Bicycle rear suspension
A bicycle frame includes substantially rigid front and rear triangles that are pivotally connected to one another by a pair of pivoting linkages.
1. A bicycle frame, comprising:
a substantially rigid front triangle including a bottom bracket shell and a head tube for holding a front wheel via a fork;
a substantially rigid rear triangle for holding a rear wheel;
a top linkage pivotally connected to the front triangle at a top-front pivot axis and pivotally connected to the rear triangle at a top-rear pivot axis; and
a bottom linkage pivotally connected to the front triangle at a bottom-front pivot axis and pivotally connected to the rear triangle at a bottom-rear pivot axis;
the top-front, top-rear, bottom-front, and bottom-rear pivot axes positioned such that at 0% suspension compression, a line extending from the top-rear pivot axis through the top-front pivot axis intersects a line extending from the bottom-rear pivot axis through the bottom-front pivot axis at a focus that is located in a space bounded by:
a front line that is an axis of the head tube,
a bottom line extending horizontally from an axis of the bottom bracket shell,
a top line 130 mm above and parallel to the bottom line, and
a rear line that is perpendicular to the bottom line and the top line and 200 mm in front of an axis of the bottom bracket shell.
2. The bicycle frame of claim 1 , wherein the fork and the rear triangle are sized to accommodate twenty-nine inch wheels.
3. The bicycle frame of claim 1 , wherein an effective length of the bottom linkage is substantially equal to an effective length of the top linkage.
4. The bicycle frame of claim 1 , wherein the bottom linkage extends under the bottom bracket shell of the front triangle and connects to the front triangle in front of and below the bottom bracket shell.
5. The bicycle frame of claim 1 , wherein the rear triangle includes chain stays and seat stays, and wherein the chain stays do not pivot relative to the seat stays.
6. A bicycle frame, comprising:
a substantially rigid front triangle including a bottom bracket shell and a head tube for holding a front wheel via a fork;
a substantially rigid rear triangle for holding a rear wheel;
a top linkage pivotally connected to the front triangle at a top-front pivot axis and pivotally connected to the rear triangle at a top-rear pivot axis; and
a bottom linkage pivotally connected to the front triangle at a bottom-front pivot axis and pivotally connected to the rear triangle at a bottom-rear pivot axis;
the top-front, top-rear, bottom-front, and bottom-rear pivot axes positioned such that at 0% suspension compression, a line extending from the top-rear pivot axis through the top-front pivot axis intersects a line extending from the bottom-rear pivot axis through the bottom-front pivot axis at a focus that is located in a space bounded by:
a bottom line extending horizontally 80 mm above an axis of the bottom bracket shell,
a top line extending horizontally 130 mm above an axis of the bottom bracket shell,
a rear line that is perpendicular to the bottom line and the top line and 250 mm in front of an axis of the bottom bracket shell, and
a front line that is parallel to the rear line and 320 mm in front of the axis of the bottom bracket shell.
7. The bicycle frame of claim 6 , wherein the fork and the rear triangle are sized to accommodate twenty-nine inch wheels.
8. The bicycle frame of claim 6 , wherein an effective length of the bottom linkage is substantially equal to an effective length of the top linkage.
9. The bicycle frame of claim 6 , wherein the bottom linkage extends under the bottom bracket shell of the front triangle and connects to the front triangle in front of and below the bottom bracket shell.
10. The bicycle frame of claim 6 , wherein the rear triangle includes chain stays and seat stays, and wherein the chain stays do not pivot relative to the seat stays.
11. A bicycle frame, comprising:
a substantially rigid front triangle including a bottom bracket shell and a head tube for holding a front wheel via a fork;
a substantially rigid rear triangle for holding a rear wheel;
a top linkage pivotally connected to the front triangle at a top-front pivot axis and pivotally connected to the rear triangle at a top-rear pivot axis; and
a bottom linkage pivotally connected to the front triangle at a bottom-front pivot axis and pivotally connected to the rear triangle at a bottom-rear pivot axis;
the top-front, top-rear, bottom-front, and bottom-rear pivot axes positioned such that at sagged front and back suspension compression, a line extending from the top-rear pivot axis through the top-front pivot axis intersects a line extending from the bottom-rear pivot axis through the bottom-front pivot axis at a focus that is located in a space bounded by:
a front line that is an axis of the head tube,
a bottom line extending horizontally 30 mm above an axis of the bottom bracket shell,
a top line extending horizontally 70 mm above an axis of the bottom bracket shell, and
a rear line that is perpendicular to the bottom line and the top line and 190 mm in front of an axis of the bottom bracket shell.
12. The bicycle frame of claim 11 , wherein sagged front and back suspension compression is approximately 25% front fork suspension compression and 25% rear suspension compression.
13. The bicycle frame of claim 11 , wherein the bottom line is parallel to the axle line at 0% suspension compression.
14. The bicycle frame of claim 11 , wherein the fork and the rear triangle are sized to accommodate twenty-nine inch wheels.
15. The bicycle frame of claim 11 , wherein an effective length of the bottom linkage is substantially equal to an effective length of the top linkage.
16. The bicycle frame of claim 11 , wherein the bottom linkage extends under the bottom bracket shell of the front triangle and connects to the front triangle in front of and below the bottom bracket shell.
17. The bicycle frame of claim 11 , wherein the rear triangle includes chain stays and seat stays, and wherein the chain stays do not pivot relative to the seat stays.