Telescoping-type front fork bicycle suspensions

Abstract

This invention relates to front fork, telescoping type suspension systems for bicycles. The main focus of the invention is the brake bridge assembly, the fork crown assembly and the joinder of these assemblies to form the fork suspension. The brake bridge assembly serves two main functions: 1) it provides a stiff structural connection between the right and left telescoping struts, to reduce wheel wobble during high speed wheel impacts, and 2) it provides a structural support for the brake cable stop. The invention provides for increased stiffness and lower stresses in the brake bridge, which translates into improved directional stability for the front wheel, less displacement for the brake cable stop .(when the brake loads are applied) and improved fatigue life for the assembly. It also provides for a simpler and less expensive means for mounting the brake bridge to the fork assembly. The invention also encompasses the fork crown producing a lightweight structure with high torsional and bending rigidity. The connections of the stanchions to the crown are achieved through a variety of methods including, (a) interference fit and bonding, (b) collet assembly and (c) “pinch-bolt” connections.

What is claimed is:  
     
       1. An improved brake bridge in combination with a front fork bicycle suspension system having a pair of telescoping strut stanchion tubes wherein said brake bridge comprises a hollow member having two ends and a pair of socket connectors respectively securing each of said ends to each of said telescoping strut stanchion tubes, said brake bridge being made from a selected one of a metal extrusion and a reinforced plastic molding, each said socket connector comprising a shaped body with a cylindrical hole of constant diameter to accommodate one of the telescoping strut stanchion tubes, a constant diameter cylindrical socket for supporting respective ones of said ends of said hollow member and a threaded hole to support a brake stud, each said socket connector encircling a respective telescoping stanchion strut tube and secured thereto by a structural adhesive. 
     
     
       2. An improved brake bridge in combination with a front fork bicycle suspension system having a pair of telescoping strut stanchion tubes wherein said brake bridge comprises a hollow member having two ends and a pair of socket connectors respectively securing each of said ends to each of said telescoping strut stanchion tubes, said brake bridge being made from a selected one of a metal extrusion and a reinforced plastic molding, each said socketed connector comprising a shaped body with a cylindrical hole of constant diameter to accommodate one of the telescoping strut stanchion tubes, a tapered cylindrical socket having a pair of ends with a circular opening at one of said ends and a shaped an opening at the other of said ends supporting a respective end of the brake bridge and a threaded hole to support a brake stud, each said socket connector encirculing encircling a respective telescoping strut stanchion tube and secured thereto by a structural adhesive. 
     
     
       3. An improved brake bridge in combination with a front fork bicycle suspension system having a pair of telescoping strut stanchion tubes, each said telescoping strut stanchion tube having a centerline and a wall surface, wherein said brake bridge comprises a hollow member having two ends and a pair of socket connectors respectively securing each of said ends to each of said telescoping strut stanchion tubes, each socket connector comprising an adjustable collet assembly having a ramped surface with an angle from 0.1 degrees to 18 degrees relative to the respective telescoping strut stanchion tube centerline, a compression wedge, and an adjusting ring screw for forcing said compression wedge between said ramped surface and the wall surface of a respective telescoping stanchion strut tube thereby creating a locking force between said socket connector and a respective telescoping stanchion strut tube. 
     
     
       4. An improved separate, hollow, bicycle crown member for use on a telescoping bicycle front fork suspension system having a stanchion tube and a steerer tube, said bicycle crown member comprising a single light metal forging having a five intersecting hollow closed sections, said metal forging comprising a stanchion tube socket connection, a steerer tube socket connection and a structural part connecting said stanchion tube socket connection and the steerer tube socket connection, said structural part having a closed hollow shape without welding, said bicycle crown member further comprising a single light metal forging have five intersecting hollow closed sections , said metal forging being center bored and reamed, said bicycle crown member metal forging including a lightening hole drilled axially through said structural part from an outside surface of the stanchion tube socket connection to an inside surface of the steerer tube socket connection, to form a closed, tubular section thereby increasing the stiffness of the part and decreasing the stresses induced by bending and torsional loads. 
     
     
       5. The bicycle crown member defined in  claim 4  wherein said steerer and stanchion tube socket connections have openings and localized reinforcement ridges around the openings of the steerer and stanchion tube socket connections to provide localized strength and rigidity at minimum weight, said reinforcement ridges being blended into the main body to reduce stress concentrations and improve the fatigue life of the part. 
     
     
       6. In a telescoping-type front fork bicycle suspension system having a fork crown member rigidly connected to a steer tube and a pair of spaced stanchion tubes, a strut telescoped on each of said stanchion tubes having an upper ends, a brake bridge having a pair of lateral ends and means securing one of said lateral ends to one of said struts and the other of said lateral ends to the other of said struts, the improvement wherein said brake bridge is a hollow member and said brake bridge comprises a pair of socket connector members, each said socket connector member having a first end embracing the upper end of a respective strut, a second end forming a socket embracing a respective lateral end of said brake bridge and means securing said respective strut in said socket connector members, and wherein each said socket connector member includes an internal tapered cam surface, a collet member having tube gripping fingers and a tapered exterior surface, a threaded surface in said socket connector member, a threaded member engaged with said threaded surface for engaging and driving said collet member and said tapered exterior surface along said cam surface to cause said tube gripping fingers to engage and lockingly grip a respective one of said stanchion tubes received in said socket. 
     
