Abstract:
A bottom bracket assembly of a bicycle comprises two cranks, an axle integral in rotation with the cranks, and two bearings for the rotatable support of the assembly with respect to a box of the frame of the bicycle; each of the bearings is arranged inside the thickness of one of the respective cranks. In this way, the weight of the cyclist acting on a crank transfers directly onto the corresponding bearing, without any bending stress being generated on the axle of the bottom bracket.

Description:
FIELD OF INVENTION  
       [0001]     The present invention refers to a bottom bracket assembly of a bicycle.  
       BACKGROUND  
       [0002]     Known bottom bracket assemblies of a bicycle comprise two cranks, an axle integral in rotation with the cranks and two bearings for the rotatable support of the assembly with respect to a box of the bicycle frame. The bearings are directly mounted on the axle and coupled to the box through adapter supports.  
       SUMMARY  
       [0003]     In a first aspect thereof, the present invention provides a bottom bracket assembly comprising two cranks, an axle integral in rotation with the cranks, and two bearings for the rotatable support of the assembly with respect to a box of the frame of the bicycle, wherein at least one of the bearings is arranged inside the thickness of one of the cranks.  
         [0004]     In its second aspect, the invention provides a method for assembling an assembly according to the first aspect of the invention, comprising the arrangement of a sub-assembly that includes one of the adapter supports and one of the bearings mounted on the adapter support.  
         [0005]     In its third aspect, the invention provides a sub-assembly for the assembly of an assembly according to the first aspect of the invention, including one of the adapter supports and one of the bearings mounted on the adapter support.  
         [0006]     In its fourth aspect, the invention provides an adapter support suitable for being mounted on a box of the frame of a bicycle for the support of a bearing of a bottom bracket assembly, comprising a tubular body provided with an outer threading for the engagement with the box of the frame inside it and a receiving seat of the bearing, wherein the receiving seat of the bearing is an outer cylindrical seat.  
         [0007]     In its fifth aspect, the invention provides a crank for a bottom bracket assembly of a bicycle, comprising in its own thickness a receiving seat of a bearing for the rotatable support of the assembly with respect to a box of the frame of the bicycle, the receiving seat having an inner cylindrical coupling surface with the bearing.  
         [0008]     In a sixth aspect thereof, the present invention provides an adapter support suitable for being mounted to a box of a frame of a bicycle for the support of a bearing of a bottom bracket assembly, comprising a tubular body provided with fastening means for the engagement with the box of the frame and a receiving seat of the bearing, and further comprising a shaped drive profile for the actuation of the adapter support through the box of the frame.  
         [0009]     In its seventh aspect, the invention provides a subassembly of a bottom bracket assembly of a bicycle, comprising an adapter support as defined above. Preferably, the subassembly may comprise a bearing mounted thereon, and/or a crank mounted thereto, and/or an axle of the bottom bracket assembly (or at least a portion of an axle), mounted thereto.  
         [0010]     In its eighth aspect, the invention provides a bottom bracket assembly that includes an adapter support or a subassembly as defined above.  
         [0011]     In its ninth aspect, the invention provides a method of assembling a bottom bracket assembly to a box of a frame of a bicycle, comprising: 
        providing an adapter support having a fastening means for the engagement with the box of the frame and a receiving seat for a bearing of the bottom bracket assembly;     inserting the adapter support into the box of the frame from a first side thereof;     engaging the adapter support with a drive key inserted in the box from a second side thereof, opposite to the first side; and     fastening the adapter support to the box by operating the drive key.        
