Bicycle Rear Suspension

Abstract

Rear suspension for a bicycle comprising a rear swing arm ( 15 ) which carries the hub ( 19 ) of the rear wheel ( 20 ) and pivots via at least two pivot means ( 23, 24 ) on a frame ( 1 ) carrying a bottom bracket ( 12 ), the swing arm ( 15 ) pivoting about an instantaneous centre of rotation ( 25 ) corresponding to the intersection of the straight lines (d 1 , d 2 ) passing through the axes of rotation ( 23 a , 23 b ; 24 a , 24 b ) of the respective pivot means of the swing arm ( 15 ); said instantaneous centre of rotation ( 25 ) is located close to the stretch upper length of the chain ( 21 ), or to the straight line extending on from it, in a position of static equilibrium and moves inside a horizontal band ( 27 ) in such a way that said instantaneous centre of rotation ( 25 ) moves horizontally and forwards when the swing arm ( 15 ) moves upwards as the wheel goes over an obstacle.

1 . A rear suspension of a bicycle including a rear swing arm ( 15 ) bearing the hub ( 19 ) of the rear wheel ( 20 ) and articulated by at least two articulation means ( 23 ,  24 ) to a frame ( 1 ) bearing a crankset bottom bracket ( 12 ), said bicycle including a transmission chain ( 21 ) extending between a driving sprocket wheel ( 13 ), a so-called chain ring, secured to the crankset bottom bracket ( 12 ) and a driven sprocket wheel ( 22 ) secured to the axle of the hub ( 19 ) of the rear wheel ( 20 ), and the swing arm ( 15 ) pivoting around an instantaneous centre of rotation ( 25 ) corresponding to the intersection of the straight lines (d 1 , d 2 ) passing through the axes of rotation ( 23   a ,  23   b ;  24   a ,  24   b ) of the respective articulation means of the swing arm ( 15 ), wherein said instantaneous centre of rotation ( 25 ) is located close to the upper strand of the chain ( 21 ), or to the straight line which extends on from it, in a position of static equilibrium and moves inside a horizontal band ( 27 ) so that said instantaneous centre of rotation ( 25 ) moves horizontally when the swing arm ( 15 ) moves upwards upon going over an obstacle. 
   
   
       2 . The rear suspension according to  claim 1 , wherein the band ( 27 ) is delimited by an upper straight line ( 27   a ) and a lower straight line ( 27   b ) extending above and respectively below the upper strand of the chain ( 21 ), or the straight line which extends on from it, in a position of static equilibrium. 
   
   
       3 . The rear suspension according to  claim 2 , wherein the distance separating the upper straight line ( 27   a ) from the lower straight line ( 27   b ) of the band ( 27 ) is less than or equal to half the maximum vertical displacement of the hub ( 19 ) of the rear wheel ( 20 ). 
   
   
       4 . The suspension according to  claim 1 , wherein the distance between said instantaneous centre of rotation ( 25 ) and the upper strand of the transmission chain ( 21 ), or the straight line which extends on from it, increases when the swing arm ( 15 ) moves upwards. 
   
   
       5 . The suspension according to  claim 4 , wherein the distance between said instantaneous centre of rotation ( 25 ) and the upper strand of the transmission chain ( 21 ), or the straight line which extends on from it, increases linearly when the swing arm ( 15 ) moves upwards. 
   
   
       6 . The rear suspension according to  claim 5 , wherein the instantaneous centre of rotation ( 25 ) follows a linear trajectory when the swing arm ( 15 ) moves. 
   
   
       7 . The rear suspension according to  claim 4 , wherein the distance between said instantaneous centre of rotation ( 25 ) and the upper strand of the transmission chain ( 21 ) or the straight line which extends on from it, increases non-linearly when the swing arm ( 15 ) moves upwards. 
   
   
       8 . The rear suspension according to  claim 7 , wherein the instantaneous centre of rotation ( 25 ) follows a curvilinear trajectory, the concavity of which is oriented upwards when the swing arm ( 15 ) moves. 
   
   
       9 . The rear suspension according to  claim 1 , wherein the instantaneous centre of rotation ( 25 ) is located in the front quadrant. 
   
   
       10 . The rear suspension according to  claim 1 , wherein the instantaneous centre of rotation ( 25 ) is located in the rear quadrant. 
   
   
       11 . The rear suspension according to  claim 10 , wherein the instantaneous centre is located at the rear of the hub ( 19 ) of the rear wheel ( 20 ). 
   
   
       12 . The rear suspension according to  claim 1 , wherein the articulation means ( 23 ,  24 ) of the swing arm ( 15 ) consist in two connecting rods, a so-called upper connecting rod ( 24 ) articulated to the saddle tube ( 2 ) of the frame ( 1 ) and a lower connecting rod ( 23 ) articulated to said saddle tube ( 2 ) close to the crankset bottom bracket ( 12 ). 
   
   
       13 . The rear suspension according to  claim 12 , wherein the lower connecting rod ( 23 ) globally extends horizontally in a position of static equilibrium. 
   
   
       14 . The rear suspension according to  claim 12 , wherein the upper connecting rod ( 24 ) globally extends vertically in a position of static equilibrium. 
   
   
       15 . The rear suspension according to  claim 12 , wherein the upper connecting rod ( 24 ) globally extends horizontally in a position of static equilibrium.