Modular bicycle frame made of plastic

Abstract

The invention relates to a modular bicycle frame (1) made of plastic for a bicycle which provides three interfaces for a bicycle-riding person, a saddle as a first interface, a pedal crank as a second interface and handlebars as a third interface, wherein the bicycle frame (1) can be put together by means of frame elements (2, 3) which are produced from plastic and with the proviso that the frame elements (2, 3) can be connected at a dividing point (4), wherein the frame elements (2, 3) are modularly designed such that a first of the frame elements is designed as a front-structure frame element (2) and a second frame element is designed as a rear-structure frame element (3), wherein the front-structure frame element (2) comprises a lower tube unit (5) and, for the handlebars interface, a head tube portion (6), wherein the rear-structure frame element (3) is provided with a saddle tube portion (7) for the saddle interface and with a pedal drive portion (8) for the pedal crank interface, with the proviso that the dividing point (4) between the front-structure frame element (2) and the rear-structure frame element (3) is designed as a permanent connection point (V) which is to be connected one single time.

Description

[0001] Modular plastic bicycle frame. The invention relates to a modular plastic bicycle frame for a bicycle, which provides three interfaces for a person riding the bicycle, preferably in an upright position: a saddle as the first interface, a pedal crank as the second interface, and a handlebar as the third interface. The bicycle frame can be assembled using frame elements made of plastic, with the proviso that the frame elements can be connected at a dividing point. The pedal crank is expediently provided with pedals, and the handlebar preferably has grips that facilitate contact with the person riding the bicycle. Bicycle frames are known that are assembled in a modular manner from frame elements, such as tubular elements and coupling elements. The coupling elements, such as sleeves, are provided at nodes to indirectly connect the connecting ends of the frame elements.The tubular elements and coupling elements of such bicycle frames are made of metal or plastic. They are joined together using a suitable joining process, such as soldering, welding, or gluing. Furthermore, a bicycle frame is known, for example from the publication DE 74 32 809 U, preferably made of a fiber-reinforced plastic, which is manufactured using a large forming tool, for example in a monocoque design with a frame element composed of half-shell parts. Production in a large forming tool entails a high level of effort. This method is disadvantageous, for example, when bicycle frames are to be produced in different frame sizes. Several large forming tools incur high costs. In this case, bicycle frames which can be assembled from frame elements have an advantage.

[0002] A modular bicycle frame is known, for example, from DE 694 18 046 T2. It is made from a thermoplastic material and comprises frame elements (profiles) and so-called connecting housings. The frame elements have connecting ends provided with tenons. The tenons are inserted into the connecting housings. According to this prior art, the assembly and connection of a frame element to the connecting housing is supposed to be ensured by thermal shrinkage of the thermoplastic after shaping during cooling. The production of this well-known modular bicycle frame is considered to be very complex and rather inflexible.

[0003] The invention is based on the object of proposing a modular bicycle frame which comprises a plurality of frame elements and housing areas which can be connected more easily, whereby the production of a modular series of geometrically similar bicycle frames should be encouraged.

[0004] According to the invention, the object is achieved in that the frame elements are designed in a modular manner, in that a first of the frame elements is designed as a front frame element and a second frame element is designed as a rear frame element, wherein the front frame element comprises a down tube unit and a head tube section for the handlebar interface, wherein the rear frame element is provided with a seat tube section for the saddle interface and with a pedal drive section for the pedal crank interface, with the proviso that the dividing point between the front frame element and the rear frame element is designed as a permanent connection point to be connected once.

[0005] The dividing point can also be provided with a means to at least seal it and prevent dirt from penetrating the bicycle frame. Alternatively, the dividing point, or rather the connection there, can include an adhesive that contributes to the strength of the connection.

[0006] The three interfaces mentioned above provide designs on the bicycle frame through which forces transmitted from the original interfaces mentioned above—saddle, crank, and handlebars—can be introduced into the bicycle frame. For the saddle interface, this is the design of the upper end of the seat tube section; for the crank interface, this is the design of the pedal drive section; and for the handlebar interface, this is the design of the head tube section.

[0007] The down tube unit of the front frame element expediently has an elongated shape, preferably in a longitudinal axis, which expediently forms a housing, wherein the down tube unit is provided with a lower front end which has a connecting means. The elongated shape of the down tube unit facilitates its manufacture and creates usable space within the housing. The connecting means promotes a modular construction of the bicycle frame. The pedal drive section of the rear frame element is expediently provided with a complementary connecting means, wherein the two frame elements can be permanently connected at the connection point by means of the two complementary connecting means of the front frame and rear frame elements. Preferably, the connecting means of the front frame element is aligned in the direction of the pedal drive section of the rear frame element in the assembled state.The complementary connecting element promotes the modular construction of the bicycle frame.

[0008] The connecting means provided on the pedal drive section can have a distance relative to the position of a pedal crank shaft that is in a range of 0.5 times to 1.5 times the length of a standard pedal crank, or is preferably arranged at a distance that is the same size as or less than the length of a standard pedal crank. For the present invention, a length of 170 mm is considered to be the standard length of the pedal crank. This defines the division point of the bicycle frame and, concomitantly, enables usable space in the down tube unit for designing the front frame element as a housing.

