CN221163192U - Front derailleur for bicycle - Google Patents

Abstract

The application provides a front derailleur for a bicycle, which is suitable for a front sprocket with a three-speed structure, and comprises a chain guide part for a chain to pass through, wherein the chain guide part is arranged on an inner guide plate and an outer guide plate which are arranged at two sides of the chain, the outer guide plate is processed by a metal base plate to form a lower chain protruding part which is suitable for pushing the chain to be downwards linked from a large-diameter sprocket to a small-diameter sprocket, the lower chain protruding part is formed by pressing a part of the metal base plate towards one side of the chain to enable the part of the metal base plate to be protruded and deformed, the lower chain protruding part comprises a first protruding part and a second protruding part with different protruding heights, and the first protruding part and the second protruding part are connected into a whole. The front derailleur for the bicycle, provided by the application, is used for pushing the first convex part and the second convex part of the chain lower chain to be connected into a whole, and pressing one part of the outer guide plate towards one side of the chain to enable the outer guide plate to be protruded and deformed, so that the front derailleur is simpler in structure, simpler, more convenient and faster to manufacture, more reliable and more efficient in lower chain, and simultaneously, the manufacturing cost is reduced.

Description

Front derailleur for bicycle

Technical Field

The application relates to the technical field of bicycles, in particular to a front derailleur for bicycles.

Background

Speed-changing bicycles are becoming increasingly popular vehicles and recreational vehicles. The derailleur is an important part of a speed-changing bicycle for shifting the chain over different sized sheaves to effect a speed change, and is divided into a front derailleur and a rear derailleur, the front derailleur being secured to the bicycle frame below the bicycle seat, including a chain guide for the chain to pass through, for the chain guide to shift the chain to effect a back and forth shift of the chain over different diameter sprockets to effect a speed change of the bicycle. Wherein the movement of the chain from the smaller diameter sprocket to the larger diameter sprocket is referred to as a winding, and is accomplished primarily by the inner guide plate of the chain guide being closer to the bicycle frame pushing the chain; the movement of the chain from the larger diameter sprocket to the smaller diameter sprocket is called a down chain and is accomplished primarily by the outer guide plate of the chain guide being further from the bicycle frame pushing the chain. The chinese patent application publication No. CN103029800a discloses a front derailleur with a contact member, which is mounted on an inner plate of its chain guide and includes a flexible portion adapted to flex when a chain contacts the contact, so that the contact can be reduced to reduce the generation of noise when the chain contacts the contact structure, and also proposes that the contact member can be mounted on an outer plate to further reduce the generation of noise. However, in this prior art, no improvement is made to the outer plate in terms of assisting the chain down-link, but rather, if the generation of noise is not further reduced, a contact member is added to the outer plate, further increasing the process of manufacturing the front derailleur and failing to assist the chain down-link, so that the front derailleur may have drawbacks in terms of chain down-link.

In view of this, there is a need to propose a new solution to overcome the problems of the prior art.

Disclosure of utility model

The application provides a front derailleur for a bicycle, which is used for pushing a first convex part and a second convex part of a chain lower chain to be connected into a whole, and pressing one part of an outer guide plate towards one side of the chain to enable the outer guide plate to be protruded and deformed, so that the front derailleur has a simple structure, is simple, convenient and quick to manufacture, and can enable the lower chain to be more reliable and efficient.

In order to achieve the above purpose, the application adopts the following technical scheme: the utility model provides a front sprocket suitable for three-speed structure, is including the chain guide that is used for supplying the chain to pass, the chain guide includes in the relative setting of chain both sides and outer baffle, outer baffle is processed out by metal base plate and is suitable for the lower chain bellying that promotes the chain by major diameter sprocket lower chain to minor diameter sprocket, wherein, the lower chain bellying by to metal base plate's a part orientation chain one side makes its protruding deformation form that stretches, the lower chain bellying includes protruding high different first convex part and second convex part of stretching, first convex part and second convex part connect as an organic wholely.

As a further improved technical scheme of the application, a transition part formed by metal stamping and stretching is arranged between the first bulge and the second bulge.

As a further improved embodiment of the present application, the outer guide plate has base plate portions formed at front and rear sides of the lower chain protrusion portion, and the base plate portions are bent to form connection portions connected to upper and lower ends of the inner guide plate.

As a further improved technical scheme of the application, the upper edge of the lower chain protruding part is provided with a substrate connecting part for connecting the front side substrate part and the rear side substrate part of the lower chain protruding part, and the substrate connecting part and the front side substrate part and the rear side substrate part are positioned on the same plane.

