Bike power meter speedframe

A bicycle power meter is a device that measures the power delivered by the cyclist basing its technology on the principle of the strain gauge, a measuring instrument that detects deformations. Mechanical power is measured through the deformation of a body subjected to stress

The power meters base their technology on the principle of the extensometer, a measuring instrument which detects deformations. Mechanical power is measured through the deformation of a body subjected to stress. The constant deformation of these calibrated parts allows the system to measure the force torque. Angular velocity measurement depends on the component in which the power meter is integrated. So in the crankset or in the pedals it corresponds to the pedaling cadence while in the hub it corresponds to the rotation speed of the rear wheel.

You can find a power meter in almost every component of your bicycle: hub, crankset, cranks, pedals, crankset axle or chainrings.
Each choice has advantages and disadvantages, let's see them together:

1. Power meter in the crankset: it was the first potentiometer system to be presented, it is one of the most widespread and approved on the market but also the most expensive. This model measures the force near the pressure point.
   
   
2. Crank with power meter: sold as the most affordable, it can be less accurate in some cases if the power meter is only on the left crank, however the power generated by each leg can be different. One may be stronger and the other more tired (eg 48 / 52% ratio) or vice versa and this phenomenon may become more pronounced with fatigue. The ratio also varies depending on the type of effort (flat/hill) and cadence. Thus, a sensor that measures only the left leg obtains the final value by multiplying the measurement obtained by two without taking into account these possible variations.
   
   
3. Hub power meter: the rear wheel hub power meter is one of the first to be scientifically approved. It's useful when using multiple bikes because it moves easily from one to another.
   
   
4. Pedals with power meter: the measurement is made as close as possible to the power created by the cyclist and the system allows for the measurement of each leg (left/right) The meter on the pedal axis can be moved easily and quickly to all bikes and is suitable for those with several bicycles.