Spoke and method for manufacturing a spoke

Description

[0001] The present invention relates to a method for producing a spoke for a wheel of an at least partially muscle-powered bicycle and to a spoke.

[0002] Spokes play a crucial role in the strength and durability of bicycle wheels. Since spokes typically only transmit tensile forces between the rim and the hub, they must be installed with a correspondingly high preload. This preload must generally be high enough to be maintained despite the weight load and the shocks encountered while riding, as well as the torque introduced during acceleration and braking. Therefore, spokes for high-quality wheels must meet very high requirements for tensile strength and breaking strength.

[0003] Since the spokes represent a portion of the rotating mass, reducing the weight of the spokes has a significant impact on the handling characteristics of the entire bicycle. However, the previously described requirements for tensile strength and breaking strength often conflict with lightweight construction.

[0004] Double-thickness spokes have become popular for weight reduction. These are cylindrical spokes with a reduced diameter in an elongated central section. This allows weight to be reduced while still maintaining sufficient diameter at the ends to securely attach the spokes to the rim or hub. The transitions between the different diameters are usually tapered (also called conical).

[0005] A method for manufacturing such spokes is known from EP 3 135 396 B1. In addition to saving weight, such spokes have the advantage that forging also significantly improves the material properties and thus the overall load-bearing capacity of the spoke.

[0006] Furthermore, EP 1 569 809 B1 discloses spokes with an elongated aluminum center section into which steel end pieces are screwed. Steel can absorb the loads occurring at the ends better than aluminum. The aluminum material allows the center section to be easily fitted with more complex cross-sectional shapes.

[0007] In addition, particularly lightweight wheels are known in which the spokes are made of fiber composite materials.

[0008] Furthermore, the spokes have a significant influence on the wheel's aerodynamic drag. Therefore, so-called bladed spokes, for example, from DE 29 811 076 U1 or EP 1 559 583 B1, have become known. These have a flat cross-section in the direction of travel and thus contribute to reducing wind resistance.

[0009] The disadvantage of such bladed spokes, however, is that they significantly increase crosswind sensitivity, making bicycles equipped with them less steerable under wind influences. Therefore, spokes have become known under patent US 10 029 511 B2, which have a cross-section with an airfoil geometry in a radially outer area.

[0010] Spindle-shaped spokes are known from DE 10 2017 103 312 A1. These are manufactured from a round wire material using forming tools. The burrs created on the long sides during the forming process are removed by pressure rollers. Spokes that are initially manufactured in the manner of a double-thickness spoke and then undergo a second forming process to create an aerodynamic geometry have proven advantageous. One such spoke is known, for example, from EP 3 064 370 A3. However, it has been shown that while the second forming process can improve the aerodynamic properties, the overall strength properties of the spoke do not necessarily improve, and in some cases, can even deteriorate.

[0011] A generic method is known from DE 10 2015 114 051 A1. A generic spoke is known from EP 3 312 021 A1.

[0012] The object of the present invention is therefore to provide an improved method for optimizing a spoke in terms of weight and aerodynamic drag. At the same time, the reliability and strength properties of the spoke as a whole should be improved.

[0013] This object is achieved by a method having the features of claim 1 and by a spoke having the features of claim 15. Preferred developments are the subject of the subclaims. Further advantages and features of the present invention will become apparent from the general description and the description of the exemplary embodiment.

[0014] The method according to the invention is used to produce a spoke for a wheel of an at least partially muscle-powered bicycle. The spoke comprises a spoke body which, in the intended installation position in a wheel, has a hub-side first end and a rim-side second end, or extends between them. The spoke body comprises at least one central section extending between the ends and at least two transition sections. Each end is assigned an end section. At least one transition section is arranged between the at least one central section and the end sections.

[0015] The method according to the invention comprises the following method steps in this or another useful order: (First) forming and in particular cold forging of a particularly cylindrical wire material into a spoke blank using a forging device. The spoke blank has a precursor of the central section and precursors of the end sections and precursors of the transition sections. The precursors of the central section and the end sections are forged cylindrically. In particular, the precursor of the central section is reduced in diameter more than the precursors of the end sections. The precursor of the central section has a smaller diameter than the precursors of the end sections. The precursors of the transition sections are forged conically (or tapered) so that they each have a diameter that decreases towards the central section.The precursors of the transition sections are in particular each manufactured with a length that differs by a maximum of one quarter and preferably a maximum of one fifth from a respective (intended) length of the transition section (i.e., the length formed from the precursor). In other words, the lengths of the precursors of the transition sections are in particular each equal to the length of the respective transition section + / - 1 / 4 and preferably + / - 1 / 5. Inserting the spoke blank into a forming tool. The forming tool at least partially forms a negative form of the spoke body (in particular by means of at least one negative forming tool). Forming and in particular cold forging the spoke blank using the forming tool (so that the spoke body is formed). In other words, the spoke blank is converted into the spoke body by the (second) forming.In particular, the respective precursors are formed into the transition sections, end sections, and the central section. At least the transition sections (and preferably also at least one of the end sections) are each given a different cross-sectional geometry than their precursors. In other words, the cylindrical or conical cross-sectional shapes of the precursors are at least partially formed into a different, non-cylindrical or non-conical cross-sectional geometry.

[0016] In particular, the precursors of the transition sections are each manufactured with a length that differs by a maximum of one-sixth, preferably a maximum of one-seventh, and particularly preferably a maximum of one-eighth, from the respective length of the transition sections. In particular, the length of the precursors of the transition sections differs from the length of the transition sections by a maximum of + / - 2 mm, preferably + / - 1.5 mm, and particularly preferably + / - 1 mm.

[0017] The maximum differences in length described here also refer in particular to the length of the negative mold for the transition sections in the mold. In particular, the length of the transition sections in the negative mold determines the length of the transition section of the finished spoke body. This also applies in particular to the end sections and, in particular, to the central section. The mold can preferably also be referred to as a negative mold.

[0018] The present invention offers many advantages. A significant advantage is the specifically shaped precursors of the spoke blank in combination with their subsequent forming to create the new cross-sectional geometry. The precursors and the subsequently formed cross-sectional geometry are optimally coordinated. A particular advantage is that the precursors of the transition sections are manufactured with a length that is specifically adapted to the length of the finished transition sections. It has been shown that the length of the precursors of the transition sections is particularly crucial for the strength of the final spoke. At the same time, the spoke blank can be adapted very inexpensively (e.g., by means of free-die forging) yet effectively to a specific negative shape of the spoke body in the forming tool.

[0019] Studies have shown that the inventive coordination of the preliminary stages of the transition sections with the subsequent forming process has beneficial effects on the tensile strength and, in particular, the fracture strength of the finished spoke. Thus, the inventive method makes it particularly easy to forge the spoke blank (also by free-form forging or without a forming tool with a negative mold) in such a way that it can subsequently be formed into an aerodynamic cross-sectional geometry (using a forming tool with a negative mold) without adversely affecting the specific material properties of the forged spoke blank, or even significantly improving them.

[0020] It is particularly preferred and advantageous that the minimum diameter of the central section is smaller than the minimum diameter of the end sections (after forming with the forming tool). It is also advantageous and preferred that the transition sections each have a minimum diameter that decreases toward the central section. The diameter can decrease continuously or variably.

