Electric-assist bicycle

Abstract

To provide an electric assist bicycle with a simple structure that allows for easy assembly and routing of the main pipe to the bracket. [Solution] The electric assist bicycle 10 comprises a drive unit 38, a main pipe 16, and a bracket 14. The bracket 14 includes side plate portions 50a, 50b for supporting the drive unit 38, and a front plate portion 52 that connects the front edges of the side plate portions 50a, 50b. The front plate portion 52 is connected to the main pipe 16 with the upper rear end portion 68b in contact with it, without the lower rear end portion 68a of the main pipe 16 contacting it, so that the lower part of the rear end opening 68 of the main pipe 16 is exposed. The front plate portion 52 has a notch 52c that is recessed upward from its lower edge.

Description

Technical Field

[0001] This invention relates to an electric assist bicycle, and more particularly to an electric assist bicycle including a bracket connected to a main pipe and supporting a drive unit.

Background Art

[0002] An example of this type of prior art is disclosed in Patent Document 1. The frame for an electric bicycle disclosed in Patent Document 1 includes a bracket and a down tube having an opening edge at one end in the longitudinal direction. The opening edge of the down tube is connected to the front wall portion of the bracket so that the down tube extends from the bracket.

[0003] The bracket has an opening for drawing out wiring inside the down tube, and the opening is formed long in one direction so as to straddle the front wall portion, the first bent portion, and the intermediate wall portion of the bracket. The opening has a first opening portion located inside the opening edge of the down tube and a second opening portion located outside the opening edge of the down tube in a state where the down tube is joined to the front wall portion.

[0004] The down tube has an opening surrounded by the opening edge and a notch connected to this opening, and these are used for inserting wiring therethrough.

[0005] Thus, for drawing out the wiring from the down tube to the bracket, the opening and notch on the down tube side and the opening on the bracket side are used.

[0006] More specifically, the wiring can be routed through a notch that cuts forward from the upper end of the opening edge of the downtube, thereby reducing the load on the wiring while routing it. In addition, a second opening portion of the bracket opening, which extends upward and backward from the first opening portion so as to be located outside the opening edge of the downtube, is positioned to be aligned behind the notch portion in a plan view. The wiring that is pulled out from inside the downtube to the rear through the notch portion is then pulled out into the bracket through the second opening portion. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 7369965 [Overview of the project] [Problems that the invention aims to solve]

[0008] In Patent Document 1, the down tube can be connected to the bracket as described above, and the wiring inside the down tube can be pulled out, but the structure for this purpose is complex, and there is room for improvement in the wiring.

[0009] Therefore, the main objective of this invention is to provide an electric assist bicycle that has a simple structure while allowing for easy assembly and routing of the main pipe to the bracket. [Means for solving the problem]

[0010] To achieve the above objective, an electric assist bicycle is provided, comprising a drive unit, a cylindrical main pipe having a rear end opening, and a bracket connected to the main pipe and supporting the drive unit, wherein the bracket includes a pair of side plate portions for supporting the drive unit and a front plate portion connecting the front edges of the pair of side plate portions, and the front plate portion is connected such that the lower part of the rear end of the main pipe does not come into contact with the front plate portion, but the upper part of the rear end of the main pipe does come into contact with the front plate portion, so that the lower part of the rear end opening of the main pipe is exposed.

[0011] In this invention, the main pipe is connected to the front plate in such a way that the lower part of the rear end opening of the main pipe is exposed, while the upper part of the rear end of the main pipe abuts against the front plate without the lower part of the rear end making contact. By abutting the upper part of the rear end of the main pipe against the front plate in this way, the positioning and assembly of the main pipe to the front plate and, consequently, the bracket becomes easier. Furthermore, when the main pipe is assembled to the bracket, the lower part of the rear end opening of the main pipe is exposed without being covered by the front plate, so a substantially large pull-out hole can be formed at the lower part of the rear end opening of the main pipe, allowing wiring passing through the main pipe to be easily pulled out from the rear end opening of the main pipe, thus simplifying wiring.

[0012] Preferably, the front plate portion has a notch that recesses upward from its lower edge. In this case, the portion of the rear end opening of the main pipe that is not covered by the front plate portion can be made larger, making wiring even easier.

