The power meter has become the most reliable measurement tool for cycling training. It is an essential accessory for professional riders, but in recent years it has also been adopted by amateur cyclists, both for mountain bikes and road bikes. Its precision in data collection and the growing range on the market, along with falling prices, have made it more accessible for all types of cyclists.
Currently, there are different types of power meters, designed to adapt to various disciplines and needs, whether to optimize performance on demanding mountain bike routes or improve efficiency during long road sessions. Depending on the type of sensor and how it is installed on the bike, we can distinguish at least five main categories.
We explain each of them so you can choose the most suitable power meter according to your pedaling style, whether on technical and rugged terrain with a mountain bike or on high-speed routes with a road bike. But first of all...
How does a power meter work?
How about we recall how a power meter or wattmeter works and what it's for? A power meter is an electronic device installed in key areas of the bike that captures the cyclist's pedaling data: crank arms, bottom bracket, or pedals. The power meter has an electronic circuit whose main part is a strain gauge. This is a sensor made of strips or gauges that deform depending on the force applied by pedaling. This deformation changes its electrical resistance. In this way, the circuit can translate it into power values expressed in watts.
The power meter sends and displays the data via Bluetooth or ANT+ to a cycling computer installed on the handlebars.
The device is able to measure, with hardly any margin of error (2-3%), the watts generated while pedaling. A control screen installed on the handlebars (usually a cycling computer) shows the cyclist real-time data: average power, relative power, maximum power, threshold power, etc.
It is very useful information that allows you to monitor your fitness, track improvements with training, or even plan both your preparation and the races you may participate in.
Types of power meters for bicycles
We can distinguish five types of cycling power meters, with prices ranging from 200 to 600 euros. Many of them come included in crankset sets, which increases the price above 1,000 euros in some cases.
Crank power meter
This is one of the most widespread and affordable models on the market. The meter is compact, lightweight (only 20 grams in high-end models), and is easily installed on the back of the left crank arm. There are also models that mount an extra sensor on the right crank, making the measurement even more precise. Brands like Stages or 4iiii are current references in the market. The force symmetry between the left and right legs is not perfect. That is why there are crank power meters with a sensor on each arm, to provide more accurate data.
Spider power meter
The power meter is integrated into the spider (the central structure of the crank) and has a circular shape. This way it is better protected from impacts and also offers very precise measurement. It has some drawbacks: it is more expensive than the crank type, installation is more complicated, and it may have compatibility issues with some chainrings and cranks. Brands like Quarq (from SRAM) and SRM are the best-known for this type of power meter.
📺 In this video you have the DZero DUB model, Quarq's top-of-the-line power meter
Bottom bracket spindle power meter
Rotor, with its Inpower, is the clearest example of a power meter sensor installed inside the bottom bracket spindle. It is lightweight (adds only 40 grams to the bottom bracket assembly) and its location protects it from impacts or bad weather. This same location protects the power meter from interference in measurement, making it an especially precise device. It also eliminates the dead spots in pedaling that come with crank power meters, which contributes to the system's reliability. However, like spider power meters, its installation and compatibility can be an issue.
📺 Here is an analysis of the Rotor Inpower power meter.
Pedal power meter
Compatibility issues between bikes are solved with a pedal power meter. The meter is integrated into one or both pedals and is installed as easily as a conventional pedal. Its price is higher, from €400, although it includes the pair of pedals. You should take into account its exposure to impacts, both external and from cleats and shoes, weather conditions, etc. Garmin is the reference brand for this type of meter, with its RS200 models
(road) and Rally XC200 (MTB and Gravel), and also Favero.
📺 In this video you have a test of the Garmin Rally XC200 model, focused on MTB cyclists and Gravel.
Hub power meter
Finally, we will refer to a power meter that has been displaced by the rise of pedal or crank-based meters. We are talking about the power meter in the rear hub of the bike. The device measures the values of the complete pedal stroke, without interference or dead spots. In addition, its installation on a second bike is quite easy and it is enough to swap the wheel with the power meter for the conventional one. Its main drawback is the weight. Powertap was the brand that popularized this type of meter, although they no longer manufacture them.
What kind of power meter should you choose?
Having seen the most in-demand types of power meters, it's time to choose the one best suited to your needs. It will depend on several factors: your experience and technical level on the bike, or the discipline you practice. If you want to get started with watt-based training, the best option may be a crank-based or even pedal-based meter, due to their more competitive prices and easy installation. Especially if you practice road cycling.
Crank-based and pedal-based power meters are the most suitable for getting started in the world of watt-based training.
If your thing is Mountain Bike, it may be safer, although it involves a higher cost, to choose a bottom bracket or hub-based power meter. For an advanced level, spider-based power meters would be the ideal choice. In fact, they are the most used by professional riders, due to their great precision and integration with the crankset.