-section profiles or from composite C-shaped profiles.

In buildings with overhead cranes, the crane tracks at the end of the building are attached to half-timbered posts or to supporting steel beams.

In buildings with overhead cranes, a built-in crane trestle is installed, consisting of racks rigidly fixed to the foundations and typical crane beams laid on them.

In the longitudinal direction, the rigidity of the building is ensured by vertical ties installed along each row of columns and racks of the crane trestle in the middle of the temperature block with a length of no more than 72 m.

According to the series, all mounting units of frames of the Kansk type are bolted, which excludes the use of welding at the construction site.

The layouts of the frame elements and nodes of steel structures of the "Kansk" type are shown in Figure 3.2.5 - 3.2.7.

Rice. 3.2.5. Frame structures of the "Kansk" type

Rice. 3.2.6. Structural units of frame structures of the "Kansk" type

The nodes are marked in Figure 3.2.5.

Rice. 3.2.7. Structural nodes and fastening of crane tracks for frame structures of the Kansk type

Frames from I-beams of variable section(codes 828 KM, 828 KM-1, 941 KM, 961 KM) are used in one-story single-span industrial buildings with spans of 18 and 24 m and with a crossbar top mark of frames 6.940 and 8.140 m without light-aeration lamps. The frame spacing is 6 m. Buildings can be equipped with overhead cranes with a lifting capacity of up to 3.2 tons.

The frame of a building with frame structures consists of transverse frames, girders, vertical braces and braces along the frame posts, posts and beams of the end fachwerks.

Elements of variable I-section in the crossbar and posts are made from rolled I-beams with parallel flange edges by their longitudinal dissolution along an inclined line into tees of variable height.

The connection of the racks with the foundation is assumed to be articulated. The conjugations of the elements in the cornice and ridge assemblies are assumed to be rigid and are made on 25 mm thick flanges using high-strength bolts.

The rigidity of the frame in the transverse direction is ensured by the operation of the frames, in the longitudinal direction - by vertical cross braces and struts along each row of frame racks, which ensure the stability of the racks from the plane of the frames.

The slope of the upper chord of the crossbar is assumed to be 0.025 when using a typical roll roofing and 0.100 when using roofing panels with metal sheathing.

The bearing end fachwerk is designed from wide-shelf I-beams.

Frame diagrams and junctions of frame structure elements are shown in Figure 3.2.8.

Frames made of I-beams of variable section are widely used in the construction of industrial and public buildings. Frame structures can also be cited as an example. "ASTRON".

They use welded I-beams of both variable and constant section. Single-span buildings with overlapping spans of up to 72 m have been developed. With additional internal supports, overlapped spans can reach 150 m. The frame spacing is taken from 5 to 12 m. The height along the gutter can reach 20 m. If necessary, frames of other geometric dimensions can be developed .

Buildings can be equipped with overhead cranes with a lifting capacity of up to 20 tons.

Frames are usually hinged to the foundation. However, if necessary, the connection can be rigid. The end fachwerk is carried out as a carrier of welded or hot-rolled racks and crossbars. Coating purlins are adopted from cold formed galvanized Z-profile.

An example of a building made of frame structures "ASTRON" is shown in Figure 3.2.9.

Rice. 3.2.8. Steel frame structures from I-beams

variable section

Flat frame system box-section frame type "Orsk"(code 135, series 2.420-4 issue 3) consists of single-span transverse frames located in 6 m increments, purlins, vertical braces, racks and beams of end fachwerks. It is not recommended to use Orsk-type structures in multi-span buildings.

Frame structures are designed for heated buildings with spans of 18 and 24 m, having a height of 6980 mm and 8180 mm to the top of the frame crossbar on the support. They are used in buildings without lanterns and in buildings with skylights, craneless and with overhead cranes with a lifting capacity of 5 tons. The slope of the frame crossbar is assumed to be 1.5%.

The pairing of the frame racks with the foundations is assumed to be articulated. The conjugations of the elements in the ridge and cornice units are assumed to be rigid and are made on 16 mm thick flanges using high-strength bolts.