As a further improved technical scheme of the application, the first convex part and the second convex part are formed by one-time pressing.

As a further improved technical scheme of the application, the base plate part positioned at the front side of the lower chain protruding part is provided with a limit protruding part protruding towards the chain, and the limit protruding part is configured to prevent the chain from falling off from the sprocket with the largest diameter.

As a further improved technical solution of the present application, the connecting portion of the base plate portion to the lower end of the inner guide plate includes:

The first connecting part is formed by bending and extending from the lower edge of the base plate part positioned at the rear side of the lower chain protruding part towards the inner guide plate; and

The second connecting part is parallel to the inner guide plate and is connected with the first connecting part into a whole;

the second connecting part is connected with the lower end of the inner guide plate.

As a further improved technical scheme of the application, the lower end of the inner guide plate is provided with a connecting column, and the second connecting part is provided with a connecting hole for the connecting column to pass through; the fixing piece is locked on the connecting column which passes through the connecting hole so as to connect the second connecting part and the lower end of the inner guide plate.

As a further improved solution of the present application, the inner side of the inner guide plate facing the chain is configured to be adapted to push the chain to be wound from a small diameter sprocket to a large diameter sprocket, the inner side of the inner guide plate being provided with:

a recessed portion configured to be recessed from the inner side surface in a direction away from the chain; and

A protruding portion provided at a lower side of the recessed portion and protruding toward the chain with respect to the recessed portion;

Wherein the boss is configured to impart an upward pushing force to the chain when the inner side pushes the chain to shift laterally, so as to facilitate the chain to be trained from a small diameter sprocket to a large diameter sprocket.

As a further improved technical solution of the present application, the front sprocket of the three-speed structure includes three kinds of small, medium and large diameter sprockets, and the protruding portion is configured to perform a boosting function when the chain is trained on the small diameter sprocket to the medium diameter sprocket.

The application provides a front derailleur for a bicycle, which is provided with a chain guide part comprising an inner guide plate and an outer guide plate which are oppositely arranged at two sides of a chain, wherein a lower chain protruding part comprising a first protruding part and a second protruding part which are different in protruding height and integrally connected is processed on the outer guide plate in a mode of protruding and deforming the outer guide plate of the chain guide part towards one side of the chain by pressing, when the chain is downwards chain from a larger diameter chain wheel to a smaller diameter chain wheel, the first protruding part or the second protruding part pushes the chain downwards chain, and after the chain downwards chain is downwards chain to the smaller diameter chain wheel, a certain gap exists between the chain, the outer guide plate and the inner guide plate, so that riding is not affected, and noise generated by chain scraping and damage to the bicycle can be avoided. According to the application, the outer guide plate of the chain guide is enabled to be protruded and deformed towards one side of the chain by pressing, and the lower chain protruding part comprising the first protruding part and the second protruding part which are different in protruding and protruding height and connected into a whole can be processed on the outer guide plate, so that the front derailleur provided by the application is simpler in structure, simpler, more convenient and faster to manufacture, more reliable and more efficient in lower chain, and meanwhile, the manufacturing cost is reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following brief description of the drawings of the embodiments will make it apparent that the drawings in the following description relate only to some embodiments of the present application and are not limiting of the present application.

FIG. 1 is a perspective view of a bicycle front derailleur in accordance with an embodiment of the present application.

FIG. 2 is a first perspective view of a chain guide of a bicycle front derailleur in accordance with an embodiment of the present application.

FIG. 3 is a second perspective view of the chain guide of the front bicycle derailleur in accordance with an embodiment of the present application.

FIG. 4 is a third perspective view of the chain guide of the front bicycle derailleur in accordance with an embodiment of the present application.

FIG. 5 is a fourth perspective view of the chain guide of the front bicycle derailleur illustrated in an embodiment of the present application.

