A power meter accurately measures and monitors your output to help make progress towards your goals. Power meters work by using strain gauges in order to measure the force applied during the pedal stroke and have become a popular measurement tool over the years. There are different power meters available and they can be placed in various areas of your bike. These include the crank arm, rear wheel hub, bottom bracket, chainring or pedals. Some are more accurate than others, so make sure you are investing in the right one for your needs.