# POWERMETER? YES!

Riding with a power meter requires a little knowledge but can significantly improve the way you ride your bike. The more knowledge you have about your own performance, the easier it becomes to define your goals.

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# Are power meters only for pros?

Cycling intensity is measured in watts (what’s a watt?) “a watt is a physical unit of energy generated during a certain time period.” Power is a direct measurement of force applied to the crank over time and provides the cyclist’s true output (or wattage).Cycling intensity is measured in watts (what’s a watt?) “a watt is a physical unit of energy generated during a certain time period.”

Power is a direct measurement of force applied to the crank over time and provides the cyclist’s true output
(or wattage).

Measuring performance in watts claims significant advantages since watt measurement is independent of circumstantial influences (such as temperature, hydration, altitude, nutrition, stress etc.), and is precise.

# “Watt” do you mean?

# Let’s take two people with the same height, the same position on the bike, and the same bike; they are riding side-by-side.

On a flat course, if both ride at the same speed, they would pedal at the same wattage no matter which gear they are using (the gear alone doesn’t decide wattage). When they approach a hill, body weight becomes a factor and has an impact on wattage because, if one calculates five watts per kg of body weight, a heavier rider has to pedal more on an ascent in order to reach the same speed as a lighter rider. When comparing the wattage of different riders, it is imperative to analyze values in relation to body weight.

Wattage can be manipulated if, for example, we swap out components, install aero wheels, maintain a more compact position on the bike, or reduce the bike’s overall weight. Doing this may favorably result in needing to pedal 20-30 watts less at the same speed on a flat course.

# How can I find my strengths?

My weaknesses?##### + Pedal efficiency

Let’s assume you could apply maximal force throughout the entire 360º of a pedal rotation, this would make your pedaling efficiency 100%. This is never the case since the net weight of your legs alone would lower the negative “force” on the pedal stroke’s rebound. PE values enable you to modify the way you pedal to become more efficient. Sophisticated systems measure the left and right legs independently.

##### + Left/Right balance

Different leg lengths, hip disequilibrium or simply stronger/weaker muscles in one of your legs lead to left/right irregularities. Here you have the chance to optimize your pedal stroke to the extent that both legs deliver 50% of pedaling performance.

##### + Pedal smoothness

This function demonstrates the fluidity of your legs’ movement. It’s the relation between average and maximal force during a pedal stroke, measured in percentages. Pedal Smoothness is simply average power versus maximum power.

##### + Torque effectiveness

The ratio of total torque versus positive torque. During a complete pedal rotation, data gets sampled to measure force and crank velocity. Resulting values will determine your torque effectiveness.

##### + Torque 360º

Represents your distribution of force throughout a pedal rotation. This metric reveals how your force is applied to the pedal during 360º of pedaling and yields your Optimum Chainring Angle

##### + Optimum Chainring Angle

Your OCA value indicates the angular position where the work from pedaling is concentrated. This will help you understand how you pedal and will enable you to optimize the position of your Q-Rings.

# Whoever pedals poorly, wastes power! Before modern power meters arrived, cyclists relied on laboratory testing to analyze pedal performance and provide data with which to optimize it. Now power meters with dual-sided sensors allow every amateur rider to obtain information about the quality of his/her pedal stroke.

**Power meter, yes!**

# But which one?

### Advantages and disadvantages of various power meter systems

**Crank Arm**

With this particular type of power meter you’ll find power-measuring strain gauges in the crank arm. There are systems that only measure power in the left leg, as well as those that can measure power in both crank arms. A significant advantage of dual-sided systems is that you can get separate values for both left/right. When measuring just one side, the values get multiplied by two. Since the majority of riders don’t show a significant difference between left/right power output, multiplying one leg’s value by two is considered to be a sufficient value.

**Crank Axle**

Some years ago measuring power output in the crank axle was introduced but then quickly disappeared. This type of system recently made a comeback in ROTOR’s INpower <link>, which measures the left side and doubles the results for the total value. New systems, like ROTOR’s 2INpower (“twin” power) provide all the necessary data to analyze separate values for both positive and negative power, as well as L/R power balance.

**Spider**

Measuring power in the spider was first introduced by the pioneer of power meter training, SRM. Total power output is measured; the left/right distribution comes from the crank’s position throughout the pedal rotation. During the right leg’s push phase, it is interpreted as this leg’s entire power output, while it is assumed that the left leg is in the pull phase. Since power output always consists of one complete push-and-pull phase per pedal rotation, this is technically incorrect. A more precise analysis of power distribution for each leg is therefore systematically not possible.

**Rear Hub**

Measuring power in the rear wheel hub has the advantage that switching from one equal frame to another can happen quickly. However, the disadvantage is that wheels cannot be easily swapped out between bikes, which poses a problem for cyclists with several purpose-oriented bikes, e.g. for competition, descending or wet weather. Measuring power is only possible with the one hub, so installing it on another wheel would require complex spoke lacing. Also, accurate measurements for left/right power distribution are not possible.

**Pedal**

There are several manufacturers that offer pedals with integrated power measuring technology. One major advantage to this system is its rapid installation and uninstallation, which becomes significant with respect to renting bikes for training camps. One drawback however has to do with the crank arm’s thickness, which can interfere with the interior sensor.

**Shoes**

The concept of integrating power measurement into shoes is an interesting approach, but one whose precision and functionality in everyday use still needs to be proven. Two companies, Luck Shoes and Brim Brothers, have been developing two different systems. One has integrated its power measuring technology in the outsole of the shoe, whereas the other has developed a power measurement plate for the pedal system.

**Technology in Training**

If you want to dig a little deeper into the science and technology behind power meters (with a specific emphasis on ROTOR’s power meters), download our White Paper “Technology in Training: Refining the Pursuit of Physiological Gains” here <link>