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An image of multiple types of power meters with the words "Power Meter Types" over a red banner.

Power Meter Types

Power meters have been around for quite some time, dating back to the late 80’s when SRM introduced its first wired system. However, in just the last few years, the power meter market has blown wide open. In addition to power meters with improved features and functionality, we are seeing new manufacturers enter the market with some different types of power meters. In this article, we want to focus on these different power meter types, explaining exactly how they differ from one another. We will also lay out some advantages and considerations of each that you will want to consider when deciding which power meter is right for you. Let’s check em’ out!

An image of multiple types of power meters with the words "Power Meter Types" over a red banner.

 

When we talk about “type”, we mean where the power meter is located on the bike. For example, some power meters are built into your crank and measure force at the crank spider. Other power meters are built into the pedals. Currently, there are approximately 4 locations to measure power. They are:

1. Pedal
2. Crank arm
3. Spider
4. Crankset

1. Pedal

Pedal-based road power meters incorporate strain gauges inside the pedal itself. Favero Electronics, Garmin, and SRM/LOOK all make a pedal-based power meter. These power meters come with proprietary, LOOK Keo style cleats that must be used with the pedal. Of all the power meter types, pedal-based systems are perhaps the most convenient in terms of compatibility and installation. These advantages make them one of the most popular power meter types.

Advantages:

  • This design typically allows for easy installation and pedals can be quickly moved between bikes
  • They are compatible with almost any bike since they attach just like a normal pedal (note the SRM/LOOK EXAKT takes a bit more work to install)
  • You can measure each leg’s power independently (if you purchase a dual-sided system)

Considerations:

  • You must use the cleat system that is specific to your power meter. Currently, all pedal-based power meters use cleats that are similar to LOOK Keo cleats. Note that Favero, Garmin and SRM/LOOK pedals can also be used with original LOOK Keo cleats
  • Speedplay pedals remain unsupported by existing pedal-based power meter offerings

Favero Assioma DUO

Image of Favero Assioma DUO Power Meter Pedals

LOOK Keo Blade

A black, silver and gold LOOK Keo Blade Power Meter Pedal against a white background.

2. Crank Arm

A crank arm-based power meter measures the forces in the crank arm. Several manufacturers make a crank-arm based power meter, however there are a few different ways they go about measuring things. In addition, there are left-only crank arms (power meters that measure left leg power only), as well as complete cranksets that can measure left and right leg power. When most people talk about crank-arm based power meters, they are referring to left-only crank arms, so let’s start with these.

A left side crank arm-based power meter doubles your left leg power in order to get a total power figure. This method of calculation assumes that both legs produce the same force. Stages Cycling and 4iiii Innovations use an OEM left crank arm (such as Shimano or Campagnolo) and attach their power sensor (strain gauges, electronics and battery) to the inside of the crank arm.

Note because the electronics sit on the inside of the crank arm, there exists the possibility of clearance issues with your bike frame (the chainstay). So pay special attention to frame compatibility when purchasing these power meter types.

Advantages:

  • More affordable than most power meter types since you are just buying the left side crank arm
  • Lightweight as these power meters only add about 10-20 grams to the weight of the crank arm
  • This design allows for easy installation and swapping of the power meter between bikes (assuming both bikes have compatible cranksets)

Considerations:

  • You should always be sure your bike frame is compatible before buying a power meter. This is especially true with crank arm-based power meters as there can be clearance issues with the frame and the crank arm
  • If for some reason (perhaps due to a previous injury), you produce more power with one leg versus the other, these left only power meters can lead to less accurate results. For the majority of riders however, this isn’t much of a concern

Stages Cycling

Stages Shimano Ultegra R8100 Power Meter

4iiii Innovations

4iiii PRECISION Shimano R7000 Power Meter

3. Spider

Spider-based power meters are located on the cranks of the bike. They measure torque using a strain gauge positioned inside the crank spider. These units require specific cranks or cranksets, but can be interchanged between bikes, depending on compatibility. A typical crank power meter adds approximately 50-250 grams to the crankset. Crank-based power meters were the first type of power meter ever made and they remain the most heavily adopted system by professional athletes due to their accuracy and reliability.

Advantages:

  • Proven, reliable and accurate. Pros often rely on crank-based power meters for a reason
  • You can find a crank power meter to fit just about any bike type and crankset. The SRM Origin Road Carbon Power Meter for example, is compatible with a wide range of bikes simply by changing out the spindle and spacers. In addition, the power2max power meter is a spider-based system that allows you to just swap spiders on your existing crankset. They make power meter spiders for a variety of cranksets including SRAM, Specialized, ROTOR, Easton, Campagnolo, FSA and Race Face

Considerations:

  • Can cost more than other options as most crank-based power meters sell in the $1,000 – $1,500 range. However this isn’t always the case. The power2max NGeco starts at only $490. In addition, the FSA PowerBox Alloy starts at $649. Both of these power meters represent great values
  • Cranksets are not as easy to install or swap out as say a pedal or crank arm. This makes installing the power meter and moving it between bikes more difficult

power2max NGeco

A black and green 5-bolt 110 BCD power2max NGeco SRAM Road Power Meter.

Sigeyi

Sigeyi AXO SRAM 8-Bolt MTB Power Meter

4. Crankset

A crankset power meter is similar to a crank-based power meter in that your current crankset is often replaced for a new, power-equipped one (but not always, as you will see below). However, the location of power measurement differs. Bottom bracket-based power meters measure torque in the axle. ROTOR manufactures its 2INpower DM and INpower DM power meters.

Advantages:

  • The axle-based design means that the critical components of the power meter are safe from impact, dirt and water
  • The 2INpower DM, INpower DM and CINCH all offer compatibility with almost every bottom bracket standard which means there is a high likelihood of compatibility with your bike
  • More affordable than some other power meter types as the INpower DM and CINCH sell for $715 and $599, respectively

Considerations:

  • The INpower DM and CINCH measure left side power only. (However ROTOR’s 2INpower DM measures total power including left/right power independently)
  • If you decide to purchase an entire crankset, note that they can take more time to install and are generally not transferred between bikes

SRM PM9 Origin Road Carbon

A black SRM PM9 Origin Road Carbon Power Meter crankset with yellow PM9 logo.

4iiii PRECISION 3+ PRO Shimano Ultegra R8100

A grey 4iiii PRECISION 3+ PRO Shimano Ultegra R8100 Dual-Sided Crankset with Apple Find My logo next to it.

Summary – Power Meter Types

There are several power meter types and they all have their own set of advantages, price points and considerations. Remember, with power meters it’s never about better or worse. Rather it’s about finding one that fits your budget, is compatible with your bike and offers the features and functionality you desire. If you have questions on anything here, or need any guidance, just give us a call. We’re here and ready to help.

Josh Matthew

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