[0013] Preferably, the bracket further includes a pair of extensions extending forward from the front ends of a pair of side plates, the pair of extensions being connected to the sides of the main pipe so as to sandwich the main pipe from the sides. In this case, since the pair of extensions are connected to the sides of the main pipe so as to sandwich the main pipe from the sides in front of the front plate, the bracket and the main pipe can be connected more firmly, and the positioning of the main pipe in the left-right direction can be made easier.

[0014] More preferably, the pair of extensions are connected to the main pipe along the neutral axis of the main pipe. In this case, less stress is applied to the connection point between the pair of extensions and the main pipe, thus further improving the connection strength.

[0015] Preferably, the vertical dimension of each extension is smaller than the vertical dimension of the main pipe. In this case, each extension can be made compact.

[0016] Preferably, the front plate portion is provided so as to bend inward relative to each side plate portion. In this case, the upper rear end of the main pipe can easily come into contact with the front plate portion, making it easier to position the main pipe relative to the front plate portion and, consequently, the bracket. Therefore, misalignment between the main pipe and the drive unit can be suppressed. In addition, by connecting the upper rear end of the main pipe to the front plate portion, the rigidity of the main pipe is improved compared to the case where a bracket without a front plate portion is connected to the side of the main pipe without being connected to the rear end of the main pipe.

[0017] More preferably, the front plate is inclined to the main pipe at an obtuse angle with respect to the axial direction of the main pipe and connected to it. In this case, the area of ​​the rear end of the main pipe that contacts the front plate can be increased, and the bracket and the main pipe can be connected more firmly.

[0018] Preferably, each side plate extends at least in the front-to-back direction. In this case, the drive unit can be supported at more points on the pair of side plates.

[0019] Preferably, the bracket further includes a plate-like portion located below the main pipe and connecting a pair of extensions. In this case, lateral displacement of the pair of extensions can be suppressed.

[0020] More preferably, the plate-like portion is connected to the bottom surface of the main pipe. In this case, deformation of the main pipe can be suppressed.

[0021] Preferably, the plate-like part is provided near the front ends of the pair of extension parts. In this case, the displacement near the front ends of the pair of extension parts can be effectively suppressed.

Advantages of the Invention

[0022] According to this invention, an electric assist bicycle can be obtained which has a simple structure while facilitating the assembly and arrangement of the main pipe with respect to the bracket.

Brief Description of the Drawings

[0023] [Figure 1] It is a side view showing an electric assist bicycle according to an embodiment of this invention. [Figure 2] It is a front perspective view showing a main part of the frame. [Figure 3] It is a perspective view showing a state where a part of the frame is disassembled and a perspective view showing a state where a part of the bracket is assembled in a main part of the frame. [Figure 4] It is a side view showing a main part of the frame. [Figure 5] It is a bottom view showing the bracket and its vicinity. [Figure 6] It is a perspective view showing the rear end opening of the main pipe and the vicinity of the front plate part of the bracket in the embodiment of FIG. 1. [Figure 7] It is a plan view showing the seat post and the seat stay. [Figure 8] It is a perspective view showing the rear end opening of the main pipe and the vicinity of the front plate part of the bracket in another embodiment.

Modes for Carrying Out the Invention

[0024] Hereinafter, embodiments of this invention will be described with reference to the drawings. In the drawings, "Fr" indicates the front, "Rr" indicates the rear, "R" indicates the right, "L" indicates the left, "U" indicates the upper, and "Lo" indicates the lower.

[0025] Referring to Figure 1, an electric assist bicycle 10 according to one embodiment of the present invention includes a frame 12. Also referring to Figures 2 and 4, the frame 12 includes a bracket 14, a main pipe 16 corresponding to a down tube, a seat post 18, a seat stay 20, a pair of chain stays 22, a head tube 24, and a front fork 26.

[0026] A main pipe 16 curves and extends diagonally upward and forward from the bracket 14, a seat post 18 extends upward from the bracket 14 at a slight rearward angle, and a pair of chainstays 22 extend rearward from the bracket 14. A seatstay 20 connects the upper part of the seatpost 18 to the rear ends of the pair of chainstays 22. The head tube 24 is connected to the front end of the main pipe 16. The front fork 26 is rotatably inserted into the head tube 24 and is mounted at a slight rearward angle.