[0009] At the lower end of the down tube unit, the connection point is preferably arranged in a connection plane that is orthogonal to the longitudinal axis of the down tube unit, wherein an intersection point of this connection plane with a longitudinal axis of the down tube unit defines a connection center point of the down tube unit, or a connection center point for the front frame element as a whole.

[0010] It is also useful to define an upper head tube point of the head tube section, which is located at the upper end of the head tube section, namely at the intersection point of the longitudinal axis of the head tube section with the upper end of the head tube section. The upper end of the head tube section includes an upper end face, which is arranged in a plane that is orthogonal to the longitudinal axis of the head tube section (head tube plane).

[0011] The head tube section expediently has a length A and the down tube unit has a length B, which length B is defined as the distance between the upper head tube point S1 of the head tube section and the connection center point Ml of the down tube unit, wherein a front end length C directed in the direction of travel is defined, namely as the horizontal distance between the upper head tube point S1 of the head tube section and the connection center point Ml. The front end length C refers to the horizontal distance under the proviso that an assembled bicycle is horizontal and upright on a surface or its spatial position is parallel to an upright position.

[0012] The length A of the head tube section relative to the length B of the down tube unit is expediently in a ratio of 1:4 to 1:5.5, and preferably in a ratio of 1:4.2 to 1:5.2. This enables a practical size range for the front frame element.

[0013] The length A of the head tube section is appropriately in a ratio of 1:2 to 1:3 relative to the front end length C and is preferably in a ratio of 1 / 2.1 to 1 / 2.6. This also promotes an appropriate size range for the front end frame element.

[0014] The longitudinal axis running through the elongated down tube unit expediently forms an intersection point with a longitudinal axis of the seat tube section when the two frame elements are joined together, the intersection point being on a side of the pedal drive section facing away from the seat tube section (below). The down tube unit preferably has an elongated straight section. The straight section has a center line which runs at a distance relative to the position of the pedal crank, as in a so-called curved single-tube unisex frame (wave frame). This design favors a universal shape of the bicycle frame which provides a low step-through so that a cyclist can simply get on and ride off.

[0015] There is an angle bisector between the longitudinal axis of the down tube unit and the longitudinal axis of the seat tube section, with the pedal drive section being designed in such a way that the position of a pedal crank shaft is between the angle bisector and the longitudinal axis of the seat tube section.

[0016] An "effective seat tube angle" is formed by a straight line that runs through the pedal crank and through the center of the seat and thus deviates slightly from the seat tube centerline. The position of the pedal crank is expediently located in the direction of travel in front of the seat tube centerline, which shows the actual angle at which the seat tube section is arranged. This geometric design is expedient for a bicycle frame that has a low step-through. It appears to be advantageous, among other things, for bicycles whose pedal drive is supported by an auxiliary motor, in particular a mid-engine arranged in the pedal drive section.

[0017] The rear triangle frame element can comprise at least one lower strut with an associated dropout for a wheel axle of a rear wheel. The dropout can be designed as a slotted hole open on one side (dropout) or, alternatively, as a bore into which a wheel axle can be inserted.

[0018] The lower strut is advantageously rooted at the pedal drive section. A strongly developed lower strut can be configured as a one-sided mount for a rear wheel axle, or two lower struts can be provided, between which a rear wheel can be accommodated, and the rear wheel axle can be attached to a lower strut on either side.

[0019] The rear frame element can also have at least one seat stay, which is connected on one side to the dropout and on the other side to the seat tube section. The seat stay and a lower stay form two sides of a stable frame triangle, with an angle s being provided between the lower stay and the associated seat stay, which is identical for every size variant of the bicycle frame.

[0020] The seat stay and the lower stay are conveniently arranged at a defined angle to each other. The seat stay and the lower stay each form two sides of a rear frame triangle, the third side of which is composed of parts of the seat tube section and the pedal drive section.

[0021] The connecting means on the front end of the down tube unit of the front frame element is expediently facing the connecting means of the pedal drive section when assembled, with the two connecting means being concealed when assembled. This means that the connecting means cover each other in such a way that, when assembled, they are not visible on the bicycle frame when viewed from the outside.

[0022] The connecting means of the down tube unit has at least one wedge surface inclined to its longitudinal axis, wherein the connecting means of the pedal drive section is provided with at least one associated wedge surface that is complementary to the wedge surface of the connecting means of the down tube unit. In this way, a wedge connection is provided that acts similarly to an external square of a pedal crank shaft, to which a pedal crank with a matching internal square can be reliably fastened by elastic tensioning.

[0023] The wedge surface of the connecting means of the down tube unit is preferably an outwardly directed wedge surface, while the wedge surface of the connecting means of the pedal drive section is preferably an inwardly directed wedge surface. Alternatively, conversely, the outwardly directed wedge surface can be arranged on the pedal drive section and the inwardly directed wedge surface on the down tube unit.

[0024] On the connecting means of the down tube unit, several wedge surfaces are expediently provided, whereby these wedge surfaces can be arranged in a polygonal manner.

[0025] At least two wedge surfaces of one connecting element and two wedge surfaces of the associated connecting element can advantageously be arranged opposite one another as a pair of wedge surfaces. Particularly preferably, two of these pairs of wedge surfaces are provided. Any corner areas between the pairs of wedge surfaces can have surfaces or radii that can also be inclined in a wedge shape.