 
     
    
     BRIEF DESCRIPTION OF THE DRAWING(S)  
       [0016]     Further characteristics and advantages of the invention shall become clearer from the following description of a bottom bracket assembly made with reference to the attached drawings, in which:  
         [0017]      FIG. 1  is a longitudinal section of a bottom bracket assembly according to the present invention;  
         [0018]     FIGS.  2  to  6  show steps of a possible assembly sequence of the assembly of  FIG. 1 ;  
         [0019]      FIGS. 7A and 7B  show a first adapter support according to the present invention;  
         [0020]      FIGS. 8A and 8B  show a second adapter support according to the present invention;  
         [0021]      FIG. 9  is a longitudinal section of a bottom bracket assembly according to an alternative embodiment of the present invention;  
         [0022]      FIG. 10  is a perspective view of the axle of the assembly of  FIG. 9 ;  
         [0023]      FIGS. 11A and 11B  show an insert of the right crank of the assembly of  FIG. 1 ;  
         [0024]      FIGS. 12A and 12B  show an insert of the left crank of the assembly of  FIG. 1 ;  
         [0025]      FIG. 13  shows a perspective view of a sub-assembly according to the invention, with a crank and a bearing mounted in it;  
         [0026]      FIG. 14  shows a bottom bracket assembly according to an alternative embodiment of the present invention;  
         [0027]      FIG. 15  shows a bottom bracket assembly according to another alternative embodiment of the present invention; and  
         [0028]      FIG. 16  shows a bottom bracket assembly according to still another alternative embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
       [0029]     Introduction  
         [0030]     Consequently, in a first aspect thereof, the present invention provides a bottom bracket assembly of a bicycle, comprising two cranks, an axle integral in rotation with the cranks and two bearings for the rotatable support of the assembly with respect to a box of the bicycle frame, wherein at least one of the bearings is arranged inside the thickness of one of the cranks.  
         [0031]     In this way the weight of the cyclist acting on the crank transfers directly on the corresponding bearing, thus, without any bending stress being generated on the axle of the bottom bracket; consequently, since there is no stress, there is no bending deformation of the axle. Moreover, the housing of the bearing in the thickness of the crank allows the length of the axle to be reduced, with a consequent reduction both of the weight and of the torsional deformation of the axle itself, for the same power exerted by the cyclist.  
         [0032]     To take the bearing in such a way that it is inside the thickness of the crank it is possible to suitably shape the box of the frame. Preferably, however, at the crank an adapter support is provided fixed integrally and cantilevered to the box of the frame, in which the bearing is arranged between the crank and the adapter support. The use of an adapter support allows an assembly according to the invention to be mounted on any frame, even a pre-existing one.  
         [0033]     Preferably, the bearing is mounted externally about the adapter support. This makes it possible to use both an axle and bearings of greater diameter than what would be allowed by a conventional assembly of the bearing in the box of the frame; the greater diameter of the bearings ensures less wear of the moving parts, whereas the greater diameter of the axle reduces the torsional deformation, for the same power exerted by the cyclist.  
         [0034]     Preferably, the crank comprises a seat for receiving the bearing, with an inner cylindrical coupling surface with the bearing; in this way the coupling with an adapter support provided for the assembly of the bearing in an outer position is simplified.  
         [0035]     The seat for receiving the bearing can be formed directly in the body of the crank; preferably, however, in the case of a crank made from non-metallic material, the receiving seat is formed in an insert, inserted integrally in a recess formed in the crank.  
         [0036]     Preferably, the receiving seat and even more preferably the recess (if present) have a smaller depth than the thickness of the crank. This ensures that the crank maintains its greater structural rigidity.  
         [0037]     In a bottom bracket assembly, it is also possible for just one of the bearings to be arranged inside the thickness of the respective crank, whereas the other bearing is housed conventionally. Preferably, however, both of the bearings are arranged inside the thickness of a respective one of the cranks.  
         [0038]     The two adapter supports can be independent from each other; preferably, however, the two adapter supports extend inside the box of the frame until they couple with each other, for example, and preferably since the two adapter supports comprise mutual coupling means.  
         [0039]     In its second aspect, the invention provides a method for assembling an assembly according to the first aspect of the invention, comprising the arrangement of a sub-assembly that includes one of the adapter supports and one of the bearings mounted on the adapter support. The invention further provides a method for assembling an assembly according to the first aspect of the invention, comprising the arrangement of a sub-assembly that includes one of the cranks and one of the bearings mounted in the crank. Preferably, such a sub-assembly also includes the axle, integrally coupled with the crank, and even more preferably also one of the adapter supports, mounted in the bearing.  
