CA2656761A1 - Eccentric bottom bracket for a bicycle - Google Patents
Eccentric bottom bracket for a bicycle Download PDFInfo
- Publication number
- CA2656761A1 CA2656761A1 CA 2656761 CA2656761A CA2656761A1 CA 2656761 A1 CA2656761 A1 CA 2656761A1 CA 2656761 CA2656761 CA 2656761 CA 2656761 A CA2656761 A CA 2656761A CA 2656761 A1 CA2656761 A1 CA 2656761A1
- Authority
- CA
- Canada
- Prior art keywords
- bottom bracket
- bicycle
- eccentric
- crank arm
- eccentric bottom
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K19/00—Cycle frames
- B62K19/30—Frame parts shaped to receive other cycle parts or accessories
- B62K19/34—Bottom brackets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M3/00—Construction of cranks operated by hand or foot
- B62M3/003—Combination of crank axles and bearings housed in the bottom bracket
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M9/00—Transmissions characterised by use of an endless chain, belt, or the like
- B62M9/16—Tensioning or adjusting equipment for chains, belts or the like
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Motorcycle And Bicycle Frame (AREA)
Abstract
This patent discloses an eccentric bottom bracket for a bicycle. Said bottom bracket is composed of two similar tubular threaded retainers which are mounted symmetrically to opposite ends of the bottom bracket shell of a bicycle. Within each of said similar retainers are similar discs housing bearings. These bearings are the means by which the crank arm spindle is supported within the bottom bracket shell. Said discs may be rotated and fixed into a desired position by a plurality of fasteners. By rotationally positioning these discs, the spindle and attached crank arms locate the attached chainring forward or back relative to the center of the bottom bracket shell. This chainring positioning may impart greater or lesser tension onto the drive chain of the bicycle. This adjustment system is advantageous for achieving optimal chain tension on bicycles.
Description
flat sections which may allow it to be easily and conveniently manipulated with a wrench or other suitable tool.
Description:
FIELD OF INVENTION
1. The invention describes an eccentric bottom bracket for a bicycle. It is desirable to adjust chain tension in bicycles so that related drivetrain components may function properly. This invention allows one to install an eccentric bottom bracket into a frame with a standard bottom bracket shell, as understood within the industry. The present invention has a more limited range than traditional eccentric bottom brackets, but offers the advantage of being able to be installed into any bicycle frame with a standard sized threaded bottom bracket shell. It does not require a frame with an oversized bottom bracket shell, as is usually needed to install an eccentric bottom bracket on a bicycle. It is further advantageous in that it does not require a separate oversized eccentric bottom bracket to be installed into.
BACKGROUND OF THE INVENTION
1. A bicycle drivetrain must maintain optimal chain tension in order for the chain and related components to function properly. Chain tension is achieved by a number of methods. One of these uses a device known within the industry as an eccentric bottom bracket.
In a traditional eccentric bottom bracket, a standard bottom bracket is installed within a secondary cylinder.
The housing for the standard bottom bracket is eccentrically offset from the central axis of the secondary cylinder. Rotating the secondary cylinder within its oversized frame shell positions the axle fore or aft of the shell center. The resulting orientation provides greater or lesser tensiori on the drive chrin of the bicycle. Once oriented, the main cylinder is locked into position by diverse means, allowing the chain to retain it's set tension.
The present invention addresses the need within the bicycle industry for an eccentric bottom bracket of that may be installed into a standard bottom bracket shell, and is of a unitary design. Current designs for eccentric bottom brackets require that a bottom bracket of standard size be installed into a secondary, oversized cylinder. This secondary cylinder features an offset chamber into which the standard bottom bracket is installed (US PATENT
4,808,147, US PATENT 697,944). This prevailing method requires that the bicycle frame be fitted with an oversized bottom bracket shell to accommodate the secondary cylinder. Said arrangement contributes weight, complexity, and cost to the incorporation of an eccentric bottom bracket. There is one known eccentric bottom bracket with some similar features as the proposed invention, but no patent or patent application is known. This product is known as the Exzentriker, and is manufactured in Germany by a company called Trickstuff. This present invention contains features not found on the Trickstuff eccentric bottom bracket, which make the present invention advantageous and unique.