Schemes and nodes of frame structures of the "Orsk" type are shown in Figures 3.2.10 and 3.2.11.

UNITEC steel frames of one-story industrial buildings using structures made of bent-welded pipes are designed for use in heated and unheated buildings without cranes, with overhead cranes with a lifting capacity of 1 to 5 tons and with overhead support cranes with a lifting capacity of 5, 10 and 16 tons with operating modes 1K-5K with non-aggressive or a slightly aggressive environment with a relative humidity of no more than 70% indoors.

Cranes are suspended symmetrically about the central axis of the frame span. At the ends of the building with overhead cranes, the crane tracks rest on beams or directly on the racks of the supporting half-timbered frame.

As enclosing structures, as a rule, panels with profiled sheet sheathing or layered assembly structures for heated buildings and profiled sheet for unheated buildings are used.

The main load-bearing structures of UNITEC frameworks are through single- and multi-span frames made of bent-welded pipes. The step of the main supporting structures is 6 m. If necessary, with large vertical loads (snow bag, etc.), the step of the frames can be reduced.

The coupling of the structures of the outer racks of frames with the foundation is articulated, the middle racks of frames and racks of half-timbered houses are rigid.

The connection of the crossbar of the frame with the outer posts is rigid, with the middle posts - articulated.

The mark of the bottom of the supporting structure of the crossbar at the point of junction with the extreme rack of the frame ( H) is provided from 4.8 to 14.4 m.

The binding of the extreme racks to the longitudinal axes is accepted as "0" or "250" for spans of 12 - 18 m, depending on the possibility of placing an overhead crane. In craneless buildings with a span of 21-30 m, zero binding is accepted.

The length of the temperature block is not more than 96 m.

At the end of the building, a supporting end fachwerk is installed, consisting of racks and beams. The rigidity of the half-timbered system is ensured by the installation of a system of flexible connections and struts. In the case of the proposed expansion

the main bearing frame with self-supporting half-timbered racks is installed at the end of the building.

The stability and geometric immutability of the building is ensured by:

in the transverse direction - by the structures of the supporting frames;

in the longitudinal direction - a system of vertical ties and struts.

The rigidity of the coating is provided by a system of horizontal braces and spacers along the crossbar of the frame.

Coating runs are made according to the cut scheme. The spacing of the roof runs is assumed to be 1.5 or 3.0 m, depending on the load on the roof and the bearing capacity of the roofing enclosing structures. With a run spacing of 1.5 m, the crossbar lattice is made with additional posts. The sections of the coating runs are taken from rolled and bent channels.

The wall purlins are made according to the split scheme. The spacing of wall purlins is assigned from 1.2 to 3.0 m in multiples of 0.6 m in accordance with the location of windows, gates and other openings, as well as depending on the vertical and horizontal loads and bearing capacity of wall enclosing structures. Sections of wall girders are taken from rolled and bent channels, as well as from bent-welded pipes.

Horizontal and vertical connections on the frame and fachwerk - cross flexible from round steel Ø 20 and Ø 24 mm.

Spacers between frames are made of bent-welded pipes.

All factory connections are welded. Mounting connections on bushings and on ordinary and high-strength bolts.

Dimensional diagrams of buildings with overhead cranes are shown in Figure 3.2.12, structural junctions for frames - in Figures 3.2.13 and 3.2.14.

Buildings equipped with overhead cranes with a lifting capacity of 5, 10 and 16 tons can be single or double-span with a span of 12 and 18 m with a mark to the bottom of the crossbar H from 6.0 to 14.4 m.

steel arches can also have a solid or through section.

Solid arches usually have a constant cross section and are used for spans up to 60 m (Fig. 3.2.15). The sectional height of such arches ( h) is usually taken equal to 1/50 - 1/80 of the span ( L). With spans of more than 60 m, through (lattice) arches are usually used. The height of the section in this case is 1/30-1/60 of the span. Geometric schemes and types of sections of through frames are shown in fig. 3.2.16.