[0027] Returning to Figure 1, a handle stem 28 is attached to the upper end of the front fork 26, and the handle 30 is supported by the handle stem 28. The saddle 32 is supported by the seat post 18. The front wheel 34 is rotatably supported by the lower end of the front fork 26, and the rear wheel 36 is rotatably supported by the rear ends of a pair of chainstays 22.

[0028] The drive unit 38 is supported by the bracket 14.

[0029] A pair of crank arms 42 are attached to both ends of the crankshaft 40 of the drive unit 38. Pedals 44 are attached to the ends of each crank arm 42. A drive sprocket (not shown) that is linked to the output shaft is attached to the end of the output shaft (not shown) of the drive unit 38. The rear wheel 36 has a rear sprocket (not shown). The drive sprocket and the rear sprocket are connected by a chain (not shown).

[0030] A control unit consisting of a CPU and an inverter device (neither shown) are provided near the bracket 14, and a battery 46 is attached to the seat post 18. Based on instructions from the control unit, the inverter device converts the DC power from the battery 46 into AC power and supplies it to the motor 48 included in the drive unit 38. The motor 48 generates a driving force corresponding to the input AC power. This driving force is transmitted to the drive sprocket via a reduction mechanism (not shown) and an output shaft.

[0031] When the drive unit 38 receives pedaling force input from the pedal 44, it generates a drive assist output corresponding to the pedaling force using the motor 48 to supplement the pedaling force. The drive sprocket rotates in conjunction with the rotation of the crank arm 42 and also receives output from the motor 48. In other words, the drive unit 38 transmits the pedaling force from the pedal 44 and crank arm 42 and the output from the motor 48 to the drive sprocket. The power transmitted to the drive sprocket is then transmitted to the rear wheel 36 via the chain.

[0032] Here, we will describe in detail the configuration of bracket 14 and its vicinity.

[0033] Referring to Figure 3, the bracket 14 includes a pair of side plate portions 50a, 50b, a front plate portion 52, a pair of extension portions 54a, 54b, cross members 56, 58, and plate-shaped portions 60, 62.

[0034] The pair of side plates 50a and 50b are plate-shaped members for supporting the drive unit 38 and are spaced apart from each other in the vehicle width direction. The side plates 50a and 50b extend at least in the front-rear direction. In this embodiment, the side plates 50a and 50b are formed in a substantially inverted V shape when viewed from the side. The side plate 50a has a plurality (three in this embodiment) of through holes 64a, and similarly, the side plate 50b has a plurality (three in this embodiment) of through holes 64b.

[0035] The front plate portion 52 includes a first piece 52a provided on the front edge of the side plate portion 50a so as to bend inward relative to the side plate portion 50a, and a second piece 52b provided on the front edge of the side plate portion 50b so as to bend inward relative to the side plate portion 50b, and is obtained by combining and connecting the first piece 52a and the second piece 52b. In this way, the front plate portion 52 is provided so as to bend inward relative to each side plate portion 50a, 50b, and connects the front edges of the pair of side plate portions 50a, 50b. In this embodiment, the front plate portion 52 is bent at approximately a right angle relative to each side plate portion 50a, 50b to form a flat surface. This makes it easier to abut the rear end of the main pipe 16, and increases the connection strength between the bracket 14 and the main pipe 16. The front plate portion 52 also has a notch 52c that is recessed upward from the lower edge. In other words, the front plate portion 52 has a notch 52c that is not a closed hole.

[0036] The pair of extensions 54a and 54b extend forward from the front ends of the pair of side plates 50a and 50b without being bent inward relative to the pair of side plates 50a and 50b. Therefore, the front ends of the extensions 54a and 54b are located in front of the front ends of the side plates 50a and 50b. The vertical dimension D1 of each extension 54a and 54b is smaller than the vertical dimension D2 of the main pipe 16 (see Figure 4). The pair of extensions 54a and 54b are not provided with a front plate 52, and the pair of extensions 54a and 54b are located below the front plate 52.

[0037] In this embodiment, the side plate portion 50a, the first piece 52a, and the extension portion 54a are formed integrally beforehand and consist of a sheet metal member 66a. Similarly, the side plate portion 50b, the second piece 52b, and the extension portion 54b are formed integrally beforehand and consist of a sheet metal member 66b. The sheet metal members 66a and 66b are connected to each other. The sheet metal members 66a and 66b are joined to each other, for example, by welding. That is, the first piece 52a and the second piece 52b are joined to each other, for example, by welding.

