How long you use your Harness lines depends a lot on your stance on the board and the kind of equipment you use (race, freestyle, wave..) but for me it also really depends what kind of conditions I sail in! In flat light wind conditions I like shorter lines in choppy strong wind conditions its best when they are as long as 34 ! So to find the right length for for you I really recommend having adjustable lines so you can play around a bit till you find the settings that are best for you.