[0021] It has been shown that by matching the cross-sectional geometries of the spoke blank and the finished spoke body in this way, the advantageous strength properties of the spoke blank are retained or even improved even after the new cross-sectional geometry has been formed. For example, an aerodynamic cross-sectional geometry with particularly high tensile strength and fracture toughness is possible. Furthermore, with such a design, strength is not undesirably compromised even if the preliminary stage of the transition section is slightly longer or shorter than the finished transition section.

[0022] It is preferred and advantageous for the preliminary stages of the transition sections to each have a cone angle of a maximum of 11°, preferably a maximum of 10°, and particularly preferably a maximum of 9°. Such cone angles allow the preliminary stages of the transition sections to be manufactured particularly inexpensively with a suitable tolerance. At the same time, rapid and therefore economical production of the spoke blank is possible, e.g., by means of free-form forging. In particular, within the scope of the present invention, a cone angle is understood to mean the opening angle of the cone. If an angle between the lateral surface of the cone and the central axis of the spoke body is to be considered, the angle specifications given here must be halved.

[0023] It is preferred that the size of the cone angle be determined as a function of the length of the transition section and / or a diameter difference that is to be overcome by the transition section. In particular, the cone angle lies at an upper end of the angles or angle ranges defined here if the transition section must overcome a large diameter difference between the end section and the central section. In particular, the cone angle lies at a lower end of the angles or angle ranges defined here if the transition section must overcome a small diameter difference between the end section and the central section.

[0024] Additionally or alternatively, the cone angle can be selected based on the length of the preliminary stage of the transition section. In particular, for a maximum diameter difference of 0.75 mm, a cone angle of a maximum of 11°, preferably a maximum of 10°, and particularly preferably a maximum of 9° is provided. In particular, for a maximum diameter difference of 0.6 mm or 0.5 mm, a cone angle of a maximum of 8°, preferably a maximum of 7°, and particularly preferably a maximum of 6° is provided.

[0025] It is preferred and advantageous for the transition sections to each receive a minimum diameter that decreases toward the central section as a result of the forming process with the forming tool. In particular, the decrease in the minimum diameter corresponds to the respective diameter of the precursors of the transition sections (decreasing toward the central section). It is also possible for the decrease in the minimum diameter of the transition sections to correspond to the cone angle of the precursors of the transition sections. It is possible for the transition sections to each have a cone angle that corresponds to the cone angle of the respective precursors of the transition sections. The term "correspond" is understood in particular to mean that the cone angles are related by a function or factor, or that they differ by a maximum of 10% and preferably a maximum of 5%.

[0026] Preferably, the precursors of the transition sections are manufactured with a length that is at least fourteen times, in particular at least sixteen times, and particularly preferably at least eighteen times the difference between the diameter of the precursor of the central section and the diameter of the precursor of the end sections. In particular, the transition sections of the finished spoke body then also have such a length.

[0027] It is also possible and advantageous that the precursors of the transition sections are manufactured with a length which is at least fifteen times and preferably at least sixteen times and particularly preferably at least eighteen times the difference between the minimum diameter of the end sections and the minimum diameter of the central section.

[0028] Such dimensions of the precursors of the transition sections are preferably provided for designs in which the difference is at least 0.35 mm and preferably at least 0.4 mm. For designs with a smaller difference, for example, less than 0.3 mm and preferably less than 0.27 mm, it is preferred that the precursors of the transition sections be manufactured with a length that is at least twenty times, in particular at least 23 times, and particularly preferably at least 25 times the difference between the diameter of the precursor of the central section and the diameter of the precursor of the end sections.

[0029] It is preferred that the precursors of the transition sections are manufactured with a length which is at least three times and in particular at least 3.5 times and particularly preferably at least four times the diameter of the precursors of the end sections.

[0030] In advantageous embodiments, the precursors of the transition sections each have a length of at least 7 mm and preferably at least 7.5 mm. It is preferred and advantageous for the precursors of the transition sections each to have a length between 8 mm + / - 1 mm and 10 mm + / - 1 mm, and preferably a length of 9 mm + / - 1 mm.

[0031] It has been shown that such length specifications allow spoke blanks to be manufactured with particularly suitable tolerances. This is particularly advantageous when the spoke blank is formed by free forging a continuous wire material (i.e., without a forming tool with a negative mold). Furthermore, the tolerances at such lengths do not adversely affect the strength of the finished spoke.

[0032] In a particularly advantageous embodiment, the transition sections each have a length that is at least five times, and preferably at least six times, the minimum diameter of the central section. In particular, the minimum diameter of the central section is smaller than the minimum and, in particular, also the maximum diameter of the end sections. This is particularly provided where the end section has a cylindrical cross-section.

[0033] In an advantageous embodiment, the transition sections differ from their respective precursors in terms of their length and / or their position along a longitudinal axis of the spoke body by a maximum of 2 mm, preferably a maximum of 1.5 mm, and particularly preferably a maximum of 1 mm. The position along the longitudinal axis of the spoke body can be defined, for example, by the distance of the transition section from the central section or from an end section or from an end of the spoke.

[0034] In particular, a diameter difference of between 0.4 mm and 0.8 mm is provided between the diameter of the preliminary stage of the central section and the respective diameters of the preliminary stages of the end sections. In particular, the preliminary stages of the transition sections bridge this diameter difference. A diameter difference of 0.43 mm (in particular + / - 0.02 mm), for example, is particularly advantageous. Designs with a smaller diameter difference are also possible, for example for impellers with particularly high load inputs. In this case, the diameter difference can be between 0.20 mm and 0.4 mm. A diameter difference of 0.25 mm (in particular + / - 0.02 mm), for example, is particularly advantageous.

[0035] The previously described lengths for the preliminary stages of the transition sections are particularly advantageous when the difference is at least one-sixth, preferably at least one-fifth, and particularly preferably at least one-quarter of the diameter of the preliminary stages of the end sections. For example, it is advantageous for the difference to be 0.5 mm + / - 0.1 mm. In special cases, such as particularly lightweight spokes for road bicycles, the difference can also be 0.7 mm + / - 0.1 mm.

[0036] For designs with smaller diameter differences, it is preferred and advantageous if the difference is at least one-ninth, preferably at least one-eighth, and particularly preferably at least one-seventh of the diameter of the precursors of the end sections. For example, it is then advantageous for the difference to be 0.3 mm + / - 0.1 mm.

[0037] In advantageous embodiments, the diameter of the preliminary stages of the end sections is, for example, 2 mm + / - 0.1 mm and essentially 2 mm. In advantageous configurations, the diameter of the preliminary stage of the central section is, for example, 1.5 mm + / - 0.25 mm. In particular, the diameter of the preliminary stage of the central section is at least 1.25 mm and at most 1.65 mm. In particular, the preliminary stage of the central section has a diameter of 1.5 mm + / - 0.1 mm. Also possible and advantageous are embodiments (for example for particularly light impellers) in which the preliminary stage of the central section has a diameter of 1.3 mm + / - 0.1 mm.

