The pipes for carbon bikes manufactured in Italy reach a superior quality for resistance, elasticity, traction and withstanding the breaking load.
The carbon fibres
The external lamination does not give the quality of a carbon frame. This is expressed in “K”, which represents the fibres’ intertwining. But most important is the direction given to this intertwining of fibres inside the pipes, and by alternating unidirectional fibres overlapping at 90 ° with the fibres intertwining of 45 °. The arrangement of the fibres is called lay-up and is essential for the strength of the frame at all layers, especially the innermost ones and not visible to the naked eye. But also to the intermediate layers: the carbon tubing for bicycles, in fact, usually has 6 to 10 layers. The innermost and hidden parts give strength and the desired mechanical characteristics.
The fibres used are all carbon-based pre-impregnated with resin. The carbon called Very High Modulus – Very High Resistance achieves the best mechanical capabilities. Daccordi processing implements carbon with special resins and Kevlar to increase elasticity, break load, resist material fatigue, and avoid the classic “glass effect” break. “The glass effect” is the sudden and unannounced breaking of the fibres of the material. This situation may be due to previous impacts that have affected the innermost carbohydrate fibres. The craftsmanship through stratification allows positioning the best layers of carbon fibres and kevlar most properly according to the stress of the specific part of the frame. In this – giving a touch of elasticity to the fibres – any breakage occurs with a minimum notice margin.
The stratification process
Layering is a process that occurs after glueing. In practice, glueing almost only creates the right shape, with the right angles and the right measurements, but does not offer the frame strength. Furthermore, this overlap must take place in the absolute absence of oxygen. An eventual air bubble would cause the weakening of the entire production process, with a probable breakage of the frame.
This production process is also called Mandrel Wrapping in High-Pressure Autoclave. The tensions of the heat shrink material used, which generates compaction pressure and the pressure on the autoclave male mandrel are added together. The result increases the material’s resistance by distributing the resin, slightly increasing the specific weight. This guarantees an increase in resistance for the same material section and allows the thicknesses to be reduced to the minimum value.
Mass production versus craftsmanship
The guarantee of the quality of the craft is the limited production. The stratified frames of the carbon bikes in Italy are built one by one and therefore strictly controlled. The printed frame is born inside an assembly line. There are moulded frames worked in Italy that offer high construction qualities. The limited numbers always give this value compared to the large oriental productions. But the Italian production of carbon frames is mainly given by the layered model, also for the customization possibilities. Last but not least, the possibility of using pipes from different suppliers and mixing them in a single frame in order to obtain personalized mechanical characteristics.