By combining the bearing assembly of a standard bottom bracket with a cylinder incorporating offset housing for said assembly, the present invention results in a unitary design. Said unitary eccentric bottom bracket eliminates the secondary cylinder typical of traditional eccentric bottom brackets. A further important benefit of the unitary eccentric bottom bracket is that a compact arrangement is achieved. This compact unitary eccentric bottom bracket can easily be installed into a bicycle frame bottom bracket shell of standard width and diameter, as understood within the bicycle industry.
Further, the proposed positioning and retaining system for the present invention allows simple installation into a standard bottom bracket shell without modification of the bottom bracket shell. This system provides for an extremely compact and robust method of maintaining rotational position of the unitary eccentric bottom bracket discs, well understand by those skilled in the arts of bicycle component design.
SUMMARY OF THE INVENTION
1. An eccentric bottom bracket for a bicycle that may be installed into a standard bottom bracket shell, as understood within the bicycle industry. Said eccentric bottom bracket utilizes the threads contained within a standard bottom bracket shell for installation into the frame of a bicycle. The eccentric bottom bracket can be installed into a bicycle frame bottom bracket shell of standard width and diameter, as understood within the bicycle industry. No specialized frame details or modifications such as set screws or pinch bolts are required.
The frame attachment elements of the eccentric bottom bracket are two similarly configured tubular threaded cups. The threaded cups are externally threaded so that they may be installed into a standard threaded bottom bracket shell of a bicycle, just as any standard bottom bracket would. The invention does not depend on an oversized bottom bracket shell in which to be installed. The eccentric bottom bracket is composed of two similar assemblies, each of which thread into one end of a threaded bottom bracket shell of a bicycle. Together the assemblies support the crank arm spindle of the bicycle, at both ends of the spindle.
Description:
FIELD OF INVENTION
1. The invention describes an eccentric bottom bracket for a bicycle. It is desirable to adjust chain tension in bicycles so that related drivetrain components may function properly. This invention allows one to install an eccentric bottom bracket into a frame with a standard bottom bracket shell, as understood within the industry. The present invention has a more limited range than traditional eccentric bottom brackets, but offers the advantage of being able to be installed into any bicycle frame with a standard sized threaded bottom bracket shell. It does not require a frame with an oversized bottom bracket shell, as is usually needed to install an eccentric bottom bracket on a bicycle. It is further advantageous in that it does not require a separate oversized eccentric bottom bracket to be installed into.
BACKGROUND OF THE INVENTION
1. A bicycle drivetrain must maintain optimal chain tension in order for the chain and related components to function properly. Chain tension is achieved by a number of methods. One of these uses a device known within the industry as an eccentric bottom bracket.
In a traditional eccentric bottom bracket, a standard bottom bracket is installed within a secondary cylinder.
The housing for the standard bottom bracket is eccentrically offset from the central axis of the secondary cylinder. Rotating the secondary cylinder within its oversized frame shell positions the axle fore or aft of the shell center. The resulting orientation provides greater or lesser tensiori on the drive chrin of the bicycle. Once oriented, the main cylinder is locked into position by diverse means, allowing the chain to retain it's set tension.
The present invention addresses the need within the bicycle industry for an eccentric bottom bracket of that may be installed into a standard bottom bracket shell, and is of a unitary design. Current designs for eccentric bottom brackets require that a bottom bracket of standard size be installed into a secondary, oversized cylinder. This secondary cylinder features an offset chamber into which the standard bottom bracket is installed (US PATENT
4,808,147, US PATENT 697,944). This prevailing method requires that the bicycle frame be fitted with an oversized bottom bracket shell to accommodate the secondary cylinder. Said arrangement contributes weight, complexity, and cost to the incorporation of an eccentric bottom bracket. There is one known eccentric bottom bracket with some similar features as the proposed invention, but no patent or patent application is known. This product is known as the Exzentriker, and is manufactured in Germany by a company called Trickstuff. This present invention contains features not found on the Trickstuff eccentric bottom bracket, which make the present invention advantageous and unique.
By combining the bearing assembly of a standard bottom bracket with a cylinder incorporating offset housing for said assembly, the present invention results in a unitary design. Said unitary eccentric bottom bracket eliminates the secondary cylinder typical of traditional eccentric bottom brackets. A further important benefit of the unitary eccentric bottom bracket is that a compact arrangement is achieved. This compact unitary eccentric bottom bracket can easily be installed into a bicycle frame bottom bracket shell of standard width and diameter, as understood within the bicycle industry.
