Bicycle steel or aluminum, which is better? Bicycles with an aluminum frame: advantages and disadvantages. Folding bikes. Disadvantages of an aluminum frame

A 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 available. It is the frame that should be the first significant factor when choosing the entire bicycle, both when assembling it and when choosing a finished copy in the store. After all, the frame determines the purpose that the bicycle will serve, the rider’s position, the essence and weight of body kits and fastenings. This also has a big impact on the final weight of the bike. What difference does it make what weight the bike is?

Bicycle with aluminum frame

Does it matter how much a bike weighs?

There are three basic parameters that affect the weight of a bicycle - its stability on the road surface, controllability during maneuvers and inertia. The last parameter takes into account not only the inertia itself, but also the energy that needs to be expended to compensate for it. As strange as it may sound, when the weight of the bike drops, all these indicators improve. The rule does not work here - the heavier, the more stable, since you have to often change the center of gravity, and it is more difficult to compensate for inertia.

So the weight of the entire bike is an extremely important parameter, and its frame bears most of the weight.

She may be steel frame, aluminum or chrome-molybdenum. Sometimes titanium specimens are found. Weight depends not only on the frame, but also on all parts of the kit together, as well as on the purpose of the bicycle. 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 specimens for downhill can reach an average weight of 20 kg.

Individual sports bikes are expensive and weigh a strictly defined number of kg, but they vary too much depending on the manufacturer and purpose, so it is pointless to indicate their average weight. The cheapest solyanka bicycles from Auchan and other large hypermarkets cost little, but their equipment is usually heavy, unreliable and inharmonious. It will be inconvenient, difficult to ride, and it will quickly become unusable, and they, as a rule, cannot be repaired.

Steel frame

Both a steel frame and a frame made of various alloys containing steel have approximately the same weight. To make the frame as strong as possible, chromium or molybdenum is added to the alloy. This addition 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 an original color scheme. Compared to aluminum frame tubes, these are thinner and more flexible.

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 touring bike this would be the best option, since they are inexpensive, but at the same time they lend themselves well to minor repairs. The problem with a steel bike is that it can easily corrode and is heavier than an aluminum frame. The advantages of this frame made of this material include:

• Excellent inertia - after the owner has stopped pedaling, the bike for a long time maintains excellent speed;
• Soft steel frame - steel softens shock and vibration, in combination with a carbon fork, it turns cycling into pure pleasure;
• Bending - often a steel frame bends at unusual angles, which is great for cornering;
• Durability and excellent ability to repair the material - 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

Nowadays, bicycles with an aluminum frame are most often made. Such specimens are lighter, more responsive to road irregularities, inexpensive both to repair and to purchase, and they are not susceptible to corrosion. The rigidity and weight of such a frame will be better than that of a steel frame, but the metal itself will have a lower density. The aluminum frame is light and rigid, although the diameter itself is larger for the pipe. When compared with steel, an increase in the diameter of the pipes of such a frame will lead to a more rigid option, but at the same time it is an order of magnitude lighter.

There will be practically no change in stiffness, but if this is felt, then you can put carbon forks on the bike, which 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 weighs no more than 2 kg, and good quality- no more than 1.5 kg;
• Sharp and good acceleration on any terrain;
• Aluminum is not subject to metal corrosion;
• It is the best option for heavy cyclists.

The disadvantages of this frame are exactly the opposite of 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, riding can turn into torture.
3. People with low weight will have difficulty riding it.
4. Such a frame will not last more than 10 years, as it accumulates its fatigue and will simply burst at the most inopportune moment.
5. Also, not every breakdown of such a frame can be repaired.

Bicycles with an aluminum frame are among the most common on the market today. This is due to the lightness of the material combined with low cost. If steel has a specific gravity of 7.8 grams per cubic centimeter, then for aluminum this figure is about 2.7 grams. In terms of thicker walls, this material also outperforms iron, since the minimum parameter is 0.8 mm, and the product will weigh less than a steel frame with a thickness of 0.4 mm. Reliability is further enhanced by the absence of welded seams. In addition, they can be performed in various configurations. Let's consider their features, advantages and disadvantages.

