Power meters are useful tools that help us monitor our effort and track progress. However, due to their complexity, it is pretty overwhelming to know all the available options and choose the one that will suit you best.
In this power meter guide, you learn how power meters work, what types there are, their pros & cons, and finally, how to choose the best power meter for your use case.
Are you ready to get started?
Let’s dive in.
What Is a Cycling Power Meter?
A cycling power meter is a device that measures the power output of a rider. There are many types of power meters – pedal, crank, spider, wheel, etc. (more about them below). Although they differ, the power output they measure should be the same.
How Do Power Meters Work?
Cycling power meters measure torque using strain gauges. The strain gauges measure a rider’s force on a given component (pedal, crank, etc.).
This torque is later converted to power by multiplying it by that component’s cadence (angular velocity). The power data are then transferred via ANT+ to a cycling head unit (or another device).
Handlebar power meters utilize Newton’s Third Law. They measure opposite forces like wind resistance, inertia, gravity, etc., and combine them with the rider’s velocity to determine the power output. (Source)
Learn more about how power meters work in my fully dedicated article.
Why Use a Power Meter?
When cyclists train, they can use multiple metrics to determine their efforts like speed, heart rate, power, etc. Naturally, some are more accurate and effective than others.
Training based on speed doesn’t make much sense because too many external factors may influence your effort.
Training with heart rate is popular thanks to the low costs of heart rate monitors and relatively easy-to-understand metrics.
But unlike power training, HR training only measures your body’s physiological response. Heart response to the work is delayed, so variable training with many changing intensities is difficult. Training based on your HR is more suitable for steady efforts.
TIP: Read this article for more reasons to use a power meter.
Power meters can measure your instantaneous power output. It is an objective metric that is not influenced by external factors like wind, road surface, fatigue, etc. In other words, when you push 200W to your pedals, you push 200W.
This objectivity means you can train more efficiently and easily track your long-term progress. Although it is more challenging to understand your power data, power meters revolutionized cycling training.
However, they are not as widespread among amateur cyclists as HR monitors due to their higher costs.
The following table shows the advantages and disadvantages of training with a power meter vs. a heart monitor.
| Device | Pros | Cons |
|---|---|---|
| Power Meters | • Measure your efforts instantaneously (without lag) • Objective (not influenced by external factors) • Better for tracking your long-term progress • More expensive models can show leg imbalances | • More expensive • More difficult to understand and interpret the data • Some power meters need regular calibration |
| HR Monitors | • Less expensive • Easy to use • Easy to understand the data | • HR lag • HR may be affected by external factors like fatigue, air temperature, sleep quality, etc. • HR straps may be uncomfortable |
Sources: roadcyclinguk.com, bikeradar.com, trainerroad.com
You might also be interested in this article: What makes you faster, a power meter or carbon wheels?
Power Meter Types
Below, I guide you through power meters available on the market. You learn which power meters are the most affordable, which ones are the most versatile, and much more.
To compare all power meter types, feel free to skip to this comparison table.
Pedal Power Meters
Pedal power meters are among the most popular types thanks to their high versatility, accuracy, and ease of setup.
They are compatible with virtually any bike because the pedal threads are standardized across road and mountain bikes.
Additionally, if you buy a dual-sided power meter, they can measure your L/R balance and other cool features (more about them here).
Their downsides are that they are more prone to mechanical damage – as you have to clip in and out of them.
Furthermore, they add more rotating weight to your cranks than crank power meters.
Examples: Favero Assioma, Garmin Rally
Crank Arm Power Meters
Crank-based power meters are also popular among amateur cyclists because of their affordability, accuracy, and low weight.
Crank power meters can be one-sided (crank arm) or dual-sided (crankset). Naturally, dual-sided are more expensive but can measure the power of both legs.
This type is not as easily transferable between bikes as pedal power meters if you don’t use the same groupsets on bikes.
Also, you may run into compatibility issues – some crank-based power meters may not be compatible with your groupset.
Examples: 4iiii Precision Power Meters, Stages Shimano Power Meters
Spider Power Meters
Spider power meters, also called crank power meters, are accurate, prone to damage, and reliable.
They share the most features with crank arm power meters, but they don’t add as much rotating weight as pedal power meters, for example.
However, their overall weight is higher, but it also depends on what components you replace.