         [0040]     In its third aspect, the invention provides a sub-assembly for the assembly of an assembly according to the first aspect of the invention, including one of the adapter supports and one of the bearings mounted on the adapter support. The invention further provides a sub-assembly for the assembly of an assembly according to the first aspect of the invention, including one of the cranks and one of the bearings mounted in the crank. Preferably, such a sub-assembly also includes the axle, integrally coupled with the crank, and even more preferably also one of the adapter supports, mounted in the bearing.  
         [0041]     In its fourth aspect, the invention provides an adapter support suitable for being mounted on a box of the frame of a bicycle for the support of a bearing of a bottom bracket assembly, comprising a tubular body provided with an outer threading for the engagement with the box of the frame inside it and a receiving seat of the bearing, wherein the receiving seat of the bearing is an outer cylindrical seat.  
         [0042]     Preferably, the adapter support comprises—on the opposite side to the receiving seat of the bearing—coupling means suitable for engaging the adapter support with another adapter support, mounted in the same bottom bracket assembly. In such a way, the assembly of the two adapter supports also acts as a spacer, i.e., it determines the distance in the axial sense between the two cranks. Preferably, the adapter support comprises a shaped drive profile for the actuation of the adapter support through the box of the frame.  
         [0043]     In its fifth aspect, the invention provides a crank for a bottom bracket assembly of a bicycle, comprising in its own thickness a receiving seat of a bearing for the rotatable support of the assembly with respect to a box of the frame of the bicycle, the receiving seat having an inner cylindrical coupling surface with the bearing. Preferably, the receiving seat of the bearing is formed in an insert, inserted integrally in a recess formed in the crank. Preferably, moreover, the receiving seat comprises a bottom surface surrounded by an annular abutment surface, slightly raised with respect to the bottom surface; the outer ring of the bearing abuts against this annular surface, once it has been mounted in the crank.  
         [0044]     In a sixth aspect thereof, the present invention concerns an adapter support suitable for being mounted to a box of a frame of a bicycle for the support of a bearing of a bottom bracket assembly, comprising a tubular body provided with fastening means for the engagement with the box of the frame and a receiving seat of the bearing, and further comprising a shaped drive profile for the actuation of the adapter support through the box of the frame.  
         [0045]     The drive profile allows operation of the adapter support from within the box of the frame, i.e.—more precisely—from the other side of the box with respect to where the adapter support is mounted. This possibility makes assembling easier in all cases where the kind and shape of the adapter support is such as to create an obstacle to its operation from the side of the box where the adapter support is mounted. Preferably, the fastening means is a threading, although other means can be used, such as a bayonet coupling.  
         [0046]     The drive profile can comprise a front toothing formed in the tubular body and extending therefrom in an axial direction, a radial toothing formed in the tubular body and extending therefrom in an inward radial direction, or a toothing extending in both directions. Normally, a front toothing will be provided on an adapter support that is to be mounted first on the box of the frame, while a radial toothing will be provided on an adapter support that is to be mounted last.  
         [0047]     In its seventh aspect, the invention provides a subassembly of a bottom bracket assembly of a bicycle, comprising an adapter support as defined above. Preferably, the subassembly may comprise a bearing mounted thereon, and/or a crank mounted thereto, and/or an axle of the bottom bracket assembly (or at least a portion of an axle), mounted thereto.  
         [0048]     In its eighth aspect, the invention provides a bottom bracket assembly that includes an adapter support or a subassembly as defined above.  
         [0049]     In its ninth aspect, the invention provides a method of assembling a bottom bracket assembly to a box of a frame of a bicycle, comprising: 
        providing an adapter support having a fastening means for the engagement with the box of the frame and a receiving seat for a bearing of the bottom bracket assembly;     inserting the adapter support into the box of the frame from a first side thereof;     engaging the adapter support with a drive key inserted in the box from a second side thereof, opposite to the first side; and fastening the adapter support to the box by operating the drive key.        
 
         [0053]     This method allows an easy mounting of the adapter support even under conditions in which the adapter support is difficult to access and operate from the same side of the box of the frame where it is to be mounted.  
         [0054]     Preferably, the method further comprises mounting a bearing onto the adapter support, prior to inserting it into the box of the frame, and possibly mounting a sub-assembly onto the bearing, prior to inserting the adapter support into the box, the sub-assembly including at least one of a crank and an axle (or at least a portion of an axle).  