Further, the proposed positioning and retaining system for the present invention allows simple installation into a standard bottom bracket shell without modification of the bottom bracket shell. This system provides for an extremely compact and robust method of maintaining rotational position of the unitary eccentric bottom bracket discs, well understand by those skilled in the arts of bicycle component design.
SUMMARY OF THE INVENTION
1. An eccentric bottom bracket for a bicycle that may be installed into a standard bottom bracket shell, as understood within the bicycle industry. Said eccentric bottom bracket utilizes the threads contained within a standard bottom bracket shell for installation into the frame of a bicycle. The eccentric bottom bracket can be installed into a bicycle frame bottom bracket shell of standard width and diameter, as understood within the bicycle industry. No specialized frame details or modifications such as set screws or pinch bolts are required.
The frame attachment elements of the eccentric bottom bracket are two similarly configured tubular threaded cups. The threaded cups are externally threaded so that they may be installed into a standard threaded bottom bracket shell of a bicycle, just as any standard bottom bracket would. The invention does not depend on an oversized bottom bracket shell in which to be installed. The eccentric bottom bracket is composed of two similar assemblies, each of which thread into one end of a threaded bottom bracket shell of a bicycle. Together the assemblies support the crank arm spindle of the bicycle, at both ends of the spindle.
2. An eccentric bottom bracket for a bicycle that is of a unitary design and construction. The bearing and spindles of the crank arms are fitted directly within said eccentric bottom bracket, eliminating the need for a second, oversized cylinder for a bottom bracket to be installed eccentrically into. The unitary eccentric bottom bracket may be installed into, but is not restricted to, a bottom bracket shell of standard size and width, as understood within the bicycle industry. The eccentric bottom bracket incorporates bearings within it, and does not require a separate bottom bracket to be installed within it in order to support the crank arm spindle. Each threaded cup of the invention contains a receptacle in which a disc is installed, at either end of the bottom bracket shell in order to support the crank arm spindle. In each disc is an offset bore. In each offset bore is installed a bearing. A spacer ring separates each bearing from the inner face of the crank arm attached. This spacer ring rotates with the crank arm during pedaling, and prevents the crank arm from contacting the non rotating elements of the eccentric bottom bracket. The spacer rings have a secondary purpose, and that is to locate the crank arm at the correct distance from the bottom bracket shell, in order to assure that correct chain line is achieved between the front and rear drive sprockets of the bicycle. By rotationally positioning the two bearing discs, the crank arm spindle may be positioned forward or aft of the bottom bracket shell center. By positioning these discs, the installed crank arm spindle is moved forward or back relative to the center of the bottom bracket shell.
This position adjustment moves the front drive sprocket of the bicycle forward or back relative to the drive sprocket of the rear wheel. This position adjustment allows the eccentric bottom bracket to impart greater or lesser tension onto the attached drive chain of the bicycle, which is advantageous for maintaining optimal chain tension.
This position adjustment moves the front drive sprocket of the bicycle forward or back relative to the drive sprocket of the rear wheel. This position adjustment allows the eccentric bottom bracket to impart greater or lesser tension onto the attached drive chain of the bicycle, which is advantageous for maintaining optimal chain tension.
3. An eccentric bottom bracket for a standard bicycle frame with a unique and advantageous method for rotationally adjusting and positioning the crank spindle in order to optimize chain tension. This method utilizes a pair of similar attachments that do not require tools in order to be manipulated. Said attachments are affixed to the discs that contain the bearings which support the crank arm spindle. The attachments may contain features such as notches along their perimeter, or other features that provide for gripping by hand or with tools, in order to rotationally position the attached discs and bearings contained within them.
4. An eccentric bottom bracket for a standard bicycle frame with a simple method for fixing the spindle into the desired orientation. Said eccentric bottom bracket may be installed into a bicycle bottom bracket shell of standard width and diameter, as understood within the bicycle industry. The method for fixing the discs into position utilizes a plurality of fasteners such as set screws. These fasteners are distributed around the perimeter of the retaining cups. The fasteners are of sufficient quantity, and of uniform distribution that they may be tightened against the bearing disc regardless of it's rotational orientation without damaging the bearing disc. The fact that there are a plurality of fasteners, and their distribution is essentially uniform, means that one or more may be left untightened, or only lightly tightened, so that no damage is done to the thin section of the bearing disc wall.
