4iiii powermeter

Power data is a must-have for us for training. It's more accurate than heart rate and is a very powerful training tool. We love our 4iiii crank-based power meters because they're light and accurate and connect to any ANT+ or Bluetooth-enabled cycling computer (which is most of them). If you want to save a good bit, do the Factory Install where you send in your existing crank arm and have them add the power meter.