Adjustable backrest

1. A back support for use with a chair comprising:

a first support;

a second support spaced from the first support; and

an adjustable support extending between the first and second supports, the adjustable support including:

a cable;

an adjustable tensioning assembly operably connected to the cable and positioned in an area flanked by the first and second supports;

a first portion that carries the adjustable tensioning assembly and a second portion spaced from the first portion, the first and second portions connected by the cable;

a first guide member positioned on the second portion;

a second guide member positioned on the first portion; and

a third guide member positioned on the second portion,

wherein the adjustable tensioning assembly is positioned between the first guide member and the second guide member, and

wherein the cable extends from the adjustable tensioning assembly to the first guide member, from the first guide member to the second guide member, from the second guide member to the third guide member, and from the third guide member back to the adjustable tensioning assembly, and

wherein the adjustable tensioning assembly is operable to adjust a tension of the cable extending between the first and second supports.

2. The back support of claim 1 , wherein the adjustable tensioning assembly is operable to secure the cable at a given length.

3. The back support of claim 1 , wherein the chair is a wheelchair.

4. The back support of claim 1 , wherein the cable includes a first end and a second end, the first and second ends being coupled to the adjustable tensioning assembly.

5. The back support of claim 1 , wherein the first guide member is spaced from the adjustable tensioning assembly, the cable extending from the adjustable tensioning assembly to the first guide member.

6. The back support of claim 1 , wherein in response to actuation of the adjustable tensioning assembly the cable slides relative to the first guide portion, the second guide portion, and the third guide portion.

7. The back support of claim 1 , wherein the cable extends from the adjustable tensioning assembly to the first guide member and back to the adjustable tensioning assembly.

8. The back support of claim 7 , wherein in response to actuation of the adjustable tensioning assembly the cable slides relative to the first guide portion.

9. An adjustable back support for use with a chair comprising:

a first upright support spaced from a second upright support;

an adjustable support having a first end opposite a second end, a cable, an adjustable tensioning assembly operably connected to the cable, and a first guide member spaced from the adjustable tensioning assembly, the cable extending from the adjustable tensioning assembly to the first guide member and back to the adjustable tensioning assembly,

wherein the first end is coupled to the first upright support, and the second end is coupled to the second upright support such that the adjustable support horizontally extends between the first and second upright supports and the cable extends between the first and second upright supports at least three times, and

wherein in response to actuation of the adjustable tensioning assembly a length of the adjustable support changes.

10. The back support of claim 9 , wherein the adjustable support includes a first portion that carries the adjustable tensioning assembly and a second portion spaced from the first portion, the first and second portions connected by the cable.

11. The back support of claim 9 , wherein the adjustable tensioning assembly is positioned between the first end and the second end.

12. The back support of claim 9 , wherein the chair is a wheelchair.

13. The back support of claim 12 , wherein the first upright support is a first wheelchair cane, and the second upright support is a second wheelchair cane.