The most widespread are metal arches operating on a two-hinged scheme. The design of the support hinge is determined by the span of the arch and the magnitude of the acting load. Figure 3.2.17 a shows the most simple design(with the help of a tiled hinge), characteristic of a light arch of a solid section.

Rice. 3.2.10. Steel frame structures of box-section type "Orsk

Rice. 3.2.11. Schemes of end faces, arrangement of girders and vertical connections in buildings with steel frame structures of box section of the "Orsk" type

Rice. 3.2.12. Dimensional schemes of buildings using

frames UNITEC

The most complex solution, with the help of a balancing hinge, is the support units of heavy large-span arches (Fig. 3.2.17 b). Because near the support, the sections of the through arches turn into solid ones; the supporting nodes of such arches are performed similarly.

Rice. 3.2.13. Eaves and support units of the UNITEC frame

(nodes are marked in Fig. 3.2.12)

Rice. 3.2.14. Overhead track beam attachment points

and half-timbered racks to the frame crossbar

Rice. 3.2.15. Structural scheme and types of sections of solid arches

The bicycle frame is designed to hold the handlebars in front of the owner and the wheels underneath. There are many shapes, metals, colors and frame designs. It is the frame that should be the first significant factor when choosing the whole bike, both when assembling it and when choosing a finished copy in the store. After all, the frame determines the purpose that the bike will perform, the rider's landing, the essence and severity of body kits and mounts. It also provides great importance for the final weight of the bike. What difference does it make how much the bike weighs?

Aluminum Frame Bicycle

What difference does it make how much the bike weighs

There are three basic parameters that affect the weight of a bike - its stability on the road surface, handling during maneuvers and inertia. The last parameter takes into account not only the inertia itself, but also the energy that must be expended to compensate for it. No matter how strange it may sound, but when the weight of the bike drops, then all these indicators improve. The rule does not work here - the heavier, the more stable, since you often have to change the center of gravity, and inertia is more difficult to compensate.

So the weight of the entire bike is extremely important, and the frame carries most of the weight.

It can be a steel frame, aluminum or chrome-molybdenum. Sometimes there are titanium specimens. Weight depends not only on the frame, but also on all parts of the kit together, as well as on the purpose of the bike. Road versions usually weigh 8-9 kilograms, mountain ones vary - there are lightweight options with a weight of 9 kg, average adult devices weigh up to 11 kg, and downhill specimens can reach an average weight of 20 kg.

Separate sports bikes they are expensive and weigh a strictly verified amount of kg, but they vary too much depending on the manufacturer and purpose, so it makes no sense to indicate their average weight. The cheapest hodgepodge bikes from Auchan and other large hypermarkets cost little, but their equipment is usually heavy, unreliable and inharmonious. It will be inconvenient, hard to ride on this, and it will quickly become unusable, and, as a rule, they cannot be repaired.

steel frame

Both a steel frame and a frame made of various alloys with steel have approximately the same weight. In order for the frame to be as strong as possible, chromium or molybdenum is added to the alloy. This additive also allows you to make unusual frame designs - thinner in the middle and thicker towards the edges. This makes the frame lighter and more comfortable, and interesting appearance attracts attention especially in combination with the original color scheme. Compared with aluminum pipes for the frame, these are thinner and more elastic.

When using a steel frame, there is no need to install a carbon fork or frame on the bike. After all, the more flexible the frame is, the longer it will serve its owner. For a touring bike this would be the best option, as they are inexpensive, but at the same time they lend themselves perfectly to minor repairs. The problem with a steel bike is that it rusts easily and is heavier than an aluminum frame. The advantages of this frame made of such material include:

• Excellent inertia - after the owner stopped pedaling, the bike for a long time maintains excellent speed;
• Soft steel frame - steel softens shock and vibration, combined with a carbon fork, makes cycling a pleasure;
• Bend - often a steel frame bends at unusual angles, which helps a lot when cornering;
• Durability and excellent material repair ability - every second welder can help.

