As mentioned previously, trikes legally require a handbrake nowdays and mine is operated by what used to be the Harley clutch lever. The cable that comes from the lever is what you see coming from the right side of this picture, i made up a pivoting arm that connects the front handbrake cable to the rear handbrake cables. It’s mounted so that when the handbrake lever gets pulled in the front cable travels roughly 30mm and because it goes through this pivoting arm with the rear cable attached further towards the end of the arm, the rear cables get pulled roughly twice the distance that the front cable moves