Bicycle frames and bicycles

Abstract

To improve the shape accuracy of a bicycle frame.SOLUTION: A bicycle frame 10 includes: a head tube 1; a rear-wheel support portion 3 supporting an axle of a rear wheel of a bicycle; a long tube 2 formed of one tube extending from the head tube 1 to a rear-wheel support portion 3 without including a joint portion; and a seat tube 4 supported by the long tube 2 and extending upward from between a front end and a rear end of the long tube, as viewed from rightward and leftward directions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bicycle frame and a bicycle. [Background technology]

[0002] Conventional bicycle frames, for example, have a structure in which a down tube extends from the head tube and reaches near the crankshaft. A seat tube and chainstays extend from near the crankshaft. For example, Japanese Patent Application Laid-Open Publication No. 2021-107176 discloses an electrically assisted bicycle. The frame of this electrically assisted bicycle includes a down tube, seat tube, chainstays, a bracket, and seatstays. The bracket is connected to the down tube, seat tube, and chainstays. A mounting portion integral with the drive unit housing is attached to the frame. The mounting portion contacts the bracket. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-107176 Summary of the Invention [Problem to be solved by the invention]

[0004] A bicycle frame is made up of multiple components, such as a down tube, seat tube, and chain stays, joined together. Errors in the joining process during frame manufacturing can affect the frame's geometric accuracy. The inventors focused on this issue and investigated how to join the components together to improve the frame's geometric accuracy.

[0005] The present application discloses a bicycle frame and a bicycle that can improve the shape accuracy of the frame. [Means for solving the problem]

[0006] In an embodiment of the present invention, the bicycle frame comprises a head tube, a rear wheel support section that supports the axle of the rear wheel of the bicycle, a long tube formed from a single tube that extends from the head tube to the rear wheel support section without any joints, and a seat tube that is supported by the long tube and extends upward from between the front and rear ends of the long tube when viewed from the left-right direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing an example of the structure of a bicycle frame according to this embodiment. [Figure 2] FIG. 2 is a right side view showing an example of the configuration of the bicycle frame of this embodiment. [Figure 3] FIG. 3 is a right side view of an example bicycle including the frame 10 shown in FIGS. [Figure 4] FIG. 4 is a top view showing the positional relationship between the long tube 2 of the bicycle shown in FIG. 3 and other members. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Configuration 1) In an embodiment of the present invention, the bicycle frame comprises a head tube, a rear wheel support section that supports the axle of the rear wheel of the bicycle, a long tube formed from a single tube that extends from the head tube to the rear wheel support section without any joints, and a seat tube that is supported by the long tube and extends upward from between the front and rear ends of the long tube when viewed from the left-right direction.

[0009] According to the above configuration, a single long tube extends from the down tube to the rear wheel support portion without any joints. The seat tube is supported between the front and rear ends of the long tube. This prevents a decrease in shape accuracy due to joint errors. In other words, the shape accuracy of the frame can be improved. Furthermore, since the long tube connecting the head tube and the rear wheel support portion does not have any joints, such as welding or bolting, the frame strength is increased. This makes it possible to increase the strength of the frame without increasing its weight.

[0010] The form in which one member supports another member includes a case in which one member directly supports another member by being in contact with the other member, and a case in which one member indirectly supports another member by having another member between the first and second members. For example, another member may be between the long tube and the seat tube, or the long tube may support the seat tube by being in direct contact with the seat tube.

[0011] A single tube extending from the head tube to the rear wheel support without any joints means that the section from the head tube to the rear wheel support is formed of a single tube, rather than multiple joined tubes. The form of joining is not particularly limited. The joining may be, for example, welding, fastening with fasteners, adhesive bonding, press fitting, or a mechanical structure such as a screw joint. Furthermore, this joint refers to a joint that connects the path from the head tube to the rear wheel support, and does not refer to a joint that connects the long tube to another member such as the seat tube. Furthermore, at least one of the head tube or the rear wheel support may be formed of multiple members joined together.

[0012] (Configuration 2) In the above configuration 1, the rear wheel support portion may include a left rear wheel support portion that supports the left side of the rear wheel axle and a right rear wheel support portion that supports the right side of the rear wheel axle. The long tube may include a left long tube formed from a single tube that extends from the head tube to the left rear wheel support portion without any joints, and a right long tube formed from a single tube that extends from the head tube to the right rear wheel support portion without any joints. By forming each of the left long tube and the right long tube from a single tube in this way, the shape precision of the frame can be further improved. In addition, the frame strength can be further increased.

