Single-track, motorized two-wheeler

Abstract

A single-track, motor-driven two-wheeler, with a one-piece, self-supporting passenger cell (16) made of fiber-reinforced plastic mounted on a frame (14), the passenger cell having two lateral, spaced-apart side rails (20) extending upwards from their front ends and forming front pillars (24) which transition into lateral roof rails (26) which form sections of the side rails (20), the roof rails (26) adjoining rear pillars (28) which extend downwards to the frame (14), and the side rails (20) being hollow bodies and being formed section by at least one plate-shaped cladding element (62, 68) extending towards the opposite side rail (20) and containing an integrated fiber-reinforced mat.

Description

[0001] The invention relates to a single-track, motor-driven two-wheeler.

[0002] To enable helmet-free riding on motorized two-wheelers, especially motorcycles, it is known to equip the motorized two-wheelers with a dome-shaped passenger compartment that simultaneously forms the roof of the two-wheeler. This makes it possible to operate the two-wheeler in public road traffic without having to wear additional protective clothing or a helmet.

[0003] In the well-known motorized two-wheelers with a roof structure, the passenger cell is formed by an aluminum tubular frame, with the tubes forming side beams which are then coupled together by means of a separate roof section.

[0004] US 2002 / 0130496A1 concerns a motorcycle with a seat and side sills to which airbags are attached.

[0005] The JP 2013-67 370 A concerns a motorcycle with a roof that can be attached to the motorcycle when needed.

[0006] The object of the invention is to improve such a two-wheeler in such a way that it becomes more stable and at the same time lighter.

[0007] This task is solved by a single-track, motorized two-wheeler with a one-piece, self-supporting passenger cell made of fiber-reinforced plastic, mounted on a frame. The passenger cell has two lateral, spaced-apart side rails extending upwards from their front ends, forming front pillars that transition into lateral roof rails, which are sections of the side rails. The roof rails adjoin rear pillars, and in particular, the roof rails transition into the rear pillars, thereby forming further sections of the side rails. The rear pillars extend downwards towards the frame, and the side rails are hollow bodies, i.e., tubular parts. These side rails extend in one piece at least along the front pillars to the roof rail, and in particular even to the rear pillars and downwards, in order to be attached to the vehicle frame there as well.However, these tubular columns are not prefabricated, closed sections along their entire length; rather, the hollow cross-section is formed section by section by one or more sheathing panels. The advantage lies in the fact that, firstly, material is saved, and secondly, the connection of the sheathing panels and their integration into the side beams is improved.

[0008] The passenger cell can be composed of several fiber-reinforced parts joined by hot bonding or cold bonding.

[0009] In hot bonding, resin-impregnated fabrics with a high fiber volume fraction (prepregs) are cured in an autoclave, or dry non-woven fabrics and / or braided semi-finished products are cured in one piece by subsequent resin infusion in a resin injection process (also called resin transfer molding) at high temperature and high pressure. In cold bonding, finished carbon fiber reinforced plastic parts are bonded together.

[0010] In both methods, components that are connected to each other in this way can no longer be separated from each other without damage and, according to the present invention, constitute one-piece parts.

[0011] According to a preferred embodiment, the parts that are attached to one another are prefabricated parts that are glued together by cold bonding.

[0012] The side rails can be connected to each other by at least one paneling section, which forms a projection below a windshield, a roof, and / or a rear wall in the area of ​​the rear pillars. This means that there can be one, two, or, for example, three paneling sections running laterally from one side rail to the opposite side rail, thus connecting the side rails.

[0013] The side rails can have lower, free-ending end sections, each formed by a tubular, fiber-reinforced, particularly prefabricated plastic part with an integrated, continuous, circumferential fiber reinforcement layer. This means that these end sections are circumferentially closed, tubular parts. Specifically, the fiber reinforcement layer is a wound layer.

[0014] The fibers can run in a crisscrossed pattern, and a predominant proportion, for example more than 65%, of the fibers run diagonally to the longitudinal center axis of the spars. This makes the spars both sufficiently stable and sufficiently flexible.

[0015] Multiple fiber layers can also be arranged on top of each other.

[0016] These tubular, fiber-reinforced plastic parts can be designed open on one side, creating a U-shaped profile that is closed by the cladding. This means that the side rails are formed over one section by circumferentially closed sections of a prefabricated plastic part, and over another section by sections where this plastic part is not circumferentially closed, but rather open in sections and only closed by the cladding.