[0026] It is expedient to provide at least one suitable clamping means by means of which a pre-tension can be generated between the wedge surfaces of the connecting means of the down tube unit and the wedge surfaces of the connecting means of the pedal drive section in the manner of the screw connection of a pedal crank square, with which an axial tightening force can be generated between the inner square of the pedal crank shaft and the inner square of the pedal crank.

[0027] The clamping device is attached to the lower end, preferably within the down tube unit. When assembled, the clamping device is concealed from the outside. It is not visible from the outside of the assembled bicycle frame.

[0028] Advantageously, a support surface for a cover element is provided at the top of the head tube section of the front frame element and in an upper region of the seat tube section. As a cover element, a separate cover element can be provided for the support surface of the front frame element and a separate cover element for the support surface of the rear frame element. Alternatively, an integrated cover element can be provided which, when the two frame elements are joined together, covers both the support surface of the front frame element and the support surface of the rear frame element. The integrated cover element is then spatially arranged like a top tube of a diamond frame and can therefore also be aptly referred to as a top tube cover element.However, unlike a conventional top tube of a diamond frame, the integrated top tube cover element does not have to fulfill a corresponding load-bearing function for the operational safety of the plastic bicycle frame. Instead, it is sufficient if the top tube cover element is suitable for lifting a ready-to-use bicycle. The support surface of the front frame element is conveniently aligned with the support surface of the rear frame element, so that the top tube cover element can simply be designed straight.

[0029] At least one of the frame elements and / or a top tube cover element is suitably made of a plastic selected from the following group of plastics: polyamide, polyacetal / polyoxymethylene, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, polytetrafluoroethylene, acrylonitrile butadiene styrene, polyketone, polyether ketone, polyether ether ketone, polysulfone, polybutylene terephthalate, polyphthalamide, polyphenylene sulfide, polyphenyl sulfone, thermoplastic polyurethane, thermoplastic elastomer.

[0030] The plastic may contain at least one filler in the form of reinforcing particles and / or reinforcing fibers (compound).

[0031] At least one of the frame elements is expediently designed as a primary molded component, preferably as an injection molded component.

[0032] In the rear triangle frame element of the present invention, the pedal drive section forms a central component. The central component forms a stable base of the rear triangle frame element.

[0033] For this purpose, the seat tube section is provided as an integral component on the pedal drive section and is designed in one piece (monolithic) with the pedal drive section.

[0034] Furthermore, the lower stays are provided on the pedal drive section and are also designed as one piece with it as integral components. The two seat stays are in turn designed as one piece on the seat tube section, with the seat stays being designed as one piece at their other ends with one of the lower stays. The pedal drive section also has the connecting means by means of which the front frame element is to be connected to the rear frame element. This connecting means of the pedal drive section is located, in side view, within the crank circle of a standard pedal crank. Furthermore, with regard to the rear frame element, this connecting center point of the pedal drive section is located at a distance in front of the position of the pedal crank shaft when viewed in the direction of travel.

[0035] The area consisting of the seat tube section and the pedal drive section is subject to particularly high loads during ferry operation. The one-piece design in this heavily loaded area proves advantageous for providing a highly stressed bicycle frame. The rear frame element designed in this way can therefore very well absorb the forces that enter the seat tube section from the weight of the rider, as well as those forces that enter the pedal drive section via the pedal crankshaft. Due to the rear frame element designed in this way, the invention is particularly suitable for arranging an auxiliary motor in the pedal drive section, which introduces additional forces.It has been shown that it is advantageous to provide the required dividing point between the rear frame element and the front frame element at a distance from the seat tube section and to shift it slightly forward on the pedal drive section. For this purpose, the dividing point, or rather the connection center, is advantageously arranged at a (horizontal) distance in front of the position of the pedal crankshaft.

[0036] The invention is illustrated below by way of example in a drawing and described in detail with reference to several figures. In the drawings: Fig. 1 shows a first embodiment of the modular plastic bicycle frame according to the invention,

[0037] Fig. 2 shows a second embodiment of the modular bicycle frame made of plastic according to the invention,

[0038] Fig. 3 shows a side view of the bicycle frame according to Fig. 1,

[0039] Fig. 4 shows a side view of the bicycle frame according to Fig. 2,

[0040] Fig. 5 shows a variant of the bicycle frame of Fig. 1 with a partial section,

[0041] Fig. 6 is a side view of the bicycle frame of Fig. 5,

[0042] Fig. 7 shows an enlarged section of the area shown in

[0043] Fig. 6 is marked VII.

[0044] Figures 1 and 2 show a first exemplary embodiment and a second exemplary embodiment of a modular bicycle frame 1 according to the invention, respectively. In each case, this is a bicycle frame 1 with a rigid, unsprung rear triangle (hardtail). The proposed modular bicycle frame 1 is designed to be ridden in a right-seated position. For this purpose, it has provisions to offer a cyclist three interfaces. The first interface is a saddle interface, the second a pedal crank interface, and the third a handlebar interface. Both bicycle frames 1 in Figures 1 and 2 are essentially made of plastic, namely from two joined frame elements, namely a front frame element 2 and a rear frame element 3. The bicycle frames produced in this way in Figures 1 and 2 differ in frame size. Fig.Fig. 1 shows a smaller bicycle frame 1, and Fig. 2 shows a larger bicycle frame 1. Following, identical reference numerals are used for identical features of the two bicycle frames. The different frame sizes of the bicycle frame are designed for the same wheel size, for example, a wheel size of 28 inches.

