As someone who doesn't own a smartphone, I use my garmin 1000 on the bars. I have a cheap pay-as-you go burner phone in a ziploc baggie in my jersey pocket for emergencies (used it when I got hit earlier this year and was glad it was there). That works pretty well. I've thought about just letting my garmin watch track my ride, but I like to be able to look down and see my speed (and more importantly the time so that I can compare it to how long I told my wife I'd be gone) right in front of my face. Plus, my chest strap HR meter is much more accurate than my watch. My power meter is my powertap hub, so that provides rotational data. I occasionally calibrate the wheel size using gps, so it's instantaneous and fairly accurate.