Description

Due to their low weight, bicycles with an aluminum frame pick up speed faster and are easier to climb. This is also why the bike stops faster after the rider stops pedaling. Aluminum is not used in its pure form; this material means an alloy of it with zinc, manganese, nickel, copper or magnesium.

It is more difficult to take sharp turns on such bicycles, since they are stiffer than their steel counterparts and cannot bend as well. Due to the rigidity of the frame, the energy from the cyclist's efforts is transferred to the wheels with less loss. Such subtleties play a role for professionals; for amateurs this is not a critical indicator. A harsher and less comfortable ride becomes noticeable. Bicycles with an aluminum frame practically do not absorb vibrations transmitted to the saddle and handlebars on uneven surfaces and bumps. A bike like this requires good shock absorption and a comfortable saddle. This will allow some of the impacts to be leveled out, which will have a beneficial effect on movement.

pros

Let's start with the advantages of the product in question. These include:

• Low weight, allowing for improved speed characteristics and acceleration.
• Maximum resistance to corrosive processes.
• High driving characteristics even when driving uphill.

Minuses

Bicycles with an aluminum frame have a number of disadvantages, namely:

• High rigidity, which is especially noticeable on models without a suspension fork.
• Rapid loss of momentum. Due to its light weight, the bike stops faster than its steel-frame counterpart once the rider stops pedaling.
• Small working life during active use. After just a few years, cracks may appear. Manufacturers provide a warranty of 5 to 10 years, but after this period it is recommended to lubricate the part to check for possible deformations.
• If dropped, an aluminum frame is more likely to cause dents.
• Poor maintainability. It is very problematic to weld such a part; it is better to purchase a new one.
• Quite a high price.

Folding bicycles with aluminum frame

Below we list several popular brands of this type and give their brief characteristics:

1. The expensive city bike Strida SX has an original exterior. It folds down to the size of a compact cart that can be transported under its own power. The steering wheel can also be transformed. The advantages of the bicycle include the fact that the cables and wires are hidden in the cavity of the frame, it is easy to assemble, there is a trunk, and disc brakes. With good maneuverability, the device weighs only 11.6 kg. Among the disadvantages are small carrying capacity, narrow wheels, poor shock absorption.
2. Smart 20. A stylish city bike, considered one of the best in its price category. Can be used by women without problems. Among the advantages are a durable frame, a convenient transformation mechanism, the presence of reflectors and other accessories. Disadvantages include the lack of a handbrake and the quality of the wing alignment.
3. Bicycle "Stealth". The aluminum frame of the Pilot-710 model does not interfere with the smooth ride. The vehicle picks up speed well when coasting, has a discreet design, when folded it fits into the luggage compartment of any car, and is equipped as standard with a luggage rack and chain protection. Disadvantages include a wide handlebar and an awkward seating position for tall people. The intended purpose of the modification is city travel.

Children's bicycles with aluminum frame

Below is short description some children's and teenage models:

• Mars. This one is for children over 3 years old. The kit includes additional polyurethane wheels. The frame and fork are made of aluminum alloy, and there is a handlebar height adjuster. Wheel diameter is 12 inches, model weight is 4.5 kg.
• Forward Timba‏. One of the best for children 6-9 years old. It has a beautiful design, affordable price, chain protection and removable safety wheels. The disadvantages include a decent weight (almost 14 kg), as well as the need to adjust some moving parts.
• Shulz Max. These children's bicycles with an aluminum frame fall into the mid-price category. The bike weighs 14.3 kg. It is aimed at teenagers 12-16 years old and has a load capacity of up to 110 kg. The advantages of the model are ease of assembly/disassembly, good speed, equipped with 20-inch wheels and quality. Among the disadvantages are incorrect factory adjustments and brake pads of dubious quality.

Peculiarities

When choosing a bike, the question often arises of whether to choose an aluminum or steel bicycle frame. The final decision depends on the financial capabilities of the buyer, the purpose of the machine and the subjective requirements of the user. It is worth noting that in the manufacture of aluminum structures, thick-walled pipes of large diameter are used.