[0013] (Configuration 3) In the above configuration 2, the frame may further include a bridge portion provided between the left long tube and the right long tube and joined to both the left long tube and the right long tube. The seat tube may be supported by the long tubes via the bridge portion. This allows the seat tube to be supported between the left long tube and the right long tube. This increases the rigidity of the entire frame.

[0014] The seat tube may be joined to the bridge portion. A hanger to which a drive unit is fastened may be joined to the bridge portion. A battery support portion for supporting the battery may be provided to the bridge portion.

[0015] (Configuration 4) In the above-described configurations 2 and 3, the left long tube and the right long tube may be disposed so as to at least partially overlap when viewed from the left-right direction. That is, the left long tube and the right long tube may be disposed side by side in the left-right direction. This improves the balance of the frame in the left-right direction.

[0016] For example, the left long tube and the right long tube may overlap continuously at least in the section from the seat tube to the head tube when viewed from the left-right direction. As an example, the left long tube and the right long tube may overlap continuously at least in the section in front of the seat tube where the battery is stored when viewed from the left-right direction.

[0017] (Configuration 5) In any of the above configurations 1 to 4, the long tube may have a curved portion that is curved convexly upward or downward when viewed from the left-right direction. This increases the degree of freedom in designing the frame shape. For example, the curved portion of the long tube may be curved convexly downward when viewed from the left-right direction. In this case, the inclination of the portion of the long tube forward of the curved portion may be greater than the inclination of the portion of the long tube rearward of the curved portion when viewed from the left-right direction.

[0018] (Configuration 6) In the above-described configuration 5, the curved portion of the long tube may be curved downwardly in a convex manner when viewed from the left and right, and may be located forward of the seat tube. This makes it easier to ensure vertical space below the head tube in front of the seat tube. For example, space for storing a battery or space for the movable range of the front fork suspension can be ensured forward of the seat tube.

[0019] For example, a battery housing portion for housing a battery may be provided forward of the curved portion of the long tube. For example, the lower end of the seat tube may be supported by the bridge portion rearward of the curved portion of the long tube.

[0020] The long tube may further include, in addition to the curved portion, a rear straight portion that extends linearly from the curved portion to the rear wheel support portion when viewed in the left-right direction without curving. A hanger to which a drive unit is fastened may be attached to the rear straight portion of the long tube.

[0021] In addition to the curved portion, the long tube may further include a front straight portion that extends linearly from the curved portion to the head tube when viewed from the left and right. For example, a battery storage section may be provided in the front straight portion of the long tube.

[0022] For example, the long tube may include the front straight section, the curved section, and the rear straight section.

[0023] (Configuration 7) In any of the above configurations 1 to 6, a battery storage section for storing a battery may be provided between a portion of the left long tube forward of the seat tube and a portion of the right long tube forward of the seat tube. This allows the battery to be positioned efficiently. The battery storage section may be formed, for example, by a protrusion provided on the left long tube and the right long tube.

[0024] (Configuration 8) In any of the above configurations 1 to 7, the frame may further include a hanger that is attached to the long tube by fastening with a fastener. The hanger may have a hole for fastening with a fastener a drive unit that supports a crankshaft and holds a motor that is a power source for rotating the crankshaft. This allows the drive unit to be attached to the frame via the hanger. Therefore, the attachment structure of the drive unit is not restricted by the structure of the long tube. This increases the design freedom of the drive unit. Also, it becomes easier to attach the drive unit to the frame.

[0025] The configuration in which the hanger is attached to the long tube by fastening includes a configuration in which the hanger is fastened directly or indirectly to the long tube. For example, the hanger may be fastened directly to the long tube. Alternatively, the hanger may be fastened to a member joined to the long tube. As an example of the latter, the frame may further include a bridge portion provided between the left long tube and the right long tube and joined to both the left long tube and the right long tube, and a hanger fastened to the bridge portion with a fastener.

[0026] In a frame having a hanger, the right long tube or the left long tube does not have to be formed from a single tube that extends from the head tube to the rear wheel support part without any joints. For example, at least one of the right long tube or the left long tube may be formed from multiple tubes joined together, rather than from a single tube.