5. An eccentric bottom bracket with a nominal 1/4 inch total adjustment range.
That is, nominally 1/8 inch forward of the center position, and nominally 1/8 inch rearward of the center position of the bottom bracket shell. The actual range may be fractionally less or more, varying with manufacturing and assembly tolerances.
That is, nominally 1/8 inch forward of the center position, and nominally 1/8 inch rearward of the center position of the bottom bracket shell. The actual range may be fractionally less or more, varying with manufacturing and assembly tolerances.
6. An eccentric bottom bracket that incorporates spacer rings between the bearings and the crank arms. The rings assist in locating the crank arms at the correct distance from the bicycle bottom bracket shell. The rings also allows the crank arm to press against them, imparting thrust against the bearings so that there is no lateral play within the assembly. The ring is of a sufficient thickness that it prevents the rotating crank arms from contacting the non rotating elements of the eccentric bottom bracket.
7. A dedicated tool to facilitate the installation, adjustment, and removal of the eccentric bottom bracket invention with economy and simplicity. The tools is affixed to the threaded cups in the same manner as the bearing discs are, that is by means of fasteners such as set screws or other threaded fasteners. After installation or removal, the tool may be removed from the threaded cups. The installation and removal tool has features such as raised parallel flat sections which may allow it to be easily and conveniently manipulated with a wrench or other suitable tool.
BRIEF DESCRIPTION OF THE DRAWINGS
1. Figure 1 is a side view of the bottom bracket of a typical bicycle frame.
The circular feature at the junction of the three tubes is known as the bottom bracket shell of the frame. For purposes of clarity, this threaded tube will be referred to in this patent as the bottom bracket shell. In the case of the present invention, the bottom bracket component being claimed is known as an eccentric bottom bracket. The present invention will be described by it's full description of eccentric bottom bracket in this patent for purposes of clarity.
The frame shown is a typical "double diamond" frame design. The present invention is not limited to any type of frame configuration. It is suitable for installation in any bottom bracket of standard size, as understood within the bicycle industry.
2. Figure 2 is a side view of the present invention installed into a bottom bracket. The bearing discs are in their rearward most position relative to the bottom bracket center.
3. Figure 3 is a side view of the present invention installed into a bottom bracket. The bearing discs are in their forward most position relative to the bottom bracket center, 4. Figure 4 is a section view of the eccentric bottom bracket installed in a bottom bracket. The attached crank arms and spindle are shown to illustrate the complete assembly.
The eccentric bottom bracket is depicted in it's neutral position. The bearing discs are capable of being moved nominally 1/8 inch forward of this position, or nominally 1/8 inch rearward of this position.
5. Figure 5 is an exploded section drawing showing all the component elements of the eccentric bottom bracket, as well as the bottom bracket into which they are to be installed.
The eccentric bottom bracket is depicted in it's neutral position. The bearing discs are capable of being moved nominally 1/8 inch forward of this position, or nominally 1/8 inch rearward of this position.
6. Figure 6 is a section view of the bottom bracket with eccentric bottom bracket installed. The eccentric bottom bracket is depicted in it's neutral position. The bearing discs are capable of being moved nominally 1/8 inch forward of this position, or nominally 1/8 inch rearward of this position.
7. Figure 7 is a side view of the component elements of the eccentric bottom bracket.
BRIEF DESCRIPTION OF THE DRAWINGS
1. Figure 1 is a side view of the bottom bracket of a typical bicycle frame.
The circular feature at the junction of the three tubes is known as the bottom bracket shell of the frame. For purposes of clarity, this threaded tube will be referred to in this patent as the bottom bracket shell. In the case of the present invention, the bottom bracket component being claimed is known as an eccentric bottom bracket. The present invention will be described by it's full description of eccentric bottom bracket in this patent for purposes of clarity.
The frame shown is a typical "double diamond" frame design. The present invention is not limited to any type of frame configuration. It is suitable for installation in any bottom bracket of standard size, as understood within the bicycle industry.
2. Figure 2 is a side view of the present invention installed into a bottom bracket. The bearing discs are in their rearward most position relative to the bottom bracket center.
3. Figure 3 is a side view of the present invention installed into a bottom bracket. The bearing discs are in their forward most position relative to the bottom bracket center, 4. Figure 4 is a section view of the eccentric bottom bracket installed in a bottom bracket. The attached crank arms and spindle are shown to illustrate the complete assembly.