[0038] In all embodiments, it is preferred that by forming the spoke blank with the forming tool, a spoke body is formed in which at least 75% of the length of the transition sections and preferably at least 90% of the length of the transition sections and particularly preferably at least the entire length of the transition sections is required to adjust the minimum diameter of the central section to the respective minimum diameter of the end sections. This allows a large part or the entire transition section to be used to adjust the different diameters. This avoids short or steep transitions. Furthermore, this can be an inexpensive and reliable way to ensure that the finished spoke body does not have any unfavorable geometric deviations from the spoke blank, which could lead to a reduction in tensile strength and / or breaking strength.

[0039] By forming the spoke blank with the forming tool, at least the preliminary stages of the transition sections and the preliminary stage of the central section are preferably formed in such a way that their cross-sectional circumference is changed more than their cross-sectional area. In other words, by forming the spoke blank with the forming tool, the ratio of cross-sectional circumference to cross-sectional area is specifically changed. This reliably ensures that larger tolerances and, for example, length deviations in the preliminary stages of the transition sections do not affect, or only slightly affect, the tensile strength and fracture strength of the finished spoke.

[0040] In the spoke blank, the cross-sectional circumference is in particular proportional to the cross-sectional area. In the finished spoke body, the cross-sectional circumference in the transition section can be inversely proportional to the cross-sectional area in some sections. In other words, in the finished spoke body, the cross-sectional circumference can increase in the transition section, even though the cross-sectional area decreases towards the central section. It is also possible and advantageous for the finished spoke body to have a cross-sectional circumference in the transition section decrease towards the central section less than the cross-sectional area. In particular, it is envisaged that a proportionality factor, or the ratio of cross-sectional circumference to cross-sectional area, changes as a result of the forming of the spoke blank into the spoke body.

[0041] After forming with the forming tool, the cross-sectional circumference decreases less than the cross-sectional area. In particular, the cross-sectional circumference even increases in sections toward the central section, while the cross-sectional area decreases. The cross-sectional circumference and cross-sectional area remain constant (essentially, e.g., by 90% or more) in the central section.

[0042] In particular, the spoke blank is formed with the forming tool in such a way that at least the central section has a larger cross-sectional circumference than a preliminary stage and / or that at least the transition sections each have a larger cross-sectional circumference than their preliminary stages. In particular, the cross-sectional circumference is increased at least in the central section during forming with the forming tool.

[0043] In particular, the cross-sectional area is essentially unchanged during the forming of the spoke blank with the forming tool. In particular, a maximum reduction in the cross-sectional area of ​​10%, and particularly preferably of a maximum of 5% or even only 2%, is envisaged. In particular, the cross-sectional area is not increased by forming with the forming tool.

[0044] In particular, in one transition section, preferably in both transition sections, a cross-sectional area of ​​the spoke body decreases in the direction of the central section, in particular while at the same time the cross-sectional circumference either decreases by a lesser amount than the cross-sectional area or even increases.

[0045] In particular, the cross-sectional circumference in the transition section initially decreases by a lesser amount than the cross-sectional area toward the central section and subsequently increases. In particular, the ratio of cross-sectional circumference to cross-sectional area is (essentially and, for example, 90% or more) constant in the central section. In particular, the ratio of cross-sectional circumference to cross-sectional area is greater in the central section than in the end sections and / or in the transition sections.

[0046] In a particularly advantageous development, the spoke blank is formed with the forming tool in such a way that the spoke body, at least in the transition sections, has a body and two wings. This geometry has proven advantageous because undesirable tolerances and, for example, length deviations in the preliminary stages of the transition sections do not, or only insignificantly, impair the desired tensile strength and fracture strength of the finished spoke. In particular, the wings and body enable advantageous stabilization of the transition sections when they are specifically positioned in the preliminary stages of the transition sections.

[0047] By shaping the fuselage and wings, combined with arranging these structures in the transition sections, both fracture strength and tensile strength could be improved. At the same time, the shaping of the fuselage and wings allows for weight savings, as the transitions can be made thinner overall without adversely affecting durability. Furthermore, a geometry with a fuselage and wings offers advantageous aerodynamic properties. It has been observed that shaping the fuselage and wings without considering the geometric properties of the precursors of the transition sections does not lead to any significant improvements.

[0048] In particular, the wings are integrally connected to the fuselage. In particular, the wings extend along opposite longitudinal sides of the fuselage. In particular, the fuselage and the wings are formed at least partially in the central section. In particular, the fuselage and wings are formed in the entire central section. The fuselage and wings can also be formed partially in at least one of the end sections. In particular, the molding tool comprises a negative mold of the spoke body with fuselage and wings. In other words, the molding tool forms a negative mold of the spoke body with fuselage and wings. In particular, the molding tool is designed such that the properties of the fuselage and wing described here can be formed from the spoke blank.

[0049] In particular, the wings extend laterally along the fuselage. In particular, the wings are arranged opposite one another on the fuselage. In particular, the wings and the fuselage extend over the entire length of at least one transition section and preferably both transition sections. In particular, the fuselage and the wings are continuous in the central section and in the transition sections. In particular, the fuselage and the wings are continuous from one transition section across the central section to the next transition section.

[0050] Preferably, the wingspan is increased at least where the diameters of the precursors of the transition sections were previously decreased. In particular, the wings are formed wherever the precursors of the transition sections were formed in the spoke blank.

[0051] In particular, the wings and the fuselage extend into at least one of the two end sections, and preferably into both end sections. In particular, the end sections outside the wings and the fuselage are cylindrical in shape, at least in sections.

[0052] Preferably, the fuselage has a cross-sectional height that is greater than the cross-sectional height of the wings. In particular, the cross-sectional height of the wings in the central section is less than the cross-sectional height of the fuselage.

[0053] The fuselage preferably has a rounded cross-sectional geometry. The fuselage in particular has a round or oval, in particular elliptical, cross-section. In particular, the fuselage is cylindrical or designed as a prism with an oval or elliptical cross-section. The fuselage can also have a cross-section corresponding to a rounded rectangle or a rounded square. In particular, the fuselage is then designed as a prism with such a cross-section. In particular, a portion of the fuselage is concealed by the wings. In particular, the fuselage projects beyond the wings above and below a main side of the wings.

[0054] In particular, the cross-sectional geometry of the fuselage is merged with the cross-sectional geometry of the wings. In particular, the spoke body has a cross-sectional geometry composed of the cross-sectional geometry of the fuselage and the wings. It is possible for the cross-sectional geometry of the fuselage in the central section to be compressed relative to the cross-sectional geometry of the fuselage in the transition sections and / or in the end sections.

[0055] Preferably, the spoke body has a cross-sectional geometry, at least in the transition sections and in the central section, in which the wings each transition into the fuselage with a curved profile. In particular, the wings each transition into the fuselage with a curved profile with a turning point. In particular, the fuselage transitions into the wings by changing a radius of curvature. In particular, the fuselage and wings have different radii of curvature.

[0056] It is also possible for the wings to merge into the fuselage in a curved manner without a turning point. In such a case, the cross-sectional geometry of the spoke body can be described as lens-shaped.

[0057] In particular, the wings are curved along their main sides. Preferably, the wings are curved with a different radius than the cross-sectional geometry of the fuselage. It is also possible for the wings to have straight main sides, at least in sections.

