PowerTap G3 Hub The G3’s design allows for a simple, straight-forward way to measure power. By mounting the strain gauges in an area where external forces, such as spoken tension, cannot impact power measurement, the PowerTap G3 is able to deliver +/- 1.5% accuracy ride after ride. Advice on Warranty detailing more information. More than just a power meter, The G3 delivers speed, cadence and power with pin-point accuracy all in one product. And its ability to be easily switched between bikes means you’ll never miss a watt….