       DETAILED DESCRIPTION  
       [0055]     With reference to  FIG. 1 , a bottom bracket assembly  1  comprises an axle  2  coupled with a right crank  4  and with a left crank  6 . The cranks  4  and  6  incorporate inside their own thickness respective bearings  8  and  9 , respectively carried by a right adapter support  12  and by a left adapter support  14 , screwed into a box  16  of a bicycle frame. The arrangement of the bearings  8  and  9  is such that the axle  2  is supported in the box  16  in a so-called indirect way, by means of the cranks  4  and  6 .  
         [0056]     The cranks are preferably made from a composite material that can comprise structural fibers incorporated in a polymeric material. Typically, the structural fibers are selected from the group consisting of: carbon fibers, glass fibers, aramid fibers, ceramic fibers, boron fibers, and combinations thereof, carbon fibers being preferred. The arrangement of the structural fibers in the polymeric material can be a random arrangement of small pieces or sheets of structural fibers, a substantially unidirectional ordered arrangement of fibers, a substantially two-directional ordered arrangement of fibers, or a combination of the above. Preferably, the polymeric material is thermosetting; however, this does not rule out the possibility of using a thermoplastic material. Moreover, it is also possible for the cranks to be made from metallic material, for example, aluminum alloys.  
         [0057]     Hereafter, the structure of the bottom bracket assembly  1  is described with reference to a preferred assembly method, so as to illustrate the possible pre-assembled sub-assemblies that can be provided in the embodiment of the assembly  1 .  
         [0058]     With reference to  FIG. 2 , the right crank  4  has an end  17  for coupling with the axle  2  in which a recess  15  is formed where an annular insert  18  is inserted and fixed, as shown in detail in  FIGS. 11A and 11B . The insert  18  is made integral with the crank  4 , for example, by gluing or co-molding. The insert  18  is particularly preferred to insert the bearings in a crank made of composite material.  
         [0059]     In order to increase the adhesion surface, the insert  18  has—on a wall  19  facing in the axial direction—a projecting annular flange  20  intended to penetrate in a corresponding annular groove  13  (shown in  FIG. 3 ) formed in the body of the crank  4 . In addition, or alternatively, it is also possible to provide an outer threading  22  that, like the flange  20 , receives the glue for gluing or co-molding to the composite material.  
         [0060]     On the side of the insert  18  opposite that of the flange  20 , an annular seat  24  for receiving the bearing  8  is formed; the seat  24  comprises a cylindrical surface with a large diameter  26 , a cylindrical surface with a small diameter  27 , and a bottom surface  29  surrounded by an annular abutment surface  30 , slightly raised with respect to the bottom surface  29 . The cylindrical surface with a large diameter  26  is adapted to couple with the outer ring of the bearing  8 , which also axially abuts against the annular surface  30 . A groove  28  for the insertion of a locking ring  31  (represented only in  FIG. 13 ) of the bearing  8  is also formed on the outer cylindrical surface  26 . Alternatively, the bearing  8  can be inserted in the insert  18  with a coupling with interference between its outer ring and the surface with a large diameter  26 .  
         [0061]     It should be noted that both the recess  15  and even more so the seat  24  have depths that are less than the thickness of the crank  4 .  
         [0062]     Generally, coupling with interference between a first element that is inserted in the opening of a second element is obtained by making the first element slightly larger in size than the opening of the second element, so that the second element and the first element must be forced both to be able to penetrate one another, and to be able to be disengaged from each other.  
         [0063]     The width of the annular seat  24  between the surface with a small diameter  27  and the surface with a large diameter  26  is sufficient to accommodate the housing of the bearing  8  and of a part of the right adapter support  12 . It is also possible to provide that the bearing  8  be co-molded in the crank  4 , by this term meaning that the bearing  8  is pre-positioned in the mold in which the crank  4  is formed. Alternatively, the seat  24  can be made directly in the body of the crank  4 , especially when the crank is metallic.  
