C4-TECNIC Composites of carbon fiber and epoxy printed hot and pressure make the best building material known to man. The specialization of C4 is to use these materials to create complex structures, without joints, such as frames and bicycle forks. Since its inception in 1986, C4 has developed a special composite molding system, called NJC (No Joint Construction), which allows high-performance carbon cable artefacts to be printed. The NJC system monitors the pressure of temperature and quantity of resin during the printing of the artifact, a system that C4 has been perfecting since 1986, controlling all the production process that has been taking place in its entirety since 1993 at the Airuno headquarters. The equipment needed for processing is also designed and built by C4, this allows a continuous evolution of the product and the best quality control. Since 1989, all the metal parts inserted into the frames and forks, necessary for the assembly of the bicycle, are glued directly in print making this type of junction absolutely indestructible. The combination of the orientation of the fibers in the frames and bicycle forks makes these structures particularly rigid and elastic, with low energy dispersion. Perhaps not everyone knows that the racing bike is the mechanical means that, driven by human force alone, produces the highest speed. Necessarily, different bikes have different returns, resulting in different speeds. Technologies, materials, measurements and construction quality affect the performance of the bike. The rider applies his energy through traction on the handlebars, the support on the saddle and the push on the pedals. The bicycle "machine" transforms this energy into the movement of rotation of the rear wheel that, thanks to the friction of the rubber with the ground, allows movement and consequently, speed. From physics texts we know that friction is always less than one, which means that the rear tyre is always slipping, a little, but sledging. Since the application of energy by the cyclist is not constant, but the applied force has maximum and minimum points due to the mechanism of the cranves, during the pedaling there are continuous variations of stress between a maximum and a minimum to the rear tyre. With the power at the maximum value, you will have the maximum of the slip of the rear wheel, corresponding to a minimum yield. That is, we struggle, the legs turn fast but the street bike makes little of it. If at this point we are pedaling on a C4, our chassis will automatically remedy the problem thanks to its extraordinary elasticity. It is built to work like a large rigid spring, deforms elastically at times of maximum energy application reducing the force (torque) applied to the rear tyre, decreasing the slip on the ground and increasing the performance of the bike.   The energy accumulation made by the frame during the maximum thrust phase, is rendered by the same in the phases of minimal thrust, increasing it in a pedaling phase where the rear tyre is under-stressed and can transmit more torque to the ground without significantly increasing the slip. The carbon and epoxy composite produced by C4 has a very narrow cycle of hysteria. (The hysteria of a material is the amount of energy that it absorbs to deform without being able to make it anymore). Our value of hysteria is close to zero, and this means two things: the first is that the energy absorbed by our frames during the stresses is practically rendered all in the "death" phases of the pedaling; the second gives the guarantee of an exceptional resistance to the fatigue of the material, a characteristic that the composite has always possessed. Riding on a carbon monocoque frame, printed in one piece without joints, designed and built to function like a large spring, not only guarantees a very high performance thanks to the best rear wheel drive, but also ensures unparalleled comfort. The very rigid carbon and back split is due to frames built with incorrect design concepts. A glued junction has good resistance to fatigue only if the junction is extremely rigid, with very little elastic movements between the connected elements, vice versa the cracks are almost guaranteed, to avoid the price to pay is back pain. A spring has never arrived, glued or welded, it is always in one piece. Not all of our frame is made of composites: for rear and front pointed pins we use the highest quality aluminum alloys (avional 2024). As everyone knows, lightweight alloys are basically plastic materials of reduced elastic field, with a very wide cycle of hysteria, and thanks to the very small dimensions of the details made with these materials, they fail to spoil the elasticity of our frames. Carbon, while costing 20 times more than the aluminum alloys we bought, is bad enough to be punctured, threaded and mechanically tightened by bolts. Therefore, metal inserts are necessary for the assembly of the bicycle. Without them and without paint our CLASS frame would weigh about 700 grams. Not bad, is it? But, you wonder, is it rigid? It is rigid the maximum that the current wheels and tires can stand to better convey the power on the ground (always concepts expressed in the 90s) The " the stiffer the better ", it is a huge technical error.   