This is due to the fact that, according to the laws of physics, if the size of a pipe is doubled, its rigidity will increase eight times, and if the wall thickness is doubled, the rigidity indicator increases by the same amount. Therefore, of the available options, increasing the diameter is preferable.

Typically, the minimum pipe wall thickness on an aluminum frame is 0.8 mm. Manufacturers often make pipes by butting or using different sections, which also makes it possible to strengthen the product.

Alloys used

There are many aluminum alloys used to make bicycle frames. The most common brands are 7005T6 and 6061T6. The T index indicates that the material has undergone heat treatment. For example, a product made of 6061 alloy is heated to 530 degrees Celsius, then actively cooled by liquid. Then, for 8 hours, the material is artificially aged at a temperature of 180 degrees. The output is 6061-T6. The analogue number 7007 is cooled by air, not water.

Below are comparative characteristics of materials before and after heat treatment (in parentheses):

• Alloy 2014 (2014T6) - tensile strength is 27 (70) thousand PSL, yield strength - 14 (60), elongation percentage - 18 (13), Brinell hardness - 45 (135).
• Similar indicators for material 6061 (6061T6) are 18 (45), 8 (40), 25 (17), 30 (95).

The first alloy uses 4.5% copper, 0.8% carbon and manganese, 0.5% magnesium. The second material includes 1% magnesium, 0.6% silicon, 0.3% copper, 0.2% chromium, about 0.7% iron.

Finally

The strongest bike is a 16” bike, the aluminum frame of which is made of alloy 70005 or 7005. However, the 6061 analogue is more technologically advanced, which makes it possible to make pipes with a complex cross-section from it, and this increases the strength of the product. In addition, such aluminum is better weldable. When choosing a frame, consider your financial capabilities and intended use of the bike. If used properly, a bike with a frame made of any material, including steel, aluminum or carbon, will last quite a long time.

Bicycle frame - the basis of any bicycle. And you should pay special attention to its choice: you will replace all other blocks and accessories as they wear out (or simply gradually buy better ones). And it will still be the same bike. And if you replace the frame, then it’s a new bike.

The frame is characterized by three main parameters:

• Material
• Type(design)
• Size (size)

Material

For your first bike, you should probably choose a frame steel or aluminum. We will talk about these - the most affordable materials - a little lower, but first, a few words about the more expensive options (and, accordingly, about why perhaps you should not overpay for them yet).

Carbon

If you are a fan of quality and are convinced that “the higher the price, the higher the quality”, and based on this, decide to choose carbon frame bike(“so that it will last forever!”), then at first glance, this will really be an excellent investment. Expensive carbon fiber is extremely light (the weight of the frame is especially important for girls). But keep in mind that at the same time it is a rather brittle material (especially in the cold), and therefore the service life of a carbon frame is less than that of an aluminum one. Cracks on such a frame can even appear from excessive tightening of the eccentric, and an unsuccessful fall can simply destroy it.

Titanium

Another rather expensive material for frames is titanium. Everyone knows that it is lightweight, corrosion resistant, durable metal. Such frames are most often used in sports bikes. Due to the fact that titanium is a somewhat “sticky” metal, frames made from it “swallow” minor road defects well.

Magnesium alloys

Recently, frames have become more often made from magnesium alloy V. These frames are lightweight (twice lighter than similar aluminum ones and six times lighter than steel ones) and absorb vibration well. In addition, they have good “fatigue” characteristics. But they are quite demanding in maintenance: they easily oxidize and break down. Therefore, even small scratches and chips of paint are dangerous. So don’t rush into buying “titaniums” with “carbons”. They will, of course, add coolness to you in the eyes of others and your own, but along with it they will also add possible problems, the grief of which can ruin your pleasure from owning a bicycle. It makes sense to install a frame of this level only when you have driven a couple of thousand kilometers, gained experience and understand what exactly you are paying money for. Now let's turn to more “budget” materials and see what their pros and cons are. Cheaper does not always mean worse!