The eccentric bottom bracket is depicted in it's neutral position. The bearing discs are capable of being moved nominally 1/8 inch forward of this position, or nominally 1/8 inch rearward of this position.
5. Figure 5 is an exploded section drawing showing all the component elements of the eccentric bottom bracket, as well as the bottom bracket into which they are to be installed.
The eccentric bottom bracket is depicted in it's neutral position. The bearing discs are capable of being moved nominally 1/8 inch forward of this position, or nominally 1/8 inch rearward of this position.
6. Figure 6 is a section view of the bottom bracket with eccentric bottom bracket installed. The eccentric bottom bracket is depicted in it's neutral position. The bearing discs are capable of being moved nominally 1/8 inch forward of this position, or nominally 1/8 inch rearward of this position.
7. Figure 7 is a side view of the component elements of the eccentric bottom bracket.
8. Figure 8 is a side view of the installation tool, with the flats for tool attachment facing the viewer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is composed of similar left side and right side elements, with the exception of the installation tool. In order to simplify the descriptions, the preferred embodiments described below refer singularly to the elements of one side only, but apply equally to both the left and right side elements of the eccentric bottom bracket.
1. A threaded retainer which is tubular in nature. The inside diameter is large enough to accommodate a 24mm diameter spindle, with room to move the spindle radially in relation to the central axis of the bottom bracket shell. The range of motion of the spindle is nominally 1/8 of an inch forward or nominally 1/8 of an inch rearward, or to any point in between, in order that an attached crank and chainring assembly may impart adequate tension on the drive chain of the bicycle.
2. A threaded cup which is tubular in nature. One end is narrower on the outside, and externally threaded to install into a bottom bracket shell.
3. A threaded cup which is tubular in nature. One end is wider. The wider end of the threaded cup has a plurality of threaded holes located radially around it such that set screws or other fasteners may be used to fix a disc into a desired position within.
4. A threaded cup which is tubular in nature. One end is wider. The wider end of the threaded cup has a plurality of threaded holes located radially around it such that set screws or other fasteners may be used to fix a disc into a desired position within. The threaded holes are of a sufficient number that the disc may be fixed into any position without any of the fasteners placing undue pressure against the thin wall region of the disc.
5. A disc that fits into the large end of the threaded cup. The disc may be fixed into place within the threaded cup by means of set screws or other fasteners.
6. A disc that fits into the large end of the threaded cup. This disc has an offset or eccentric hole to accommodate a bearing. The hole is offset nominally 1/8 of an inch from the center of the disc so that the disc, when being rotated, may impart adequate tension on the drive train of the bicycle. The disc may then be fixed into place within the threaded cup by means of set screws or other fasteners, as described in embodiment 4.
7. A bearing that supports the spindle element of the crank arm assembly. The bearing is installed into the disc, as described in embodiment 6.
8. A ring which transfers thrust loads from the crank arm to the bearing. The ring has an inner diameter which is no smaller than the inner diameter of the spindle. The ring has an outer diameter that is small enough that it may not interfere with other elements of the eccentric bottom bracket assembly. The ring assists in locating the crank arm at the correct distance from the bicycle bottom bracket shell. The ring also allows the crank arm to press against it, imparting thrust against the inner race bearings so that there is no play within the assembly.
The ring is of a sufficient thickness that it prevents the rotating crank arms from contacting the non rotating elements of the eccentric bottom bracket.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is composed of similar left side and right side elements, with the exception of the installation tool. In order to simplify the descriptions, the preferred embodiments described below refer singularly to the elements of one side only, but apply equally to both the left and right side elements of the eccentric bottom bracket.
1. A threaded retainer which is tubular in nature. The inside diameter is large enough to accommodate a 24mm diameter spindle, with room to move the spindle radially in relation to the central axis of the bottom bracket shell. The range of motion of the spindle is nominally 1/8 of an inch forward or nominally 1/8 of an inch rearward, or to any point in between, in order that an attached crank and chainring assembly may impart adequate tension on the drive chain of the bicycle.
2. A threaded cup which is tubular in nature. One end is narrower on the outside, and externally threaded to install into a bottom bracket shell.