[0017] To improve the connection of the sheathing components to the respective tubular, fiber-reinforced plastic part within the U-shaped profile, the respective plastic part, for example, has a laterally projecting, integrally molded flange at at least one free end of the U, to which the sheathing component is fully attached. If both legs have a flange, the two flanges preferably point away from each other.

[0018] An additional improvement in the connection, and above all an option for better securing the plastic components to their sheathing components, can be achieved through the following variant. The tubular, fiber-reinforced, especially prefabricated, plastic components have a circumferentially closed intermediate section adjacent to their open end. This intermediate section ends at a step, from which the plastic component has a greater depth. This depth is measured longitudinally along the imaginary central axis of the "U". As mentioned, the plastic component has a greater depth after the intermediate section, so the step forms a boundary surface for the immediately adjacent sheathing component. The sheathing component is thus placed onto the step, which thereby creates a kind of stop and fastening structure.

[0019] The side rails can also be formed, in sections, solely by two overlapping, attached sheathing sections. This means that in one section of the side rails, they are formed by the aforementioned tubular, preferably prefabricated plastic parts, while in other sections, e.g., in the roof, rear wall area, or porch, the sheathing sections themselves form the rails. This creates transition areas where the tubular plastic parts are attached to the sheathing sections.

[0020] Furthermore, the roof beams can be formed, at least in sections, by at least one plate-shaped sheathing element that merges seamlessly into the roof beams and defines the roof. This sheathing element extends from one roof beam towards the opposite roof beam. The side beams are also hollow bodies in this case.

[0021] One variation involves creating the roof by a single outer shell and at least one inner shell. The roof thus has an outer wall and an inner wall to form a hollow structure characterized by greater stability and lower weight.

[0022] The inner paneling section can have two inner shells extending from an associated roof beam to the center of the vehicle. Each shell thus begins at its roof beam and extends towards the center of the vehicle, where these inner shells are attached to each other.

[0023] The inner shells can overlap in the area of ​​the vehicle's center and be fully bonded to each other at this overlap point, e.g. by cold bonding.

[0024] Viewed in the longitudinal direction of the vehicle, the outer paneling section can curve downwards and then inwards along its side edges to form an inwardly open cross-section in the shape of a horizontal "U". The inner paneling section is then fully attached to one of the lower legs of the "U" with a projecting, preferably angled, edge. In a section perpendicular to the longitudinal axis of the vehicle, the inner paneling section extends upwards along this projecting edge and then curves towards the center of the vehicle. The area of ​​the "U" then forms the hollow roof beam.

[0025] The inner sheathing parts or the inner singular sheathing part may be connected to the outer sheathing part at a distance from the roof beam, or only partially connected to it, or there may be spacers between the inner and outer sheathing parts that are connected to both.

[0026] The passenger compartment preferably has side panels extending laterally and forward from the rear pillars. These panels are plate-shaped and project forward as part of the passenger compartment. They extend to the front edge of a rear seat backrest in the thorax and / or thigh and / or lower leg area of ​​the occupant, in order to protect them laterally, at least in part. The one-piece connection of the side panels and rear pillars allows for high stability transverse to the vehicle's longitudinal direction.

[0027] The side spars can be formed section by section by an associated tubular, prefabricated, fiber-reinforced plastic part with an integrated, continuous fiber reinforcement layer, whereby the plastic parts have a greater edge thickness than the adjacent sheathing parts. Due to the larger surface area of ​​the sheathing part, it has greater stability and can be made thinner in this area.

[0028] The fiber reinforcement layer can, in particular, be a wound fiber reinforcement layer. Advantageous fiber orientations have already been mentioned.

[0029] Preferably, the passenger cell is a fiber-reinforced plastic component. For example, the passenger cell is made of carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP). Furthermore, the passenger cell can also be a composite of different fibers, such as CFRP and Kevlar, CFRP and glass fibers, CFRP, Kevlar and glass fibers, or glass fibers and Kevlar. Alternatively or additionally, natural fibers may be included.

[0030] In general, a composite of different layers made of the same material is also conceivable. Such a composite could, for example, comprise one layer of CFRP, two layers of GFRP, and another layer of CFRP. By using a fiber-reinforced component, the weight of the passenger cell is significantly reduced compared to a passenger cell with a structure made of conventional materials, such as aluminum. This reduces the energy consumption of the two-wheeler during operation and improves its handling due to the lowered center of gravity.