Aluminum frames

Aluminum frames(which are 10 times cheaper than carbon and 6 times cheaper than magnesium, statistics for basic models), unlike magnesium, they have high corrosion resistance, with a fairly low weight. Aluminum has only two drawbacks: this material, compared to others, absorbs vibration somewhat worse, so on uneven areas you will shake more (of course, if there are no shock absorbers), and aluminum frames gradually accumulate fatigue and collapse suddenly. This can be especially unpleasant on a long hike: damaged aluminum frame(unlike steel) not every village will help you weld. However, it is important to note that manufacturers, knowing about this feature of aluminum, provide a greater margin of safety when designing: they use pipes of a larger cross-section, pipes with variable wall thickness, etc.

Steel frames

And finally, there are steel frames. This is the heaviest option, which, we repeat, does not mean “the worst” - such frames are used to solve their problems. Note: steel can be worse and good - the cheapest bicycles are made from low quality steel, which means more weight and poor corrosion resistance. If the material is good chrome-molybdenum steel (which, of course, costs more), then you will get a rigid frame with good “fatigue” characteristics. It won't fall apart unexpectedly. Over the years of use, microcracks will first appear, which will make themselves felt by creaking and some decrease in rigidity. You will hear a creak and feel a decrease in rigidity. Steel frames will last much longer than aluminum frames. For long hikes on difficult trails, it makes sense to take a more expensive steel frame rather than an aluminum frame. Metal is metal, but sometimes it bursts. You can weld steel almost anywhere.

Frame design

Classic bicycle frame has a diamond shape. Almost all bicycles have this design, except for city ones ( city ​​bikes, road bikes ). This is the most severe option, the so-called female (“open”) frames. They are considered to be less durable.

Of the frames found today, we can also mention folding− they are all made on the basis of open ones. All folding bicycles are recreational bicycles and cannot be used for sports or tourism.

Of course, there are also tandems and various kinds of experimental models (such, for example, where the cyclist lies), but in this article we will not touch on them.

Classic diamond-shaped frames come in four types of bicycles:

• Without shock absorbers
• With front shock absorber− hardtail (from English “hard tail”)
• With front shock absorber and rear wheel suspension− soft tail (“soft tail”)
• With front and rear shock absorber(double suspension)

We will talk about shock absorbers in more detail in another article, because the so-called “auchanbike” is, of course, a hardtail type, but, on the other hand, it is better without shock absorbers at all than with such. The main thing you need to know is that if you drive on difficult trails, then, of course, you need a front shock absorber. And if you need a bike for hiking, then a dual-suspension bike is not the best for you. the best option: They don’t make any good racks for frames of this type, you can only use those that are attached to the seatpost, but they are not very load-bearing. Of course, some people walk hundreds of cycling kilometers with a backpack on their shoulders, but the author of the article is categorically against such tourism.

Frame size

This section does not apply to those who choose a stunt bike. But everyone else needs to read it carefully. From frame geometry depends to a large extent on your landing: on a racing (road) it will be more recumbent than on a mountain bike. And on the mountain it is more recumbent than on the road. But in any case, you should adhere to an important principle: the frame must fit. On a bicycle with a frame that is too small, your knees (and they always have it the worst) and elbows will be uncomfortable, although maneuverability and controllability will increase. But if the frame is too large, then it will be more difficult for you to get on such a bicycle, and the risk of injury will increase (especially on classic diamond-shaped closed frames, especially for men).

In the cycling world there is a very high degree of standardization of sizes and compatibility of different components, but with the definition frame sizes there is no consensus. For example, frame size road bikes traditionally indicated in centimeters, while others use inches. Some manufacturers make frames with odd sizes (17, 19, 21, etc. inches), while others, on the contrary, with even ones. But the most interesting thing is that each company has its own principles of where to start and where to end the measurement.

How to choose a bike according to your height We recommend you when choosing sizes not only focus on the sign below, but also do the following. Saddle the bike, but don’t sit in the saddle yet, stand with both feet on the ground, with a fist between the top crossbar of the frame and your groin. Now sit on the bike (with the saddle extended so that your fully extended leg is on the pedal in its lowest position). And ride it - if you don’t feel any acute discomfort, then everything is fine. Of course, when you get on a bike for the first time and ride around the store for two minutes, it is very difficult to understand whether it will be comfortable for you to clock up kilometer after kilometer in this position. Therefore, the main advice: before you go shopping, find the opportunity to try several different bicycles (rent or from friends). Take a short walk on each one. Then you will have an idea of ​​what sensations to pay attention to, in what position your body will be more comfortable: everything is individual, some people like a more horizontal, “lying” position, while for others, their shoulders or neck get tired in this position. This is why he will prefer a frame that allows him to sit more upright.