3. A threaded cup which is tubular in nature. One end is wider. The wider end of the threaded cup has a plurality of threaded holes located radially around it such that set screws or other fasteners may be used to fix a disc into a desired position within.
4. A threaded cup which is tubular in nature. One end is wider. The wider end of the threaded cup has a plurality of threaded holes located radially around it such that set screws or other fasteners may be used to fix a disc into a desired position within. The threaded holes are of a sufficient number that the disc may be fixed into any position without any of the fasteners placing undue pressure against the thin wall region of the disc.
5. A disc that fits into the large end of the threaded cup. The disc may be fixed into place within the threaded cup by means of set screws or other fasteners.
6. A disc that fits into the large end of the threaded cup. This disc has an offset or eccentric hole to accommodate a bearing. The hole is offset nominally 1/8 of an inch from the center of the disc so that the disc, when being rotated, may impart adequate tension on the drive train of the bicycle. The disc may then be fixed into place within the threaded cup by means of set screws or other fasteners, as described in embodiment 4.
7. A bearing that supports the spindle element of the crank arm assembly. The bearing is installed into the disc, as described in embodiment 6.
8. A ring which transfers thrust loads from the crank arm to the bearing. The ring has an inner diameter which is no smaller than the inner diameter of the spindle. The ring has an outer diameter that is small enough that it may not interfere with other elements of the eccentric bottom bracket assembly. The ring assists in locating the crank arm at the correct distance from the bicycle bottom bracket shell. The ring also allows the crank arm to press against it, imparting thrust against the inner race bearings so that there is no play within the assembly.
The ring is of a sufficient thickness that it prevents the rotating crank arms from contacting the non rotating elements of the eccentric bottom bracket.
9. A manipulation disc which is attached to the bearing disc described in embodiment 5.
10. A manipulation disc which is attached to the bearing disc described in embodiment 5. This attachment allows the bearing disc to be manipulated into the desired position after the crank arm and spindle assembly has been installed. The manipulation disc is attached to the bearing disc by fasteners or other means. The inside surface of the manipulation disc attaches to the outside surface of the bearing disc.
11. A manipulation disc which is attached to the bearing disc described in embodiment 5. This attachment allows the bearing disc to be manipulated into the desired position after the crank arm and spindle assembly has been installed. The manipulation disc has features and or a texture which allows it to be manipulated by hand or by tools such that it hay be rotated in order to rotate the attached bearing disc into the desired position.
12. An installation tool that consists of a disc with features for manipulation by a tool such as a wrench, spanner, pliers, or other device. The installation tool fits temporarily into the threaded cup, in the location where the bearing disc is normally placed. The fixing screws of the threaded cup hold the installation tool in place. Rotating the installation tools allows the threaded cup to be threaded into the bottom bracket shell with adequate torque.
VARIANTS
1. The invention embodies principles that can be applied to various bottom bracket shell and thread standards. The bicycle industry defines a standard bottom bracket shell as one being 68mm or 73mm or sometimes 100mm in width, with a so called English (also known as British and I.S.O.) thread of 1.37 inches diameter with a thread pitch of 24 threads per inch. This standard uses right hand threads on the left side of the bottom bracket shell, and left hand threads on the right side of the bottom bracket shell. The various other less typical thread standards, known commonly as Italian, French, Swiss, Raleigh, and others can also be covered under this patent, since all that is required to work with those standards is a minor change in thread diameter, thread pitch, and thread direction.
2. A manipulation disc described in embodiment 9. may also be integrated as part of one single component with the bearing disc to which it is attached. This unitary manipulation disc and bearing disc would function exactly as described in the preferred embodiments where they are described as separate elements.
3. An installation or removal tool as described in claim 6 may be configured to allow for interface with tools other than a standard wrench, such as hex wrenches or even custom designed tools.
VARIANTS
1. The invention embodies principles that can be applied to various bottom bracket shell and thread standards. The bicycle industry defines a standard bottom bracket shell as one being 68mm or 73mm or sometimes 100mm in width, with a so called English (also known as British and I.S.O.) thread of 1.37 inches diameter with a thread pitch of 24 threads per inch. This standard uses right hand threads on the left side of the bottom bracket shell, and left hand threads on the right side of the bottom bracket shell. The various other less typical thread standards, known commonly as Italian, French, Swiss, Raleigh, and others can also be covered under this patent, since all that is required to work with those standards is a minor change in thread diameter, thread pitch, and thread direction.