[0027] (Configuration 9) A bicycle equipped with a frame according to any one of the above configurations 1 to 8 is also included in embodiments of the present invention. The bicycle may include a crankshaft and a chain ring that rotates in conjunction with the crankshaft. The long tube of the frame may extend from the head tube, over the chain ring, to the rear wheel support portion when viewed from the left-right direction.

[0028] As a result, the long tube extends forward from the rear wheel support section, passing above the crankshaft, and reaches the head tube. The rear wheel support section is connected to the long tube in the fore-and-aft direction. This allows the frame to more easily absorb impacts from the rear wheel. In addition, the long tube is positioned away from components around the crankshaft, such as the chain, chainring, crankshaft, and seat tube, allowing for greater freedom in frame design.

[0029] For example, if the width of the rear tire is increased, the width of the chainstay must be increased in a conventional bicycle. Increasing the width of the chainstay requires a longer wheelbase to avoid interference with the chainring. In contrast, in configuration 9, even if the width of the rear tire is increased and the distance between the left long tube and the right long tube is widened, interference with the chainring, etc. is unlikely. Therefore, there is no need to increase the wheelbase.

[0030] (Configuration 10) A bicycle equipped with a frame according to any one of the above configurations 1 to 8 is also included in the embodiments of the present invention. The bicycle may include a crankshaft, a drive unit that supports the crankshaft and holds a motor that is a power source for rotating the crankshaft, and a hanger that is attached to the long tube by fastening with a fastener. The drive unit may be fastened to the hanger with a fastener. This increases the design flexibility of the drive unit and makes it easier to attach the drive unit to the frame. For example, the drive unit may be located below the long tube when viewed from the left-right direction.

[0031] (Configuration 11) A bicycle equipped with a frame according to any one of the above configurations 1 to 8 is also included in the embodiments of the present invention. The bicycle may include at least two batteries housed between the left long tube and the right long tube. This allows for efficient placement of large-capacity batteries.

[0032] The at least two batteries may be arranged side by side in the vertical direction between the left long tube and the right long tube, thereby enabling efficient arrangement of a plurality of batteries.

[0033] The at least two batteries may be housed so that the longitudinal direction of each of the at least two batteries is the same as the extending direction of the portions of the left long tube and the right long tube that house the plurality of batteries, thereby enabling efficient arrangement of the plurality of batteries.

[0034] The at least two batteries may be stored in a state in which a rotation angle of one of the at least two batteries about an axis in the longitudinal direction is different from a rotation angle of the other battery about an axis in the longitudinal direction, thereby enabling efficient arrangement of the plurality of batteries.

[0035] The right and left long tubes having the battery storage compartments do not have to be formed from a single tube extending from the head tube to the rear wheel support section without any joints. For example, at least one of the right and left long tubes may be formed from multiple tubes joined together.

[0036] A bicycle according to an embodiment of the present invention will now be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and descriptions of those parts will not be repeated. Furthermore, the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components or the dimensional ratios of the components. In this application, the front-to-rear, left-to-right, and up-to-down directions of the frame are the same as the front-to-rear, left-to-right, and up-to-down directions of the bicycle including the frame. The front-to-rear, left-to-right, and up-to-down directions of the bicycle refer to the front-to-rear, left-to-right, and up-to-down directions of the bicycle when the rider is seated on the seat and gripping the handlebars. The left-to-right direction is the same as the vehicle width direction. The frame configuration viewed from the left-to-right direction has the same meaning as the frame configuration viewed from the side.

[0037] The manner in which one component is connected or attached to another component includes a case in which one component is directly connected or attached to the other component while in contact with the other component, and a case in which one component is indirectly connected or attached to the other component while there is another component between the two components.

[0038] FIG. 1 is a perspective view showing an example of the configuration of a bicycle frame according to this embodiment. In the example of FIG. 1, a frame 10 includes a head tube 1, a rear wheel support portion 3, a long tube 2, and a seat tube 4. The long tube 2 is a single tube that connects the head tube 1 and the rear wheel support portion 3. In other words, the long tube 2 extends from the head tube 1 to the rear wheel support portion 3 without any joints formed by welding, fastening, or the like. The seat tube 4 is supported by the portion of the long tube 2 between the head tube 1 and the rear wheel support portion 3. When viewed from the left-right direction (side view), the seat tube 4 extends upward from between the front and rear ends of the long tube 2.