Mountain bike frame sizes

You can make more “fine” adjustments to the position of your body on the bike later by adjusting or replacing the handlebar stem, extending or retracting the seat.

The frame is the main and most important part of the bicycle.

The question of which frame material is better has remained open for many years now, since the approach to choosing a material is a purely individual one.

The main materials today are chrome-molybdenum steel and aluminum alloys.

1. Steel is the first material from which bicycle frames were made. Recently, there has been a trend towards the revival of steel frames, this is caused by the emergence of new technologies that make it possible to make a material that would satisfy the high demands of modern cycling.

Steel is generally attractive due to its reliability, ease of processing and repair, and relative cheapness. Steel dampens vibrations well. This material has a fairly long service life and does not have the ability to accumulate “fatigue”. If the frame begins to age, it warns about this - cracks and rust appear.

Several types of steel are known:

• - Hi-Ten (Hi Tensile) - “improved quality structural steel”, this is the cheapest material. Frames made of this steel are quite heavy and do not have good rolling.
• - Cro-Mo (cromomolybden) - chromium-molybdenum alloys. Frames made of this material are lighter than those made of Hi-Ten, more rigid, but also more expensive.

The advantages of a chrome-molybdenum frame also include its ability to bend on turns and thereby facilitate control, significantly dampen small vibrations and even soften impacts a little. In addition, they are slightly susceptible to corrosion. Such frames are almost never used in cross-country bikes high level, but popular among tourists, marathon runners and winter skiers.

Higher class frames are made with variable pipe thickness (butting). Triple butted frames are strong and lightweight at the same time.

2. Alu (Aluminum) - aluminum alloys. This material allows for an even stiffer and in many cases lighter frame than Cro-Mo. There are a number of aluminum alloys and methods for processing them (7000, 7005, 7005T6, 7009T6, 7010T6, 6061, 6061T6, 6065, etc.). Magnesium is added to alloys of the 6000 series, and zinc is added to the 7000 series. The most common (due to price) is 7005. The lower the aluminum alloy number, the more expensive it is, and the better its quality. More advanced companies use alloy 6061.

An aluminum frame corrodes significantly less in an aggressive environment than a chrome-molybdenum frame, and even more so than a steel one.

It is easier to accelerate on aluminum frames, it is better to climb hills, they allow you to feel the road well, however, compared to chrome-molybdenum frames, aluminum ones have less rolling. The frame stops rolling as soon as you stop pedaling. Turning is more difficult than on a chrome-molybdenum frame, but the turn itself is faster.

Aluminum frames do not have the ability to dampen vibrations. The lifespan of these frames is usually shorter (about 10 years). Aluminum frames accumulate fatigue and (after 10-15 years) can collapse suddenly. However, many manufacturers now offer lifetime warranties on aluminum alloy frames. This suggests that improving technologies make it possible to increase the service life of the material.

Aluminum frames can also be butted.

One of rare species aluminum alloys - scandium. Scandium is similar to titanium in weight and flexibility, but has very high surface strength. Scandium frames must be manufactured very carefully, since the frame cannot be straightened (cold leveled) after welding.

The latest achievement in aluminum frame construction is hydroformed pipes. This technology avoids seams in the frame structure, which significantly increases the reliability of the frames.

On Russian market from quality foreign manufacturers aluminum bicycles represented: USA - GT, TREK, MARIN, SCOTT; Germany - WHEELER, Taiwan - GIANT.

In general, an aluminum frame today is the best option when it comes to the ratio of quality, performance properties and price.

3. Magnesium is perhaps the rarest material for bicycle frames.

• Low weight
• Good roll
• Excellent rigidity.

• High price
• Very low resource (up to 2-3 years).
• Subject to severe corrosion.