FIG. 6 is a fifth perspective view of the chain guide of the front bicycle derailleur illustrated in an embodiment of the present application. Reference numerals illustrate:

100-chain guide; 101-a first connection plate; 102-a second connection plate; 1-an inner guide plate; 11-inner side; 1101-a first inner base surface; 1102-a second inner base surface; 1103-a third medial base surface; 111-a depression; 112-a boss; 1131-a first base; 1132-a second base; 114-a transitional coupling surface; 115-a material reduction through hole; 116-a placement section; 13-connecting columns; 2-an outer guide plate; 20-limit convex parts; 21-an upper end connection; 22-a lower end connection; 221-a first connection portion; 222-a second connection; 223-connecting holes; 24-downlink boss; 241-first protrusions; 242-second protrusions; 243-transition; 25-a substrate portion; 26-substrate connection; 200-fixing seats; 201-a mounting portion; 300-connecting plates; 400-stay wire seat.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the present application will be described in further detail with reference to the accompanying drawings. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

Unless defined otherwise, technical or scientific terms used in this patent document should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The terms "first," "second," and the like in the description and in the claims, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Likewise, the terms "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, is intended to mean that elements or items that are present in front of "comprising" or "comprising" are included in the word "comprising" or "comprising", and equivalents thereof, without excluding other elements or items. "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used merely to denote relative positional relationships, which may be changed accordingly when the absolute position of the object being described is changed, merely to facilitate description of the present application and to simplify description, and not to indicate or imply that the apparatus or elements being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the application.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.

Some embodiments of the present application are described in detail below with reference to the accompanying drawings. Features of the embodiments described below may be combined with each other without conflict.

Referring to FIGS. 1 to 6, the present application provides a front derailleur for a bicycle, which is adapted to a three-speed front sprocket, which is a sprocket having at least three different diameter crankset. The front derailleur includes a chain guide 100 for passing a chain, the chain guide 100 includes an inner guide plate 1 and an outer guide plate 2 which are oppositely arranged at both sides of the chain, the outer guide plate 2 is processed by a metal base plate to form a lower chain protrusion 24 which is suitable for pushing the chain to be downwards extended from a larger diameter sprocket to a smaller diameter sprocket, wherein the lower chain protrusion 24 is formed by pressing a part of the metal base plate towards one side of the chain to enable the part to be protruded and deformed, the lower chain protrusion 24 includes a first protrusion 241 and a second protrusion 242 with different protrusion heights, the first protrusion 241 and the second protrusion 242 are connected into a whole, and the protrusion height of the first protrusion 241 is higher than that of the second protrusion 242.

In this embodiment, the chain guide 100 in the front derailleur includes an inner guide plate 1 and an outer guide plate 2 that are spaced apart and connected to form a chain guide slot for a chain to pass through during rotation on the front sprocket. During shifting of the bicycle, the inner guide plate 1 and the outer guide plate 2 push chains to be respectively meshed with front chain wheels with different diameters, so that the bicycle shifting speed is finished. Further, first protrusions 241 and second protrusions 242 having different protruding heights are formed on the outer guide plate 2 of the chain guide 100 toward the chain side; when the chain is from the large-diameter chain wheel to the medium-diameter chain wheel, the first convex part 241 pushes the chain down-chain, when the chain is from the medium-diameter chain wheel to the small-diameter chain wheel, the second convex part 242 pushes the chain down-chain, and after the chain is from the medium-diameter chain wheel or the small-diameter chain wheel, a certain gap exists between the chain and the outer guide plate 2 and the inner guide plate 1, so that riding cannot be influenced, and noise generated by chain wiping and damage to a bicycle can be avoided. In this embodiment, the outer guide plate 2 of the chain guide 100 is deformed by pressing to protrude toward one side of the chain, so that the lower chain protruding portion 24 including the first protruding portion 241 and the second protruding portion 242 with different protruding heights and integrally connected can be machined on the outer guide plate 2.

Further, in the present embodiment, as shown in fig. 2 and 4, a transition portion 243 formed by metal stamping and stretching is provided between the first protrusion 241 and the second protrusion 242. The provision of the transition portion 243 allows for a smoother and smoother chain down-link process.

Referring to fig. 2, the outer guide plate 2 has base plate portions 25 formed at front and rear sides of the lower chain protrusion portion 24, and the base plate portions 25 are bent to form upper and lower end connection portions 21 and 22 connected to upper and lower ends of the inner guide plate 1. It will be appreciated that the front and rear are described herein as being in agreement with the front and rear of the bicycle, the front wheel being the front and the rear wheel being the rear. The base plate portion 25 formed on the front side of the lower chain boss portion 24 refers to the base plate portion 25 that is closer to the front wheel of the bicycle than the lower chain boss portion 24 in the horizontal direction, and the base plate portion 25 formed on the rear side of the lower chain boss portion 24 refers to the base plate portion 25 that is closer to the rear wheel of the bicycle than the lower chain boss portion 24 in the horizontal direction.