Speaking of components, this is one of the main disadvantages of spider power meters – you need to find one that will be compatible with your groupset.
This also results in bad transferability and a more difficult setup.
Examples: power2max NG / NGECO, Quarq DZERO, SRM Power Meters, SRAM Red Power Meter, ROTOR Power Meters
Handlebar Power Meters
Handlebar power meters use opposite forces for measuring your power. This means they don’t use strain gauges but measure the wind speed and other metrics.
They use multiple sensors like accelerometer, wind pressure sensor, elevation sensor, and speed sensor.
Their major advantage is that they are transferable to any bike and are easy to set up.
On the other hand, they tend to be less accurate than most direct force power meters and require attaching additional sensors to your bike.
Examples: PowerPod, AeroPod
Bottom Bracket Power Meters
BB power meters are direct force power meters protected against mechanical damage thanks to their placement in the bottom bracket.
They are accurate and reliable. However, their installation requires a specific skill set, and you also have to ensure they will be compatible with your bike.
This also results in a very limited transferability to other bikes.
Examples: ROTOR 2INpower, Easton CINCH
Hub Power Meters
Hub power meters are used in the rear hub. They come either as a standalone hub or as a complete wheel.
This type of power meter is precise and relatively affordable. If you use the same bike type and components, also pretty easily transferable.
On the other hand, they can be heavier than your standard hubs. Additionally, the offer of pre-built wheels with hub power meters was pretty limited. This fact also contributed to their lower popularity among riders.
PowerTap, a company known for hub power meters, was acquired by SRAM not long after, and they discontinued hub power meters (here is why).
You can see the comparison of different types of power meters in the following table.
| Power Meter Type | Pros | Cons |
|---|---|---|
| Pedal | • Easily transferable between bikes • Compatible with almost any bike (assuming you use it with a particular bike type) • Easy to set up • Very accurate • Can measure both legs independently | • Prone to mechanical damage (clipping in, crashes, etc.) • High added (rotating) weight (assuming you have lighter pedals) |
| Crank Arm | • Low added (rotating) weight • Very accurate • More affordable | • Not easily transferable between bikes (unless both bikes use the same cranks) • Limited components compatibility • Can't measure both legs independently (unless you use dual-sided crank arm power meters) |
| Spider | • Low added (rotating) weight • Very accurate • Reliable | • Limited components compatibility • Less affordable • Not easy to set up |
| Bottom Bracket | • Low added (rotating) weight • Very accurate • Reliable • Protected against mechanical damage | • Limited components compatibility • Complicated installation • Not easily transferable between bikes |
| Handlebar | • No added (rotating) weight • Easily transferable between bikes • Compatible with virtually any bike | • Less accurate • Require attaching other sensors (speed + cadence) to your bike • Prone to damage when crashing • Can't detect cadence |
| Hub | • No added (rotating) weight • Easily transferable between bikes (assuming the bikes use the same wheels) | • Require replacing your current hubs or buying a whole wheelset • Can be heavier than your current hubs |
Sources: powermetercity.com, GC Performance, discussions with pro cyclists
How to Choose a Power Meter?
Let’s dive deeper into the individual features to consider when purchasing a power meter.
Compatibility & Versatility
Depending on the type of power meter, you will need to consider its compatibility with your bike or components eventually.
When you discover that the power meter isn’t compatible with your current setup, you need to find a compatible alternative unless you want to change the components.
This is the reason why pedal power meters are popular among beginners. They are compatible with all cranks and are super easy to set up.
Furthermore, their versatility allows you to use them on more than one bike. This may be a problem with the spider or crank-based power meters.
Data Accuracy & Consistency
Power meter accuracy is given in percentages. It ranges from around 1% to ±3% on most power meters—naturally, the higher accuracy, the better.
However, data consistency is no less important. A power meter should provide accurate and consistent data so you can precisely track your progress over time.
The following table shows the power deviation of power meters with different accuracy rates.
| Accuracy Rate / Power Output | 250W | 500W | 1000W |
|---|---|---|---|
| 0.5% | 248.8-251.3 | 497.5-502.5 | 502.5-1005 |
| 1% | 247.5-252.5 | 495-505 | 990-1010 |
| 1.5% | 246.3-253.8 | 492.5-507.5 | 985-1015 |
| 2% | 245-255 | 490-510 | 980-1020 |
| 2.5% | 243.8-256.3 | 487.5-512.5 | 975-1025 |
| 3% | 242.5-257.5 | 485-515 | 970-1030 |
The question is, do you need a super precise power meter with ±0.5% accuracy? Well, unless you are a pro or cycle on a high level, probably not.
