Single shoe C4 200 – Different Colors

C4 200 liner = ZERO FATIGUEFins with modified biomechanics, with minimal energy consumption.1) Introduction.In free diving, performance depends on the amount of energy needed to advance by finning. Even more so in freediving, the more energy the fins require to function, the more effort will be made with less performance and safety, so it's not a question of being able to put more force, it's a question of using less. In water there are no references and the biomechanical kicking movement moment by moment is based on the resistance induced by the fins. Fatigue is therefore a direct consequence of how they are conceived and how they work moment by moment. Traditional fins have blades stuck and/or glued into a pocket of the rubber shoes, so that the blade becomes an extension of the feet. It's been like this for at least 70 years. This determines some negative aspects for biomechanics, which lead to additional fatigue and reductions in performance and safety.2) Posture.When we look at a vertically ascending diver from the side, we notice that the blades of traditional fins, protruding beyond the toes, lie on a different plane than the neutral axis of the body ( fig. 1 ). This determines a rotation around the center of gravity which the diver automatically compensates for by bending his torso forward and partially flexing his legs (fig. 2). The "curved" posture assumed by the diver in reality (evident in any video of a bi-fins constant weight record) worsens the shape coefficient and increases the frontal section. Moving forward in the water with this posture requires more effort. THEfurthermore iThe consequent imbalance of the stride forwards and backwards is an element that generates worse muscular performance. For the 200 we designed the fin with the blade position aligned under the metatarsal and no further than the toes. Automatically the diver will remain upright, aligned with the direction of movement and his forward and backward stride will become perfectly balanced. We simply prevented resistance due to posture from arising.3) Hydrodynamics.This C4 had already done it in 2006 with the Mustang fins, the first in the world to have the blade aligned under the metatarsal. These fins continued to have the blade inserted inside the foot pocket, generating, as in all traditional fins, a large inflexible area which will position itself in opposition to the movement (fig. 3). The cause is insufficient rotation of the ankle at the end of the stride and a design that is not suited to human morphology. The 200 are designed "around the man" with the blade positioned under the metatarsal, with a shoe-blade connection of minimal dimensions that separates the hydrodynamics of shoe and blade, and blades with controlled curvature close to the foot. By effectively eliminating the "traditional" resistant surface, the 200 transforms the biomechanics of the kick into agile and less tiring.4) The mass.We use a significant amount of energy to move the mass (weight) of the fins. The necessary force is directly proportional to the mass (weight) as demonstrated by Newton with the second law of dynamics F=mx a. The kicking movement is an alternating motion, a complete cycle of the two legs involves 4 reversals of direction. With each inversion our muscles must accelerate the masses to be put back into opposite motion. Using shoes weighing hundreds of grams is evidently very different from using shoes like the 200 which weigh half or even a third of the traditional ones The 200 weigh 189g in size 42-43, are by far the shoes with the least mass ( lightest) in the world and the difference in mass with heavier shoes, multiplied by 4 and by the number of kicks performed in a day of swimming diving, means hundreds and hundreds of kg that must not be moved. All less effort, it's mathematical. Let's remember that a neutral buoyancy in water CANNOT cancel out the mass to be moved, physics prevents it from doing so. We would like to say that to pollute the seas less we need to limit plastic. Reducing the weight of the shoes by half or a third is definitely a good result.5) Personalization.For all this to work best, the fins must be able to adapt to our personal physical characteristics. The best sports equipment derives its superior performance from the possibility of customization and adjustment. The extension of the ankle joint and the foot, the muscle mass, the physical dimensions of our joints and our previous habits are different. Thinking that a single solution is optimal for everyone is simply a contradiction. The 200 shoes introduce, first in the world, the possibility of adjustment also for divers. In the 200, the blades located under the metatarsal can be easily adjusted to three distinct positions (H/M/S) to balance the stride with personal characteristics. The adjustment is sensitive and noticeable. Of the three, there is no privileged position on the table, no instructor will be able to tell us which position to adopt, only by trying will we find the most balanced one for us and it will be the one of the three that will make us work less, which we will feel as more "agile". We will be able to feel a different "hardness" of the blades, because the lever arm with which we are interacting will be more or less favorable but the blades will not be able to "push more or less" in relation to the adjustment you choose, because they will remain the same.6) Reliability.The 200 series fins have been tested for over 18 months by an international team of divers and in the laboratory applying triple force compared to human force with fatigue tests of over 1.6 million complete cycles. Only two longitudinal fixing screws with the interposition between blades and shoes of a polyurethane "shock absorber" allow rapid setups and protect against anomalous stresses. The 200 have dedicated blades, not interchangeable with other existing C4 models. The attachment of the blades is of very small extension, therefore the area is highly stressed. The blades of other models, not specifically designed for this use, do not have sufficient resistance, adaptation is strictly not recommended as it is risky.7) The construction technique.Using a refined and complex construction technique, the 200 liners are made with two distinct materials, overmolding a soft, thin, resistant and self-shaping thermoplastic elastomer upper onto a rigid PP insole. The upper material is softer 65 ShA in the sizes 36/37, 38/39 and 40/41 and slightly stiffer 74 ShA for the sizes 41/42, 42/43, 43/44 and 44/45 to guarantee the better comfort and performance. The 6 threaded bushes that allow customization of the blade position are applied directly in co-moulding. The blade tightening screws have an anti-unscrewing thread lock applied. On the blades, the 3D shaped water rails are applied with the overmolding technique developed by C4 specifically for the 200 series blades. The OPS (Over-moulding Protection System) shaping of the water rails protects the blade from unwanted impacts and damage.8) ComfortThe upper of the 200 is made with a resistant and elastic material that gives great comfort and maximum ease of fit. Thanks to the combination of the C4 anatomy and calibrated thicknesses, the upper is self-shaping, adapting to the shape of the right or left foot. The diver's foot, in a relaxed position, is housed without forcing in the anatomically pre-shaped 3° shoe, in this way there are no constraints and/or limits to movement. The rigid plastic insole flawlessly transmits all the applied energy.Conclusions:Having made the leap in performance, the objective of the 200 project, these fins do not have a single prevailing characteristic.The extraordinary efficiency of the 200 series derives from the amalgam of unique characteristics which together profoundly modify the biomechanics of the kick.For all our testers, the 200 are "addictive" fins such is the positive change in their performance compared to the previous ones.Choose the right LINER: Model 200