Linear derailleur mechanism
A derailleur system is provided that moves the derailleur cage in a substantially rectilinear path. The derailleur is mounted to a frame having a gear cassette mounted thereon. The gear cassette includes an axis of rotation. The derailleur includes a drive member engaging the gear cassette. The derailleur is positioned on the frame adjacent the gear cassette, and including a spatial linkage having a stationary link, a floating link, and a cage assembly having two pulleys each defining an axis of rotation. The drive member engages each of the pulleys. The path of the floating link is substantially linear through substantially its entire range of motion and variously aligns at least one of the pulleys with the gear cassette.
1. A six-bar linkage for a bicycle rear derailleur comprising:
a stationary link ( 140 );
a floating link ( 150 );
a first link ( 142 );
a second link ( 144 );
a third link ( 152 );
a fourth link ( 154 ), wherein the links are operatively coupled by at least six joints, and wherein a path of the floating link ( 150 ) is constrained to one degree of freedom.
2. The six-bar linkage of claim 1 , further comprising a torsion spring positioned about a joint of the at least six joints, wherein the torsion spring resists relative motion between the stationary link ( 140 ) and the floating link ( 150 ).
3. The six-bar linkage of claim 1 , wherein:
the first link ( 142 ) and the second link ( 144 ) comprise a first link set ( 145 a ); and
the third link ( 152 ) and the fourth link ( 154 ) comprise a second link set ( 145 b ).
4. The six-bar linkage of claim 3 , wherein the first link set ( 145 a ) and the second link set ( 145 b ) are arranged in a crossed configuration with respect to one another.
5. The six-bar linkage of claim 4 , wherein the floating link ( 150 ) is configured to move along the path between an extended configuration and a retracted configuration.
6. The six-bar linkage of claim 4 , wherein the first link set ( 145 a ) and the second link set ( 145 b ) are configured to fold in on one another.
7. The six-bar linkage of claim 3 , wherein:
the links of the first link set include a first plurality of axes at respective joints therebetween;
the links of the second link set include a second plurality of axes at respective joints therebetween.
8. The six-bar linkage of claim 7 , wherein the first plurality of axes is substantially parallel to the second of respective axes.
9. The six-bar linkage of claim 7 , wherein the first plurality of axes is not parallel to the second of respective axes.
10. A two-wheeled vehicle comprising:
a frame having a gear cassette mounted thereon, the gear cassette having an axis of rotation;
a drive member engaging the gear cassette;
a derailleur positioned on the frame adjacent the gear cassette, the derailleur comprising a six bar linkage including:
a stationary link ( 140 );
a floating link ( 150 );
a first link ( 142 );
a second link ( 144 );
a third link ( 152 );
a fourth link ( 154 ), wherein the links are operatively coupled by at least six joints, and wherein a path of the floating link ( 150 ) is constrained to one degree of freedom.
11. The two-wheeled vehicle of claim 10 , wherein the derailleur further comprises a torsion spring positioned about a joint of the at least six joints, wherein the torsion spring resists relative motion between the stationary link ( 140 ) and the floating link ( 150 ).
12. The two-wheeled vehicle of claim 10 , wherein the derailleur further comprises:
a cage assembly coupled to the floating link ( 150 ), wherein the cage assembly includes:
a derailleur cage,
a first pulley rotationally coupled to the derailleur cage, and
a second pulley rotationally coupled to the derailleur cage, and wherein the first pulley and the second pulley are configured to engage the drive member.
13. The two-wheeled vehicle of claim 10 , wherein:
the first link ( 142 ) and the second link ( 144 ) comprise a first link set ( 145 a );
the third link ( 152 ) and the fourth link ( 154 ) comprise a second link set ( 145 b ).
14. The two-wheeled vehicle of claim 13 , wherein the first link set ( 145 a ) and the second link set ( 145 b ) are arranged in a crossed configuration with respect to one another.
15. The two-wheeled vehicle of claim 13 , wherein the floating link 150 is configured to move along the path between an extended configuration and a retracted configuration.
16. The two-wheeled vehicle of claim 15 , wherein the first link set ( 145 a ) and the second link set ( 145 b ) are configured to fold in on one another when the floating link ( 150 ) is in one of the retracted configuration.
17. A derailleur for a two-wheeled vehicle comprising:
a six-bar linkage including:
a stationary link ( 140 );
a floating link ( 150 );
a first link ( 142 );
a second link ( 144 );
a third link ( 152 );
a fourth link ( 154 ), wherein the links are operatively coupled by at least six joints, and wherein a path of the floating link ( 150 ) is constrained to one rectilinear degree of freedom.
18. The derailleur of claim 17 , further comprising a torsion spring positioned about a joint of the at least six joints, wherein the torsion spring resists relative motion between the stationary link ( 140 ) and the floating link ( 150 ).
19. The derailleur of claim 17 , wherein:
the first link ( 142 ) and the second link ( 144 ) comprise a first link set ( 145 a ); and
the third link ( 152 ) and the fourth link ( 154 ) comprise a second link set ( 145 b ).
20. The derailleur of claim 19 , wherein the first link set ( 145 a ) and the second link set ( 145 b ) are arranged in a crossed configuration with respect to one another.