[0045] The modular bicycle frame 1 comprises the two aforementioned frame elements 2 and 3. Each frame element is designed to be connected once and permanently to the other frame element 2 or 3 at a dividing point 4.

[0046] The handlebar interface is assigned to the front frame element 2. It comprises a down tube unit 5 and, for the aforementioned handlebar interface, a head tube section 6 for accommodating a steering bearing and a front wheel fork. The rear frame element 3 comprises a seat tube section 7 for the saddle interface and is provided with a pedal drive section 8 for the pedal crank interface.

[0047] The connection of the front frame element to the rear frame element at the dividing point 8 is designed as a permanent connection 9. During the normal life cycle of the bicycle frame 1, separation of the two frame elements 2 and 3 is avoided. The permanent connection 9 is carefully manufactured to ensure the operational reliability of the bicycle frame over its entire life cycle.

[0048] According to the examples in Figures 1 and 2, the pedal drive section 8 of the rear frame element 3 is designed to accommodate a pedal drive which has a pedal crank drive and an auxiliary drive with an electric motor for support.

[0049] The front frame element 2 offers space to accommodate a battery unit for supplying the electric motor with electrical energy. The space for the battery unit is provided in the down tube unit 5, which has an elongated section 10 that forms a housing 11 (housing section). The housing section is open on an underside. A closure lid can be provided for the housing opening formed in this way. Alternatively, a closure lid can be designed as a component of a battery unit. Along a longitudinal axis 12 of the down tube unit 5, the cross-section of the housing is essentially constant. At a lower end 13 of the down tube unit 5 there is a connecting means 14 that is concealed inside the assembled bicycle frame 1. This can be seen from the outside in Fig. 1 only the division point 4 of the bicycle frame 1 as a circumferential line or as a circumferential joint 15 .The division point 4 is arranged in an orthogonal plane 16 relative to the longitudinal axis 12 of the down tube unit 5.

[0050] The head tube section 6 is provided with a cylindrical head tube opening 17 for receiving a steering bearing. An underside of the head tube section 6 forms a lower end face 18 at the edge of the head tube opening 17. The lower end face 18 is arranged orthogonally relative to a longitudinal axis 19 of the head tube opening 17. An upper side of the head tube section 6 has an upper end face 20 which borders the head tube opening 17 and is also arranged orthogonally relative to the longitudinal axis 19 of the head tube section 6. In addition to the upper end face 20, a further circumferential housing edge 21 is provided on the upper side of the head tube section 6, which surrounds the upper end face 20. This housing edge 21 forms a support surface 22 which extends slightly backwards in the direction of travel in the direction of the down tube unit 5.In addition, the support surface 22 is arranged with an inclination 5 relative to the plane of the upper end face 20 of the head tube section 6, as noted in Fig. 3.

[0051] The rear frame element 3 has two frame triangles, namely a left frame triangle 23, which comprises a left lower strut 24, a left seat stay 25 and a third side 26, which is composed of part of the seat tube section 7 and part of the pedal drive section 8. In addition, a right frame triangle 27 is provided, which is a mirror image of the left frame triangle 23 and has a lower strut 28 and a seat stay 29. The left seat stay 25 and the right seat stay 29 are connected to the seat tube section 7 and, together with the seat tube section 7, form a seat stay node 30 of the rear frame element 3. A second support surface 31 is formed in the area of ​​the seat stay node 30.

[0052] According to Fig. 1 and Fig. 2, a cover element is provided for the front frame element 2 and for the rear frame element 3, or rather, Figures 1 and 2 each show two variants of cover elements. According to the first variant, a separate cover element 32 is provided for the front frame element 2, which covers the support surface 22 of the front frame element 2, and a separate cover element 33 is provided for the rear frame element 2, which covers its support surface 31. The cover element 32 of the front frame element 2 has a contour that is complementary to the aforementioned housing edge 21 of the head tube section 6. It also has an opening 34 through which a fork shaft of a front wheel fork fits. If the end of a fork shaft is inserted through the opening 34, a handlebar mount can be attached to it, for example a standard ahead handlebar stem.If the separate cover elements 32 and 33 are used, the assembled state results in a bicycle frame 1 with a low step-through.

[0053] The second variant of the cover element is an integrated cover element which, when the two frame elements 2 and 3 are joined together, covers both the support surface 22 of the front frame element 2 and the support surface 31 of the rear frame element 3. The integrated cover element is then spatially arranged like a top tube of a diamond frame and can therefore also be aptly referred to as a top tube cover element 35. In contrast to a conventional top tube of a diamond frame, however, the integrated top tube cover element 35 does not have to fulfill a corresponding load-bearing function for the operational safety of the plastic bicycle frame 1. Instead, it is sufficient if the top tube cover element 35 is suitable for lifting a bicycle that is ready for use and for shouldering the bicycle, for example using the top tube cover element 35.