[0038] Both cross members 56 and 58 are formed in a hollow cylindrical shape. Cross member 56 extends in the vehicle width direction and connects the approximate center portions of the side plate portions 50a and 50b. The cross member 56 and the side plate portions 50a and 50b are joined, for example, by welding. Cross member 58 extends in the vehicle width direction and connects the rear ends of the side plate portions 50a and 50b. The cross member 58 and the side plate portions 50a and 50b are joined, for example, by welding.

[0039] The plate-like portion 60 is formed in a roughly rectangular shape and is provided so as to span across the pair of side plate portions 50a, 50b in the region enclosed by the pair of side plate portions 50a, 50b and the cross members 56, 58. The plate-like portion 60 and the side plate portions 50a, 50b are joined together, for example, by welding.

[0040] The plate-like portion 62 is provided near the front ends of the pair of extensions 54a and 54b, and connects the pair of extensions 54a and 54b. In this embodiment, the plate-like portion 62 is slightly curved and formed in a substantially U-shape. The plate-like portion 62 and the extensions 54a and 54b are joined together, for example, by welding.

[0041] Looking at the bracket 14 as a whole, a front plate portion 52 is provided on the front upper part of the bracket 14, and a plate-like portion 62 is provided on the front lower part of the bracket 14. The front plate portion 52 is not provided on the front lower part of the bracket 14. Therefore, a space S is formed between the front plate portion 52 and the plate-like portion 62. The space S can be made larger by having a notch 52c in the front plate portion 52.

[0042] Multiple fastening members (three in this embodiment) are attached to such a bracket 14 to connect the side plate portions 50a and 50b. Each fastening member includes, for example, a bolt and a nut, and is inserted through the corresponding through holes 64a and 64b to attach to the side plate portions 50a and 50b. The drive unit 38 is supported by these fastening members and is also held in place by the pair of side plate portions 50a and 50b (see Figure 4). In this embodiment, the drive unit 38 is suspended from the bracket 14 via the three fastening members. Therefore, the bracket 14 can be described as a suspension bracket.

[0043] Furthermore, the rear end of the main pipe 16 is connected to the bracket 14. The bracket 14 and the main pipe 16 are joined together, for example, by welding.

[0044] Referring also to Figures 5 and 6, the main pipe 16 is formed in a cylindrical shape with a rear end opening 68. This allows the wiring 70 to be passed through the main pipe 16 and pulled out to the rear. The front plate portion 52 of the bracket 14 is connected to the main pipe 16 with the upper rear end 68b in contact with it, without the lower rear end 68a of the main pipe 16 making contact, so that the lower part of the rear end opening 68 of the main pipe 16 is exposed. At this time, the upper rear end 68b of the main pipe 16 is positioned along the notch 52c. A part of the rear end opening 68 of the main pipe 16 is covered by the front plate portion 52. In this embodiment, about half of the entire circumference of the rear end of the main pipe 16 is connected to the front plate portion 52. Preferably, at least about one-third of the entire circumference of the rear end of the main pipe 16 is connected to the front plate portion 52. As shown in Figure 4, the front plate portion 52 of the bracket 14 is inclined to form an obtuse angle A with respect to the axial direction of the main pipe 16 and connected to the rear end of the main pipe 16. In other words, the front plate portion 52 does not extend vertically but tilts backward. The front plate portion 52 and the main pipe 16 are joined together, for example, by welding.

[0045] Furthermore, the pair of extensions 54a and 54b are connected to the rear side of the main pipe 16 so as to sandwich the main pipe 16 from the side. The extensions 54a and 54b and the main pipe 16 are joined, for example, by welding. When joined by welding, it is preferable that the lengths of the welds between the front plate 52 and the main pipe 16, the length of the welds between the extension 54a and the main pipe 16, and the length of the welds between the extension 54b and the main pipe 16 are approximately equal. In this embodiment, the pair of extensions 54a and 54b are connected to the side of the main pipe 16 below the neutral axis N of the main pipe 16 when an external force is applied from a direction perpendicular to the axial direction of the main pipe 16 (in other words, when bending stress is applied to the main pipe 16). That is, the pair of extensions 54a and 54b are connected to the lower side of the main pipe 16. In this case, the connection strength can be increased compared to when the pair of extensions 54a and 54b are connected to the bottom surface of the main pipe 16. In this embodiment, since the cross-sectional shape of the main pipe 16 is substantially symmetrical vertically, the neutral axis N passes near the center of the main pipe 16.