     
       7. In a telescoping-type front fork bicycle suspension system having a fork crown member rigidly connected to a steerer tube, a pair of spaced stanchion tubes, a strut telescoped on each of said stanchion tubes, a brake bridge having a pair of lateral ends, and means securing one of said lateral ends to one of said struts and the other of said lateral ends to the other of said struts, the improvement wherein said fork crown member has a portion thereof extending between said steerer tube and each of said stanchion tubes, each said portion being a closed hollow integrally formed member, and wherein said fork crown member further comprises a single lightweight center bored and reamed forging having five intersecting hollow, closed sections. 
     
     
       8. In a telescoping-type front fork bicycle suspension system having a fork crown member rigidly connected to a steering tube, a pair of spaced stanchion nubes tubes having upper ends, a strut telescoped on each of said stanchion tubes, a brake bridge having a pair of lateral ends, and means securing one of said lateral ends to one of said struts and the other of said lateral ends to the other of said struts, the improvement wherein said fork crown member comprises a portion thereof extending between said steerer tube and each of said stanchion tubes, each said portion being a closed hollow integrally formed member, and wherein said fork crown member further comprises a pair of lateral ends, a pair of stanchion tube receiving sockets therein and means securing the upper ends of said stanchion tubes in said sockets, respectively, wherein said means securing the upper ends of said stanchion tubes in said sockets includes a collet member having stanchion tube gripping fingers, a tapered exterior surface, a cam surface formed in said socket, a threaded surface in said socket, and a threaded member engaged with said threaded surface for engaging and driving said collet member tapered exterior surface along said cam surface to cause said stanchion tube gripping fingers to engage and lockingly grip said stanchion tube. 
     
     
       9. A crown member for use with a telescoping front fork assembly and a steerer tube of a bicycle, wherein the telescoping front fork assembly includes a pair of spaced stanchion tubes, a pair of struts, each of the struts telescoped on one of the stanchion tubes, and a brake bridge connected between upper ends of the struts, wherein the crown member comprises a single light metal forging made without welding, said forging including: 
       
         a center portion configured for attachment to the steerer tube;  
       
       
         an end portion which defines a first stanchion tube socket having a first hole machined therethrough;  
       
       
         an opposite end portion which defines a second stanchion tube socket having a second hole machined therethrough;  
       
         a first structural portion between the center portion and the end portion, the first structural portion having a first lightening cavity machined therein such that said first structural portion has a hollow, closed cross - section around the first lightening cavity; and    
         a second structural portion between the center portion and the opposite end portion, the second structural portion having a second lightening cavity machined therein such that said second structural portion has a hollow, closed cross - section around the second lightening cavity.   
     
     
       10. The crown member of  claim 9 , wherein the first lightening cavity is laterally machined into the first structural portion, and the second lightening cavity is laterally machined into the second structural portion. 
     
     
       11. The crown member of  claim 9 , wherein the center portion defines a steerer tube socket having a third hole machined therethrough for receiving the steerer tube. 
     
     
       12. The crown member of  claim 11 , wherein the first lightening cavity extends through the first structural portion from an outside surface of the first stanchion tube socket to an inside surface of the steerer tube socket. 
     
     
       13. The crown member of crown  11 , wherein the first lightening cavity is laterally bored through the first structural portion from the first stanchion tube socket to the steerer tube socket, and the second lightening cavity is laterally bored through the second structural portion from the second stanchion tube socket to the steerer tube socket. 
     
     
       14. The crown member of  claim 13 , wherein the first structural portion has a generally rectangular cross- section with rounded corners, and the first lightening cavity has a cylindrical periphery.   
     
     
       15. The crown member of  claim 11 , wherein the first lightening cavity is laterally bored through the first structural portion from an outside surface of the first stanchion tube socket to an inside surface of the steerer tube socket. 
     
     
       16. The crown member of  claim 11 , wherein the first lightening cavity is axially drilled through the first structural portion from the first stanchion tube socket to the steerer tube socket, and the second lightening cavity is axially drilled through the second structural portion from the second stanchion tube socket to the steerer tube socket. 
     
     
       17. A telescoping front fork assembly for a bicycle, said assembly including: 
       
         a pair of stanchion tubes;  
       
       
         a pair of struts, each of the struts telescoped on one of the stanchion tubes; a brake bridge connected between upper ends of the struts; and  
       
         a crown member comprising a single light metal forging made without welding, said forging including a center portion which is configured for attachment to a steerer tube, an end portion which defines a first stanchion tube socket and which has a first hole machined therethrough, an opposite end portion which defines a second stanchion tube socket and which has a second hole machined therethrough, a first structural portion between the center portion and the end portion, the first structural portion having a first lightening cavity formed therein such that said first structural portion has a hollow, closed cross - section around the first lightening cavity, and a second structural portion between the center portion and the opposite end portion, the second structural portion having a second lightening cavity formed therein such that said second structural portion has a hollow, closed cross - section around the second lightening cavity.   
     
     
       18. The assembly of  claim 17 , wherein an upper end of a first one of the stanchion tubes is attached by at least one of an interference fit and an adhesive bond to the first stanchion tube socket of the forging, and an upper end of a second one of the stanchion tubes is attached by at least one of an interference fit and an adhesive bond to the second stanchion tube socket of the forging. 
     
     
       19. The assembly of  claim 17 , wherein the first lightening cavity is machined in the first structural portion such that said first structural portion has said hollow, closed cross- section around said first lightening cavity, and the second lightening cavity is machined in the second structural portion such that said second structural portion has said hollow, closed cross - section around said second lightening cavity.   
     
     
       20. The assembly of  claim 17 , wherein each of the first structural portion and the second structural portion has a generally rectangular cross- section with rounded corners.