Referring again to fig. 2, the upper edge of the lower chain protrusion 24 has a substrate connection portion 26 connecting the front and rear side substrate portions 25 of the lower chain protrusion 24, and the substrate connection portion 26 and the front and rear side substrate portions 25 are located on the same plane.

To further simplify the manufacturing process and reduce the manufacturing cost, in one embodiment, the first protrusion 241 and the second protrusion 242 are formed by one pressing.

Referring to fig. 3, in the present embodiment, in order to prevent the chain from falling outward from the large diameter sprocket when the chain is trained from the small diameter sprocket to the large diameter sprocket, a limit protrusion 20 protruding toward the chain is provided at the front end of the outer guide plate 2.

Preferably, as shown in fig. 4 and 5, in the present embodiment, the lower end connecting portion 22 includes a first connecting portion 221 formed by bending and extending from the lower edge of the rear end of the outer guide plate 2 toward the inner guide plate 1, and a second connecting portion 222 parallel to the inner guide plate 1 and integrally connected to the first connecting portion 221, wherein the second connecting portion 222 is connected to the lower end of the inner guide plate 1.

In this embodiment, in order to make the connection between the outer guide plate 2 and the inner guide plate 1 more stable, a connection post 13 is disposed at the lower end of the inner guide plate 1, and a connection hole 223 through which the connection post 223 can pass is formed on the second connection portion 222; the fixing member is locked to the connection post 13 having passed through the connection hole 223 to connect the second connection part 222 and the lower end of the inner guide plate 1.

Referring to fig. 3 to 6, in the present embodiment, the second connecting portion 222 is closely attached to the inner side surface 11 of the inner guide plate 1. Further, in order to avoid the second connection portion 222 affecting the chain winding, in this embodiment, a placement portion 116 capable of placing the second connection portion 222 is provided at the lower end of the inner side surface 11 of the inner guide plate 1, and the placement portion 116 is configured to be recessed from the inner side surface 11 in a direction away from the chain.

Referring to fig. 1 to 6, in the present embodiment, the inner guide plate 1 has an inner side 11 facing the chain, the inner side 11 being configured to push the chain to switch over on sprockets of three diameters, small, medium and large; the inner side surface 11 of the inner guide plate 1 is provided with a recess portion 111 configured to be recessed from the inner side surface 11 toward a direction away from the chain, and a protruding portion 112 provided on a lower side of the recess portion 111 and protruding toward the chain with respect to the recess portion 111. Wherein the bosses 112 are configured to assist in winding the chain from the small diameter sprocket onto the medium diameter sprocket as the chain is more difficult to wind from the small diameter sprocket onto the medium diameter sprocket than from the medium diameter sprocket onto the large diameter sprocket. The recess 111 divides the inner side surface 11 into a first inner side base surface 1101, a third inner side base surface 1103 and a second inner side base surface 1102 corresponding to the sprockets of three diameters, respectively, and the third inner side base surface 1103 includes the recess 111 and the boss 112, the first inner side base surface 1101 being located at the rear side of the recess 111, and the second inner side base surface 1102 being located at the front side of the recess 111.

Referring to fig. 4 to 6, the inner side 11 includes a first base 1131 and a second base 1132 that are protruded toward the chain as compared to the recess 111; the first base surface 1131 is located behind the recess 111 as a first inner base surface 1101, and the second base surface 1132 is located in front of the recess 111 as a second inner base surface 1102. Further, the protruding amounts of the first base surface 1131, the protruding portion 112, and the second base surface 1132, which protrude toward the chain with respect to the concave portion 111, decrease in order.

In this embodiment, the chain guide 100 in the front derailleur includes an inner guide plate 1 and an outer guide plate 2, which push chains respectively engaged with front sprockets of different diameters to complete a bicycle front derailleur shift. Further, a concave portion 111 and a convex portion 112 are provided on an inner side surface 11 of the inner guide plate 1 facing the chain; the concave portion 111 may divide the inner side surface 11 into three first inner side base surfaces 1101, second inner side base surfaces 1103 and second inner side base surfaces 1102 corresponding to the small, medium and large diameter sprockets, respectively, and the third inner side base surface 1103 includes the concave portion 111 and the convex portion 112, so that when the inner side surface 11 pushes the chain to be trained from the small diameter sprocket to the medium diameter sprocket, the convex portion 112 applies upward pushing force to the chain, which may assist the chain to be shifted obliquely upward, so that the chain is more reliable, smooth and relaxed from the small diameter sprocket to the medium diameter sprocket, and the bicycle front shifting speed is more efficient; in addition, after the chain is wound from the small-diameter chain wheel to the medium-diameter chain wheel or from the medium-diameter chain wheel to the large-diameter chain wheel, a certain gap is reserved between the chain and the inner guide plate 1 and the outer guide plate 2, so that riding is not affected, and noise and damage to a bicycle caused by chain cleaning can be avoided.

