Wattmeter is a specialised instrument designed to measure electrical power, which is the rate at which electrical energy is transferred or used. The primary unit of measurement for. Measuring your power on the bike is one of the best ways to track your cycling progress, giving you live and recorded data on how many Watts you produce at any given time during a ride. There are many types of power meters – pedal, crank, spider, wheel, etc. Although they differ, the power output they measure should be the same.