Sprocket support member for a bicycle sprocket assembly

Abstract

A bicycle sprocket assembly having at least one subassembly including a sprocket support member and two sprockets is presented. The support member has at least one engagement portion for coupling it to a bicycle freewheel and at least one fastening portion arranged in a radially external position with respect to the engagement portion. Both sprockets are fixed on the sprocket support member on the same side of the fastening portion.

1 . A sprocket support member for a bicycle sprocket assembly, the sprocket support member comprising: 
 at least one freewheel hub engagement portion having at least one tooth engagable with a splined surface of a bicycle freewheel hub; and    at least one fastening portion having at least one hole for mounting the sprocket support member to at least one sprocket, the fastening portion lies in a first plane and the engagement portion lies in a second plane which is axially displaced from and parallel to the first plane.    
   
   
       2 . The sprocket support member of  claim 1 , wherein the fastening portion has an axial thickness substantially equal to a desired axial distance between multiple sprockets of the sprocket assembly.  
   
   
       3 . The sprocket support member of  claim 1 , including an axial projection located between the engagement portion and the fastening portion.  
   
   
       4 . The sprocket support member of  claim 3 , wherein the axial projection forms a support against which a radially projecting portion of a fastening element can rest.  
   
   
       5 . The sprocket support member of  claim 4 , wherein the axial projection has a centering and support seat having the shape of a cylindrical sector coaxial with a fastening hole of the fastening portion.  
   
   
       6 . The sprocket support member of  claim 4 , wherein the axial projection is located at the base of a radial contact surface of the fastening portion.  
   
   
       7 . The sprocket support member of  claim 1 , wherein one of the at least one fastening portion and one of the at least one engagement portion form at least one single structural unit, the one of the at least one engagement portion being aligned with the one of the at least one fastening portion in a radial direction.  
   
   
       8 . The sprocket support member of  claim 7 , wherein the structural unit includes at least one weight-saving cavity located between the engagement portion and the fastening portion.  
   
   
       9 . The sprocket support member of  claim 7 , including a plurality of single structural units angularly equidistant from each other and connected together by zones having reduced dimensions in the radial direction.  
   
   
       10 . The sprocket support member of  claim 1 , wherein the support member is made of a material chosen among the group consisting of: steel, aluminum and its alloys, titanium, and fabric made of structural fibers incorporated in a matrix of plastic material, in which the fibers are chosen among carbon fibers, glass fibers, aramid fibers, boron fibers, ceramic fibers or any combination thereof.  
   
   
       11 . A sprocket support member for a bicycle sprocket assembly comprising: 
 an inner engagement portion having at least one tooth adapted for engagement with a spline of a bicycle freewheel hub, the inner engagement portion defining a first plane; and,    an outer fastening portion having at least one position defined for the mounting the sprocket support member to a sprocket, the outer fastening portion defines a second plane that is immediately adjacent to and parallel with the first plane.    
   
   
       12 . The sprocket support member of  claim 11  wherein the inner engagement portion and the outer fastening portion have adjacent faces and free faces and wherein the free face of the inner engagement portion is spaced from the free face of the outer fastening portion by a predetermined distance adapted for a defined sprocket assembly.  
   
   
       13 . A sprocket support member for a bicycle sprocket assembly comprising: 
 an inner engagement portion having at least one tooth adapted for engagement with a spline of a bicycle freewheel hub, the inner engagement portion defining a first plane; and,    an outer fastening portion having at least one position defined for the mounting the sprocket support member to a sprocket, the outer fastening portion defines a second plane that is immediately tangent to and parallel with the first plane.    
   
   
       14 . A sprocket assembly for a bicycle comprising: 
 at least one subgroup including a sprocket support member comprising at least one engagement portion provided with means for coupling with a bicycle freewheel and at least one fastening portion arranged in a radially external position with respect to the engagement portion, the fastening portion presenting at least one hole for the mounting of at least one sprocket to the sprocket support member, wherein the fastening portion is axially displaced with respect to the engagement portion; and    at least two sprockets fixed to the fastening portion, wherein at least two of the sprockets are fixed on the same side of the fastening portion.    
   
   
       15 . The sprocket assembly of  claim 14 , including a plurality of fastening elements for mounting at least a first and a second sprocket against a contact surface of the sprocket support member.  
   