But such a frame also has a small number of disadvantages, including increased weight - in the lightest versions, such a frame will weigh 1 - 1.5 kg more than other options.

Sharp acceleration on such a frame will also not work.

aluminum frame

Now most bikes are made with an aluminum frame. Such specimens are lighter, more responsive to road irregularities, inexpensive both to repair and to buy, and they are not subject to corrosion. The rigidity and weight of such a frame will be better than that of steel, but the metal itself will have a lower density. The aluminum frame is light and rigid, although the diameter itself is larger at the pipe. If compared with steel, then increasing the diameter of the pipes of such a frame will lead to a more rigid version, but at the same time it is an order of magnitude lighter.

There will be practically no change in stiffness, but if it is felt, then you can put carbon forks on the bike that will soften the road.

Broken aluminum frame

To the benefits aluminum frame can be attributed:

• The best possible ratio between weight and cost of the final result. The lowest grade frame does not weigh more than 2 kg, while the good quality frame weighs no more than 1.5 kg;
• Sharp and good acceleration on any terrain;
• Aluminum does not corrode metal;
• It is the best option for heavier cyclists.

The disadvantages of this frame are in direct contrast to the advantages of a steel frame.

1. A frame made of such material not only accelerates quickly, but also quickly loses all its inertia.
2. It is rigid - aluminum cannot dampen vibrations when riding. In combination with a rigid fork, skating can turn into torment.
3. People with a small weight will have difficulty riding it.
4. Such a frame will not last more than 10 years, as it accumulates its fatigue and simply bursts at the most inopportune moment.
5. Not every breakdown of such a frame is also subject to repair.

Fragment of a metal frame welded from two corners

Very often, during the construction of residential buildings, situations arise when it is necessary to close up an opening in the wall of a building or use a metal frame for the opening. The frame, in turn, serves as the basis for fastening doors, hatches, louvered grilles to it, filling various profiles such as round timber, square, or simply the opening is “sewn up” with solid sheet metal. One way or another, the metal frame for the opening plays an important role in the construction of buildings. Therefore, it makes sense to talk about it separately from the point of view:

• Rolled metal for the frame.
• Frame details.
• How to weld a metal frame.

Rolled metal for the opening frame

Which profile to use to frame the opening with a frame depends on the size of the opening itself. If we have a small opening, for example, 500 x 500 mm, where the louvered grille will be inserted, a small door will be enough ∟ 45 x 45 x 5 or ∟ 50 x 50 x 5. In the case of mounting a simple metal gate in the opening, the size of the corner can be will apply 63 x 63 x6 or 70 x 70 x 7. In some cases, if these corners are not available, you can use channel N 8 - 10.

Main parts of the metal frame

As noted above, the details of the frame include a metal profile corner or channel, which are prepared taking into account the width and length of the frame. Moreover, it is very important to prepare cutouts in one of the parts for docking with other parts. In the corners, these can be 45º cutouts or special cutouts in a shelf of one of the sizes. In the channel, a shelf is also cut off on one of the parts for connection with another part so that the connected unit looks like one piece. It should be noted that steel for welding frames should be grade St 3 PS or St 3 SP, but not carbon steel.

You can learn about carving in the corners by reading my previous article about. As for how the joining of the spirit of the channels will look like, just look at the attached drawing.

Docking channels at 90 degrees

An important role is played by anchors that are welded to the frame to fix it in the opening. If the opening is any type of brickwork, then round steel anchors are welded to the frame. Usually it is round steel Ǿ 10 - 16 A II - III. If the opening is wooden, self-tapping screws of the appropriate length are used, but for this, a hole of the required diameter is pre-drilled in the frame. The diameter of the metal anchors depends on the size of the frame. If the perimeter of the structure is small and it is welded from a small angle, it will be enough to make an anchor from wire rod Ǿ 5-6 mm.