2. A manipulation disc described in embodiment 9. may also be integrated as part of one single component with the bearing disc to which it is attached. This unitary manipulation disc and bearing disc would function exactly as described in the preferred embodiments where they are described as separate elements.
3. An installation or removal tool as described in claim 6 may be configured to allow for interface with tools other than a standard wrench, such as hex wrenches or even custom designed tools.
Claims (7)
1. An eccentric bottom bracket for a bicycle that may be installed into a standard bottom bracket shell, as understood within the bicycle industry. Said eccentric bottom bracket utilizes the threads contained within a standard bottom bracket shell for installation into the frame of a bicycle. The eccentric bottom bracket can be installed into a bicycle frame bottom bracket shell of standard width and diameter, as understood within the bicycle industry. No specialized frame details or modifications such as set screws or pinch bolts are required.
The frame attachment elements of the eccentric bottom bracket are two similarly configured tubular threaded cups. The threaded cups are externally threaded so that they may be installed into a standard threaded bottom bracket shell of a bicycle, just as any standard bottom bracket would. The invention does not depend on an oversized bottom bracket shell in which to be installed. The eccentric bottom bracket is composed of two similar assemblies, each of which thread into one end of a threaded bottom bracket shell of a bicycle. Together the assemblies support the crank arm spindle of the bicycle, at both ends of the spindle.
The frame attachment elements of the eccentric bottom bracket are two similarly configured tubular threaded cups. The threaded cups are externally threaded so that they may be installed into a standard threaded bottom bracket shell of a bicycle, just as any standard bottom bracket would. The invention does not depend on an oversized bottom bracket shell in which to be installed. The eccentric bottom bracket is composed of two similar assemblies, each of which thread into one end of a threaded bottom bracket shell of a bicycle. Together the assemblies support the crank arm spindle of the bicycle, at both ends of the spindle.
2. An eccentric bottom bracket for a bicycle that is of a unitary design and construction. The bearing and spindles of the crank arms are fitted directly within said eccentric bottom bracket, eliminating the need for a second, oversized cylinder for a bottom bracket to be installed eccentrically into. The unitary eccentric bottom bracket may be installed into, but is not restricted to, a bottom bracket shell of standard size and width, as understood within the bicycle industry. The eccentric bottom bracket incorporates bearings within it, and does not require a separate bottom bracket to be installed within it in order to support the crank arm spindle. Each threaded cup of the invention contains a receptacle in which a disc is installed, at either end of the bottom bracket shell in order to support the crank arm spindle. In each disc is an offset bore. In each offset bore is installed a bearing. A spacer ring separates each bearing from the inner face of the crank arm attached. This spacer ring rotates with the crank arm during pedaling, and prevents the crank arm from contacting the non rotating elements of the eccentric bottom bracket. The spacer rings have a secondary purpose, and that is to locate the crank arm at the correct distance from the bottom bracket shell, in order to assure that correct chain line is achieved between the front and rear drive sprockets of the bicycle. By rotationally positioning the two bearing discs, the crank arm spindle may be positioned forward or aft of the bottom bracket shell center. By positioning these discs, the installed crank arm spindle is moved forward or back relative to the center of the bottom bracket shell.
This position adjustment moves the front drive sprocket of the bicycle forward or back relative to the drive sprocket of the rear wheel. This position adjustment allows the eccentric bottom bracket to impart greater or lesser tension onto the attached drive chain of the bicycle, which is advantageous for maintaining optimal chain tension.
This position adjustment moves the front drive sprocket of the bicycle forward or back relative to the drive sprocket of the rear wheel. This position adjustment allows the eccentric bottom bracket to impart greater or lesser tension onto the attached drive chain of the bicycle, which is advantageous for maintaining optimal chain tension.
3. An eccentric bottom bracket for a standard bicycle frame with a unique and advantageous method for rotationally adjusting and positioning the crank spindle in order to optimize chain tension. This method utilizes a pair of similar attachments that do not require tools in order to be manipulated. Said attachments are affixed to the discs that contain the bearings which support the crank arm spindle. The attachments may contain features such as notches along their perimeter, or other features that provide for gripping by hand or with tools, in order to rotationally position the attached discs and bearings contained within them.
