Back then, Tom Ritchey probably assembled the first aluminium prototype frames by hand in his legendary garage faster than it takes to build a production carbon frame today. You don't think so? But it's true.
Today, it takes around 40 hours to produce a full-suspension mountain bike carbon frame. Converted to one person, this figure means that a factory worker produces four frames a month, a full 48 frames a year - not including holidays and sick days. Simplified in this way, it quickly becomes clear why countries such as China, Indonesia and Vietnam are the main suppliers of products made from this high-tech fibre. Only with armies of labourers working for low wages does the enormous amount of time required seem economically viable. This is mainly due to the fact that the geometry and strength requirements for bikes are so complex. A simple tube can be produced automatically from carbon fibre, but different forces act on the frame of a full-suspension mountain bike everywhere and the material must be distributed according to defined rules - depending on how much stress is placed on the area.
Another factor also drives up the price: the production of carbon fibres requires an extreme amount of energy in the form of heat: At 1500 degrees Celsius, the fibres are elaborately manufactured in several stages. The production process costs a lot of electricity and also drives up the price. In a second processing stage, the fibres are turned into mats, so-called prepregs, which are still the base material for bicycle construction today. However, there are no material alternatives to carbon when it comes to maximising lightweight construction and stability. Titanium is rare, expensive and also not easy to process. Steel is far too heavy. Aluminium is more suitable, is easy to process, but has no chance in a direct comparison in terms of stiffness and weight. To find out how big the differences are, we visualised them in a graphic and combed through our BIKE test fields from the last nine years. We compared the lightest frames in our tests on the timeline. This makes the standstill visible: not much has actually happened in terms of weight over the past nine years - neither with aluminium nor with carbon. However, this analysis ignores the fact that the new lightweight frames are designed for 29-inch wheels without any significant increase in weight.
The Scott Scale, which we wrote into our books in 2010 with a frame weight of 860 grams at 26 inches, is a clear downward outlier. The current 29-inch Cube Elite is still 13 per cent heavier at 989 grams. If you compare it to aluminium, you can simply say that carbon makes a hardtail frame around 500 grams lighter. The same applies to the fully. The lightest model in both of our tests was a 26-inch Cannondale Scalpel. In 2007 the scales showed 1804 grams for the aluminium version and four years later 1372 grams for the carbon version of the Team version. Of course, frame and component manufacturers have learnt a lot over the past 20 years, components have become safer and production more efficient. But the basic problem remains: Almost all components are laid by hand from so-called prepreg mats. This process is like a very complicated jigsaw puzzle. Only when all the parts are in the correct position is the component perfect and the stability optimised. However, manual labour is always a source of errors: if a part is inserted incorrectly or in the wrong place, not fastened properly or stored at the wrong temperature for too long, there is a risk that the component will not hold. Air pockets in particular can become a problem if the work is not done properly.
This is another hidden cost driver: in order to detect errors, each individual component is weighed separately and very precisely before the frame is baked. If there is a deviation, the component is rejected. For this reason, manufacturers work with safety factors during development that allow room for deviations. If all factors are met, the frame has to be reworked at great expense to ensure that the surface meets the critical requirements of the end consumer.
These facts make it clear why carbon bikes are still so expensive. But the innovative strength of the bicycle industry has always been strong. And because the wage level at production sites in the Far East is also constantly rising, some innovative companies are working flat out on solutions for producing carbon components without a lot of manual labour - i.e. automatically. However, a complete series frame has not yet rolled off the production line anywhere, but some young companies are already producing bike components in series from newly developed carbon production facilities. These include the companies Biontec from Sankt Gallen in Switzerland and Munich Composites from Munich. But what exactly is different here?
The first big difference: it is produced directly from the fibre. Carbon fibres look and feel like extremely thin, black hair. The carbon fibres run from large spools in bundles directly into the manufacturing process. At Munich Composites, the fibres slide from numerous spools in parallel into a huge, circular braiding machine. At the centre of this machine is a core that is held and guided by a robot arm. The fibres are applied to this core in defined patterns. The core is later removed again. While the braiding machine spins an even web, the robot arm holds the core so that the fibres land in the correct position. No manual labour is required for this; the braiding machine and robot are perfectly coordinated. The textile fibre mesh does not yet have any stability; this is only provided by the resin, which bonds the fibres together and thus supports them. For this purpose, the components are placed in a metal mould and the liquid resin is injected under high pressure at a high temperature. In addition, the core, which was previously held by the robot, is inflated at high pressure and the fibres are pressed against the mould from the inside. When the mould opens, the component is as good as finished.
The development of such manufacturing processes also harbours high risks. At great technical and financial expense, the Swiss bike manufacturer BMC built its own production line in its Impec Lab in Grenchen. Braided frames were to roll off the production line on a similar basis to Munich Composites - today, the multi-million euro plant is at a standstill and it is unclear when and if it will start up again, according to BMC.
It is interesting to note that the textile industry, of all industries, is currently proving to be an accelerator for carbon development. Because fibre bundles made of carbon behave similarly to textile yarns, machines are being used to produce fabrics. Tests are now underway with all forms of textile production possibilities. At Biontec, the embroidery process has been adapted so that the blanks for several components are laid down in parallel on the huge CNC-controlled machines. The carbon fibres are placed on a carrier material in a way that is optimal for the component strength. Just like at Munich Composites, the blanks are then placed in moulds, saturated with resin and cured. At first glance, this process is only two-dimensional. However, complex 3D components can be created by skilfully placing the blanks. This has already resulted in brake levers, cranks, saddle racks and fork crowns.
Conclusion Dipl.-Ing. Stephan Ottmar:
"New production methods bring a breath of fresh air to the world of components. This makes the components safer and, once the technologies have been fully utilised, perhaps cheaper one day. But the egg of Columbus for the production of complex frame constructions has not yet been laid. We will probably have to wait a while before frames start rolling off the production line fully automatically. Nevertheless, it's always exciting to see how quickly the bike industry implements new technologies, something that hasn't changed since Tom Ritchey's pioneering days."
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On a plastic diet: aluminium has no chance against carbon
A look at the test protocols of recent years proves this: The gap between aluminium and carbon frames is huge. Here is a direct comparison of the lightest models from nine years of bike tests.
Record in 2010: Scott holds the weight record of the bikes tested with the Scale. 860 grams with a frame height of 44 cm - all respect. Why hasn't anything else followed in five years? Quite simply: from 2011, the ultra-light bikes rolled on 29-inch wheels, which required larger frames. But the weight spiral continues. It seems only a matter of time before the first 29er equals the 26-inch record set in 2010. The values of carbon fibre bikes can definitely not be achieved with aluminium. Those who prefer metal carry around 500 grams more. For the fullys, the value is even around 600 grams.
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Puzzle for advanced users
That's why carbon bikes are so expensive: a frame is assembled from 400 parts. In addition, there are expensive raw materials and complex finishing work.
The basic material is so-called prepregs - soft, sticky mats in which the carbon fibres (held in place by resin as an adhesive) lie parallel to each other. Depending on the thickness of the mat, several layers of fibres lie on top of each other, always connected by the resin. To ensure that the mats can be transported and processed, there is a protective film on both sides. Another point that complicates the process: the prepreg mats are only durable when frozen, but are too hard to process. In the heat, the material initially softens and is easy to process, but if too much time passes, it begins to harden.
1. cutting with the laser: The starting material for a bike frame is flexible fibre mats impregnated with resin. The mats are cut into pieces using a laser cutter. Important: The fibres must point in the right direction for each piece so that the strength is correct later on. To minimise material loss, the pieces are positioned with the help of computers and then sorted so that each section ends up in the right place in the component.
2. sort parts: Each snippet is glued into position by hand. As with double-sided adhesive tape, the worker first removes the protective film and then attaches the sticky section to the correct position on the frame mould. The position and fibre direction must be correct.
3. positive form: Inflatable silicone frame preforms are covered with the snippets. Alternatively, there are also processes in which the mats are placed directly into the negative mould. A fully frame including rear triangle is created from around 400 parts. If all the steps were carried out by a single worker, he would be busy for a week.
4. into the oven: Finally, the preform is placed in the oven together with the fibre mats. To ensure that the fibres are optimally positioned and a smooth surface is created, the frame preform is inflated during the baking process. The pressure presses the fibres into the negative mould made of steel. Within a short time, the resin between the fibres hardens and gives the material stability. The frame is then reworked and sent to the paint shop.
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How carbon works
A look under the paint layer shows: The properties of carbon - unlike those of metals - are direction-dependent. The plastic can transfer extreme forces in the direction of the fibre.
The fibre: Individual fibres are barely visible to the naked eye. The fibres are processed in rovings (bundles). In bike production, 1000-6000 fibres form a roving. Carbon has enormous strength - but only under certain conditions: With metal, the strength is almost the same in all directions. With a carbon component, it depends on how the fibres are arranged inside. If carbon has to be equally strong in all directions, the strength quickly falls below that of aluminium. With an optimal component design, however, carbon exceeds the values of aluminium tenfold.
The resin: The resin supports the fibres and keeps them in position. In principle, it plays a subordinate role in terms of strength, but defects in the resin layer cause the fibres to collapse.
The layers: Components are always made up of several layers. If forces act in different directions, several fibre mats must be laid on top of each other at exact angles. Joints on the frame such as the bottom bracket and head tube are very complex.
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The future will be high-tech
Manual labour leaves room for error. This is why some companies are working on automated production processes. This makes the components more reliable and therefore lighter or more stable - and perhaps also cheaper.
LichensIf you take a closer look at the production facility at Munich Composites, the picture blurs before your eyes: numerous spindles with carbon fibres whiz around in circles, circling and dancing around each other in seemingly chaotic patterns. It is only when you take a closer look that the picture becomes more organised and it becomes clear that a high-precision, high-tech machine is at work here. Individual carbon rovings (fibre bundles) are woven onto a plastic core. This creates a uniform pattern that is optimised for the loads in the component. After braiding, the component is placed in a negative mould. The mould is closed tightly and the resin is injected, which holds the fibres in position. This process is called resin transfer moulding (RTM). An SQlab handlebar is created here.
EmbroideryEmbroidery machines several metres long, anchored deep in the Swiss rock, rattle the needles in one go. However, this has nothing to do with manual labour. Like Swiss clockwork, the computer-controlled system fixes bundles of carbon fibres onto a carrier fabric. The highlight: the fibres can be laid exactly as required for the component. If, for example, a hole is to be drilled at one point, the fibres are laid in a circle so that as few carbon fibres as possible are damaged during drilling. Biontec started out with brake levers for Magura and now counts several bike manufacturers among its customers. Later, the carrier material is removed and the fibre blanks are impregnated with resin and hardened using the RTM process. This creates a good surface and the precision of the production is extremely high.
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7 answers about carbon as a material
The triumph of aluminium began in the 60s. Carbon, on the other hand, is young and there are many questions - especially for mountain bikes:
1. how is the quality of components ensured?
Because carbon components require a lot of manual labour, there are often fluctuations in production. Manufacturers measure quality by weight. Each raw part is checked individually. If the component is within the correct range, that is half the battle. Stiffness is an additional indicator. Damage such as cracks or bubbles in the material can be detected using an X-ray machine - but this is time-consuming and very expensive.
2. handling and transport
Pipe jamming is a problem, whether in the repair stand in the workshop or on the car rack. In particular, systems that put high pressure on the tube should be avoided at all costs. A simple and inexpensive way is to attach it to the seat post: simply use an old aluminium post instead of the ultralight post.
3. repair: What is possible?
As a general rule, add-on parts such as handlebars and seat posts should not be repaired - so replace them. There are now several competent repairers for broken frames. If the tube is broken on the open road, the chances of success are high. WEBCODE # 13975 For emergencies on the road, there is the practical and affordable repair kit from www.youfix.de. This can be used to splint fractures in a makeshift manner.
4. what does carbon cost?
A kilo of fibres in a quality that is used in bike frame construction costs from 25 euros. The scale is open at the top. Fibres for high-end frames sometimes cost 100 euros per kilo, but there are also much more expensive fibres. The resin is not an issue.
5. what is the life expectancy of a carbon bike?
With appropriate care, the service life is long. Only unpainted models are affected negatively by prolonged exposure to sunlight. With mountain bikes, it is more likely to be falls that reduce the service life. This is also the core of the problem why many people refuse to buy carbon components: Damage to the material is not necessarily recognisable from the outside.
6. can carbon be recycled?
Basically no. Once the carbon fibres have been brought together with the resin, this bond can no longer be released. New products can only be created from old, shredded carbon components - albeit with significantly reduced strength properties. Research is underway in which bacteria decompose the resin and expose the fibres again. Incineration remains the current method.
7. how much carbon does the bike industry use?
Compared to the aeroplane, car or wind power industry, high-end bikes probably make up a small proportion - you think? Wrong! Around 15-20 percent of global fibre production ends up in products for the sports and leisure industry. Bikes, along with surf poles and trekking poles, make up a considerable proportion of this.
Sinfully expensive and ultra-light
These components are the tip of the iceberg and show what is possible. But be careful: bring plenty of money and always read the small print.
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"Folds break the frame."
Interview with Peter Denk (mastermind at Carbon, developer at Specialized)
When did you realise that carbon was the right material for high-end bikes?
I was always sure that we could build excellent frames from carbon. But the road to success was rocky. After a brief gold-rush period, many companies put their ambitions on ice again at the end of the 1990s. Development was extremely expensive and the frames were unfortunately inferior to aluminium frames. In 1999, we then developed the Scott Strike (editor's note: Denk used to work for Scott). The frame was almost unbelievably light, stiff and stable by the standards of the time.
What were the problems?
Even back then, straight tubes were easy to manufacture. The difficulty lay in the connection points. Folds constantly crept into the carbon structure during processing and the frames broke.
The secret was to harmonise the production process and design and avoid wrinkles. We had to develop several new production processes for this. Nevertheless, the effort required for a new top product is immense: at Specialized, we build, test and destroy around 250 prototype frames before the new model is released to the customer.
Will carbon bikes one day become cheaper and also affordable for lower price categories?
Certainly not in the near future. Production requires expensive raw materials, a lot of manual labour and complex production monitoring. Only when robots take over the manual labour will things change. The first systems are already in operation for simple components. Frames are complex - that will take time.
Do aluminium frames still have a chance?
In the high-end segment, aluminium has absolutely no chance. When it comes to maximum performance, it has to be carbon fibre. However, as soon as economic aspects play a role, aluminium is the best choice. Aluminium is the perfect material in the medium and lower price segments. With clever detailed solutions, the potential can certainly be exploited even further here.
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