[0054] The support surface 22 of the front frame element 2 and the

[0055] The support surface 31 of the rear frame element 3 lies in a line 36 when the two frame elements are joined together. The aligned arrangement of the support surfaces 22 and 31 can best be seen in Figures 3 and 4, which show the smaller and larger bicycle frames respectively as side views, both of which are shown with the variant of the integrated top tube cover element 35. The top tube cover element 35 is shown in Figures 1 and 2 with four screws, two of which are for fastening to the support surface 22 of the front frame element 2 and two of which are for fastening to the support surface 31 of the rear frame element 3, which have corresponding threaded holes assigned to them. Instead of the top tube cover element 35, the separate cover elements 32 and 33 can be fastened using the same screws. This connection does not have to be a permanent connection.The screws can be loosened and the cover elements 32 / 33 or 35 can be screwed on.

[0056] Fig. 3 shows a side view of the smaller bicycle frame 1 according to Fig. 1. Fig. 4 shows a side view of the larger bicycle frame of Fig. 2. For the purpose of comparability of the two frame sizes, the position of a pedal crank shaft 37 is shown in both Figures 3 and 4 and aligned on a common vertical dash-dot line 38. Furthermore, a connection center point M1 is noted between the front frame element 2 and the rear frame element 3 in the area of ​​the division point 4 provided there.

[0057] In the side views of Figures 3 and 4, a crank radius K is also shown, which corresponds to the standard length of a pedal crank. When the bicycle is fully assembled, the pedals rotate on the crank circle indicated by a dash-dot line. The connection center M1, or rather the division point 4 of the bicycle frame, is located within the crank circle in the side view of these examples and is thus closer to position 37 of the pedal crankshaft than the pedals.

[0058] In addition, an upper head tube point S 1 is marked on the top of each head tube section 6. The connection center point M 1 is assigned to the front end of the down tube unit 5. Its position M 1 is identical in the examples in Figures 3 and 4; the position is always the same regardless of the frame size. When the frame elements 2 and 3 are joined together, both connection center points M 1 have the same spatial position relative to the position of the pedal crankshaft 37. The spatial position of the upper head tube point S 1, however, is somewhat further away from the position of the pedal crankshaft 37 in Figure 4 than in Figure 3, both further away in the vertical direction and further away in the horizontal direction (direction of travel). Between Figures 3 and 4, a measurement AL is entered that shows the horizontal length difference between the two frame sizes.Furthermore, the direct distance between the connection center point M1 and the upper head tube point S1 is defined as a down tube dimension B of the front frame element, and the length of the head tube section 6 is defined as dimension A. A lower end of the head tube section 6 is at the same level for both the smaller bicycle frame in Fig. 3 and the larger bicycle frame according to Fig. 4. An identical front wheel fork can then be used for both frame sizes, with the same wheel size installed, for example a 28-inch wheel.

[0059] Furthermore, a length measurement C is entered in the direction of travel, which indicates the horizontal distance between the connection center point M1 and the head tube point S1. The down tube unit 5 is arranged at an angle α relative to the horizontal. The angle α is identical in the examples in Figures 3 and 4. The seat tube section 7 of the larger bicycle frame 1 in Figure 4 is longer by the dimension R than the seat tube section 7 of the smaller bicycle frame 1 according to Figure 3. A drawn seat tube angle β is identical in Figures 3 and 4. Likewise, the steering angle γ is identical in Figures 3 and 4.

[0060] The level of the upper head tube point S 1 and the level of the connection center point M 1 have a difference, which is noted in Figures 3 and 4 with a dimension D. The dimension D of the smaller bicycle frame in Fig. 3 is smaller than the dimension D of the larger bicycle frame according to Fig. 4.

[0061] A longitudinal axis 39 of the seat tube section 7 and the longitudinal axis 12 of the down tube unit 5 form an intersection point Z in the example of the smaller bicycle frame 1 in Fig. 3 and also in the example of the larger bicycle frame 1 in Fig. 4. In both examples in Figs. 3 and 4, the intersection point Z is at an identical position relative to the position of the pedal crank shaft 37.

[0062] In Figures 3 and 4, an angle bisector 40 is drawn between the longitudinal axis 39 of the seat tube section 7 and the longitudinal axis 12 of the down tube unit 5. The position of the pedal crank shaft 37 in both Fig. 3 and Fig. 4 lies in the direction of travel between the angle bisector 40 and the longitudinal axis 39 of the seat tube section 7.

[0063] In the rear frame element 3 of the present invention, the pedal drive section 8 forms a central component which forms a stable base of this rear frame element 3.

[0064] For this purpose, the seat tube section 6 is provided as an integral component on the pedal drive section 8 and is designed as a single piece (monolithic) with the pedal drive section 8. Furthermore, the lower struts 24 and 28 are provided on the pedal drive section 8 and are also designed as single piece therewith as integral components. The two seat stays 25 and 29 are in turn designed as a single piece on the seat tube section 6, with the seat stays being designed as a single piece at their other ends with one of the lower struts 24 and 28 respectively. The connecting means M1, by means of which the front frame element 2 is to be connected to the rear frame element 3, is also provided on the pedal drive section 8.This connecting means M1 of the pedal drive section 8 is located, when viewed from the side, within the crank circle, or rather the crank radius K, of a standard pedal crank. Furthermore, with respect to the rear frame element 3, this connecting center point M1 of the pedal drive section 8 is located, viewed in the direction of travel, at a distance P in front of the position 37 of the pedal crank shaft. In the exemplary embodiment in Fig. 3, a distance P is not noted, but is present there too.