4. An eccentric bottom bracket for a standard bicycle frame with a simple method for fixing the spindle into the desired orientation. Said eccentric bottom bracket may be installed into a bicycle bottom bracket shell of standard width and diameter, as understood within the bicycle industry. The method for fixing the discs into position utilizes a plurality of fasteners such as set screws. These fasteners are distributed around the perimeter of the retaining cups. The fasteners are of sufficient quantity, and of uniform distribution that they may be tightened against the bearing disc regardless of it's rotational orientation without damaging the bearing disc. The fact that there are a plurality of fasteners, and their distribution is essentially uniform, means that one or more may be left untightened, or only lightly tightened, so that no damage is done to the thin section of the bearing disc wall.
5. An eccentric bottom bracket with a nominal 1/4 inch total adjustment range.
That is, nominally 1/8 inch forward of the center position, and nominally 1/8 inch rearward of the center position of the bottom bracket shell. The actual range may be fractionally less or more, varying with manufacturing and assembly tolerances.
That is, nominally 1/8 inch forward of the center position, and nominally 1/8 inch rearward of the center position of the bottom bracket shell. The actual range may be fractionally less or more, varying with manufacturing and assembly tolerances.
6. An eccentric bottom bracket that incorporates spacer rings between the bearings and the crank arms. The rings assist in locating the crank arms at the correct distance from the bicycle bottom bracket shell. The rings also allows the crank arm to press against them, imparting thrust against the bearings so that there is no lateral play within the assembly. The ring is of a sufficient thickness that it prevents the rotating crank arms from contacting the non rotating elements of the eccentric bottom bracket.
7. A dedicated tool to facilitate the installation, adjustment, and removal of the eccentric bottom bracket invention with economy and simplicity. The tools is affixed to the threaded cups in the same manner as the bearing discs are, that is by means of fasteners such as set screws or other threaded fasteners. After installation or removal, the tool may be removed from the threaded cups. The installation and removal tool has features such as raised parallel
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2656761 CA2656761A1 (en) | 2008-12-02 | 2008-12-02 | Eccentric bottom bracket for a bicycle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2656761 CA2656761A1 (en) | 2008-12-02 | 2008-12-02 | Eccentric bottom bracket for a bicycle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2656761A1 true CA2656761A1 (en) | 2010-06-02 |
Family
ID=42229340
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2656761 Abandoned CA2656761A1 (en) | 2008-12-02 | 2008-12-02 | Eccentric bottom bracket for a bicycle |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2656761A1 (en) |
-
2008
- 2008-12-02 CA CA 2656761 patent/CA2656761A1/en not_active Abandoned
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11975801B2 (en) | Rear gearshift mechanism for coaxial installation | |
| US7753454B2 (en) | Bicycle wheel securing structure | |
| US7537291B2 (en) | Bicycle wheel securing structure | |
| EP1964767B1 (en) | Quick release mechanism for securing a bicycle wheel | |
| TWI353935B (en) | Bicycle wheel securing structure | |
| EP1762481B1 (en) | Bicycle crank assembly | |
| US6435622B1 (en) | Bicycle hub with threaded spacer and detachable freewheel | |
| US8052225B2 (en) | Bicycle wheel securing structure | |
| US6116114A (en) | Rotatable spindle assembly utilizing two-piece spindle | |
| US7654546B2 (en) | Bicycle wheel securing structure | |
| US7628416B2 (en) | Bicycle wheel securing structure | |
| US8721187B2 (en) | Bicycle axle assembly | |
| CN203511155U (en) | Bicycle hub assembly | |
| US20040003482A1 (en) | Adjustable wheel assembly | |
| EP3401203A1 (en) | A chainring assembly | |
| US7441842B2 (en) | Bicycle hub | |
| EP1659056A2 (en) | Bicycle crank axle assembly | |
| US7217037B2 (en) | Eccentric bracket assembly | |
| US8079288B2 (en) | Bicycle gear crank | |
| US20080067861A1 (en) | Retrofit adjustable eccentric front motorcycle axle | |
| CA2656761A1 (en) | Eccentric bottom bracket for a bicycle | |
| US5335928A (en) | Bicycle bottom bracket/crank assembly | |
| US9738117B1 (en) | Double-step offset axle | |
| JPH0882204A (en) | Cassette type cam gear driving mechanism | |
| EP1747913A2 (en) | Ball pushing unit for internally geared hub |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |