Which power meter should you buy? A power meter shopping guide.

how to choose a power meter Time-Crunched Cyclist TCC3

The Time-Crunched Cyclist reveals the fastest way to get fit for bike rides and races of all kinds. With elite cycling coach Chris Carmichael’s innovative, time-saving approach, busy cyclists will develop fitness, speed, and power in just 6 hours a week.

Enjoy this power meter shopping guide from the book!

The number of power meters on the market continues to grow, and the fea­tures change rapidly as technology improves. For this reason, any list of power meters I include here will be obsolete within months. Instead, let’s take a look at the essential aspects you should look for—or be aware of—when it comes to purchasing and using a power meter.

Accuracy is different than consistency. Obviously, you want your power data to be accurate, so manufacturers spend a lot of time telling you their meter is accurate within a certain range—let’s say 2 percent. That’s great, but it’s actually more important that your power meter measures workload consistently from day to day. If it’s within 2 percent today, it needs to be within 2 percent tomorrow and next month. If it is measuring 2 percent low today and 5 percent high tomorrow, that’s a problem. Consistency is important because you are typically using the same power meter over and over again, so even if it is less accurate (measures 10 watts less than you actually produce, for instance) you will still be able to accurately track and measure your progress as long as its level of precision is consistent over time.

A power meter is only accurate to itself. Your power readings are likely to be different on different power meters, despite the obvious fact that your actual ability to produce power hasn’t changed. As quality control and technology improve, these differences are getting smaller, but it is still important to always use the same power meter for workouts and races you want to be able to compare. Now that power meters have come down in price and increased in variety and compatibility, many athletes put them on multiple bikes. This is great, but comparisons of power files from the same athlete using different power meters on different bikes in different conditions can be difficult, especially if the ath­lete does not consistently zero the meters or take good care of them.

Single-leg versus double-leg measurement. Innovative companies have successfully put strain gauges in a variety of places to measure power. You can get a power meter that measures strain at the crank spider (where the chainrings attach), the chainrings themselves, the rear hub, the pedals, or from within the non-driveside crank arm. Some meters directly measure strain from the entire pedal stroke (spider, chainrings, rear hub). Others can only measure one half of the pedal stroke and essentially double it to calculate your power output. And some pedal-based systems measure power in both pedals and then combine the data to deliver an overall power output. There are pros and cons to each method. The single-leg meters tend to be less expensive, more easily compatible with a wider range of bikes, and more easily swapped from bike to bike. I prefer power meters that measure double-leg data, because then all of your data is the result of direct measurement instead of arithmetic.

Get a head unit that allows you to set the recording interval. To help extend battery life and manage data storage, some head units allow you to change how frequently they record data from the power meter. More data points yield greater accuracy, so if possible set the recording frequency at one second or faster. For the vast majority of your training sessions and rides, battery life isn’t going to be a limiting factor. If you are getting ready to ride the Dirty Kanza 200 or some other ultraendurance event, you could reduce this recording frequency.

Choose a power meter with a “zero offset” option. The “zero offset” on your power meter measures the sensor value when there is no torque applied to the strain gauges. This establishes the baseline value so your workload above zero can be measured accurately. It’s important because heat, humidity, vibration, and other environmental factors can affect the zero offset of your power meter from ride to ride. Two hundred watts today is not 200 watts tomorrow if the zero offset is wrong. Many power meters can set zero offset automatically, so the important point is to make sure you either have it set to do that or that you do it manually.

Check compatibility before you buy. We have sold a lot of power meters in the past 16 years, and one of the most frustrating experiences for an athlete is ordering a power meter and then realizing it won’t work with existing equipment. It’s not just whether it will fit onto your existing crank or bottom bracket, or whether the hub has the right spacing for your bike’s frame. It’s also whether you’ll be able to ride the pedals or wheels or other equipment you want to use in different situations. If you want to race different wheels than you train on, a crank- or pedal-based power meter is a better option than a hub-based meter. If you ride multiple bikes, a pedal-based system may be easiest to move between bikes.

The Time-Crunched Cyclist reveals the fastest way to get fit for road racing, century rides, gravel grinders, cyclocross, Gran Fondos, and mountain bike events. With elite cycling coach Chris Carmichael’s innovative, time-saving approach, busy cyclists will develop fitness, speed, and power in just 6 hours a week.