[0065] The area consisting of the seat tube section 6 and the pedal drive section 8 is subject to particularly high loads during ferry operation. The one-piece design in this heavily loaded area proves to be advantageous for providing a highly stressed bicycle frame. The rear frame element 3 designed in this way can therefore very well absorb the forces that enter the seat tube section 6 from the weight of the rider, as well as those forces that enter the pedal drive section 8 via the pedal crankshaft. Last but not least, due to the rear frame element 3 designed in this way, the invention is particularly suitable for arranging an auxiliary motor in the pedal drive section 8, which introduces additional forces.It has been shown that it is advantageous to provide the required dividing point between the rear frame element 3 and the front frame element 2 at a distance from the seat tube section 6 and to shift it slightly forward on the pedal drive section 8. For this purpose, the dividing point, or rather the connection center M1, is advantageously arranged at a distance P in front of the position 37 of the pedal crankshaft.

[0066] A ratio of the length A of the head tube section relative to the down tube dimension B can be defined (A / B), as can a ratio of the length A of the head tube section relative to the length dimension C (A / C). In the present example in Fig. 3 regarding the smaller bicycle frame, the ratio A / B is 1:5.18 and the ratio A / C is 1:2.59. In the example of the larger bicycle frame according to Fig. 4, the ratio A / B is 1:4.29 and the ratio A / C is 1:2.14.

[0067] Fig. 5 shows an example of the smaller bicycle frame 1 according to Fig. 1, wherein the two frame elements 2 and 3 in Fig. 5 are not yet joined together. In addition, a partial section is shown, which shows connecting means of the front frame element 2 and the rear frame element 3, which serve for the permanent connection 9 of the frame elements 2 and 3. In the present example, the connecting means are designed as a wedge connection 41, similar to the wedge connection between a pedal crank shaft with an outer square and a pedal crank with a matching inner square, which are connected to one another by elastic tension. For this purpose, the connecting means 14 of the front frame element 2 is provided on a projection 42 which is arranged on the lower end 13 of the down tube unit 5. The projection 42 has inclined surfaces on its outer circumference, which can be referred to as wedge surfaces.In the present example, the projection is provided with a left-hand wedge surface 43 in the direction of travel and an opposite right-hand wedge surface, which interact with complementary wedge surfaces on the pedal drive section 8, such as the wedge surface 43'. The left-hand wedge surface forms a first wedge surface pair with the right-hand wedge surface of the projection 42. In addition, a front wedge surface 45 and a rear wedge surface 46 in the direction of travel are provided, which likewise form a wedge surface pair. These interact with complementary wedge surfaces 45' and 46' that are assigned to the pedal drive section 8. Between the two wedge surface pairs, four corner regions are provided on the projection 42, which form smaller surfaces that are also arranged with a wedge inclination. All wedge surfaces on the circumference of the projection 42 form an irregular polygon with eight sides when viewed in cross section.

[0068] Matching the projection 42 on the down tube unit 5 of the front frame element 2, a connecting means 47 is provided on the pedal drive section 8 of the rear frame element 3, said connecting means providing a complementary recess 48. In this recess 48, inwardly directed surfaces are provided which form wedge surfaces, like the aforementioned wedge surfaces 43' and which interact with the outwardly directed wedge surfaces of the projection of the front frame element 2. Relative to the longitudinal axis 12 of the down tube unit 5, the wedge inclination is dimensioned such that a permanent connection can be achieved with the plastic material used, which connection should not come loose during normal operation and is permanently reliable. In the elastically tensioned state, the plastic wedge connection prepared in this way creates a self-locking effect that the plastic material can maintain permanently.

[0069] In order to create the elastic tension, a tensioning means 49 is provided, specifically in the form of a screw connection 50. In the present example, the screw connection comprises three push-through screws 51, 52 and 53, as shown in Fig. 5, and three hexagon nuts 54, 55 and 56. The pedal drive section 8 and the lower end 13 of the down tube unit 5 each have three holes which, when the frame elements 2 and 3 are joined together, are aligned in pairs so that a screw can be pushed through into an aligned opening. In Fig. 5 and in Fig. 6, using the example of screw 53, it is shown that the screws are pushed through from the side of the pedal drive section 8 into the projection 42 of the down tube unit 5. There, the screw 53 is screwed with the hexagon nut 56 and the other screws in the same way.On an inner side 57 of the projection 42, three hexagonal retaining openings are advantageously provided, such as the retaining opening 58 for the hexagonal nut 56. The retaining opening 58 acts as an anti-twist device for the hexagonal nut 56. As a result, the screw connection can be established at this point in the lower ear unit 5 without the aid of a tool. A tool is then only required for actuating the screw head in the pedal drive section 8 in order to apply a torque at this point that generates a tightening force for the wedge connection.

[0070] The permanent connection is carefully created and for this purpose the screws 51, 52 and 53 are tightened in a defined sequence. This can be done in several passes. For the individual passes or at least in the final state, a defined tightening torque for each screw must be carefully adhered to. Furthermore, care is taken to ensure that the frame elements 2 and 3 are precisely aligned to one another so that both frame elements are aligned in the direction of travel and are connected to one another without distortion or twisting. Alternatively, an auxiliary device can be used to create the permanent connection in which the front frame element 2 and the rear frame element 3 can be aligned to one another in order to build up the tightening force for the wedge connection in exact spatial positions relative to one another.