         [0064]     The seat  24  extends in the crank  4  concentrically about a hole  32  for coupling with the axle  2 . The coupling hole  32  has a cylindrical surface, preferably smooth or knurled, to make a coupling with interference such that the crank  4  is integral with the axle  2 .  
         [0065]     What has been described with reference to the right crank  4  is substantially also valid (in a mirrored configuration) for the left crank  6 , even if it is preferable to use a slightly different insert  18 ′, illustrated in  FIGS. 12A and 12B . The main difference with respect to the insert  18  is in the hole  32 ′, which is defined by a surface shaped so as to make a shape coupling with the axle  2 . In the example shown, the profile is grooved. Consequently, the left crank  6  is not described any further in detail.  
         [0066]     With reference to  FIG. 3 , the right crank  4  coupled with the axle  2  forms a right crank assembly  33 , which thus constitutes a sub-assembly of the bottom bracket  1 . As stated above, the axle  2  and the crank  4  are preferably coupled together with interference, but it is possible to adopt any other type of known coupling, like a shape coupling. The right end  61  of the axle  2  that couples with the right crank  4  has a preferably smooth or knurled cylindrical coupling surface, like the hole  32  of the insert  18 .  
         [0067]     In  FIGS. 4 and 5 , the coupling step of a right adapter assembly  36  with the crank assembly  33  is illustrated. The right adapter assembly  36  comprises the right adapter support  12  and the bearing  8 . It should be noted that both the adapter assembly  36  and the assembly formed by the adapter assembly  36  coupled with the crank assembly  33  constitute sub-assemblies of the bottom bracket  1 .  
         [0068]     The right adapter support  12 , illustrated in greater detail in  FIGS. 8A and 8B , comprises a tubular body  38  with a first end  40  and a second end  42 . Near to the first end  40 , the adapter support  12  comprises both an outer threading  44  formed on the tubular body  38 , for the coupling with the box  16  of the frame inside it, and an outer cylindrical seat  46 , intended to project cantilevered from the box  16  and to receive the inner ring of the bearing  8 . The coupling between the adapter support  12  and the bearing  8 , preferably, is with interference. The outer cylindrical seat  46  and the bearing  8  insert into the annular seat  24  of the crank  4  ( FIG. 5 ).  
         [0069]     The illustrated assembly methods ( FIGS. 4 and 5 ) include the provision of a sub-assembly of the bottom bracket that comprises the adapter assembly  36  coupled with the crank assembly  33  already pre-assembled before being mounted to the box  16  of the frame, at the right side  16   a  of the box. However, it should be noted that—in the case in which one wished to assemble the adapter support  12  at the box  16  of the frame before the assembly of the bearing  8  and of the crank assembly  33 —the outer cylindrical seat  46  of the adapter support  12  is also accessible after the adapter support  12  has been mounted on the box  16  of the frame.  
         [0070]     At the second end  42 , the right adapter support  12  is provided with a shaped profile formed by a front toothing  48 , for engagement with a drive key  50  ( FIG. 5 ) on which a matching toothing  52  is made. Due to the front toothing  48  and by means of the key  50 , the right adapter support  12  can be actuated into rotation through the box  16  of the frame, i.e., by inserting the drive key  50  from the left side  16   b  of the box  16 , so as to be able to screw and unscrew the threading  44  in the box  16  itself.  
         [0071]     The left adapter support  14 , illustrated in greater detail in  FIGS. 7A and 7B , comprises a tubular body  39  with a first end  41  and a second end  43 . Near to the second end  43 , the adapter support  14  comprises an outer threading  45  formed on the tubular body  39 , for the coupling with the box  16  of the frame inside it; at the first end  41  the left adapter support  14  comprises an outer cylindrical seat  47 , intended to project cantilevered from the box  16  and to receive the inner ring of the bearing  9 . The coupling between the adapter support  14  and the bearing  9 , preferably, is with interference. The outer cylindrical seat  47  and the bearing  9  insert into an annular seat  24 ′ of the left crank  6  ( FIG. 1 ), similar to the seat  24  of the right crank  4 .  