[0058] It is also possible for the fuselage and wings to have cross-sectional geometries that are curved with the same radii. In this case, it is preferable for the radii for the fuselage and the wings to originate from different (imaginary) circle centers. For example, this results in a cross-sectional geometry for the spoke body formed by four circles that partially overlap. One circle is provided for each of the wings, while the fuselage is formed by two circles. Such a cross-sectional geometry can also be referred to as a quatrefoil.

[0059] In particular, the wings are aligned centrally on the fuselage. In particular, the wings are arranged mirror-symmetrically to each other on the fuselage. In particular, the longitudinal axis of the spoke body forms the axis of symmetry. In particular, the wings are of identical design. In particular, the wings are of equal length. In particular, the fuselage and the wings together form a symmetrical cross-section.

[0060] In particular, the wings are convexly curved at least in sections on their transverse sides facing away from the fuselage. In other words, the wings are curved outward on their transverse sides.

[0061] In particular, the cross-sectional height of the wings is designed to increase toward the fuselage. In particular, the cross-sectional height of the wings increases transversely to the longitudinal direction. Such a design is provided, in particular, at least in the central section. This results in a smooth transition from the wings to the fuselage.

[0062] In particular, the wings and / or the fuselage remain unchanged over at least a predominant part of the central section and preferably over at least 90% of the central section or even over the entire central section.

[0063] It is advantageous and preferred that the wings and / or the fuselage have a variable cross-sectional geometry in at least one of the transition sections, and preferably in both transition sections. In particular, the degree of change in the cross-sectional geometry is the same in both transition sections.

[0064] Preferably, the span of the wings increases in at least one of the transition sections, and in particular in both transition sections, toward the central section. In particular, the span of the wings decreases in the transition sections toward the end section. The span of the wings in the central section, and in particular also in some sections of the transition sections, is greater than the minimum and preferably also the maximum diameter in the end sections. Preferably, the span of the wings in the central section is (substantially) constant.

[0065] Preferably, a cross-sectional height of the wings decreases in at least one of the transition sections, and preferably in both transition sections, towards the central section. In particular, a cross-sectional height of the wings increases in the transition sections towards the end section. In particular, the wings thereby transition smoothly into a cylindrical geometry of the end section. In other words, the wings have a cross-sectional height that increases and / or a span that decreases in the transition sections towards the end section. It is also possible for the cross-sectional height of the wings to remain unchanged in the transition section. The cross-sectional height of the fuselage in the central section is, in particular, less than the minimum diameter in the end sections.

[0066] Preferably, the cross-sectional height of the fuselage decreases in at least one of the transition sections, and preferably in both transition sections, toward the central section. In particular, the fuselage has a cross-sectional height that increases and / or a cross-sectional width that decreases in the direction of the end section. The fuselage can be tapered (parabolically) in the transition section. The cross-sectional geometry of the fuselage can change in the longitudinal direction such that at least one of the longitudinal ends of the fuselage (in particular both) is parabolically shaped. The cross-sectional width of the fuselage can also remain unchanged in the transition sections.

[0067] The cross-sectional width of the hull refers in particular to an imaginary cross-section of the hull, which is projected into the overall cross-section of the spoke body with the help of a geometric shape (e.g. a circle or an ellipse or a quadrilateral).

[0068] Advantageous embodiments can also be provided in which the spoke blank is formed with the forming tool in such a way that the spoke body, at least in the transition sections and preferably also in the central section, has at least in sections a cross-sectional geometry which is designed in the manner of a blade spoke or in the manner of a bearing surface or is oval or elliptical.

[0069] The forming of the wire material into the spoke blank is carried out in particular by cold forging the wire material using at least one forging device. The forming of the wire material into the spoke blank is carried out in particular with at least two oppositely arranged impact tools of the forging device, which act on the wire material in a percussive manner and preferably rotate around the longitudinal axis of the wire material (so-called rotary swaging). This type of forging is also referred to as free forging or free-form forging, since no forming tool with a negative mold is used, which would predetermine the shape of the resulting product.

[0070] In addition to the well-known advantages, the free forging of the wire material into the spoke blank also entails, for technical reasons, significant deviations in the length and position of the individual pre-stages, especially the transition sections. However, the problem arises that, for technical reasons, the negative shape of the forming tool cannot be changed for the subsequent forming of the spoke blank. In other words, the lengths of the individual sections, and, for example, the transition sections, are fixed by the forming tool.

[0071] One way to produce the spoke blank with particularly tight tolerances is to reduce the relative speed between the wire material and the forging device (as described, for example, in EP 3 135 396 B1).

[0072] Tensile tests have shown that reshaping the spoke blank to create a new cross-sectional geometry can lead to a deterioration in spoke strength if the new cross-sectional geometry is created without taking into account the length of the precursors of the transition sections. Therefore, it is crucial that the spoke blank and the negative mold of the forming tool are specifically adapted to each other.

[0073] With the present invention, however, it can be ensured very easily that the negative mold for the new transition sections in the forming tool is located as precisely as possible where the preliminary stages of the transition sections are located in the spoke blank. Furthermore, the geometric configurations of the preliminary stages (especially length, cone angle) and the transition sections (especially fuselage and wing) presented here ensure particularly high spoke strength even when the preliminary stages have larger tolerances. Thus, the preliminary stages of the transition sections can be formed in such a way that the subsequent forming with the forming tool does not adversely affect the strength of the finished spoke, or that the strength is even increased. Furthermore, a reduction in speed can be completely or at least partially dispensed with.

[0074] In particular, the impact tools each comprise a channel-like forging section. The forging section serves to partially enclose the wire material. In particular, the forging sections each comprise two secondary sections and a main section located between the secondary sections (in the longitudinal direction of the forging section and / or the wire material). In particular, the secondary sections are each arranged at an angle to the main section. In particular, the secondary sections lie in a common plane with the main section. In particular, the longitudinal axis of the wire material to be machined also runs through this plane. With such impact tools, the properties of the spoke blank described here can be produced particularly well. Preferably, the forging section has a concave rounding formed at least in sections transversely to the longitudinal direction (and / or feed direction) of the wire material to be machined.In a particularly advantageous embodiment, the negative mold of the body serves as a positioning aid when inserting the spoke blank into the forming tool. Preferably, the negative mold of the body also serves to secure the spoke blank during forming with the forming tool.

[0075] In particular, the wire material moves relative to the forging device in the direction of its longitudinal axis during forming. The speed of this relative movement is preferably reduced when the transition sections are forged. This allows the shape of the transition sections to be adapted even more precisely to the negative shape of the forming tool.

[0076] The spoke according to the invention is intended for a wheel of an at least partially muscle-powered bicycle. The spoke comprises a spoke body which (in the intended installation position in the wheel) has a hub-side first end and a rim-side second end, and at least one central section extending between the ends. Each end is assigned an end section. A minimum diameter of the central section is smaller than a minimum diameter of the end sections. A transition section is arranged between the at least one central section and the end sections. The transition section has a minimum diameter decreasing toward the central section. At least in the transition sections, the spoke body has, at least in sections, a body and two wings. The wings extend along opposite longitudinal sides of the body.Preferably, the wingspan of at least one of the transition sections increases toward the central section. In particular, the transition sections each have a length that is at least four times, preferably at least five times, and particularly preferably at least six times the minimum diameter of the central section and / or at least 3.5 times, preferably at least four times, the minimum diameter of the end sections. In particular, the transition sections each have a length that is at least 4.5 times, or even at least five times, the minimum diameter of the end sections.

