Meet the Vector S from Garmin: a nifty device that measures force on the left pedal to estimate and report power and cadence. Cyclists will be able to track power output and other metrics. The Vector S system can be installed or transferred between bikes easily. It has a built-in accelerometer that measures cadence. Vector S is compatible with Edge cycling computers or other ANT+ enabled devices.
The device can determine how much force is being applied to the pedal. Those of you who are serious about cycling can get the upgrade pedal to track more data, including left/right balance data and Cycling Dynamics.