[0046] Furthermore, the plate-like portion 62 is located below the main pipe 16 and is connected to the bottom surface of the main pipe 16. The plate-like portion 62 and the main pipe 16 are joined together, for example, by welding.

[0047] The lower end of the seatpost 18 is connected to the crossmember 56. The crossmember 56 and the seatpost 18 are joined, for example, by welding. A reinforcing member 72 is attached so as to extend from the rear upper surface of the main pipe 16 to the lower front surface of the seatpost 18. The reinforcing member 72 and the main pipe 16 and seatpost 18 are joined, for example, by welding.

[0048] The front ends of a pair of chainstays 22 are connected to the cross member 58. As can be seen in Figures 5 and 6, the front ends of the pair of chainstays 22 are also connected to each other by a reinforcing member 74 attached to the cross member 58. The reinforcing member 74, the cross member 58, and the pair of chainstays 22 are joined together, for example, by welding.

[0049] Referring to Figure 7, the seat stay 20 includes a front stay 20a and a pair of rear stays 20b connected to the front stay 20a. Referring to Figures 2 to 4, the front stay 20a is connected to the top of the seat post 18, and the pair of rear stays 20b are connected to the rear ends of a pair of chainstays 22.

[0050] In this type of electric assist bicycle 10, the front plate portion 52 is connected to the main pipe 16 with the upper rear end portion 68b in contact with it, without the lower rear end portion 68a of the main pipe 16 making contact, so that the lower part of the rear end opening 68 of the main pipe 16 is exposed. By bringing the upper rear end portion 68b of the main pipe 16 into contact with the front plate portion 52 in this way, the positioning and assembly of the main pipe 16 with respect to the front plate portion 52 and, consequently, the bracket 14 becomes easier. Furthermore, when the main pipe 16 is assembled to the bracket 14, the lower part of the rear end opening 68 of the main pipe 16 is exposed without being covered by the front plate portion 52, so a substantially large pull-out hole can be formed at the bottom of the rear end opening 68 of the main pipe 16, and the wiring 70 passing through the main pipe 16 can be easily pulled out from the rear end opening 68 of the main pipe 16, making wiring easier.

[0051] Since the front plate portion 52 has a notch 52c that is recessed upward from its lower edge, the portion of the rear end opening 68 of the main pipe 16 that is not covered by the front plate portion 52 can be made larger, making the wiring even easier.

[0052] The pair of extensions 54a and 54b are connected to the sides of the main pipe 16 so that they sandwich the main pipe 16 from the side in front of the front plate portion 52. This allows for a stronger connection between the bracket 14 and the main pipe 16, and also facilitates the left-right positioning of the main pipe 16.

[0053] Since the vertical dimension D1 of each extension 54a, 54b is smaller than the vertical dimension D2 of the main pipe 16, each extension 54a, 54b can be formed compactly.

[0054] Since the front plate portion 52 is provided so as to bend inward relative to each side plate portion 50a, 50b, the upper rear end portion 68b of the main pipe 16 can easily come into contact with the front plate portion 52, making it easier to position the main pipe 16 relative to the front plate portion 52 and, consequently, the bracket 14. Therefore, misalignment between the main pipe 16 and the drive unit 38 can be suppressed. In addition, by connecting the upper rear end portion 68b of the main pipe 16 to the front plate portion 52, the rigidity of the main pipe 16 is improved compared to the case where a bracket without a front plate portion is connected to the side of the main pipe 16 without being connected to the rear end of the main pipe 16.

[0055] Since the front plate portion 52 is inclined to form an obtuse angle A with respect to the axial direction of the main pipe 16 and connected to the main pipe 16, the area of ​​the rear end of the main pipe 16 that abuts against the front plate portion 52 can be increased, and the bracket 14 and the main pipe 16 can be connected more firmly.

[0056] Since each side plate portion 50a, 50b extends at least in the front-to-back direction, the drive unit 38 can be supported at more points on the pair of side plate portions 50a, 50b.

[0057] By positioning the plate-shaped portion 62 below the main pipe 16 and connecting the pair of extensions 54a and 54b, lateral displacement of the pair of extensions 54a and 54b can be suppressed.