[0077] The spoke according to the invention also solves the aforementioned problem particularly advantageously. It has been shown that such a length of the transition sections, in combination with the fuselage-wing geometry, is particularly crucial for the strength of the resulting spoke.

[0078] The minimum diameter of the central section corresponds in particular to the (minimum) cross-sectional height of the fuselage in the central section. The minimum diameter of the end sections corresponds in particular to the diameter of the end sections if they are cylindrical.

[0079] It is possible and advantageous for the transition sections to each have a length which is at least fourteen times, in particular at least sixteen times, and particularly preferably at least eighteen times, the difference between the minimum diameter of the end sections and the minimum diameter of the central section.

[0080] Such dimensions of the precursors of the transition sections are preferably provided for designs in which the difference is at least 0.35 mm and preferably at least 0.4 mm. For designs with a smaller difference, for example, less than 0.3 mm and preferably less than 0.27 mm, it is preferred that the precursors of the transition sections be manufactured with a length that is at least twenty times, in particular at least 23 times, and particularly preferably at least 25 times the difference between the diameter of the precursor of the central section and the diameter of the precursor of the end sections.

[0081] The spoke according to the invention is manufactured in particular according to the method described above. In particular, the method is designed such that the spoke described here can be manufactured. In particular, the spoke is designed such that it can be manufactured according to the method described here. It is possible, and independent of the selected manufacturing method, for the spoke according to the invention to have spatial and physical features as previously described in the context of the manufacturing method for the spoke. The spoke according to the invention can also be manufactured using a different method.

[0082] A wheel intended for an at least partially human-powered bicycle comprises at least one hub and at least one rim. The hub is connected to the rim via a plurality of spokes. The spokes are each designed as described above. In particular, the spokes are manufactured using the method described above.

[0083] Preferably, the wheel is designed such that the spokes each have a transition section located closer to the hub end and a transition section located closer to the rim end. The transition sections associated with the same ends differ in their position along a longitudinal axis of the spoke by a maximum of 2 mm, in particular by a maximum of 1.5 mm, and preferably by a maximum of 1 mm.

[0084] With regard to a proper installation position in an impeller, the vanes are in particular aligned such that a plane extending through both vanes is parallel to the impeller plane.

[0085] In particular, the spoke comprises at least one spoke head and / or at least one thread. In particular, the spoke head is formed at one end of the spoke. In particular, the spoke head is positioned downstream of the end portion. In particular, the thread is formed at the other end portion. In particular, the spoke head and / or the thread are formed integrally with the spoke body. In particular, the spoke is provided by the spoke body and the spoke head and / or the thread.

[0086] In particular, the spoke body is formed as a single piece. In particular, the wings are connected as a single piece to the fuselage. In particular, the central section, the end sections, and the transition sections are formed as a single piece with the spoke body.

[0087] In particular, the transition sections are designed symmetrically with respect to one another. In particular, the transition sections are designed identically. It is possible that the transition sections may be designed differently, for example, in their length. In particular, the transition sections are designed symmetrically with respect to their cross-sectional geometry and / or with respect to changes in their cross-sectional geometry along the longitudinal axis. For technical reasons, the conical shape of the precursors of the transition sections may deviate from an ideal conical shape.

[0088] The end sections can be identically designed. It is also possible for the end sections to differ in length. In particular, the end sections each have the same cross-sectional geometry. However, it is also possible for the end sections to differ in their cross-sectional geometry.

[0089] In a design with a fuselage and wings, the cross-sectional height of the fuselage corresponds, in particular, to the minimum diameter. Thus, in the previously described designs, the minimum diameter can be used synonymously with the cross-sectional height of the fuselage.

[0090] The forming tool is preferably designed such that the spoke described here can be formed (in a single operation). In particular, the negative mold of the forming tool is designed such that the spoke body described here is formed. The forming tool comprises, in particular, at least two tool units. In particular, the at least two tool units together form the negative mold of the spoke body. In particular, the at least two tool units are pressed onto the spoke blank, thereby forming it into the spoke body with the new cross-sectional geometry.

[0091] The boundary between the transition section and the adjacent central section or end section is defined in particular by the fact that the minimum diameter in the transition section decreases toward the central section and that the minimum diameter in the central section or end section remains (essentially) constant. In other words, the central section or end section preferably begins where the variable cross-sectional geometry of the transition section ends (and a constant cross-sectional geometry begins). In particular, the transition section provides a transition from one (essentially) constant cross-sectional geometry to another (essentially) constant cross-sectional geometry.

[0092] In particular, the minimum diameter in the central section and / or in the end sections is (essentially) constant. In particular, a cross-sectional geometry of the central section and / or the end sections is (essentially) constant. In particular, the cross-sectional circumference and cross-sectional area of ​​the central section and / or the end sections are (essentially) constant. In particular, the fuselage and wings are (essentially) constant in terms of their cross-sectional geometry (cross-sectional height, cross-sectional width, span, etc.) in the central section. In particular, the fuselage and wings are not formed at all in the end sections or are (essentially) constant in terms of their cross-sectional geometry in the end sections.

[0093] Further advantages and features of the present invention will become apparent from the embodiments which are explained below with reference to the accompanying figures.

[0094] The figures show: Fig. 1 a schematic side view of a bicycle; Fig. 2 a purely schematic representation of a spoke in a plan view; Fig. 3 the spoke according to Fig. 2 in a side view; Fig. 3a a purely schematic representation of a spoke in a side view; Fig. 4 a cross-section of the spoke according to Fig. 2 ; Fig. 4a a cross-section of a design of the spoke according to Fig. 2 ; Fig. 5 a detailed view of the spoke according to Fig. 2in a perspective view; Fig. 6 a highly schematic representation of a process step in the production of a spoke blank; Fig. 7 a highly schematic representation of a spoke blank in a side view and cross sections of the spoke blank; Fig. 8 a purely schematic detailed representation of a forming tool for forming a spoke blank in a sectional side view; and Fig. 9 a sketch illustrating geometric properties of a spoke.

[0095] The Figure 1shows a schematic representation of an at least partially muscle-powered bicycle (101). The bicycle 101 has two wheels 100, namely a front wheel and a rear wheel. Furthermore, a frame 104, a fork 105, a handlebar 107, and a saddle 106 are provided. Pedals, in this case a derailleur, are provided as the drive. The drive can also include electric assistance. The front wheel and the rear wheel are each attached to dropouts on the fork 105 and the frame 104, respectively.

[0096] The wheels 100 each have a rim 103 and a hub 102 and spokes 1 manufactured according to the invention. The spokes 1 connect the rim 103 to the hub 102. Due to the scale of the illustration, the spokes 1 are only shown schematically here.

[0097] In the following, a spoke 1 according to the invention is described with reference to the Figures 2 to 5described in more detail. Spoke 1, for example, is manufactured according to the method according to the invention.