[0031] A composite material with different fibers can be produced, for example, by having at least one layer used to manufacture a fiber-reinforced component contain different fibers. Alternatively, several layers can be used to manufacture a component, each containing different fibers, in particular, each layer containing only one type of fiber. The aforementioned examples can also be combined. That is, at least one layer contains different fibers and at least one other layer contains only one type of fiber.

[0032] Further features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made. The drawings show: - Fig. 1 a perspective view of a possible variant of a two-wheeler according to the invention, - Fig. 2 those who are on a two-wheeler Fig. 1 inserted, self-supporting passenger cell, - Fig. 3 a sectional view through a roof beam and the roof along line III-III as well as an enlargement of the roof in the area of ​​the middle, - Fig. 4 an enlarged view of a spar section in the area of ​​the transition of the side spar to the front section, - Fig. 5a to 5c each show a sectional view through a beam along lines IV-IV, VV and VI-VI in Fig. 4, - Fig. 6 a perspective view of the passenger compartment provided in the two-wheeler according to the invention in the area of ​​the front pillars from a low angle, and - Fig. 7 a perspective view of a free-ending end section that is part of the front or rear column.

[0033] Fig. Figure 1 schematically shows a single-track, motor-driven two-wheeler 10 according to the invention. The two-wheeler is, for example, electrically driven and includes a battery pack 12, which is part of a frame 14.

[0034] The two-wheeler has a preferably one-piece, self-supporting passenger compartment 16 with a roof 22, wherein the passenger compartment 16 is firmly attached to the vehicle structure, in particular to the frame.

[0035] The frame 14 can be formed mainly by a housing 18 of the battery pack 12.

[0036] The passenger cell is a fiber-reinforced plastic part, especially with CFRP fibers or a mixture of CFRP, glass fibers and / or Kevlar.

[0037] As will be explained below, the passenger cell 16 is preferably manufactured using hot bonding or cold bonding.

[0038] The passenger compartment 16 has two lateral, spaced-apart side rails 20, which extend upwards from the front towards the roof 22, forming front columns 24. These front columns 24 merge seamlessly into roof rails 26, and these in turn merge seamlessly into rear columns 28, which in Fig. The two columns are shown separately for identification purposes only. The rear columns 28 are part of a rear roof support structure, which will be discussed in more detail later.

[0039] Alternatively, the rear columns 28 can be attached to the associated roof beams 26 by a node part in the area of ​​the rear end of these.

[0040] The roof 22 is formed by at least one plate-shaped planking section, which connects the roof beams 26. The roof merges seamlessly into the roof beams 26, as will be explained further below.

[0041] Furthermore, the rear columns 28 are connected to each other by another paneling section, which forms a back wall 29. Here too, the connection is a one-piece connection.

[0042] Finally, in the illustrated embodiment, a so-called extension 30 is also provided, which connects the two front pillars 24 to each other, specifically below a windshield 32. This extension 30 is also a plate-shaped paneling element that merges seamlessly into the front pillars 24. The extension 30 comprises a cross member directly below the windshield 32 and a side panel 34, which, as shown in Fig. 2 can be seen, extending forward from the front pillar 24.

[0043] Side planks 38, extending laterally to the front of the seat back 26 and protecting the upper body and pelvic area, are integrally molded onto the rear columns 28.

[0044] The rear pillars 28 extend forward in an S-shape below the side panels 38 to be attached to the frame 14 at two attachment points 40. Corresponding attachment points 42 are also shown for the lower ends of the front pillars 24.

[0045] Overall, this results in a dome shape for the one-piece, self-supporting passenger cell 16.

[0046] The side rails 20 have a hollow chamber structure and are formed section by section by prefabricated, tubular, fiber-reinforced plastic parts.

[0047] With reference to Fig. 2. The individual sections of passenger compartment 16 are explained.

[0048] Viewed from the side, the passenger compartment 16 has lower ends 46 of the front pillars 24 below the front section 30. These lower ends 46 are formed by the previously mentioned circumferentially closed, tubular fiber-reinforced plastic parts, in which a fiber reinforcement layer 50 with intersecting fibers is embedded in the plastic, the fiber direction, viewed from the side, runs at an angle of 30° to 60° to a drawn longitudinal center axis to the associated front pillar 24, in particular at an angle of 45° thereto.