[0071] In Fig. 5, a cavity 59 formed in the down tube unit 5 can also be seen, which forms a housing 60 which can be used to accommodate a battery unit.

[0072] Fig. 6 shows a reduced side view of the bicycle frame 1 of Fig. 1, wherein in Fig. 6 a detail VI I is marked, which is shown enlarged in Fig. 7. Fig. 7 is a sectional view in the area of ​​the dividing point 4 between the front frame element 2 and the rear frame element 3. The two frame elements 2 and 3 are shown in Fig. 7 in the joined state. The sectional plane of the sectional view runs through one of the through-openings for the lower screw connection, which includes the screw 53 and the hexagon nut 56. The two other screw connections are located outside the sectional plane. The projection 42 provided with the wedge surfaces on the lower end 13 of the down tube unit 5 has a distal front surface 59 and the recess 48 provided with the inwardly directed wedge surfaces on the pedal drive section 8 is provided with a bottom surface 60.In the assembled state according to Fig. 7, a gap 61 is provided between the front surface 59 and the bottom surface 60.

[0073] Viewed from the outside, the circumferential joint 15 is provided between the down tube unit 5 of the front frame element 2 and the pedal drive section 8 of the rear frame element 3, which is also shown as a gap 62 in Fig. 7. Therefore, contact occurs exclusively between the complementary wedge surfaces involved between the connecting means 14 of the down tube unit 5 of the front frame element 2 and the connecting means 47 of the pedal drive section 8 of the rear frame element 3. This ensures a permanent and reliable connection through the elastic tensioning between the connecting means.

[0074] List of reference symbols 1 Bicycle frame 2 Front frame element 3 Rear frame element 4 Division point 5 Down tube unit 6 Head tube section 7 Seat tube section 8 Pedal drive section 9 Permanent connection 10 Elongated section 11 Housing 12 Longitudinal axis (down tube unit) 13 Lower end face 14 Connecting means (down tube unit) 15 Circumferential joint 16 Orthogonal plane 17 Head tube opening 18 Lower end face 19 Longitudinal axis (head tube section) 20 Upper end face 21 Housing edge 22 Contact surface 23 Left frame triangle 24 Lower strut 25 Seat stay 26 Third side 27 Right frame triangle 28 Lower strut 29 Seat stay 30 Seat stay node 31 Second contact surface 32 Separate cover element (front triangle) 33 Separate cover element (rear triangle) 34 Opening 35 Top tube cover element 36 Flucht37 Crankshaft, position of the... 38 Dash-dot line vertical 39 Longitudinal axis (seat tube section) 40 Angle bisector 41 Wedge connection 42 Projection 43, 43' left wedge surface 45, 45' front wedge surface 46, 46' rear wedge surface 47 Connecting element 48 Recess 49 Clamping element 50 Screw connection 51 Screw 52 Screw 53 Screw 54 Hexagon nut 55 Hexagon nut 56 Hexagon nut 57 Inside 58 Hexagonal retaining opening

[0075] 59 Cavity

[0076] 60 housings

[0077] 61 Front surface (projection)

[0078] 62 Floor area (connection)

[0079] 63 gap

[0080] 64 Gap a Down tube angle ß Seat tube angle

[0081] Y steering angle

[0082] 5 Inclination (contact surface 22 )

[0083] AL length difference s angle

[0084] A Length of head tube section

[0085] B Down tube dimension

[0086] C Length unit

[0087] K Crank radius

[0088] Ml connection center

[0089] P distance

[0090] S 1 head tube point

[0091] V Connection point

[0092] Z intersection point

Claims

Claims 1. A modular bicycle frame (1) made of plastic for a bicycle, which provides three interfaces for a cyclist, a saddle as the first interface, a pedal crank as the second interface, and a handlebar as the third interface, wherein the bicycle frame (1) can be assembled by means of frame elements (2, 39) made of plastic and with the proviso that the frame elements (2, 3) can be connected at a dividing point (4), characterized in that the frame elements (2, 3) are designed modularly, that a first of the frame elements is designed as a front frame element (2) and a second frame element as a rear frame element (3), wherein the front frame element (2) comprises a down tube unit (5) and a head tube section (6) for the handlebar interface,wherein the rear frame element (3) is provided with a seat tube section (7) for the saddle interface and with a pedal drive section (8) for the pedal crank interface, with the proviso that the division point (4) between the front frame element (2) and the rear frame element (3) is to be considered unique, connecting permanent connection point (V).

2. Modular bicycle frame (1) according to claim 1, characterized in that the down tube unit (5) of the front frame element (2) has an elongated shape, and that the down tube unit (5) is provided with a lower end face (13) which has a connecting means (14).

3. Modular bicycle frame (1) according to claim 2, characterized in that the pedal drive section (8) of the rear frame element (3) is provided with a complementary connecting means (47), and that by means of the two complementary connecting means (14, 47) of the front and rear frame elements, the two frame elements (2, 3) can be permanently connected at the connection point (4).

4. Modular bicycle frame (1) according to claim 3, characterized in that the connecting means (V) provided on the pedal drive section (8) has a distance relative to the position (37) of a pedal crank shaft which is in a range of 0.5 times to 1.5 times the length of a standard pedal crank, or is preferably arranged at a distance which is equal to or smaller than the length of a standard pedal crank.

