Methods and apparatus for suspending vehicles

1. A shock absorber for a vehicle comprising:

a gas spring having first and second gas chambers, wherein the first gas chamber is utilized during a first travel portion of a piston and the first and second gas chambers are both utilized during a second travel portion of the piston; and

a travel adjustment assembly configured to selectively communicate said first gas chamber with a negative gas chamber, the travel adjustment assembly comprising:

an outer tube; and

an inner tube, the inner tube at least partially disposed within and moveable relative to the outer tube, said inner tube and said outer tube defining an annular space therebetween, each of the inner tube and the outer tube having at least one aperture in a wall thereof forming a communication path in said annular space between the first gas chamber and the negative gas chamber at predetermined positions of the piston in a compression stroke of the shock absorber.

2. The shock absorber of claim 1 , further comprising:

the piston movable relative to the outer tube.

3. The shock absorber of claim 1 , wherein utilization of the second gas chamber is brought about by a predetermined pressure developed in the first gas chamber.

4. The shock absorber of claim 1 , wherein the outer tube and the inner tube are concentric tubular members.

5. The shock absorber of claim 1 , further including a seal ring for sealing an annulus between the inner tube and the outer tube.

6. The shock absorber of claim 5 , wherein communication between the first gas chamber and the negative gas chamber is blocked by the seal ring when the piston reaches a predetermined position on the outer tube.

7. A shock absorber for a vehicle comprising:

a gas spring having a piston and first and second gas chambers in a housing with a first inner diameter, wherein the first gas chamber is compressed by the piston during a first travel portion of the piston and the first and second gas chambers are both compressed during a second travel portion of the piston; and

wherein fluid communication between the first gas chamber and the second gas chamber is via an annular area formable between the piston and an enlarged second inner diameter of the housing; and

a travel adjustment assembly configured to selectively communicate the first gas chamber with a negative gas chamber, said travel adjustment assembly comprising:

an outer tube; and

an inner tube, the inner tube at least partially disposed within the outer tube, the piston movable relative to the outer tube and the inner tube movable relative to the outer tube, said inner tube and said outer tube defining an annular space therebetween, the inner and outer tubes each having at least one aperture in a wall thereof forming a fluid path in said annular space between the first gas chamber and the negative gas chamber at predetermined positions of the piston during a compression stroke of shock absorber.

8. The shock absorber of claim 7 , wherein during the first travel portion the piston is sealed against the housing and during the second travel portion, the annular area is formed therebetween.

9. The shock absorber of claim 8 , wherein during a third travel portion, the piston is sealed against the housing.

10. The shock absorber of claim 7 , wherein a portion of the housing having the enlarged second inner diameter is disposed between two portions of the housing having the first inner diameter.

11. An air shock comprising:

a first chamber at a first pressure;

a second chamber at a second pressure;

a communication valve having an open position at a predetermined point of axial compression of the air shock where the open position permits fluid flow between the first and second chambers; and

a travel adjuster having a position permitting fluid flow between the first chamber and a negative chamber, the travel adjuster comprising:

an outer tube; and

an inner tube, the inner tube at least partially disposed within the outer tube, the inner tube movable relative to the outer tube, said inner tube and said outer tube defining an annular space therebetween, the inner and outer tubes each having at least one aperture in a wall thereof forming a fluid path in said annular space between the first chamber and the negative chamber.

12. The air shock of claim 11 , wherein the outer tube and the inner tube are concentric tubular members.

13. The air shock of claim 12 , further including a seal ring for sealing an annulus between the inner tube and the outer tube.

14. The air shock of claim 13 , wherein communication between the first chamber and the negative chamber is blocked by the seal ring when a piston reaches a predetermined position on the outer tube.