[0049] The lower ends 46 then transition into a section 52, which is marked by a circle formed by a broken line. In this section 52, the front columns 24 transition into the extension 30. This section is constructed in the same way as section 54 of the rear columns 28, which will be discussed in more detail later.

[0050] In an area 56, where the front columns 24 extend above the porch 30 to the roof 22, the front columns 24, like those at the lower ends 46, have a tubular cross-section and form circumferentially closed hollow profiles. This hollow profile also extends into the roof area and is in Fig. 3 marked with reference number 60.

[0051] At the latest with the start of the roof 22, the prefabricated hollow profile of the beams 22 is opened, whereby the two beams 22 have plate-like, inwardly extending widenings that form shells 70, 72. These sheathing sections simultaneously form the roof 22 together with a singular, outer sheathing section 62.

[0052] The singular, outer planking part 62 (see Fig. 3) forms the outer skin of the vehicle in the roof area and is a fiber-reinforced plastic part with an inserted fiber mat 64, which is only shown symbolically. The fiber mat 64 extends over the entire extent of the outer cladding part.

[0053] The outer cladding section 62 has a shell shape with side edges 66 that curve downwards and then inwards to form an inwards open cross-section in the shape of a horizontal U. The two U-shaped sections of the side edges 66 then face each other with their open sides. An inner cladding section 68 is composed of two shells 70, 72, which overlap each other in the area of ​​the vehicle's center 74 and are completely connected in the overlap area. For this purpose, one of the shells 70, 72 can have an upwardly or downwardly angled edge, on which the opposite shell, which is not angled in this case, can then rest. This also ensures longitudinal alignment of the shells 70, 72 with respect to each other and improved force transmission in the lateral direction.

[0054] The shells 70, 72 extend towards the side edge 66 just below the outer sheathing section 62 and then curve downwards, here further spaced from the outer sheathing section 62, to form the cavities for the roof beams 26. The edges 80 of the shells 70, 72 are then angled outwards and abut the lower legs 82 of the side edges 66, where they are also fully bonded together, in particular by cold bonding. This closes the U-shaped cross-section of the respective side edge 66 and simultaneously forms the roof beam 26. As a result, the closed hollow profile of the front columns 24 continues into the roof beams.

[0055] The same type of fastening is also possible for the rear pillars 28 on the roof 22.

[0056] Alternatively, the shells 70, 72 are not prefabricated units together with the front columns 24, whose reinforcement layers are formed as a common, one-piece reinforcement layer. Rather, the side beams 20 are completely prefabricated, tube-like parts made of fiber-reinforced plastic. The shells 70, 72 are manufactured separately from these. The shells 70, 72 and the outer cladding section 62 are then attached to the roof beams 26 by cold bonding or thermal joining. It is possible and conceivable that the roof beams 26 are open in sections and then closed again in sections by one of the cladding sections 64, 68.

[0057] Optionally, the roof 22 can also transition seamlessly into the rear wall 29, so that the planking parts 62 and the shells 70, 72 can be extended further to the rear and downwards to form the rear wall 29.

[0058] If no rear wall 29 extending into the roof 22 is provided, prefabricated, tubular and fiber-reinforced plastic parts may also be provided here.

[0059] In the illustrated embodiment, the sections of the roof 22 and the rear wall 29, i.e., the sheathing sections 62, 68, are also responsible for forming the rear columns 28. In area 54, the columns 28 are shown section by section with dashed lines to illustrate that in this area the columns 28 are formed by outer and inner sheathing sections 62 and that in this area a quasi-tube-like structure is formed by these sheathing sections 62, similar to the side edges 66. The side planks 38, as well as a rear roof extension 86, are formed by an outer and an inner wall, namely by an outer and an inner sheathing section, whereby here too the inner sheathing section 62 can be realized by a widening of the side rail(s) 22.

[0060] The end section 90 of the rear columns 28, which lies below the area 54, is constructed like the end area 46.

[0061] In Fig. Figure 4 shows an end section 46 of a front column 24 at the transition to the side paneling 34.

[0062] The Fig. Figures 5a to 5c each show a cross-sectional view along lines IV-IV, VV and VI-VI in Fig. 4.

