Just realized my third hand was sitting in my toolbox the whole time
Last Tuesday I was fighting a rear derailleur cable on a customer's Trek in my shop off 5th Street, and the ferrule kept slipping while I tried to hold tension and tighten the anchor bolt at the same time. After the third try the cable frayed and I had to start over with a fresh one. Then I remembered the old brake cable I bent into a hook last winter and jammed it through the anchor bolt hole to hold tension, and the whole job took 30 seconds. Six years of doing it the hard way with my teeth and a pair of needle nose pliers. What dumb little tool or trick do you keep forgetting you already have?