[0039] Because the long tube 2 does not include any joints such as welds or fastenings, there is no deviation in the tube extension direction or position due to joint errors. This reduces errors in the design shape of the frame 10, increasing shape accuracy. Also, because the long tube 2 does not include any joints, there is no reduction in strength due to joints. Therefore, compared to configurations with joints, strength increases without increasing weight. This makes it possible to reduce the weight while increasing the strength of the frame.

[0040] In the example of FIG. 1, the rear wheel support portion 3 includes a left rear wheel support portion 3L that supports the left side of the rear wheel axle, and a right rear wheel support portion 3R that supports the right side of the rear wheel axle. The long tube 2 includes a left long tube 2L and a right long tube 2R. The left long tube 2L is a single tube that connects the head tube 1 and the left rear wheel support portion 3L. The right long tube 2R is a single tube that connects the head tube 1 and the right rear wheel support portion 3R. The seat tube 4 is inserted between the left long tube 2L and the right long tube 2R.

[0041] This configuration increases the degree of freedom in the height at which the long tube 2 intersects with the seat tube 4. This also increases the degree of freedom in the spacing between the left long tube 2L and the right long tube 2R. For example, by positioning the long tube 2 at a height that does not interfere with the chain, the left-right position of the long tube 2 is not restricted by the chain or chainring. For example, if you want to increase the width of the rear tire, you can increase the left-right spacing between the left long tube 2L and the right long tube 2R without having to lengthen the wheelbase.

[0042] Furthermore, by disposing the seat tube 4 between the left long tube 2L and the right long tube 2R, the support strength of the seat tube 4 is increased, and therefore the strength of the frame 10 is increased.

[0043] The long tubes 2 (in the example of FIG. 1 , the left long tube 2L and the right long tube 2R) may be formed, for example, from hollow tubular members. The cross-sectional shape of the tubes constituting the long tubes 2 and other frame elements is not limited to a closed cross-section. For example, the tubes may be channel-shaped members having a U-, V-, or L-shaped cross-section. Alternatively, the tubes may be formed from a ribbed plate. When the cross-sectional shape of the tubes is closed, the cross-sectional shape is not particularly limited and may be, for example, circular, rectangular, or another shape. The manufacturing method of the tubes is not particularly limited, and the tubes can be manufactured by, for example, casting such as die casting, press molding, or other molding methods. The material constituting the long tubes 2 is not particularly limited, and may be, for example, aluminum, magnesium, carbon, iron, chromoly, or other alloys.

[0044] In the example of FIG. 1 , the frame 10 includes a bridge portion 5 provided between the left long tube 2L and the right long tube 2R. The bridge portion 5 is joined to both the left long tube 2L and the right long tube 2R. The bridge portion 5 is joined to the left long tube 2L and the right long tube 2R by, for example, welding or fastening. The seat tube 4 is supported on the long tubes 2 via the bridge portion 5.

[0045] In the example of Fig. 1, the bridge portion 5 is joined to the right side surface of the left long tube 2L and the left side surface of the right long tube 2R. In other words, the bridge portion 5 is joined so as to contact the inner surfaces of the left long tube 2L and the right long tube 2R in the left-right direction (vehicle width direction), i.e., the surfaces that face each other. This increases the support strength of the bridge portion 5 provided by the long tubes 2.

[0046] In the example of FIG. 1, the frame 10 includes a hanger 6 that is attached to the long tube 2 by fastening. As an example, the hanger 6 is fastened to the bridge portion 5 by a fastener (not shown in FIG. 1). The hanger 6 has a hole 6a into which the fastener is inserted. The bridge portion 5 has a hole 5a into which the fastener is inserted, at a position corresponding to the hole 6a of the hanger 6. In the example of FIG. 1, the fastener that fastens the hanger 6 is inserted in the vertical direction. The insertion direction of the fastener is not limited to this. The insertion direction of the fastener of the hanger 6 may be, for example, the horizontal direction. The fastener is, for example, a screw such as a bolt, or a rivet.

[0047] Alternatively, the hanger 6 may be fastened directly to the long tube 2. In this case, the long tube 2 has a hole for inserting a fastener. For example, holes for inserting a fastener may be provided in the left long tube 2L and the right long tube 2R.

