I used 18ga. when I had to stretch those wires installing pull back handle bars. None of the handle bar controls carry much current load. But insulation thickness and number of strands in the wire can have a major effect on the overall wire bulk and flexibility. If you are making splices in the sheath along the handle bars, make sure they are well insulated and stagger them so they don't all sit on top of each other.
Thanks for the tips. I was going to run the wires through the bars but the holes ain't even close so I'm going to run em as clean as i can outside the bars. also found a guy on eBay to buy wire by the foot in several color combos.