[0063] In Fig. Figure 5b illustrates a lower transition area in which the spar 20 is still designed as a circumferentially closed hollow profile independently of the side planking 34 and the side planking 34 is attached to the side spar 20 over a large area by cold bonding.

[0064] In Fig. Figure 5c shows that the side rail 20 is open to the outside slightly higher up, and the side sheathing 34 is used to close the open side of the side rail 20. In this area, the side rail 20 has a U-shaped cross-section and a flange 94 projecting from the inner leg of the U, to which the side sheathing 34 is attached over its entire surface. The side sheathing 34 conforms to the outer leg of the U at its outer edge, ensuring a continuous surface attachment. The side sheathing 34 can seamlessly transition into the sheathing section 62.

[0065] As in Fig. As can be seen in Figure 5a, the side planking 34 overlaps the upper part of the end section 46 of the front column 24 on the outside. In this way, a closed profile can be formed by the side planking 34 and the spar 20, as shown in the sectional views in Fig. 5b and Fig. 5c is illustrated.

[0066] The transition of the end section 90 of a rear column 28 into the rear wall 29, in particular into the side plank 38, can be designed accordingly.

[0067] As an alternative to the above variants, the outer planking part 32 can also have forward-projecting arms (see Fig. 6), which either extend to the projection 30 or even form the projection 30 itself, i.e., merge seamlessly into the sheathing section 34. In this case, for the production of the front columns 24, the prefabricated tubular sections between the projection 30 and the roof 22 can also be U-shaped and open to the outside. The arms of the sheathing section 32 then close the open side to form the front columns 34 as a closed hollow profile.

[0068] Shell 72, like shell 70, extends from the roof 22 along the front pillars 24, where it forms an open U-profile to the outside, to the front extension 30 and then downwards, with the ends 46 then being closed circumferentially, as mentioned. The flanges 92 also run along the front pillars to the sides of the windshield. The outer paneling 32 is attached to these flanges 92 (accordingly). Fig. 5c).

[0069] Fig. 7 shows a variant of Fig. 5, i.e., the transition area between the front column 24 or the rear column 28 to the cladding (side cladding 34 or side plank 38).

[0070] In the region of its upper end, the tubular, fiber-reinforced, and preferably completely prefabricated plastic part, which in its completed state forms the end section 46, 90 of a front or rear pillar 24, 28 of the passenger compartment 16, is open on one side, so that a U-shaped profile is formed at the upper end in plan view. Molded flanges 92 project laterally from the free ends of the U, seamlessly merging into the rest of this plastic part. Below the open side, the end section 46, 90 is circumferentially closed, and further down, a step 94 is present, projecting away from the open side. Below this step 94, the end section 46, 90 has a greater depth T than in the intermediate section 96 formed by it, between the step 94 and the open side and the flanges 92. Here, the depth is only t. The depths t and T are measured longitudinally along a central axis M of the U.

[0071] An outer sheathing section 62, which, like the other sheathing sections, is plate-shaped, is fully attached to the end section 46. The sheathing section, which could be, for example, the sheathing section 62 or the outer sheathing section forming the projection 30, in particular the side sheathing 34, is fully connected to the flanges 92 and to the front surface 98 of the intermediate section 96. The sheathing section rests on the shoulder 94.

[0072] The transition from the rear end section 90 to the side plank 38 can be constructed accordingly.

[0073] Here too, if the corresponding column opens towards the U, it can form an inner shell and merge seamlessly into it.

[0074] As can be seen, the side rails 20 are formed section by section by sheathing parts, either completely by the sheathing parts in these areas or, as in the area of ​​the flanges 92, by a combination of partially open, otherwise tubular, fiber-reinforced plastic parts and sheathing parts to close open profiles.

[0075] Optionally, the prefabricated, tubular, fiber-reinforced plastic parts at the end sections 46, 90 can have a greater wall thickness than the sections of the side stringers 20 formed by sheathing parts.

[0076] The embedded fibers are either wound fibers, especially for the tubular plastic parts, or mats for the plate-shaped cladding parts and can be made of CFRP, fiberglass, or Kevlar or fiber mixtures.