Referring to fig. 3 and 6, the protruding portion 112 is a strip extending obliquely upward from the rear to the front. It will be appreciated that the front and rear aspects described herein are consistent with the front and rear aspects of a bicycle, where the front wheel is the front and the rear wheel is the rear, and the position closer to the rear wheel to the front wheel is the rear-to-front. That is, the rear end of the boss 112 is closer to the rear wheel of the bicycle than the front end thereof in both the horizontal and vertical directions. In the present embodiment, the convex portion 112 is adapted to the shape of the front sprocket, and has a circular arc shape in the extending direction thereof.

Preferably, in order to simplify the manufacturing process of the front derailleur and shorten the manufacturing time, in this embodiment, as shown in fig. 4, the protruding portion 112 is formed by bending and extending from the lower end edge of the recessed portion 111 toward the outer guide plate 2 and then bending and extending in opposite directions. In addition, the protruding part 112 formed by the method is connected with the chain guide part 100 into a whole, so that the protruding part 112 is more firmly connected with the inner guide plate 1, and the reliability of the chain winding can be further improved.

Referring to fig. 4 to 6, the inner side 11 includes a first base 1131 and a second base 1132 that are protruded toward the chain as compared to the recess 111; the first base surface 1131 is located behind the recess 111 as a first inner base surface 1101, and the second base surface 1132 is located in front of the recess 111 as a second inner base surface 1102. Further, the protruding amounts of the first base surface 1131, the protruding portion 112, and the second base surface 1132, which protrude toward the chain with respect to the concave portion 111, decrease in order. A slope-shaped transitional connection surface 114 is arranged between the first base surface 1131 and the concave part 111. The amount of protrusion of the transitional coupling surface 114 toward the direction approaching the chain increases as the distance from the rear end portion of the concave portion 111 to the first base surface 1131 decreases, i.e., the closer to the first base surface 1131, the more it protrudes toward the direction approaching the chain. In this embodiment, the slope-shaped transitional coupling surface 114 can make the movement of the chain in the chain guide 100 smoother, thereby further improving the reliability of the chain winding.

Referring to FIG. 3, in order to reduce the weight of the front derailleur and to reduce the amount of material required to manufacture the front derailleur, a material reduction through hole 115 is formed in the first base surface 1131 and the recess 111.

It should be noted that, in other embodiments, one or more material reducing through holes 115 may be formed only on the base surface 113 or the recess 111, or a plurality of material reducing through holes 115 may be formed on the base surface 113 and the recess 111, for the sake of overall aesthetic appearance.

Referring again to FIG. 1, in this embodiment, the front derailleur includes a fixing base 200, a connecting plate 300 and a wire pulling seat 400 in addition to the chain guide 100; the fixing seat 200 is respectively connected with the connecting plate 300 and the stay wire seat 400, the chain guide 100 is respectively connected with the connecting plate 300 and the stay wire seat 400, so that a link mechanism is formed between the connecting plate 300 and the stay wire seat 400, and the chain guide 100 can be driven to guide a chain to switch between front chain wheels with different diameters by pulling the stay wire seat 400, thereby realizing speed change. Specifically, the chain guide 100 is provided with a first connecting plate 101 and a second connecting plate 102, the first connecting plate 101 is provided with a first connecting plate connecting hole for connecting the connecting plate 300, and the second connecting plate 102 is provided with a second connecting plate connecting hole for connecting the connecting plate 300 and a wire seat connecting hole for connecting the wire seat 400. In an embodiment, the first connecting plate 101 and the second connecting plate 102 are each formed by bending and extending the inner guide plate 1 of the chain guide 100 in a direction away from the chain. In this embodiment, the fixing base 200 is connected with a mounting portion 201, the fixing base 200 and the entire front derailleur can be connected to the bicycle frame below the bicycle seat through the mounting portion 201, and the mounting portion 201 can be a screw, a buckle, a strap, etc., which is sufficient to connect the fixing base 200 to the bicycle frame.

