Rule of Thumb: Small size kites are used with narrow bars and visa versa.

This table is best suited for freeriders:

Narrow kite bars will turn your kite more slowly which is perfect for smaller kites which are already fast. The opposite is true for a large kite that already moves slowly and therefore need a wider bar.

However, the above table only applies to kitesurfers who are freeriders. The size of your kite bar also depends on the riding style and level.

Bar width based on riding style:

A kitesurfer who practices wave kitesurfing is best off with a narrow bar as they ride small kites and want to follow the waves. Freestyle kitesurfers will be better of with a wider bar.