5. Modular bicycle frame (1) according to one of claims 1 to 4, characterized in that at the lower end face (13) of the down tube unit (5) the connection point (V) is arranged in a connection plane (16) which is arranged orthogonal to a longitudinal axis (12) of the down tube unit (5), and that a The intersection point of this plane with the longitudinal axis (12) of the down tube unit (5) defines a connection center point (Ml) of the down tube unit (5).

6. Modular bicycle frame (1) according to claim 5, characterized in that an upper head tube point (S1) of the head tube section (6) is defined, which lies at the upper end of the head tube section (6), namely at the intersection point of a longitudinal axis (19) of the head tube section (6) with the upper end of the head tube section (6).

7. Modular bicycle frame (1) according to claim 6, characterized in that the head tube section (6) has a length A, that the down tube unit (5) has a length B, which length B is defined as the distance between the upper head tube point (Sl) of the head tube section (6) and the connection center point (Ml) of the down tube unit (5), and that a front end length (C) directed in the direction of travel is defined as the horizontal distance between the upper head tube point (Sl) of the head tube section (6) and the connection center point (Ml) .

8. Modular bicycle frame (1) according to claim 7, characterized in that the length A of the head tube section (6) relative to the length B of the down tube unit (5) is in a ratio of 1:4 to 1:5.5 and preferably in a ratio of 1:4.2 to 1:5.

2.

9. Modular bicycle frame (1) according to claim 7 or 8, characterized in that the length A of the head tube section (6) relative to the front Length (C) in a ratio of 1:2 to 1:3 and preferably in a ratio of 1 / 2.1 to 1 / 2.

6.

10. Modular bicycle frame (1) according to one of claims 1 to 9, characterized in that the longitudinal axis (12) running through the elongated down tube unit (5) forms an intersection point (Z) with a longitudinal axis (7a) of the seat tube section in the joined state of the two frame elements (2, 3), and in that the intersection point (Z) lies on a side of the pedal drive section (8) facing away from the seat tube section (7).

11. Modular bicycle frame (1) according to claim 10, characterized in that an angle bisector (40) lies between the longitudinal axis (12) of the down tube unit (5) and the longitudinal axis (7a) of the seat tube section (7), wherein the pedal drive section (8) is designed such that the position (37) of a pedal crank shaft is located between the angle bisector (40) and the longitudinal axis (7a) of the seat tube section (7).

12. Modular bicycle frame (1) according to one of claims 1 to 11, characterized in that the rear frame element (3) comprises at least one lower strut (24, 28) with an associated dropout for a wheel axle of a rear wheel.

13. Modular bicycle frame (1) according to claim 12, characterized in that the lower strut (24, 28) is rooted on the pedal drive section (8).

14. Modular bicycle frame (1) according to claim 12 or 13, characterized in that the rear frame element (3) has at least one seat stay (25, 29) which is connected to the dropout for the wheel axle and is connected to the seat tube section (7).

15. Modular bicycle frame (1) according to claim 14, characterized in that the seat stay (25, 29) and the lower stay (24, 28) are arranged at a defined angle (s) to one another.

16. Modular bicycle frame (1) according to one of claims 2 to 15, characterized in that the connecting means (14) on the front end (13) of the down tube unit (5) of the front frame element (2) faces the connecting means (47) of the pedal drive section (8) in the assembled state, and that the two connecting means (14, 47) are concealed in the assembled state.

17. Modular bicycle frame (1) according to one of claims 2 to 16, characterized in that the connecting means (14) of the down tube unit (5) has at least one wedge surface (43, 45, 46) inclined to its longitudinal axis (12), and in that the connecting means (47) of the pedal drive section (8) is provided with at least one associated wedge surface (43', 45', 46') which is designed to be complementary to the wedge surface of the connecting means (14) of the down tube unit (5).

18. Modular bicycle frame (1) according to claim 17, characterized in that the wedge surface (43, 45, 46) of the connecting means (14) of the down tube unit (5) has an outwardly directed wedge surface before, while the wedge surface (43', 45', 46') of the connecting means (47) of the pedal drive section (8) is an inwardly directed wedge surface.

19. Modular bicycle frame (1) according to one of claims 2 to 18, characterized in that a plurality of wedge surfaces (43, 45, 46) are provided on the connecting means (14) of the down tube unit (5), and that these wedge surfaces are arranged in a polygonal circumferential manner.

20. Modular bicycle frame (1) according to one of claims 17 to 19, characterized in that at least two wedge surfaces (45, 46) of one connecting means (14) and two wedge surfaces (45', 46') of the associated connecting means (47) are opposite one another as a pair of wedge surfaces.

21. Modular bicycle frame (1) according to one of claims 17 to 20, characterized in that at least one suitable tensioning means (49) is provided, by means of which a pre-tension can be generated between the wedge surfaces (45, 46) of the connecting means (14) of the down tube unit (5) and the wedge surfaces (45', 46') of the connecting means (47) of the pedal drive section (8).

22. Modular bicycle frame (1) according to claim 21, characterized in that the clamping means (49) is attached to the lower end face (13) within the down tube unit (5), and in that the clamping means (49) is arranged so as to be concealed when viewed from the outside in the assembled state.

23. Modular bicycle frame (1) according to one of claims 1 to 22, characterized in that at least one of the frame elements (2, 3) is designed as a primary-molded component, preferably as an injection-molded component.

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