Having accurate data is great, but if you use the same, consistent power meter, you can track your progression – just with a slightly shifted baseline. So, for example, you will think your FTP is 210 W, but the reality is 200 W.
Read my power meter consistency vs. accuracy article where I explain this in-depth.
Left/Right Leg Measurement
Power meters’ ability to measure each leg’s power output, pedal smoothness and torque effectiveness also determines their price.
There are two types of power meters:
- Single-sided (mostly left-sided) power meters simply double the value of your leg to provide you with your overall power.*
- Dual-sided power meters can either measure the power independently on the leg or estimate it using software algorithms.
Source
*If you will use a single-sided power meter during single-leg drills, you get zero power readings for the opposite leg.
Finding out your L/R imbalance info is interesting. For example, my friend’s L/R imbalance was 60:40 after his injury. So he knew that he needed to fix it to prevent further injuries.
If your L/R imbalance is 51:49, you probably don’t have to worry about it if you don’t experience any issues.
However, the leg imbalance is a pretty complex topic, and there is no easy answer to whether you should try fixing it.
If you want to learn more, I recommend watching the following video by TrainerRoad or reading this article from TrainingPeaks.
Battery Type & Battery Life
Different power meters use different battery types:
- Single-use batteries (CR2032, AAA, LR44, SR44, etc.) are typical for cheaper power meters. They tend to last longer but are less convenient because you have to replace them from time to time.
- In-built, rechargeable batteries are common in advanced and premium power meters. They are more convenient because you just need to recharge them. But they usually don’t last as long as one-use batteries.
According to Power Meter City, single-use batteries lasted 230 hours on average, while rechargeable only 140 hours.
Let’s do quick math now:
If we assume that you ride 7 hours a week, a battery with a 140-hour battery life will last you for five months.
This example shows that the battery life shouldn’t play a big role when deciding what power meter to choose, and the battery type is a matter of your preference.
Weight
Depending on how much you prioritize your bike’s weight, you should consider which power meter type to get.
Some models, mostly the left crank-based power meters, weigh just dozens of grams. On the other hand, some power meters can add hundreds of grams (compared to your current components).
Calibration vs. Zero-Offset
The difference between power meter calibration and zero-offset is that calibration is a one-time process done in the factory, while zero-offsetting should be done by the rider before every ride. (Source)
Power meters have two types of zero-offset:
- Manual zero-offset
- Automatic zero-offset
More affordable power meters require manual zero-offset done via an app or a head unit.
Advanced and higher-end power meters can do an automatic zero-offset, so you don’t need to do it manually. You can jump on your bike and start riding.
Temperature Compensation
All power meters come with passive temperature compensation. It is the process when you set a zero-offset before a ride using an app or a head unit.
Active pressure compensation is done automatically, and you can find it on advanced power meters. These power meters can compensate for the changing outside temperature, resulting in data consistency.
You can learn more about this topic on Power Meter City.
Brand
As in every industry, there are a few established brands that produce quality power meters. When you encounter the same power meters from different brands, it is up to your preference.
Here are a few tips on power meter brands (in alphabetical order):
- 4iiii
- Favero
- Garmin
- LOOK
- Quarq
- ROTOR
- SRM
- Shimano
- Stages
- Velocomp
- Verve Cycling
- Pioneer
- power2max
Q Factor, Spindle, and Stance Width
When buying pedal power meters, check out their spindle width because it affects the stance width (check out the picture below).
NOTE: Pedals don’t affect the Q factor! They affect the stance width.
If the power meter pedals have wider spindle width than your current pedals, it will cause your legs will be further apart. This may lead to bike fit issues.
Power Meters FAQ
Summary
Power meters are complicated devices, so there are many features to consider. To name a few:
- Type of power meter
- Compatibility with your bike
- Accuracy & consistency
- Battery life & battery type
- Ease of setup and use
- And many more
Read the entire article to learn more about power meter types, their benefits and disadvantages, and all other features.
If you find this article helpful, share it or add your feedback in the comments below.