[0048] A drive unit, which will be described later, is fastened to the hanger 6. The hanger 6 has a hole 6b into which a fastener for fastening the drive unit is inserted. In the example of FIG. 1, the insertion direction of the fastener for the drive unit is, for example, the left-right direction. The insertion direction of the fastener for the drive unit is not limited to this. For example, the insertion direction of the fastener for the drive unit may also be, for example, the left-right direction.

[0049] In the example of FIG. 1, the head tube 1 has a tubular portion 1a into which the steering shaft is inserted, and an extension portion 1b that is joined to the outer periphery of the tubular portion 1a and extends rearward. The extension portion 1b is joined to each of the left long tube 2L and the right long tube 2R. In this example, the head tube 1 is formed of multiple joined members, namely the tubular portion 1a and the extension portion 1b. As a variant, the head tube 1 may be formed of only the tubular portion 1a. In this case, the long tube 2 is joined to the tubular portion 1a. The head tube 1 and the long tube 2 are joined by, for example, welding or fastening.

[0050] In the example of FIG. 1, the rear wheel support part 3 has axle support parts 31L, 31R having holes into which the axles of the rear wheels are inserted, and extension parts 32L, 32R joined to the axle support parts 31L, 31R and extending forward. The extension parts 32L, 32R are joined to the left long tube 2L and the right long tube 2R, respectively. As a modified example, the rear wheel support part 3 may be formed only with the axle support parts 31L, 31R. In this case, the long tube 2 is joined to the axle support parts 31L, 31R. The rear wheel support part 3 and the long tube 2 are joined by, for example, welding or fastening.

[0051] In the example of FIG. 1, the frame 10 further includes an upper tube 7 and seat stays 8. The upper tube 7 connects the head tube 1 and the seat tube 4. The seat stays 8 connect the rear wheel support portion 3 and the seat tube 4. The seat stays 8 include a left seat stay 8L that connects the left rear wheel support portion 3L and the seat tube 4, and a right seat stay 8R that connects the right rear wheel support portion 3R and the seat tube 4. At least one of the upper tube 7 and the seat stays 8 may be omitted.

[0052] FIG. 2 is a right side view showing an example of the configuration of a bicycle frame according to this embodiment. In the example of FIG. 2, the left long tube 2L and the right long tube 2R are arranged so that they completely overlap when viewed from the left-right direction. Therefore, in FIG. 2, the left long tube 2L is hidden by the right long tube 2R and cannot be seen. However, the arrangement of the left and right long tubes is not limited to this. For example, the left long tube 2L and the right long tube 2R may be arranged so that some parts overlap when viewed from the left-right direction and other parts do not overlap.

[0053] In the example of FIG. 2, the right long tube 2R has a curved portion 2w that is curved downward convexly when viewed from the left-right direction. The curved portion 2w is located forward of the seat tube 4. The right long tube 2R includes a rear straight portion 2cb that extends linearly without curving from the curved portion 2w to the right rear wheel support portion 3R when viewed from the left-right direction. The right long tube 2R further includes a front straight portion 2cf that extends linearly without curving from the curved portion 2w to the head tube 1 when viewed from the left-right direction. The inclination of the front straight portion 2cf is steeper than the inclination of the rear straight portion 2cb. Although not shown, the left long tube 2L may also have a curved portion, a rear straight portion, and a front straight portion similar to the above-described configuration of the right long tube 2R.

[0054] In the example of FIG. 2, the bridge section 5 is joined to the rear straight section 2cb. A hanger 6 to which a drive unit is fastened is attached to the bridge section 5. Therefore, the hanger 6 is attached to the rear straight section 2cb. The bridge section 5 also supports the lower end of the seat tube 4. Therefore, the seat tube 4 is supported by the rear straight section 2cb. The lower end of the seat tube 4 is supported by the bridge section 5 behind the curved section 2w of the long tube 2.

[0055] In the example of Figure 2, the seat tube 4 is supported while inserted into a hole in the bridge portion 5. A fastener T1 for fastening the hanger 6 is inserted from below into the portion of the bridge portion 5 that supports the seat tube 4. A fastener T2 for fastening the hanger 6 is inserted from above into the portion of the bridge portion 5 other than the portion that supports the seat tube 4.

