The problem with hand signals is you already need that hand to operate brakes and gears, and maintain balance and directional control. It's hard enough to do those things with 2 hands on the handlebars on bumpy roads in dynamic traffic. So you get maybe a second or two of brief signaling, which screws up your balance and timing, and distracts you from the traffic and surface you're dealing with. Whoever thought up those hand-signals apparently rode only flat smooth roads and didn't have Joe-Bob Speed Racer breathing up their backside. There's gotta be a better way...