[0098] The spoke 1 comprises a spoke body 2 and a spoke head 52 as well as a thread 62 for screwing to a spoke nipple (not shown here). The spoke body 2 extends between a rim-side end 12, at which the thread 62 is arranged, and a hub-side end 22, at which the spoke head 52 is arranged. In the variant of the Figures 2 and 3 the head 52 is angled (so-called cranked-head spoke 1). In the variant of the Figure 3a the head is arranged straight (so-called straight-pull spoke or straight-head spoke).

[0099] Each end section 4 of the spoke body 2 is assigned to each end 12, 22. A central section 3 extends between the ends 12, 22, which here constitutes by far the largest part of the spoke 1. A transition section 5 is arranged between the central section 3 and the end sections 4.

[0100] In the central section 3 and the transition sections 5, the spoke body 2 is equipped with a fuselage 6 and two wings 7. The wings 7 extend along opposite longitudinal sides of the fuselage 6 and are both identically designed.

[0101] Spoke 1 is formed in one piece here and is made, for example, from a stainless steel alloy. Thus, spoke body 2 and spoke head 52, as well as thread 62, all sections 3, 4, and 5 of spoke body 2, as well as body 6 and wings 7, are connected to one another in one piece.

[0102] The central section 3 here has a minimum diameter 13, which is smaller than a minimum diameter 14 of the end sections 4. The transition sections 5 each have a minimum diameter 15 that decreases toward the central section 3. The differences between the diameters 13, 14 are thus bridged seamlessly by the transition sections 5.

[0103] The Figure 4shows a cross-section through the central section 3. As can be clearly seen here, the fuselage 6 has a cross-sectional height 16 which is greater than a cross-sectional height 17 of the wings 7. The fuselage 6 has a rounded cross-sectional geometry (see dashed circle). In the transition sections 5 and in the central section 3, the cross-sectional geometry of the spoke body 2 is designed such that the wings 7 each merge into the fuselage 6 with a curved course 82 with a turning point 182. For this purpose, the wings 7 are correspondingly curved on their main sides 37. As a result, the cross-sectional height 17 of the wings 7 increases here in the direction of the fuselage 6. The wings 7 are convexly curved on their transverse sides 27.

[0104] The transition section 5 and its geometric properties are shown in the enlarged detail of the Figure 5This can be seen particularly clearly. The wings 7 and the fuselage 6 have a variable cross-sectional geometry in the transition sections 5. The span 47 of the wings 7 increases in the transition sections 5 toward the central section 3. The cross-sectional height 17 of the wings 7 decreases in the transition sections 5 toward the central section 3. The cross-sectional height 16 of the fuselage 6 decreases in the transition sections 5 toward the central section 3.

[0105] For example, the wingspan 47 is 2.3 mm. The cross-sectional height 16 of the fuselage 6 is 1.3 mm.

[0106] The Figure 4a shows a cross section through the central section 3 of an embodiment of the spoke 1 described above. Here it can be clearly seen that the body 6, in contrast to the Fig. 4has a slightly larger cross-sectional height 16. For example, the cross-sectional height 16 here is 1.5 mm. In addition, the cross-sectional height 17 of the wings 7 is designed larger. The span 47 of the wings 7 is the same size as the spoke according to Fig. 4 Such a spoke 1 can be used, for example, when increased demands are placed on the stability of the wheels 100, for example in mountain bikes.

[0107] In the production of the spokes 1 described above, a spoke blank 8 is first produced. This step is described below with reference to the Figures 6 to 8 described.

[0108] First, a (continuous) wire material 18 is formed into a spoke blank 8 by cold forging with a forging device 28. The wire material 18 is previously essentially cylindrical and has, for example, a diameter 180 of slightly more than 2 mm, such as 2.2 mm or 2.3 mm.

[0109] The cold forging of the wire material 18 is carried out with a forging device 28 as described in Figure 6 is outlined. Two oppositely arranged impact tools 38 continuously strike the wire material 18 while rotating about its longitudinal axis. At the same time, the wire material 18 is advanced in its longitudinal direction and relative to the impact tools 38. The impacts reduce the diameter of the wire material 18 by 180 mm. The reduced diameter can be adjusted by how far or deep the impact tools 38 act on the wire material 18.

[0110] After cold forging with the forging device 28, the wire material 18 is cut to the desired length so that the Figure 7 The spoke blank 8 shown is present.

[0111] The spoke blank 8 here comprises a pre-stage 30 for the central section 3 and two pre-stages 40 for the end sections 4, as well as two pre-stages 50 for the transition sections 5. The pre-stages 30 and 40 for the central section 3 and for the end sections 40 were cylindrically forged. The pre-stage 30 of the central section 3 was reduced more than the pre-stages 40 of the end sections 4.

[0112] For example, the diameter 130 of the pre-stage 30 of the central section 3 is 1.57 mm + 0.03 mm - 0 mm. The diameter 140 of the pre-stage 40 of the end sections 4 is 2 mm + 0.02 mm - 0 mm. From such a spoke blank 8, for example, a spoke 1 can be forged particularly well, as described with reference to Fig. 4 described.

[0113] In another, equally advantageous example, the diameter 130 of the pre-stage 30 of the central section 3 is 1.75 mm + 0.03 mm - 0 mm. The diameter 140 of the pre-stages 40 of the end sections 4 is, for example, 2 mm + 0.02 mm - 0 mm. From such a spoke blank 8, for example, a spoke 1 can be forged particularly well, as is the case with reference to Fig. 4a described.

[0114] The spoke blank 8 described below and its processing are particularly suitable for the production of the spokes 1 according to Figure 4 and Figure 4a .

[0115] The precursors 50 of the transition sections 5 were forged conically here. As a result, the precursors 50 bridge the different diameters 130, 140 of the adjacent precursors 30, 40. Due to the conical design, the diameter 150 of the precursor 50 of the transition section 5 decreases here toward the precursor 30 of the central section 3.

[0116] The spoke blank 8 is then placed in a forming tool 9, as shown in the Figure 8 The forming tool 9 here comprises two tool units 19, which together form a negative mold of the final spoke body 2. In the cross-sectional view of the forming tool 9, the future cross-sectional geometry of the spoke body 2 with the fuselage 6 and the wings 7 can be clearly seen.

[0117] The negative mold for the fuselage 6 serves as a guide during insertion and, in particular, during the forming process itself. Such a guide allows for the production of particularly straight spokes 1. This eliminates the need for post-processing, which involves straightening the spokes 1.

[0118] The spoke blank 8 is placed between the tool units 19. The tool units 19 are moved towards each other so that the spoke blank 8 is formed. Here, the forming with the forming tool 9 is also designed as a cold forging process. After forming with the forming tool 9, the spoke body 2 is equipped with the geometry as previously described in the Figures 2 to 5 was described.

[0119] The initial cold forging process produces a spoke blank 8 with particularly high tensile strength and fracture strength. The subsequent cold forging of spoke blank 8 gives spoke 1 its new or final cross-sectional geometry, which improves its aerodynamic properties, for example. Furthermore, the tensile strength and fracture strength are further increased / improved by the subsequent cold forging process.