4. Carbon (carbon fiber). These are ultra-light frames, but extremely unstable to shock loads. These are frames for professional use.

5. Ti (Titanium) - Titanium. This material, like carbon, came to the bicycle industry from the aerospace field. Titanium combines the advantages of aluminum and steel - hardness and lightness. Resistant to corrosion. Excellent vibration dampening and long service life.

Titanium alloys are difficult to machine and require complex welding techniques. This explains such a high price for titanium alloys.

Frames made of this material are for professionals.

The WHEELER company is well known on the Russian market; they offer bicycles made of titanium alloys.

Summary: the choice of a bicycle frame is individual and depends on the preferences of the cyclist and riding style. For beginner cycling enthusiasts, we recommend choosing something made from aluminum or chrome-molybdenum alloys. Any other materials (Carbon, Titanium, Magnesium) are not for a beginner.

Edited: 02/02/2017

We continue our series of articles about various materials used in the production of bicycle frames. In the last article we talked about bicycles based on steel frames.

In the modern world, the following materials are used to make bicycle frames:

• (regular, carbon, chrome-molybdenum).
• Aluminum alloys ( Alloy)
• (Titanium)
• (carbon fiber)
• Various rare, experimental and materials (magnesium (Magnesiumc), aluminum-scandium, beryllium alloys, bamboo, etc.)

In this article we will look at the properties of a frame made of aluminum alloys.

The term aluminum frame itself is not entirely correct. Aluminum in its pure form is not used - it is too soft. This term refers to alloys with other metals: zinc, copper, magnesium, manganese, etc.

One of the big advantages of aluminum frames is their light weight. That is why bicycles with such frames pick up speed faster and are easier to climb uphill on. However, this also has a negative effect in the form of loss of momentum, i.e. When the cyclist stops pedaling, the bike stops faster.

Advantages of aluminum bicycle frame:

• Less weight, compared to steel frames, and as a result of this, good acceleration characteristics.
• Almost absolute corrosion resistance- such frames do not rust from the word “generally”.
• High speed characteristics: It’s easier to pick up speed and go uphill.

Disadvantages of a bicycle frame made of aluminum alloys:

• Rigidity. The aluminum frame practically does not dampen vibration, and all road irregularities are transmitted to the hands and through the fifth point to the spine, especially if the fork is also rigid and not shock-absorbing.
• Rapid loss of momentum. Due to its lighter weight, once the biker stops pedaling, the bike quickly loses its speed, unlike a steel frame bike.
• Fragility. If a bicycle is used actively, then after a few years the likelihood of getting a crack increases sharply. And after 10 years of regular riding, it is recommended to regularly inspect the bike before riding for their presence. Manufacturers most often provide guarantees for frames made of aluminum alloys within 5-10 years.
• More sensitive to shocks and falls than steel and titanium frames. After all, aluminum is softer than steel and a blow that steel won’t even notice can leave a dent on aluminum.
• Non-repairability. It’s too difficult to weld an aluminum frame, and it won’t really increase confidence in its strength - it’s safer to buy yourself a new one.
• High price.

Types of aluminum alloys used in the manufacture of bicycle frames.

Let's dwell a little on the types of aluminum alloys used to make bicycle frames.

There are quite a lot of grades of aluminum alloys (2014, 7000, 7005T6, 7009T6, 7010T6, 6061T6, 6065, etc.), but the grades 7005T6 and 6061T6 (analogue of the domestic alloy AD33 according to GOST 4784-97) are most often used in bicycle construction.

They are also called alloys of the six- or seven-thousandth series.

The use of the letters “T6” in the name indicates that the material has undergone heat treatment.

For example, when heat treating alloy 6061, a product made from it is heated to 530 °C, then intensively cooled with water. Then it is artificially aged for 8 hours at a temperature of about 180 °C. After this treatment, alloy 6061 is already designated 6061-T6.

During heat treatment, alloy 7005 is cooled not with water, but with air.

For example, the table below shows the composition of metals in alloys and how their physical characteristics change after heat treatment.

In the table:

Tensile strength- this is the load, when exceeded, the product is destroyed.