         [0072]     Preferably, in the assembled bottom bracket assembly  1 , the body  38  of the right adapter support  12  and the body  39  of the left adapter support are in mutual engagement at the respective second ends  42  and  43 . More specifically, the body  38  has a length about equal to that of the box  16  and its portion  54  at the end  42  is inserted in a seat  53  formed at the end  43  in the left adapter support  14 ; moreover, a shoulder  56  formed on the tubular body  38  abuts against an edge  55  at the end  43  of the tubular body  39  ( FIG. 6 ). Consequently, the seat  53 , the portion  54 , the edge  55 , and the shoulder  56  constitute coupling means for the adapter supports  12  and  14 . Due to this coupling arrangement, the right adapter support  12  also acts as a spacer, i.e., it determines the distance in the axial sense between the two cranks  4  and  6 .  
         [0073]      FIG. 6  illustrates the insertion of a left adapter assembly  58  into the box  16  of the frame. The left adapter assembly  58  is preassembled with the same methods as the right adapter assembly  36 , i.e., with the bearing  9  coupled externally on the cylindrical seat  47  of the left adapter support  14  with interference. The left adapter assembly screws into the box  16  of the frame at the left side  16   b  thereof until it abuts with its edge  55  against the shoulder  56  of the right adapter support  12 .  
         [0074]     Internally the left adapter support  14  is provided with a toothing  66  that projects radially. The toothing  66  extends on a shorter diameter than that of the front toothing  48  of the right adapter support  12 , and when the right crank  4  is not yet assembled it can be engaged by a drive key (not illustrated, similar to the key  50 ), inserted in the box  16  of the frame from the right side  16   a  thereof; this is possible because the toothing  66  is the part of the left adapter support  14  that projects most inwardly in a radial direction and because it extends inwardly more than any part of the right adapter support  12 .  
         [0075]     The left crank  6  is mounted in the assembly  1  by inserting the left end  62  of the axle  2  in its hole  32 ′, and the bearing  9  and the end  47  of the left adapter support  14  in its annular seat  24 ′. The left crank  6  is locked against accidental axial withdrawal by a nut  64  screwed onto an inner threading  65  formed in the axle  2 . The left end  62  of the axle  2  has a profile matching that of the surface of the hole  32 ′ of the left crank  6 , so as to ensure the shape coupling.  
         [0076]     With reference to  FIG. 9 , a bottom bracket assembly  101  according to an alternative embodiment of the invention is illustrated. Hereafter, the same reference numerals already introduced previously in the description to indicate the same elements of the two assemblies shall be used; elements of the assembly  101  that are analogous but different to elements of the assembly  1  are, on the other hand, indicated by numbers increased by  100  with respect to the numbers of the elements of the assembly  1 .  
         [0077]     The assembly  101  differs from the assembly  1  in that it has an axle  102  coupled by interference with the left crank  106  and with shape coupling with the right crank  104 . The right crank  104  is kept in position through an adjustment system  170  of the chain line.  
         [0078]     A first ring nut  172  with internal threading is screwed into a threaded tang  174 , which projects axially from the axle  102 , and abuts against a step  176  inside the hole  132  of the insert  118 . The first ring nut  172  prevents the accidental axial withdrawal of the right crank  104 , which could nevertheless still move axially towards the inside of the assembly  101 . In order to also prevent this second movement, a second ring nut  178  with outer threading is screwed into a threading  180  inside the hole  132  of the insert  118  and abuts upon the first ring nut  172 . A washer  182  of predetermined thickness according to the chain line that one wishes to obtain is arranged between the first and the second ring nut  172  and  178 .  
         [0079]     The axle  102  is illustrated in greater detail in  FIG. 10  and has the right end  161  grooved with the same profile on the left end  62  of the axle  2  of the assembly  1 . The threaded tang  174  projects axially at the right end  161 . The left end  162  has a smooth or knurled outer cylindrical surface to couple with interference with the left crank  106 .  
         [0080]     It is clear to the person skilled in the art that the couplings for the transmission of torque between cranks and axle can be different to those illustrated. For example, both the axle  2  and the axle  102  can have the ends  61  and  162  shaped with a grooved profile like that of the opposite ends  62  and  161 , or else vice-versa the ends  62  and  161  can be coupled by interference like the opposite ends  61  and  162 ; furthermore, the ends  61 ,  62 ,  161 , or  162  can be shaped according to polygonal profiles, per se known in the field.  