The rigid frame beyond the resistance of the wheels will make it slide a lot with a very low performance of the bike. The purpose of a good frame is to make the bike go strong, not to be the stiffest on the test bench. The rigidity of our frames is not afraid of comparisons with the best competition. From the point of view of kinematics, the bicycle is a fairly simple object, two wheels, one tractor, the other directional, without suspension. There are therefore no changes in trim during the motion. To achieve maximum smoothness in the curve, the steering geometry must be neutral, oversteer, or understeer. This is to prevent the reduced ground contact area of the front tyre (a small ellipse) from acting a side component of force that creates unwanted friction, making the bike unepens, while significantly reducing the road's handling of corners. Falling into corners, maybe downhill, is certainly not a good experience. The pedaling, alternating and with the position of application of the lateral force with respect to the axis of the vehicle, creates a force component that pushes the sideways of the bike. The right foot, pushing, moves the bike to the left, the left pushes it to the right. The rider, to proceed straight in the straight, compensates for this displacement with an appropriate small steering from the opposite side, obtained by slightly tilting the bike (due to the steering geometry, the steering always corresponds to a tilt of the bike proportional to the speed). If the frame and fork make a bike understeer or oversteer, we will always travel with extra friction, a small brake always pulled, even in the straight. For these reasons the first thing we design, designing a new frame, is the absolutely neutral steering geometry, for performance, this is as important as the monocoque construction in a piece or the goodness of the molding technology. The position of the cyclist on the bike is given by the respective reciprocal position of pedals, saddle and handlebars. Fix these positions and given to the appropriate resistance and elasticity structure, what lies in the middle is just a personal interpretation of what Marco Bonfanti, designer of all frames produced by C4, calls "traditional aesthetic rule ", which imposes a soaring seat box, a bar attachment of proportionate length (?) to the size of the chassis, and a "centering" of the position of the saddle relative to the saddle. Given that the rider has varying positions of use of the bicycle (full support on the saddle, advanced on the saddle, standing on the pedals) and the saddles have such shapes that they vary, rightly, by more than two centimeters the seating point, between model and model, to allow everyone the correct adaptability, it is deduced that the frame with perfect measures does not exist. Apart from whether or not the "traditional aesthetic rule" is responsive, which is technical to influence performance, the measurements of the frames are a consequence of the relative positions of saddle, handlebars and pedals, these are our real measures to be respected. Cycling is not a natural movement, it is a habit that we hire to use an artificial object, the bicycle. The measurements of the frame do not give as a result the bespoke bike. The choice of an appropriate saddle and handlebar model, a professional assembly, done by adjusting their positions to each other, is the only solution to the problem of the bike position, which is necessary even when mounting a custom frame, proving that what solves the problem is the mounting adjustment of the bike, not the measurements of the frame. The chain is asymmetrical on the bike. Its maximum voltage exceeds 1000 kg. As a result of these 1000 kg, asymmetrical, the frame twists, misaligning the rear wheel; fine of smoothness. You can't pretend that 1000 kg. effort do not exist. C4 has always designed and built its frames with thicknesses and direction of asymmetric fibers, to compensate for this deformation. How much and where they are asymmetrical is a little secret of C4. We advise you not to follow the fashion of using a frame smaller than what you need. Your saddle, handlebar and pedal measurements have not changed, with a smaller chassis you will apply your efforts with longer levers (canto saddle and handlebar attachment). Mathematics doesn't give way. Even if you have a stiffer frame, because it's smaller, you'll get a less stiff bike. One cannot believe that an inverted pyramid, resting on the tip, would be more stable than resting on the base. The frame is the base of the bike. A wider base increases the moment of inertia of the bike structure, the function of the frame is to support the wheels, the more the support is stable (greater moment of inertia of the structure) the less the wheels misalign during the pedaling, on equal energy applied we will get more speed.  Back to Log: C4