Front suspension for motorcycle

• US 20050127636A1
• Filed: 02/02/2005
• Published: 06/16/2005
• Est. Priority Date: 07/31/2003
• Status: Active Grant

• Current Assignee: MotoCzysz
• Original Assignee: MotoCzysz
• Inventors: Czysz, Michael
• Granted Patent: US 7,207,585 B2
• Time in Patent Office: Days
• US Class Current: 280/276
• CPC Class Codes: B62K 21/02 Front wheel forks or equivalent, e.g. single tine
• CPC Class Codes: B62K 21/20 resilient
• CPC Class Codes: B62K 25/02 for mounting axles rigidly on cycle frame or fork, e.g. adjustably
• CPC Class Codes: B62K 25/08 for front wheel

Abstract

A motorcycle whose front end has a coil-over shock disposed within the head tube and telescopic forks which include linear bearings riding between flats on the outer face of the inner fork tubes and flats on the inner face of the outer fork tubes. The linear bearings ride on hardened steel races, enabling the fork tubes to be e.g. aluminum. Using an odd number of linear bearings in each fork prevents having two linear bearings at 180° opposition which would increase sensitivity to manufacturing tolerance stackups, preload, and the like.

Claims

1. A motorcycle front suspension for use with a motorcycle having a frame and a front wheel, the motorcycle front suspension comprising:

an outer fork tube having a plurality of axially oriented flats in its inner surface;

an inner fork tube having a plurality of axially oriented flats in its outer surface;

a plurality of linear bearings disposed between corresponding flats of the outer fork tube and of the inner fork tube, such that the inner fork tube is telescopically disposed within the outer fork tube so as to ride therein upon the linear bearings;

at least one clamp for rotatably coupling an upper one of the fork tubes to the frame; and

a fork bottom coupling a lower one of the fork tubes to the wheel, the fork bottom having sufficient longitudinal stiffness to resist significant longitudinal flexing but sufficient lateral flexibility to deflect laterally in response to mid-corner bumps.

2. The motorcycle front suspension of claim 1 wherein:

at least one of the fork tubes is manufactured of a metal significantly lighter than steel; and

the motorcycle front suspension further comprises

a plurality of hardened races disposed between the linear bearings and the fork tube(s) which is lighter than steel.

3. The motorcycle front suspension of claim 2 wherein:

the flats extend radially into the fork tube to form a plurality of grooves; and

the hardened races are disposed at least partially within the grooves.

4. The motorcycle front suspension of claim 1 wherein:

the plurality of linear bearings consists of an odd number of linear bearings, whereby each linear bearing is disposed 180°

opposite a portion of the front suspension which does not have a linear bearing.

5. The motorcycle front suspension of claim 1 further comprising:

a second outer fork tube having a plurality of axially oriented flats in its inner surface;

a second inner fork tube having a plurality of axially oriented flats in its outer surface and telescopically disposed within the second outer fork tube;

a second plurality of linear bearings disposed between the second outer fork tube and the second inner fork tube; and

a second fork bottom coupled to a lower one of the second outer fork tube and the second inner fork tube.

6. The motorcycle front suspension of claim 5 further comprising:

a steering tube rotatably coupled to the clamp and coupled to the frame;

a fork bridge coupled between the lower ones of the fork tubes;

a suspension component disposed within the steering tube and coupled to the fork bridge.

7. The motorcycle front suspension of claim 6 wherein:

the suspension component is coupled to the fork bridge so as to be able to rotate out of engagement with the fork bridge, whereby the suspension component can be removed from the steering tube.

8. The motorcycle front suspension of claim 1 further comprising:

a bearing follower disposed within the outer fork tube to prevent the linear bearings from extending axially out of position.

9. The motorcycle front suspension of claim 1 further comprising:

a stop disposed within the outer fork tube to prevent the linear bearings from extending axially out of position.