[0058] Since the plate-shaped portion 62 is connected to the bottom surface of the main pipe 16, deformation of the main pipe 16 can be suppressed.

[0059] Since the plate-shaped portion 62 is provided near the front ends of the pair of extensions 54a and 54b, positional displacement near the front ends of the pair of extensions 54a and 54b can be effectively suppressed.

[0060] In the above-described embodiment, a front plate portion 52 was used that included a first piece 52a and a second piece 52b and had a notch 52c, but the invention is not limited thereto. As shown in Figure 8, a front plate portion 76 may be used that includes a first piece 76a and a second piece 76b, which are both roughly rectangular in shape. In other words, a front plate portion 76 without a notch may be used.

[0061] In the above-described embodiment, the pair of extensions 54a and 54b are connected to the main pipe 16 below the neutral axis N of the main pipe 16, but are not limited to this. The pair of extensions may be connected to the main pipe along the neutral axis of the main pipe. In this case, stress is less likely to be applied to the connection point between the pair of extensions and the main pipe, so the connection strength can be further improved.

[0062] In the above-described embodiment, the side plate portion 50a and the extension portion 54a are formed integrally beforehand, but the invention is not limited to this. The side plate portion 50a and the extension portion 54a may be constructed as separate components and ultimately integrated. The same applies to the side plate portion 50b and the extension portion 54b.

[0063] In the above-described embodiment, the side plate portions 50a and 50b are each formed in a substantially inverted V shape in a side view, but are not limited thereto. The side plate portion may be separated into a front portion and a rear portion. That is, the side plate portion may include a front portion and a rear portion as separate members. In this case, the front portion and the rear portion may be connected via a cross member 56. [Explanation of Symbols]

[0064] 10 Electric-assist bicycles 12 frames 14 brackets 16 Main pipe 38 Drive Unit 46 batteries 48 Motor 50a,50b Side plate part 52,76 Front plate part 52a,76a 1st piece 52b,76b 2nd piece 52c Notch 54a,54b extension 60, 62 Plate-like part 68 Main pipe rear end opening 68a Lower rear end of the main pipe 68b Upper rear end of the main pipe 70 Wiring A. The obtuse angle that the front plate makes with respect to the axial direction of the main pipe. D1 Vertical dimension of the extension D2 Main pipe vertical dimension N Main pipe neutral axis

Claims

1. Drive unit and A cylindrical main pipe having an opening at the rear end, It comprises a bracket connected to the main pipe and supporting the drive unit, The aforementioned bracket is A pair of side plates for supporting the drive unit, It includes a front plate portion that connects the front edges of the pair of side plate portions, An electric assist bicycle in which the upper rear end of the main pipe is in contact with the front plate portion, without the lower rear end of the main pipe contacting the front plate portion, such that the lower part of the rear end opening of the main pipe is exposed.

2. The electric assist bicycle according to claim 1, wherein the front plate portion has a notch that is recessed upward from the lower edge.

3. The bracket further includes a pair of extensions extending forward from the front ends of the pair of side plate portions, The electric assist bicycle according to claim 1, wherein the pair of extensions are connected to the side surfaces of the main pipe so as to sandwich the main pipe from the side.

4. The electric assist bicycle according to claim 3, wherein the pair of extensions are connected to the main pipe along the neutral axis of the main pipe.

5. The electric assist bicycle according to claim 3, wherein the vertical dimension of each extension is smaller than the vertical dimension of the main pipe.

6. The electric assist bicycle according to claim 1, wherein the front plate portion is provided so as to bend inward relative to each of the side plate portions.

7. The electric assist bicycle according to claim 1, wherein the front plate portion is inclined to the main pipe at an obtuse angle with respect to the axial direction of the main pipe and connected to the main pipe.

8. The electric assist bicycle according to claim 1, wherein each of the aforementioned side plate portions extends at least in the front-to-back direction.

9. The electric assist bicycle according to claim 1, wherein the bracket further includes a plate-shaped portion located below the main pipe and connecting the pair of extensions.

10. The electric assist bicycle according to claim 9, wherein the plate-like portion is connected to the bottom surface of the main pipe.

11. The electric assist bicycle according to claim 9, wherein the plate-like portion is provided near the front end of the pair of extensions.

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