         [0081]     With reference to FIGS.  14  to  16 , bottom bracket assemblies  201 ,  301 , and  401  according to alternative embodiments of the invention are illustrated. Hereafter, the same reference numerals already introduced previously in the description to indicate the same elements of the different assemblies shall be used; elements of any of the assemblies  201 ,  301 ,  401  that are analogous but different to elements of the assembly  1  are, on the other hand, indicated by numbers increased by  200 ,  300 , and  400  respectively, with respect to the numbers of the elements of the assembly  1 .  
         [0082]     In  FIG. 14 , a bottom bracket assembly  201  is shown, that differs from the assembly  1  of  FIG. 1  because of different adapter supports  212  and  214 . More in particular, right adapter support  212  has a much shorter axial extension than adapter support  12 , and thus does not reach a position where it can act as a spacer for the left adapter support  214 . Therefore, both right adapter support  212  and left adapter support  214  have respective rest flanges  215   a  and  215   b , radially outwardly projecting so as to rest against the sides  16   a  and  16   b  of the box  16 . An elastic insert  217  is provided between the left bearing  9  and the left crank  6  to accommodate possible axial positioning differences.  
         [0083]     The right adapter support  212  has a drive profile in the form of a front toothing  248 , analogous to the front toothing  48  of the adapter support  12 ; similarly, the left adapter support  214  has a drive profile in the form of a radial toothing  266 , analogous to the radial toothing  66  of the adapter support  12 .  
         [0084]     In this embodiment, the seat  24 ′ is made in an insert  218 ′ provided to the left crank  206 ; the seat  24  is made instead directly in the body of the right crank  204 , however, an insert can be used like insert  218 ′, or insert  18  of the previous embodiments. The axle  202  is preferably permanently coupled to the right crank  204 , for example by interference, gluing, or co-molding, however, a traditional removable shape coupling is not excluded.  
         [0085]     In  FIG. 15 , a bottom bracket assembly  301  is shown. This assembly  301  includes an axle  302  permanently associated to a right crank  304 , e.g., by way of co-molding, gluing, or mechanical forcing, and removably associated to a left crank  306 . The axle  302  is rotatably supported, inside of a box  316  of the frame, by right and left adapter supports  312  and  314 , through interposition of bearings  308  and  309 .  
         [0086]     The right adapter support  312  is provided with an external threading  344  for screwing engagement in the box  316  of the frame, with a rest flange  315  that projects radially outwardly from the adapter support  312  so as to rest against the side  316   a  of the box  316 , and with an internal seat  346  to receive the bearing  308 . The seat  346  includes a stop wall  346   a  on a side towards the rest flange  315 ; the bearing  308  abuts against the stop wall  346   a  and, thus, is prevented from slipping out of the box  316  once mounted. On the opposite side, towards the end  342  of the adapter support  312  facing the inside of the box  316 , the seat  346  is open to allow for insertion of the bearing  308  into the seat  346 . The end  342  of the adapter support  312  is shaped according to a drive profile, with a front toothing  348  that can be operated by the drive key  50  shown in  FIG. 5 .  
         [0087]     The left adapter support  314  is also provided with an external threading  345  for screwing engagement in the box  316  of the frame and with an internal seat  347  to receive the bearing  309  for the axle  302 ; the seat  347  includes a stop wall  347   a , against which the bearing  309  abuts, with the interposition of an elastic insert  317 .  
         [0088]     The axle  302  has a central portion  303  with a relatively wider diameter. It should be noted that the right adapter support  312  allows that a pre-assembled right subassembly  333 —comprising the so shaped axle  302  (with the relatively wider central portion  303 ), the right crank  304 , the bearing  308 , and the adapter support  312  itself—is easily mounted to the box  316 , because the adapter support  312  can be fastened to the box  316  by operating it by means of the drive key  50 , through the box  316  from the left side  316   b  of the box  316 .  