Claims

[1] Single-track, motor-driven two-wheeler, with a one-piece, self-supporting passenger cell (16) made of fiber-reinforced plastic mounted on a frame (14), the passenger cell having two lateral, spaced-apart side rails (20) extending upwards from their front ends and forming front pillars (24) which transition into lateral roof rails (26) which form sections of the side rails (20), the roof rails (26) adjoining rear pillars (28) which extend downwards to the frame (14), and the side rails (20) being hollow bodies and being formed section by at least one plate-shaped cladding element (62, 68) extending towards the opposite side rail (20) and containing an integrated fiber-reinforcing mat. [2] Two-wheeler according to claim 1, characterized by, that the passenger compartment (16) is composed of several fiber-reinforced parts joined by hot bonding or cold bonding. [3] Two-wheeler according to claim 2, characterized by , that the side rails (20) are connected to each other by at least one paneling section (62, 68) which forms a front section (30) below a windshield (32), a roof (22) and / or a rear wall (29) in the area of ​​the rear pillars (28). [4] Two-wheeler according to claim 2 or 3, characterized by , that the side rails (20) have lower, free-ending end sections (46, 90) which are each formed by a tubular, fiber-reinforced, in particular prefabricated plastic part with an integrated, closed circumferential fiber reinforcement layer, in particular wherein the fiber reinforcement layer is a wound fiber reinforcement layer. [5] Two-wheeler according to claim 4, characterized by, that the tubular, fiber-reinforced plastic parts are open on one side and have a U-shaped profile there, which is closed by the sheathing part (62). [6] Two-wheeler according to claim 5, characterized by that the tubular, fiber-reinforced plastic parts in the area of ​​the U-shaped profile of at least one free end of the U have a laterally projecting, molded flange (92) to which the sheathing part (62) is fully attached. [7] Two-wheeler according to claim 5 or 6, characterized by , that the tubular, fiber-reinforced plastic parts have a closed intermediate section (96) adjacent to their open side, which ends at a step (94) from which the plastic part has a greater depth (T) measured in the longitudinal direction of the central axis (M) of the U than in the intermediate section (96), wherein the step (94) is a boundary surface for the immediately adjacent cladding part (62). [8] Two-wheeler according to any one of the preceding claims, characterized by , that the side rails (20) are formed section by section around the circumference exclusively by two superimposed, attached planking parts (62, 68). [9] Two-wheeler according to any one of the preceding claims, characterized by , that the roof beams (26) are formed at least sectionally by at least one plate-shaped planking part (62) which merges in one piece into the roof beams (26) and defines the roof (22), extending from one roof beam (26) in the direction of the opposite roof beam (26), wherein the side beams (20) are hollow bodies. [10] Two-wheeler according to claims 8 and 9, characterized by , that the roof (22) is produced by a singular shell forming an outer sheathing part (62) and by at least one shell forming an inner sheathing part (68). [11] Two-wheeler according to claim 10, characterized by, that the inner cladding part (68) is formed by two inner shells (70, 72), each of these shells (70, 72) extending from its associated roof beam (26) to the vehicle center (74), in particular wherein the inner shells (70, 72) overlap in the area of ​​the vehicle center (74) and are fully connected to each other at the overlap point. [12] Two-wheeler according to claim 10 or 11, characterized by, that the outer paneling part (62) extends downwards and then inwards in an arc shape along its side edges (66) in the longitudinal direction of the vehicle to form an inwards open cross-section in the shape of a lying U, wherein the inner paneling part (68) is fully attached to a lower leg of the U with a projecting edge (80), wherein the inner paneling part (68) extends upwards from the projecting edge (80) on both side edges (66) and then over a radius to the center of the vehicle (74), wherein the area of ​​the U forms the roof beam (26). [13] Two-wheeler according to any one of the preceding claims, characterized by , that side panels (38) extending laterally forward from the rear pillars (28) project forward as part of the passenger compartment (16), extending to the front of a rear seat backrest (36) in the thorax area and / or thigh and / or lower leg area of ​​an occupant. [14] Two-wheeler according to any one of the preceding claims, characterized by , that the side stringers (20) are formed section by section by an associated tubular, prefabricated, fiber-reinforced plastic part with an integrated, closed circumferential fiber reinforcement layer, wherein the plastic parts have a greater wall thickness than adjacent sheathing parts (62, 68). [15] Two-wheeler according to any one of the preceding claims, characterized by , that the side stringers (20) are tubular, prefabricated, fiber-reinforced plastic parts which have an open hollow profile in sections and whose wall widens to form a shell which forms a sheathing part and extends in the direction of the opposite side stringer (20).

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