As apparent from the above description of the embodiments, the bicycle front derailleur provided by the present application has the chain guide 100 including the inner guide plate 1 and the outer guide plate 2 disposed opposite to each other on both sides of the chain, and the lower chain protrusion 24 including the first protrusion 241 and the second protrusion 242 having different protrusion heights and integrally connected to each other is formed on the outer guide plate 2 in such a manner that the outer guide plate 2 of the chain guide 100 protrudes and deforms toward one side of the chain by pressing, when the chain is down-trained from the large diameter sprocket to the medium diameter sprocket, the first protrusion 241 pushes the chain down-chain, when the chain is down-trained from the medium diameter sprocket to the small diameter sprocket, the second protrusion 242 pushes the chain down-chain, and after the chain is down-trained to the medium diameter sprocket or the small diameter sprocket, a certain gap exists between the chain and the outer guide plate 2 and the inner guide plate 1, thereby not affecting riding and also avoiding noise and damage caused by the occurrence of chain wiping. In this embodiment, the outer guide plate 2 of the chain guide 100 is deformed by pressing to protrude toward one side of the chain, so that the lower chain protruding portion 24 including the first protruding portion 241 and the second protruding portion 242 with different protruding heights and integrally connected can be machined on the outer guide plate 2.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims (10)

1. The utility model provides a front derailleur for bicycle, is applicable to the front sprocket of three-speed structure, including the chain guide that is used for supplying the chain to pass, the chain guide includes interior baffle and the outer baffle that sets up relatively in the chain both sides, its characterized in that, outer baffle is processed out by metal base plate and is suitable for pushing the chain and down chain bellying to the minor diameter sprocket by major diameter sprocket, wherein, the bellying of down chain is by to a part of metal base plate is towards chain one side makes its protruding deformation form that stretches, the bellying of down chain includes protruding first convex part and the second convex part that stretches highly different, first convex part and second convex part connect as an organic wholely.

2. The bicycle front derailleur according to claim 1, wherein the first projection and the second projection have a transition portion therebetween that is formed by metal stamping and stretching.

3. The bicycle front derailleur according to claim 1, wherein the outer guide plate has a base plate portion formed on front and rear sides of the lower chain boss, and the base plate portion is bent to form a connecting portion connected to upper and lower ends of the inner guide plate.

4. The bicycle front derailleur according to claim 3, wherein the upper edge of the lower chain protrusion has a base plate connecting portion connecting front and rear side base plate portions of the lower chain protrusion, the base plate connecting portion being in the same plane as the front and rear side base plate portions.

5. The front derailleur for a bicycle of claim 1 or 2, characterized in that the first and second bosses are formed by one pressing.

6. The bicycle front derailleur according to claim 3, wherein the base plate portion located on the front side of the lower chain boss is provided with a spacing protrusion protruding toward the chain, and the spacing protrusion is configured to prevent the chain from falling off the sprocket having the largest diameter.

7. The bicycle front derailleur according to claim 3, wherein the connecting portion of the base plate portion to the lower end of the inner guide plate includes:

The first connecting part is formed by bending and extending from the lower edge of the base plate part positioned at the rear side of the lower chain protruding part towards the inner guide plate; and

The second connecting part is parallel to the inner guide plate and is connected with the first connecting part into a whole;

the second connecting part is connected with the lower end of the inner guide plate.

8. The bicycle front derailleur according to claim 7, wherein a connecting post is provided at a lower end of the inner guide plate, and a connecting hole through which the connecting post passes is provided in the second connecting portion; the fixing piece is locked on the connecting column which passes through the connecting hole so as to connect the second connecting part and the lower end of the inner guide plate.

9. The bicycle front derailleur according to claim 1, wherein the inner side of the inner guide plate facing the chain is configured and adapted to push the chain up from a small diameter sprocket to a large diameter sprocket, wherein the inner side of the inner guide plate is provided with:

a recessed portion configured to be recessed from the inner side surface in a direction away from the chain; and

A protruding portion provided at a lower side of the recessed portion and protruding toward the chain with respect to the recessed portion;

Wherein the boss is configured to impart an upward pushing force to the chain when the inner side pushes the chain to shift laterally, so as to facilitate the chain to be trained from a small diameter sprocket to a large diameter sprocket.

10. The bicycle front derailleur according to claim 9, wherein the three speed configuration front sprocket includes three small, medium and large diameter sprockets, wherein the boss is configured to assist when the chain is trained from the small diameter sprocket to the medium diameter sprocket.