         [0089]     Indeed, the subassembly  333  is pre-assembled by fastening the right bearing  308  to the axle  302 , mounting the adapter support  312  onto the right bearing  308 , and finally fastening the right crank  304  to the axle  302 . Preferably the axle  302  is permanently coupled to the right crank  304 ; however, a removable coupling as described for the other embodiments is not excluded. Once pre-assembled, the subassembly  333  is inserted into the box  316  and the adapter support  312  is operated by means of the drive key  50 , through the box  316 , thus screwing the adapter support  312  to the box  316  until it reaches its operating position, with the rest flange  315  abutting against the right side  316   a  of the box  316 . Then, the left bearing  309  is mounted onto the axle  302  and the left adapter support  314  is screwed with its threading  345  to the box  316 , until the stop wall  347   a  of the seat  347  reaches and blocks the bearing  309 , with the interposition of the elastic insert  317 . Finally, the left crank  306  is mounted on the axle  302  and secured thereto by the nut  64 .  
         [0090]     It should be noted that the shape, dimensions, and position of the crank  304  make access and operation of the adapter support  312  very difficult from the right side  316   a  of the box  316 ; however, this difficulty is overcome by the possibility of easily accessing and operating the adapter support  312  from within the box  316 , thanks to the driving profile  348 .  
         [0091]     In  FIG. 16 , a bottom bracket assembly  401  is shown. This assembly  401  includes an axle  402  preferably permanently associated to a right crank  404 , e.g., by way of co-molding, gluing, or mechanical forcing, and removably associated to a left crank  406 . The axle  402  is rotatably supported, outside of the box  416 , by right and left adapter supports  412  and  414 , through interposition of bearings  408  and  409 .  
         [0092]     Right adapter support  412  is provided with an external threading  444  for screwing engagement in the box  416  of the frame, with a rest shoulder  415   a  that projects radially outwardly from the adapter support  412  so as to rest against the right side  416   a  of the box  416 , and with an internal seat  446  to receive the bearing  408  for the axle  402 . The seat  446  includes a stop wall  446   a  on a side towards the end  442  of the adapter support  412  facing the inside of the adapter support  412 . On the opposite side, towards the right crank  404 , the seat  446  is open to allow for insertion of the bearing  408  into the seat  446 . The bearing  408  abuts against the stop wall  446   a  and is prevented from slipping out of the box  416  by a retention ring  419 . The end  442  of the adapter support  412  is shaped according to a drive profile, with a front toothing  448  that can be operated by the drive key  50  shown in  FIG. 5 .  
         [0093]     The left adapter support  414  is also provided with an external threading  445  for screwing engagement in the box  416  of the frame, with a rest shoulder  415   b  and with an internal seat  447  to receive the bearing  409  for the axle  402 ; the seat  447  includes a stop wall  447   a , against which the bearing  409  abuts, with the interposition of an elastic insert  417 .  
         [0094]     It should be noted that the right adapter support  412  allows that a pre-assembled right subassembly  433 —comprising the axle  402 , the right crank  404 , the bearing  408 , and the adapter support  412  itself—is easily mounted to the box  416 , because the adapter support  412  can be fastened to the box  416  by operating it by means of the drive key  50 , through the box  416 , from the left side  416   b  of the box  416 .  
         [0095]     Similar to the subassembly  333 , the subassembly  433  is pre-assembled by forcing the right bearing  408  onto the axle  402  until it abuts against a shoulder  402   b , mounting the adapter support  412  onto the right bearing  408 , applying the retention ring  419  thus securing the adapter support  412  in its position, and finally fastening the right crank  404  to the axle  302 . Once pre-assembled, the subassembly  433  is inserted into the box  416  and the adapter support  412  is operated by means of the drive key  50 , through the box  416 , thus screwing the adapter support  412  to the box  416  until it reaches its operating position, with the rest shoulder  415   a  abutting against the box  416 . Then, the left adapter support  414  is screwed with its threading  445  to the box  416 , until the rest shoulder  415   b  abuts against the box  416 , and the left bearing  409  is mounted onto the axle  402  and in the seat  447  until it reaches the elastic insert  417  against the stop wall  447   a . Finally, the left crank  406  is mounted on the axle  402  and secured thereto by nut  64 .