[0056] In the example shown in FIG. 2, the bridge portion 5 supports the lower end of the seat tube 4 and fastens the hanger 6. This allows the drive unit 11 to be located below the seat tube 4. The drive unit 11 supports the crankshaft 12. Therefore, the crankshaft 12 is located below the seat tube 4. Also, in this example, the hanger 6 is fastened to the underside of the bridge portion 5. This means that the drive unit 11 is located below the long tube 2 when viewed from the left-right direction.

[0057] In the example of FIG. 2, a battery storage section for storing batteries 13a, 13b is provided in the long tube 2 in front of the seat tube 4. The battery storage section is provided between the left long tube 2L and the right long tube 2R. In the example of FIG. 2, a battery support section 5b for supporting battery 13a is provided in the bridge section 5. The battery support section 5b is a section of the bridge section 5 that protrudes in the extension direction of the front straight section 2cf. The battery support section 5b has a battery support surface that supports battery 13a. The normal direction of the battery support surface coincides with the extension direction of the front straight section 2cf. The batteries 13a, 13b are stored in the battery storage section so that the longitudinal direction of the batteries 13a, 13b coincides with the extension direction of the front straight section 2cf.

[0058] The arrangement of the front end 2ft and rear end 2bt of the long tube 2 will be described using Figure 2. The front end 2ft of the long tube 2 is joined to the head tube 1. The rear end 2bt of the long tube 2 is joined to the rear wheel support part 3. From the viewpoint of improving the shape accuracy of the long tube 2, it is preferable that the long tube 2 is long in the front-to-rear direction. Therefore, when viewed from the left-to-right direction, it is preferable that the rear end 2bt is, for example, rearward of the midpoint of an imaginary line connecting the rear wheel axle position J1 and the rear end k1 of the intersection between the seat tube 4 and the long tube. It is preferable that the linear distance between the rear end k1 of the intersection and any position on the front end 2ft is longer than the distance between the rear wheel axle position J1 and the rear end k1 of the intersection.

[0059] Figure 3 is a right side view of an example bicycle equipped with the frame 10 shown in Figures 1 and 2. The bicycle shown in Figure 3 includes, as components supported by the frame 10, a seat 14, handlebars 15, a front wheel 25f, a rear wheel 25b, a drive unit 11, batteries 13a and 13b, and a crankshaft 12. A crank arm 21 is connected to the crankshaft 12. The bicycle also has a chain ring 16 (drive sprocket) that rotates in conjunction with the crankshaft 12, and a rear sprocket 18 (driven sprocket) that rotates in conjunction with the rear wheel. A chain 17 is wound around the chain ring 16 and the rear sprocket 18.

[0060] A steering shaft (sometimes called a steering column or handle stem) is rotatably inserted into the head tube 1. A handlebar 15 is fixed to the upper end of the steering shaft 25. A front fork 23 is fixed to the lower end of the steering shaft 25. A front wheel 25f is rotatably supported by an axle at the lower end of the front fork 23. A seat 14 is provided at the upper end of the seat tube 4.

[0061] The drive unit 11 has a housing that forms the outer shape of the drive unit 11. A motor and a transmission mechanism are housed inside the housing. The transmission mechanism transmits the rotation of the motor to the crankshaft. The transmission mechanism includes, for example, a gear and a one-way clutch. A crankshaft 12 passes through the housing in the left-right direction. The crankshaft 12 is rotatably supported relative to the housing via multiple bearings.

[0062] The batteries 13a and 13b are configured, for example, as a battery pack (battery unit) in which a battery pack including a plurality of cells is enclosed. The battery pack may include a battery control unit.

[0063] 3, the long tube 2 extends from the head tube 1 over the chain ring 16 to the rear wheel support part 3 when viewed from the left and right. In other words, the long tube 2 is positioned so as not to overlap with the chain ring 16 when viewed from the left and right.

[0064] FIG. 4 is a top view showing the positional relationship between the long tube 2 and other components of the bicycle shown in FIG. 3. As shown in FIG. 4, when viewed from above, the long tube 2 extends to a position that overlaps with the chain ring 16. In this example, the extension position of the long tube 2 is not restricted by the chain ring 16. Therefore, there is a high degree of freedom in the left-right spacing between the left long tube 2L and the right long tube 2R near the seat tube 4. For example, if the rear wheel tire is wide, interference between the rear wheel and the frame can be avoided without increasing the wheelbase by widening the left-right spacing between the left long tube 2L and the right long tube 2R.

