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Serious cyclists are increasingly using power to gauge their training efforts, especially as power meters become not only more technically-capable but also more affordable. Learning the terminology that comes along with training with power can seem intimidating at first, but the glossary of common terms below will help speed your trip up the learning curve.

Power Meter

A device that measures the power you produce while riding.

How they work: A majority of available power meters use strain gauges to quantify how much your bottom bracket, crankset, freehub or pedal axles deform under the force of pedalling. Strain gauges output electrical resistance relative to the amount of mechanical deformation of the component to which they are mounted. The amount of mechanical deformation corresponds to how much torque you are applying to the pedals, and torque and pedalling cadence are used to calculate power.

Power

A product of how much torque you are applying to the pedals and how fast you are pedalling. It is also defined as the rate of energy used or the amount of work done per unit of time. Power is expressed in watts (W).

For those who prefer to think in equations: Power = Work / Time = Force * Displacement / Time = Force * Velocity = Torque * Angular Velocity

Instantaneous Power

The amount of power produced at any given moment.

Average Power

The average amount of power produced over a given period of time, such as during any given workout or race.

Max Power

The maximum amount of power produced during any given period of time, such as during any given workout or race.

Normalized Power

A measure of power calculated using an algorithm that factors in the high and low power outputs that naturally occur when a rider is sprinting, doing intervals, climbing, descending, coasting, etc. It estimates total effort over a given period of time and is considered more accurate than average power by many experts because it better accounts for the actual physiological demands of a given ride.

Threshold Power

The amount of power a rider can sustain for one hour. It is often calculated from the average power output measured during a 20-minute timed effort. Threshold Power is used to calculate training zones, and is sometimes called Functional Threshold Power.

Torque

The amount of force applied to the pedals. It is typically expressed in Newton meters (Nm).

Cadence

How fast you are pedalling. Cadence is usually measured in revolutions per minute or RPMs and can be converted into Angular Velocity, which is usually expressed in radians/second.

Calibration

The process of setting or correcting a measuring device such as a power meter so that it accurately outputs actual measurements.

Power to Weight Ratio

The amount of power you can produce divided by your weight, often measured in kilograms/watt or pounds/watt. Generally speaking, the higher the power-to-weight ratio, the better the cyclist.

Rotor INpower Powermeter

Rotor INpower Powermeter

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