[0120] However, such a two-stage production of the spoke 1 is not without problems overall, since the second cold forging in particular can lead to an undesirable deterioration in the reliability of the spoke 1. For example, the spoke blank 8 could be designed as a bladed spoke by locally pressing it flat. However, in some cases it has been observed that such bladed spokes can have poorer strength than the used spoke blank 8. Therefore, one of the objects of the invention presented here is to counteract such deterioration. The invention presented here offers a way of equipping the spoke blank 8 with a new cross-sectional geometry through further cold forging, whereby its strength is even significantly improved.

[0121] How and at which positions of the spoke blank 8 the new cross-sectional geometry is formed is particularly crucial for the strength and reliability of the finished spoke 1. In the spoke 1 presented here, for example, the cylindrical shape of the precursors 40 of the end sections 4 is retained in sections or even completely. The cylindrical precursor 30 of the central section 3, on the other hand, is continuously and uniformly formed. The precursors 50 of the transition sections 5 are only slightly formed adjacent to the precursors 40 of the end sections 4 and are increasingly formed towards the precursor 30 of the central section 3.

[0122] In particular, the preliminary stages 50 of the transition sections 5 and the forming tool 9 are coordinated in such a way that the strength of the forming basically follows the decreasing diameter of the preliminary stages 50 of the transition sections 5. This is particularly good, for example, in the Figure 5There, the end section 4 is still cylindrical, while in the transition section 5, the span 47 of the wings 7 increases in the direction of the central section 3 to the extent that the diameter 150 of the conical preliminary stage 50 of the transition section 5 has previously decreased in the direction of the central section 3. This results in a particularly optimized transition between the new geometry of the spoke body 2 and the original geometry of the spoke blank 8, whereby unfavorable stress peaks are avoided even under high loads and a uniform force distribution can be ensured.

[0123] In addition, it is taken into account that the length 151 of the precursors 50 of the transition sections 5 has a particular influence on the properties of the spoke 1 after the second cold forging. Therefore, the precursors 50 of the transition sections 5 are designed here with a length of 151 (see Figure 7) which can be extended by a maximum of one fifth of the respective intended length 25 (see Fig. 2 and 3 ) of the finished transition sections 5.

[0124] In the example shown here, the length 151 of the precursor sections 50 is 9 mm + / - 1 mm. The length 25 of the finished transition sections 5 is, for example, 9 mm. These dimensions provide optimal adaptation of the spoke blank 8 to the second cold forging process, and especially to the negative mold of the forming tool 9. As a result, the second cold forging can improve the aerodynamic properties of the spoke 1 without compromising its strength compared to the spoke blank 8.

[0125] In addition, it is advantageous that the preliminary stages 50 of the transition sections 5 each have a cone angle 152 (see Figure 7; cone opening angle) of a maximum of 11°. For the spoke blank 8 shown here, for example, the cone angle 152 is 6.3°. Such a cone angle 152 allows the spoke blank 8 to be manufactured with a particularly good tolerance for the length 151 of the pre-stage 50 and, at the same time, with an economical feed rate for the wire material 18.

[0126] In order to be able to retain the advantageous properties of the forged spoke blank 8 even after the second forming process, the new cross-sectional geometry of the spoke body 2 is optimally adapted to the geometry of the spoke blank 8 and in particular to the conical geometry of the preliminary stage 50 of the transition section 5. For this purpose, the spoke body 2 is shaped here such that a minimum diameter 13 of the central section 3 is smaller than a minimum diameter 14 of the end sections 4. In addition, the transition sections 5 of the finished spoke body 2 are shaped such that they each have a minimum diameter 15 that decreases towards the central section 3. This makes it possible to equip the spoke body 2 with a new geometry without adversely changing the original strength and shape of the spoke blank 8.

[0127] A particularly advantageous possibility for bringing the geometry of the finished spoke body 2 into line with the spoke blank 8 is also offered by the cross-sectional geometry shown here with the fuselage 6 and the wings 7. This results in the relationships between cross-sectional area 32 and cross-sectional circumference 42 shown in Figure 12.

[0128] In the diagram of the Figure 9 The cross-sectional area of ​​32 and the circumferential length of 42 of the Figure 5 shown spoke body 2 is plotted over its length at several reference points 72. For better illustration, the reference points 72 are also shown in the Figure 5 In addition, the reference points in the Figure 5 shown as cross-sections, so that the respective cross-sectional geometry along the longitudinal axis can be seen particularly well there.

[0129] In the diagram of the Fig. 9The profile 132 of the cross-sectional area of ​​the spoke body 2 is plotted. In addition, the profile 142 of the circumferential length 42 of the spoke body 2 is plotted. The profile 98 of the circumferential length 42 of the precursors 30, 40, 50 of the spoke blank 8, from which the spoke body 2 of the Figure 5 formed is shown here in dashed lines. Since the cross-sectional area 32 was only slightly altered during the forming of the spoke blank 8 into the spoke body 2, the profile 132 corresponds very closely to the profile of the cross-sectional area 32 of the spoke blank 8.

[0130] It is clearly visible that the spoke blank 8 originally had a profile 98 of the circumferential length 42, which is essentially proportional to the profile 132 of the cross-sectional area 32. It is also clearly visible that the forming of the spoke blank 8 with the forming tool 9 resulted in a spoke body 2 which has a considerably greater circumferential length 42 than the spoke blank 8. The circumferential length 42 initially decreases less than the cross-sectional area 32 and the circumferential length 42 of the spoke blank 8. Subsequently, the circumferential length 42 increases again within the transition section 5 and increases until it remains essentially constant within the central section 3.

[0131] Such an optimized adaptation of cross-sectional area 32 and circumferential length 42 in the region of the transition sections 5 ensures that no undesirable weakening of the spoke 1 occurs due to the forming of the spoke blank 8. A particular advantage is that the circumferential length 42 is already specifically adapted in the transition sections 5, while the cross-sectional area 32 remains essentially unchanged compared to the preliminary stage 50 of the transition section 5.

[0132] The invention presented here offers, in particular, optimized preliminary stages 50 of the transition sections 5 as well as a particularly ideal match of the forged spoke blank 8 with the negative mold of the forming tool 9 for forming the final spoke body 2. Furthermore, these advantages can be implemented particularly easily and economically with the method presented here. The invention offers a further advantage with the targeted forming of the body 6 and wings 7 from a spoke blank 8 that has previously been optimally adapted to this cross-sectional shape. The forming of the body 6 and wings 7 results in a particularly advantageous combination of a circular and a flat spoke cross-section, whereby particularly high strength values ​​and particularly high elongation at break values ​​can be achieved with a minimal weight of the spoke 1.Through such targeted shaping of the cross-sectional geometry, the breaking force could be significantly increased compared to spoke blank 8 or a conventional double-thickness spoke.

[0133] The dimensioning of the spoke blank 8 described here in combination with the striking tool 38 presented here enables a particularly inexpensive production of particularly precise and, in particular, ideally symmetrical transitions during the production of the spoke blank 8. This also results in a considerably better coordination of the spoke blank 8 with the forming tool for further forming.