[0065] In Figure 4, the area where the drive unit 11 is located is indicated by dots. In the example of Figure 4, when viewed from above, the drive unit 11 is located inside the area where the left long tube 2L and the right long tube 2R are located. In addition, the bridge section 5 is located in the area between the left long tube 2L and the right long tube 2R. When viewed from above, the batteries 13a, 13b are located inside the area where the left long tube 2L and the right long tube 2R are located. In this way, by locating the drive unit 11, bridge section 5, and batteries 13a, 13b inside the area where the left long tube 2L and the right long tube 2R are located, the rigidity of the bicycle can be improved and the left-right balance can be improved.

[0066] As shown in Figures 3 and 4, the bicycle of this example is equipped with multiple batteries 13a, 13b stored between the left long tube 2L and the right long tube 2R. The batteries 13a, 13b are arranged vertically side by side between the left long tube 2L and the right long tube 2R. The batteries 13a, 13b are stored so that the extension direction of the front straight portions 2cf of the left long tube 2L and the right long tube 2R is the same as the longitudinal direction of the batteries 13a, 13b. The batteries 13a, 13b are detachably supported by battery adapters 24a, 24b and a lower cover 19 provided between the left long tube 2L and the right long tube 2R. The battery adapters 24a, 24b are provided at both longitudinal ends of the batteries 13a, 13b when stored. The lower cover 19 covers the lower portion of the space between the left long tube 2L and the right long tube 2R. The lower cover 19 is connected to both the left long tube 2L and the right long tube 2R.

[0067] The bicycle may have a locking mechanism that locks the batteries 13a, 13b in a stored state. The locking mechanism may be formed, for example, by at least one of the battery adapters 24a, 24b and the lower cover 19. The locking mechanism may be operable by the rider to switch between a locked and unlocked state of the batteries 13a, 13b. For example, the battery 13a may be supported so that it can slide left and right (in the vehicle width direction) when released from the locking mechanism. Alternatively, the battery 13a may be supported so that it can be removed upward when released from the locking mechanism. For example, a guide formed by a groove or protrusion on the battery adapters 24a, 24b may restrict the movement direction of the battery 13a when released from the locking mechanism. The battery 13b may be supported so that it can be removed downward when released from the locking mechanism. For example, the lower cover 19 may be configured to be openable and closable in the vertical direction. In this manner, the multiple batteries 13a, 13b may be supported so that they move in different directions relative to the frame when attached or detached. This allows for the attachment and detachment of each battery in a manner suitable for its storage position.

[0068] FIG. 5 is a cross-sectional view of the batteries 13a, 13b and the long tubes 2L, 2R along line AA in FIG. 4. In the example shown in FIGS. 4 and 5, the batteries 13a, 13b have the same shape. The cross-sectional shape of the batteries 13a, 13b perpendicular to the longitudinal direction is a flat shape with long and short sides. The batteries 13a, 13b are housed with different rotation angles θ about the longitudinal axis. In the example of FIG. 5, the rotation angles θ of the batteries 13a, 13b differ by 90 degrees.

[0069] Of the batteries 13a, 13b, one battery 13b is disposed in a position overlapping the left long tube 2L and the right long tube 2R when viewed from the left-right direction. The underside of the battery 13b is supported by the lower cover 19. The battery 13b is housed with the short side of its cross section aligned in the left-right direction. Both longitudinal ends of the battery 13b may be supported by battery adapters 24a, 24b.

[0070] The other battery 13a is placed above battery 13b in a position overlapping the left long tube 2L and the right long tube 2R when viewed from the left-right direction. The battery 13a is housed with its long side aligned in the left-right direction. Both longitudinal ends of the battery 13a are supported by battery adapters 24a and 24b.

[0071] In the above embodiment, both the left long tube 2L and the right long tube 2R are formed from a single tube with no joints. As a variation, one of the left long tube 2L or the right long tube 2R may be formed from a single tube, and the other may be formed from multiple tubes joined in the extension direction. Alternatively, in the above embodiment, both the left long tube 2L and the right long tube 2R may be formed from multiple tubes joined in the extension direction.

