Everything You Need to Know About Cycling Power Meters (And How They Can Help Improve Your Performance)

Cycling power meters come in a variety of forms, but all measure your output in watts so you can quantify your efforts, workout effectively in training zones, and measure your improvement. Some high-end bikes now come stock with a power meter, but most often a power meter is purchased separately and installed on a bike.

Power meters require the use of a cycling computer. This allows you to both see the data in real time as you ride and also to record the data for analysis later, which is important.

Power meters are an excellent tool for training with a training plan, as they allow you to target training zones precisely instead of relying on RPE (rate of perceived effort) or heart rate. Professional and amateur riders alike benefit from cycling power meters.

What does a cycling power meter do?

As the name implies, a cycling power meter measures power output, which is the standard training measurement for the sport.

In running, your pace is the critical indicator. A five-minute-mile pace is a lot different than a 10-minute-mile pace, right? And you can do running workouts based on pace, and measure your improvement based on that measurement.

In cycling, pace is largely irrelevant, as terrain, gravity, aerodynamics and more affect how fast you are going. Instead, measuring how much power you are applying to the pedals is the best way to train, to pace yourself, and to measure improvement.

It is also an excellent way to quantify how much training load you are accumulating. For example, an easy two-hour ride can generate less training load than a very hard 40-minute ride, and your cycling computer can show you this in black and white terms when you use a power meter.

Cycling power is determined by torque times cadence. Torque is the force applied by your legs; cadence is how fast you are pedaling. A cycling power meter measures both of these, and delivers the information measured in watts to your cycling computer.

You can set your cycling computer to display your power in a variety of ways, with 3-second average being perhaps the most common. Just like with running pace, your cycling power is tied to duration, so tracking your average power output for durations like 5 minutes, 10 minutes, or 1 hour are command measurements.

What are the different types of power meters?

Cycling power meters come in a variety of styles. The most common are found on the crank or cranks, the spider, or the pedals. High-end indoor trainers also have power meters built into them, so that is another good option for measuring power if you ride inside.

The cycling power meter was first created and commercialized by Uli Schroeber and his company SRM in 1986. The SRM is sold as a complete crank system, and SRM also now has mountain-bike power meter pedals.

Quarq, Stages, Power2Max, 4iiii, and other companies make power meters. Some systems also deliver separate left- and right-leg power measurement.

Bike compatibility and personal preference are major factors in determining what’s best for you. For many riders, having the power meter built into the crank and/or spider works very well.

How accurate are power meters?

Power meter accuracy is a tricky thing to measure, but most brands claim their meters are accurate within +/-2% or better.

The most important thing is how consistent a power meter is. Think of a bathroom scale; as long as it consistently measures your weight and the fluctuations, it’s not as important if it reads a little high or a little low. What’s important is being able to track your improvement in a reliable, consistent manner.

Power meters work by using strain gauges that are built into the crank or spider or pedal. These gauges measure deflection caused by you pressing on the pedals — that is the torque. The deflection can be affected by temperature, so most power meters offer a calibration function. Calibration can be done before each ride, and many meters now have an automatic temperature compensation that works during the ride.

How can a power meter help improve cycling performance

Measuring power not only helps improve your cycling performance, but it’s a very quantifiable way to know if you are improving, and by how much. It’s also a great way to pace your efforts so that you don’t go out too hard and blow yourself up.

Without a power meter, you can use real-world benchmarks, like timing yourself up a local hill. But just clocking your time up a hill doesn’t account for changes in bike or body weight, or wind conditions, or whether you are riding in the draft of a big group or alone. Further, that time only reflects how fast you can go up that particular hill. What about your performance over different durations?

A power meter helps improve your cycling performance in two primary ways. One, a meter measures your average power output over various durations. Without this data, how can you know if you are improving? And two, a meter lets you train very specifically by training zones, which are based on power output.

Intervals are a common ingredient in cycling workouts. The idea is to break a tough workload into manageable chunks, stress the body, allow it to recover, and repeat. In doing so, you can accomplish a high total workload, and with proper recovery the body will rebuilt back stronger.

So say you want to get faster at climbing a hill that takes you about 35 minutes. You can look at your average power for your fastest time up that climb, and use that as a guidepost for doing 10-minute intervals and a slightly higher power. By doing those intervals — and allowing your body to rest on subsequent days — you will get faster when you tackle that hill. And further, you’ll be able to quantify your effort to see if your overall power over that duration has improved.

Aside from the long-term benefits of training with power, a power meter can have immediate impacts on your performance when you use it to pace your efforts. Newer cyclists will often start an effort too hard, and then fade towards the end. It is often faster to ride at a steady power output.

For professional cyclists, training and racing with a power meter is ubiquitous. Team directors, coaches, and physiologists all have access to the riders’ power meter data.

Should I use a power meter to calculate my FTP?

FTP stands for Functional Threshold Power, and it is the basis for power-based zone training. There are a few different philosophies on the number of training zones, but all are based on the maximum amount of power you can sustain for a long period, roughly defined as an hour.

In the common seven-zone system, for example, the zones are:
Zone 1 - Active Recovery - <55% of FTP
Zone 2 - Endurance - 56-75% of FTP
Zone 3 - Tempo - 76-90% of FTP
Zone 4 - Threshold - 91-105% of FTP
Zone 5 - VO2 Max - 106-120% of FTP
Zone 6 - Anaerobic Capacity - >120% of FTP
Zone 7 - Neuromuscular Power - N/A - all-out sprint

As you can see, in order to set your training zones, you need to know your FTP, which is — you guessed it — measured with a power meter. In addition to on-bike power meters, high-end indoor trainers these days now have built-in power meters.

So how do you find your FTP? A common way is to do a 20-minute test, and take 95% of your average power for that duration as your FTP. This 20-minute test is hard! And you should do it when you are rested and fresh. Get a good warm up in, then hit the lap button on your cycling computer and go as hard as you can for 20 minutes, making an effort to keep your power as steady as possible.

What is the best power meter for cycling?

Determining the best power meter for cycling is similar to determining the best bike — much of it hinges on what is best for you, taking into account budget and compatibility with your bike and component groupset.

Power-meter pedals like the Garmin Vectors are the easiest to install yourself and move from bike to bike. Crank- and spider-based systems like Quarq or Power2Max or Stages or SRM are preferred by most riders, from amateurs to professionals.

Once you have your power meter, connecting it to your cycling computer is a one-time step, and thereafter your computer will always find it to display and record your power.

Your cycling computer can be configured to show power in a variety of ways, including current power, 3sec average power, power zone, power-to-weight ratio, and much more.

Your cycling computer can also calibrate your power meter, and let you know when you need to change or charge its battery.

So what is the best power meter? A power meter is a tool, and what you do with it is the important thing.