How to weld a metal frame

First of all, you need to have a flat surface for assembling the frame. The ideal option in this case would be a steel sheet with a thickness of 10 - 12 mm. You need to have a steel square with you to control the right angles of the structure and a tape measure of at least 3 meters to measure the diagonals at the inner corners of the assembled frame.

Frame welding. You can see the abutting corners with a notch at the right

If the channel is usually even, then the corner often has a certain helical shape. This is especially true for small corners, so they need to be straightened before assembling the frame. And again, it will be more convenient to do this on a metal plate, where you can not only straighten, but also check the result on a flat surface of the plate. Everyone knows how to straighten, but the only thing I want to notice is that if the straightened shelf lies on the slab, then hammer blows must be applied to the edge of the shelf, which is perpendicular to it.

To control right angles, as already noted, measure the length of the diagonals at the inner corners of the frame. It is quite clear that they should be equal. Electrodes for frame welding should be taken grade ANO - 4, and for welding anchors made of reinforced steel, electrodes DSK - 5 are used. The diameter of the electrodes depends on the thickness of the profile shelves. For a corner of 50 x 5, 4 mm will be enough, and for welding channels - 5 mm. After welding, all welding seams, after removing the scale, are cleaned with a circular grinder.

Note

All welding work must be carried out only in a dry room and in dry welding gloves!

Edited: 10/10/2019

We are starting a series of articles in which we will talk about the materials used to make bicycle frames.

The basis of any bicycle is the frame. Almost the entire bike depends on its quality, reliability and durability.

It must be understood that the characteristics of the frame depend not only on the material from which it is made, but also to a large extent on the technology of its processing, the quality of welding (connecting the frame pipes to each other), and its. All this affects the performance and ride characteristics of the entire bike.

The following materials are commonly used in the manufacture of modern bicycle frames: :

• Steel (plain, carbon, chromoly).
• (Titanium)
• , experimental and original materials (magnesium (Magnesiumc), aluminium-scandium, beryllium alloys, bamboo, etc.)

Each type of material has its pros and cons. Let's try to deal with them.

The first article will be devoted to the most common material used in the manufacture of bicycle frames - steel.

Various steel grades have been used for this for over 100 years and, in my opinion, this is not the limit. Today, despite the widespread use of other materials, steel bikes are not getting smaller. And the prospects for the use of all-bicycles with such frames not only do not worsen, but, on the contrary, become more and more optimistic. Modern steelmaking technologies make it possible to produce mariso with ever more improved characteristics.

The steel used to make frames is usually of three types:

• Ordinary steel (steel)
• High drawn or carbon steel (High Ten)
• Chromomolybdenum alloys (Cro-Moly, chromoly)

Ordinary steel (steel)

This is the lowest type of steel used in the manufacture of frames for the cheapest bicycles. They rust quickly, are very fragile and heavy. We will not dwell on them. If you hear the saying that "this bike is made of water pipes" - this is just about them. The Chinese paint such bikes in bright colors, but this does not improve their other characteristics at all.

Bicycle frames made of carbon (high-drawn) steel (High Ten)

Frames made of these steels have very good strength characteristics and are resistant to rust. Thanks to the flexibility of steel, such frames behave well on the road, damping its bumps. Taking into account the fact that the roads in our country have not been the smoothest in the world for many years and no improvements are expected in the near future, these frames will be in demand for a long time to come.

On bicycles made from them, you can safely jump from curbs and higher obstacles. They normally withstand and in general, the load on the bike of about 150 kg is maintained by them quite calmly.

Bicycle frames made of chromoly steel (Cro-Moly, cromoly)

Chrome molybdenum steel (chromoly) is obtained by adding molybdenum during its cooking. Molybdenum gives steel a fine-grained structure, increases its strength characteristics and increases hardenability. Most often, for the production of seamless pipes, from which bicycle frames are made, alloyed structural chromium-molybdenum steel 30XMA according to GOST 4543 or steel 4130 according to the American classification is used.