   
       16 . The sprocket assembly of  claim 15 , including at least one spacer means located between the first and second sprockets.  
   
   
       17 . The sprocket assembly of  claim 16 , wherein the spacer means includes two mutually opposite contact surfaces against which respective contact portions of the first and second sprockets rest.  
   
   
       18 . The sprocket assembly of  claim 17 , wherein the contact surfaces of the spacer means are parallel to the contact surface of the fastening portion.  
   
   
       19 . The sprocket assembly of  claim 15 , wherein the fastening elements carry the spacer means.  
   
   
       20 . The sprocket assembly of  claim 19 , wherein the spacer means is integrated with the fastening elements.  
   
   
       21 . The sprocket assembly of  claim 20 , wherein each of the fastening elements includes an integral shoulder with two opposing contact surfaces.  
   
   
       22 . The sprocket assembly of  claim 14 , wherein each of the fastening elements has a first cylindrical portion that engages two aligned coaxial holes of the fastening portion and the first sprocket.  
   
   
       23 . The sprocket assembly of  claim 22 , wherein each of the fastening elements has a second cylindrical surface that engages a hole of the second sprocket.  
   
   
       24 . The sprocket assembly of  claim 23 , wherein each of the fastening elements includes a radial shoulder between the first and the second cylindrical portion.  
   
   
       25 . The sprocket assembly of  claim 14 , wherein each of the fastening elements has a first head with an outer surface substantially flush with an outer surface of the fastening portion.  
   
   
       26 . The sprocket assembly of  claim 25 , wherein each of the fastening elements has a second head with an outer surface substantially flush with an outer surface of the second sprocket.  
   
   
       27 . The sprocket assembly of  claim 14 , wherein each of the fastening elements has a radially projecting portion arranged to make contact with an axial projection located in a radially internal position with respect to the fastening portion.  
   
   
       28 . The sprocket assembly of  claim 14 , wherein each of the fastening elements is a rivet.  
   
   
       29 . A sprocket assembly for a bicycle, including a plurality of subgroups, each of which includes: 
 a sprocket support member having at least one engagement portion shaped to engage a bicycle freewheel hub and at least one fastening portion arranged in a radially external position with respect to the engagement portion; and    at least two sprockets attached to the fastening portion;    wherein the subgroups can be axially mounted on the bicycle wheel hub in contact with each other.    
   
   
       30 . The sprocket assembly of  claim 29 , wherein the fastening portion of at least one of the subgroups has an axial thickness substantially equal to the desired distance between two adjacent sprockets belonging to two different, mutually adjacent subgroups.  
   
   
       31 . The sprocket assembly of  claim 30 , wherein the fastening portion of at least one of the subgroups has an outer radial surface that rests against an outer radial surface of a sprocket of an adjacent subgroup.  
   
   
       32 . The sprocket assembly of  claim 29 , wherein the at least two sprockets are spaced apart from each other by a distance substantially equal to the axial thickness of the fastening portion.  
   
   
       33 . A bicycle sprocket assembly comprising: 
 a sprocket support member having: 
 a planar frame defining a first plane;  
 a plurality of fastening tabs fixed to and extending radially-outwardly from the frame and being co-planar with the frame, each tab having a through hole;  
 an annular step fixed to and extending axially from the planar frame;  
 a plurality of engagement teeth fixed to and extending radially-inwardly from the annular step and defining a second plane axially-spaced from the first plane; and,  
   a pair of sprockets mounted on the support member and arranged so that both sprockets are positioned on the same side of the first plane and at least a portion of the first sprocket and a portion of the second sprocket are positioned on opposite sides of the second plane.    
   
   
       34 . A bicycle sprocket assembly comprising: 
 a sprocket support member having: 
 a planar frame defining a first plane;  
 a plurality of fastening surfaces on the frame, each surface having a through hole;  
 an annular step fixed to and extending transverse to the planar frame;  
 a plurality of engagement teeth fixed to and extending radially-inwardly from the annular step and defining a second plane axially-spaced from the first plane;  
   a plurality of fasteners;    a pair of sprockets having radially-inwardly projecting fastening tabs with a through hole, the sprockets being fixed on the same side of the support member by inserting one of the fasteners within aligned through holes in the sprocket fastening tabs and the support member fastening surfaces; and    means for radially supporting each of the fasteners and the fastening tabs of at least one of the sprockets.