[0134] Tensile tests have demonstrated that an optimized combination of high tensile strength and high yield strength is achieved. Furthermore, tensile tests have shown that fracture points are no longer, or only rarely, located in the transition sections 5 and that the overall breaking force can be increased. Furthermore, the invention has significantly reduced the scrap rate in spoke production. List of reference symbols:

[0135] 1 spoke 100 balance bike 2 Spoke body 101 Bicycle 3 Central section 102 hub 4 final section 103 rim 5 Transition section 104 Frame 6 hull 105 Fork 7 wing 106 saddle 8 spoke blank 107 handlebar 9 mold tool 130 diameter 12 End 132 Course 13 diameter 140 diameter 14 diameter 142 Course 15 diameter 150 diameter 16 Cross-sectional height 151 length 17 Cross-sectional height 152 Cone angle 18 Wire material 180 diameter 19 tool unit 182 Turning point 22 End 25 length 27 Short pages 28 Forging equipment 30 Pre-stage 32 cross-sectional area 37 Main pages 38 striking tool 40 Pre-stage 42 Cross-sectional circumference 47 span 50 Pre-stage 52 Spoke head 62 thread 72 Reference point 80 radius 82 Course 98 Course

Claims

1. Method of manufacturing a spoke (1) for a wheel (100) of an at least partially muscle-powered bicycle (101), having a spoke body (2), wherein the spoke body (2) in the installed position as intended in a wheel (100), comprises a hub-side, first end (22) and a rim-side, second end (12), and wherein the spoke body (2) comprises at least one central section (3) extending between the ends (12, 22), wherein one end portion (4) is attributed to each of the ends (12, 22), and wherein one transition section (5) each is disposed between the central section (3) and the end portions (4), comprising the following process steps: reshaping a wire material (18) to obtain a spoke blank (8) by means of a forging device (28), wherein the spoke blank (8) includes pre-stages (30, 40, 50) of the central section (3) and the end portions (4) and the transition sections (5), and wherein the pre-stages (30, 40) of the central section (3) and of the end portions (4) are forged cylindrically, so that the pre-stage (30) of the central section (3) shows a smaller diameter (130) than do the pre-stages (40) of the end portions (4), and wherein the pre-stages (50) of the transition sections (5) are forged conically, so that they show a diameter (150) decreasing in the direction of the central section (3), characterized in that the pre-stages (50) of the transition sections (5) are each manufactured in a length (151) which differs by a maximum of one fourth from the pertaining length (25) of the transition sections (5), and characterized by the process steps: inserting the spoke blank (8) in a shaping tool (9), which reproduces a negative mold of the spoke body (2), reshaping the spoke blank (8) by means of the shaping tool (9), wherein at least the transition sections (5) and the central section (3) are each provided with a cross-sectional geometry different from their pre-stages (30, 50).

2. The method according to the preceding claim, wherein the minimal diameter (13) of the central section (3) is smaller than the minimal diameter (14) of the end portions (4), and wherein the transition sections (5) each show a minimal diameter (15) decreasing in the direction of the central section (3).

3. The method according to any of the preceding claims, wherein the pre-stages (50) of the transition sections (5) each show a cone angle (152) of maximally 11°.

4. The method according to any of the preceding claims, wherein due to the reshaping by means of the shaping tool (9), the transition sections (5) are each provided with a minimal diameter (15) decreasing in the direction of the central section (3), and wherein the decrease of the minimal diameter (15) corresponds to the pertaining diameters (150) of the pre-stages (50) of the transition sections (5).

5. The method according to any of the preceding claims, wherein the pre-stages (50) of the transition sections (5) are manufactured in a length (151) which is at least 14 times the differential amount between the diameter (130) of the pre-stage (30) of the central section (3) and the diameter (140) of the pre-stages (40) of the end portions (4).

6. The method according to any of the preceding claims, wherein the transition sections (5) each show a length (25) which is at least five times the minimal diameter (13) of the central section (3).

7. The method according to any of the preceding claims, wherein the difference in diameters between the diameter (130) of the pre-stage (30) of the central section (3) and the pertaining diameters (140) of the pre-stages (40) of the end portions (4) is between 0.4 mm and 0.8 mm, and wherein the pre-stages (50) of the transition sections (5) bridge this difference in diameters.

8. The method according to any of the preceding claims, wherein the reshaping of the spoke blank (8) by means of the shaping tool (9) reshapes at least the pre-stages (50) of the transition sections (5) and the pre-stage (30) of the central section (3), such that their cross sectional circumferences (42) are each modified to a greater extent than is their cross sectional area (32).

9. The method according to any of the preceding claims, wherein the spoke blank (8) is reshaped by means of the shaping tool (9), such that at least the central section (3) is provided with a larger cross sectional circumference (42) than its pre-stage (30), and / or that at least the transition sections (5) are each provided with a larger cross sectional circumference (42) than their pre-stages (50).

10. The method according to any of the preceding claims, wherein in the transition sections (5), the cross sectional area (32) of the spoke body (2) decreases in the direction of the central section (3), while at the same time the circumferential length (42) of the cross section of the spoke body (2) either decreases by a smaller measure than does the cross sectional area (32), or even increases.

11. The method according to any of the preceding claims, wherein the spoke blank (8) is reshaped by means of the shaping tool (9), such that the spoke body (2) has a body (6) and two wings (7) at least in the transition sections (5), at least in sections, wherein the wings (7) extend on opposite longitudinal faces of the body (6).

12. The method according to the preceding claim, wherein the span (47) of the wings (7) is configured increasing at least where the diameters (150) of the pre-stages (50) of the transition sections (5) had previously been configured decreasing, and wherein the span (47) of the wings (7) increases in the direction of the central section (3) at least in one of the transition sections (5).

13. The method according to any of the two preceding claims, wherein the wings (7) and / or the body (6) show a variable cross-sectional geometry in at least one of the transition sections (5).

14. The method according to any of the three preceding claims, wherein the section height (17) of the wings (7) decreases in the direction of the central section (3) at least in one of the transition sections (5), and / or wherein the section height (16) of the body (6) decreases in the direction of the central section (3) at least in one of the transition sections (5).

15. A spoke (1) for a wheel (100) of an at least partially muscle-powered bicycle (101) having a spoke body (2), wherein the spoke body (2), in the installed position in the wheel (100) as intended, comprises a hub-side, first end (22) and a rim-side, second end (12), and wherein the spoke body (2) comprises at least one central section (3) extending between the ends (12, 22), wherein one end portion (4) each is attributed to the ends (12, 22), and wherein the minimal diameter (13) of the central section (3) is smaller than the minimal diameter (14) of the end portions (4), wherein one transition section (5) each is disposed between the central section (3) and the end portions (4), and wherein the transition section (5) shows a minimal diameter (15) decreasing in the direction of the central section (3), wherein the spoke body (2) has a body (6) and two wings (7) at least in the transition sections (3), at least in sections, wherein the wings (7) extend on opposite longitudinal faces of the body (6), characterized in that the transition sections (5) each show a length (25) that is at least 4 times the minimal diameter (13) of the central section (3), and / or at least 3.5 times the minimal diameter of the end portions (4), and that the span (47) of the wings (7) increases in the direction of the central section (3) in at least one of the transition sections (5).