These steel grades are lighter, stronger and more reliable than the carbon steels described above. However, their price is much higher than carbon ones. A high quality chromoly frame will start at $400 (and that's just the frame!). So there is no need to talk about the availability of bicycles with such frames for ordinary citizens in our country.

These steel grades are much less susceptible to corrosion than the previous ones.

The problem with these frames is that finding good chromoly steel is not easy. Often these are cheaper steel grades. According to information on the Internet, real professional chrome-molybdenum steel frames are made only by Marin (well, maybe one or two more elite brands).

Properties of steel bicycle frames

Often in physical and online stores, sellers say that steel bicycles are “already the last century,” that no one rides them now. This is far from true. The modern development of technology and metallurgy makes it possible to produce steels with much better properties than in the last century. They are stronger, so that even thinner-walled tubes can easily withstand the static and dynamic loads that come with riding, with less weight.

Advantages of steel frames:

Disadvantages of a steel frame

• More weight compared to frames made from other materials we are considering.
• Corrosive - can rust. However, under normal use, if the bike is properly painted and not scratched, does not hibernate on the street and in the rain, is regularly washed and lubricated, it will last for decades.

I would like to dwell a little on the issue of weight, which is almost always brought up by opponents of steel frames.

Often this is the argument that modern marketers and sellers are pushing, calling for lighter aluminum, carbon or titanium bikes, however, forgetting to mention their price and some other shortcomings. But weight is an important, although not the most important, characteristic of a frame, especially for a regular, not a racing bike.

Its most important characteristics are strength, rigidity and reliability. The average cyclist does not participate in speed races, he uses the bike either for the pleasure of cycling or for work.

Small note: We use two terms stiffness and strength. Sometimes the question arises - what is the difference between rigidity and strength? We explain:

Rigidity is the ability of a material not to change shape under load. The lower the stiffness, the greater the flexibility, springiness and cushioning properties of the material.

Strength- this is the ability of the material not to collapse under the influence of a load on it.

In addition, often to reduce weight, steel frames are made from butted pipes (butted pipes are pipes with a variable wall thickness) or pipes with a variable or special profile that allow you to reduce the weight of the bike without compromising its strength and reliability.

Butting can be double or triple. Those. the wall thickness of the pipe can be changed two or three times. At the same time, in places of greatest loads, for example, in places of welding, the wall is thicker than in places with less loads.

About pipes with a non-round profile. As can be seen in the above photograph, near the city women's bike Formula Breeze 2016, sold in, the upper frame has a triangular shape, and the lower frame is oval, elongated in a vertical plane. Such a profile makes the whole structure more durable than if it were made of ordinary round pipes. Yes, to be honest, and the view is getting prettier.

Another very good quality of this material is that it is quite cheap and the average consumer in our country can afford to buy bicycles made on the basis of such frames. Not everyone can buy a bicycle for the price of a used car. Especially in our country.

A lot of children's and teenage bicycle models are made on the basis of steel frames. Precisely because they are reliable and cheap, they are not afraid of falls and careless attitude. Well, as for teenage models, then remember how many of you in your childhood sedately drove around on your bikes during a walk. No. Basically it was races, jumps, falls and collisions. That is why teen bike must be strong and reliable.

And how many steel bicycles in families pass from the eldest child to the youngest, and then also to the children of friends. Such bikes are completely free to serve for more than 10 years, or even more.

Remember the old Soviet bicycles? After all, they can still be found on our roads and often this is what speaks of the quality of the material from which they are made. And at that time they were made only of steel. And the fact that it weighs more than aluminum does not matter to most of our cyclists - they ride it for themselves, and do not set records on the cycle track.

As a conclusion, I would like to say the following: marketing rules the world, and we need to use common sense.

If you need a bike not for racing on the track, but for ordinary life needs: reliable, durable and, most importantly, not very expensive, then a model with a steel frame is a good choice.

Just remember that a bicycle consists not only of a frame, but also of other parts, and the comfort and safety of your trips also depend on their quality.

In the next article, we will look at how they affect the behavior of the bike.