10. A fork bottom for coupling a motorcycle'"'"'s telescopic front fork to a front wheel'"'"'s axle, the fork bottom comprising:

a body at least six inches tall and having a cross-sectional shape giving the body greater longitudinal stiffness than lateral stiffness;

a receptacle substantially at the body'"'"'s lower end, the receptacle having a ridge with a shoulder on an inwardmost side toward the wheel;

an axle positioning block having an outer surface shaped to fit within the receptacle, the outer surface having a ridge with a shoulder on an outwardmost side away from the wheel;

wherein the shoulder of the body engages the shoulder of the axle positioning block so as to prevent the axle positioning block from escaping outwardly from the receptacle in a direction generally coaxial with the axle.

11. The fork bottom of claim 10 wherein:

the axle positioning block further includes an inner opening for receiving the axle at a first predetermined longitudinal position with respect to the motorcycle.

12. The fork bottom of claim 11 further comprising:

a second axle positioning block, alternatively disposable within the body'"'"'s receptacle, and having a shoulder which engages the body'"'"'s shoulder to prevent outward escape of the second axle positioning block;

the second axle positioning block having an inner opening for receiving the axle at a second predetermined longitudinal position with respect to the motorcycle;

whereby, by swapping between the two axle positioning blocks, front suspension trail geometry of the motorcycle is altered.

13. The fork bottom of claim 10 wherein the body further includes:

gusseting of an inward facing surface of the body.

14. A motorcycle having a frame, a front axle, and a front wheel rotatably coupled to the front axle, the motorcycle further having a front end coupling the front axle to the frame, the front end comprising:

a pair of telescopic forks each including,

an inner fork tube having a plurality of axially extending flats on its outer surface,

an outer fork tube having a plurality of axially extending flats on its inner surface,

a plurality of linear bearings each disposed between a respective one of the flats of the inner fork tube and a corresponding respective one of the flats of the outer fork tube,

wherein the inner fork tube is telescopically disposed within the outer fork tube and coupled thereto by the linear bearings;

an upper triple clamp coupled to upper ones of the fork tubes of the telescopic forks and rotatably coupled to the frame;

a fork bridge coupled to lower ones of the fork tubes of the telescopic forks;

a coil-over shock coupled to the fork bridge and to the upper triple clamp and disposed within a head tube of the frame;

wherein the telescopic tubes are substantially inert sliders and wherein the coil-over shock provides substantially all of the spring and dampening characteristics of the front end.

15. The motorcycle of claim 14 wherein the front end further comprises:

a radially extending bracket coupling a lower end of the coil-over shock to the fork bridge;

wherein, when the bracket is unbolted from the fork bridge, the bracket can be rotated out of engagement with the fork bridge;

whereby the coil-over shock can be removed from the motorcycle without alteration or disassembly of the telescopic forks nor the upper triple clamp.

16. The motorcycle of claim 15 wherein each of the telescopic forks further comprises:

a fork bottom coupling a lower one of the fork tubes to the axle;

wherein the fork bottom is at least six inches tall and has greater longitudinal stiffness than lateral stiffness.

17. The motorcycle of claim 16 wherein each of the telescopic forks further comprises:

a trail adjuster block removably coupled to the fork bottom and coupling the front axle to the fork bottom;

whereby, by swapping between differently configured trail adjuster blocks, a trail geometry of the front end can be altered without significantly altering other front suspension geometry characteristics.

18. The motorcycle of claim 14 wherein each telescopic fork further includes:

a plurality of bearing races disposed between the linear bearings and at least one of the fork tubes.

19. The motorcycle of claim 18 wherein:

the inner and outer fork tubes are constructed of a material which is significantly lighter than steel; and

the bearing races are substantially as hard as steel.

20. The motorcycle of claim 19 wherein:

the inner and outer fork tubes are constructed of aluminum.

21. The motorcycle of claim 19 wherein:

the inner and outer fork tubes are constructed of carbon fiber composite material.