I just go by the odometer and fuel gauge. Once you get a baseline established in your memory, you don't need the extra thought or gadgets. I know this... the first half tank goes a lot longer than the second When I'm riding the bike off interstate, i mentally calibrate the difference. I recall a recent trip that i was being VERY mindful of fuel consumption. Turns out, I made it to the station without a clue the miles i had trekked, just using the red blinking (oh shit ima b walkin') light.