[0072] The bicycle in the above embodiment is, for example, an electrically assisted bicycle with a drive unit. Bicycles without a drive unit are also embodiments of the present invention. In bicycles without a drive unit, for example, the crankshaft may be rotatably supported at the lower end of the seat tube. In this case, the portion between the upper and lower ends of the seat tube may be supported by a long tube.

[0073] In the above embodiment, the seat tube is supported on the long tubes via the bridge portion. Alternatively, the seat tube may be directly joined to the long tubes. For example, the seat tube may be joined to the left and right long tubes by welding or fastening.

[0074] In the above embodiment, the long tube has a curved portion that is curved downwardly and convexly. The long tube may have a curved portion that is curved upwardly and convexly.

[0075] The embodiments of the present invention have been described above, but the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and any modifications and variations thereof may be made without departing from the spirit and scope of the present invention. The above-described embodiment can be appropriately modified and implemented within the scope of the present invention. [Explanation of symbols]

[0076] 1: Head tube, 2: Long tube, 2L: Left long tube, 2R: Right long tube, 3: Rear wheel support, 3L: Left rear wheel support, 3R: Right rear wheel support, 4: Seat tube, 5: Bridge, 6: Hanger, 11: Drive unit, 12: Crankshaft

Claims

1. A bicycle frame, The head tube and a rear wheel support part including a left rear wheel support part that supports the left side of the axle of the rear wheel of the bicycle, and a right rear wheel support part that supports the right side of the axle of the rear wheel; long tubes including a left long tube formed of a single tube extending from the head tube to the left rear wheel support portion, and a right long tube formed of a single tube extending from the head tube to the right rear wheel support portion; a seat tube supported by the long tube and extending upward from between the front and rear ends of the long tube when viewed in the left-right direction; a hanger attached to the long tube by fastening with a fastener; The hanger supports the crankshaft and has holes for fastening a drive unit that holds a motor that is a power source for rotating the crankshaft, using a fastener.

2. 2. A bicycle frame according to claim 1, a bridge portion provided between the left long tube and the right long tube and joined to both the left long tube and the right long tube, A bicycle frame, wherein the seat tube is supported on the long tube via the bridge portion.

3. 3. A bicycle frame according to claim 1 or 2, The bicycle frame is arranged so that the left long tube and the right long tube at least partially overlap when viewed from the left-right direction.

4. 3. A bicycle frame according to claim 1 or 2, The long tube has a curved portion that is curved convexly upward or downward when viewed from the left and right.

5. 5. A bicycle frame according to claim 4, A bicycle frame in which the curved portion of the long tube is curved downwardly and convexly when viewed from the left and right, and is located forward of the seat tube.

6. 3. A bicycle frame according to claim 1 or 2, A bicycle frame, wherein a battery housing portion for housing a battery is provided between a portion of the left long tube forward of the seat tube and a portion of the right long tube forward of the seat tube.

7. A bicycle comprising the frame according to claim 1 or 2, The crankshaft; a chain ring that rotates in conjunction with the crankshaft, The long tube of the frame extends from the head tube, over the chain ring, to the rear wheel support portion when viewed from the left and right.

8. A bicycle comprising the frame according to claim 1 or 2, the crankshaft; the drive unit supporting the crankshaft and holding a motor that is a power source for rotating the crankshaft, The drive unit is fastened to the hanger by a fastener.

9. A bicycle having a frame, The frame is The head tube and a rear wheel support part including a left rear wheel support part that supports the left side of the axle of the rear wheel of the bicycle, and a right rear wheel support part that supports the right side of the axle of the rear wheel; long tubes including a left long tube formed of a single tube extending from the head tube to the left rear wheel support portion, and a right long tube formed of a single tube extending from the head tube to the right rear wheel support portion; a seat tube supported by the long tube and extending upward from between a front end and a rear end of the long tube when viewed in the left-right direction, at least two batteries disposed inside an area in which the left long tube and the right long tube are disposed when viewed from above; a cross-sectional shape perpendicular to the longitudinal direction of each of the at least two batteries is a flat shape having long sides and short sides; A bicycle in which the at least two batteries are arranged such that a rotation angle of one of the at least two batteries about an axis in the longitudinal direction is different from a rotation angle of the other battery about an axis in the longitudinal direction.

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