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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!

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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 6 locations to measure power. They are:

1. Crank (Spider)
2. Pedal
3. Crank arm
4. Handlebars
5. Bottom bracket
6. Hub

 

1. Crank (Spider)

Crank-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 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
  • You don’t have to make any compromises to your component selection. For example, you don’t have to use different pedals (as with a pedal-based power meter) or a different hub (as with a hub-based power meter)

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

SRM Origin

SRM Origin Power Meter with DA 9100 Chainrings

power2max NGeco

power2max NGeco SRAM Road Power Meter. 110 BCD

FSA PowerBox

FSA PowerBox power meter

2. Pedal

Pedal-based road power meters incorporate strain gauges inside the pedal itself. Favero Electronics, Garmin, PowerTap 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
  • Currently, no manufacturer offers a pedal-based power meter for your mountain bike

Favero Assioma DUO

Image of Favero Assioma DUO Power Meter Pedals

Garmin Vector 3

Garmin Vector 3 Power Meter Pedal

PowerTap P2

PowerTap P2 Pedals

SRM LOOK EXAKT

SRM LOOK EXAKT Power Meter Pedals

3. 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.

 

Left Only Crank Arm

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, 4iiii Innovations and Pioneer 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 Cycling Ultegra R8000

4iiii Innovations

4iiii Podium Power Meter

Pioneer

Pioneer R8000 Single Power Meter

Dual-Sided Crank Arm

At a higher cost, Stages, 4iiii and Pioneer also sell complete cranksets. With their complete cranksets, they attach a second power sensor on the inside of the drive-side crank arm. With two sensors, one on each crank arm, these power meters can measure total and well as independent left/right power.

Verve Cycling takes a different approach with its InfoCrank Power Meter. The InfoCrank is also a complete crankset (crank arms, spider and chainrings) and also has a power sensor on both the left and right crank arm. However the InfoCrank places its strain gauges within the crank arm – the only power meter manufacturer to do this. The result is +/- 0.5% accuracy, all the way to 3,000 watts.

Advantages:

  • High level of accuracy as the crank arm is an ideal place to measure power. (This is especially true for the InfoCrank which has been certified as one of the most accurate power meters.)
  • Lightweight as these power meters don’t add more than about 20-40 grams to the weight of the crankset (with the exception of the InfoCrank which is a bit heavier)
  • You can measure each leg’s power independently (left vs. right power measurement)

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
  • Cranksets are not as easy to swap out as say a pedal or rear wheel. This makes moving the power meter between bikes more work

Stages Cycling

Stages Shimano Ultegra R8000 Dual-Sided Crankset

4iiii Innovations

4iiii Podium Shimano Ultegra R8000 Dual-Sided Crankset

Pioneer

Pioneer Shimano Ultegra R8000 Dual-Sided Crankset

Verve InfoCrank

Verve InfoCrank Power Meter

4.  Handlebars

Velocomp produces a handlebar mounted power meter called the PowerPod. Unlike direct force power meters (all the other power meter types discussed in this article) that attach to your drivetrain or pedals and measure your power using strain gauges, the PowerPod attaches to your handlebars. It measures your power through wind measurement – the forces that oppose the rider. This is called opposing force technology. The PowerPod uses an accelerometer, a wind pressure sensor, an elevation sensor and a speed sensor – all to measure power.

Advantages:

  • You don’t have to worry about compatibility because you can use the power meter with any bike. In addition, you don’t have to worry about changing out your components
  • Of all the types of power meters, the PowerPod is the easiest to transfer between bikes as it simply attaches to your handlebars
  • With models starting at $199, it is the most affordable power meter on the market

Considerations:

  • The PowerPod requires that you attach a separate speed or speed/cadence sensor to your bike for proper operation (whereas direct force power meters do not)
  • In some testing done against an SRM power meter, the PowerPod was shown to be within +/- 3.0% of the SRM. While this level of accuracy is sufficient for most riders, if you are looking for the most accurate power meter types available, you might want to consider a direct force (traditional) power meter

PowerPod Power Meter

PowerPod Power Meter with PowerStroke Upgrade

5. Bottom Bracket

A bottom bracket 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. Likewise, Easton and Race Face offer their CINCH power meter.

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 $799 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

ROTOR 2INpower DM

ROTOR 2INpower DM Power Meter with round rings

Easton & Race Face CINCH

Easton CINCH Power Meter Spindle

6. Hub

With a hub-based power meter, the strain gauges are located in the rear hub and measure power through the drive chain. PowerTap remains the only manufacturer of a hub-based power meter. Note that in theory, a small amount of power is lost or absorbed in the drivetrain. Therefore, power measured at the hub might be slightly less than power measured at the crank. To be clear, this doesn’t make hub-based power meters less accurate, they just measure power a bit differently. Hub-based power meters have been a go-to power meter for years and they remain a trusted option among cyclists of all levels.

Advantages:

  • Starting at $499, the PowerTap G3 is one of the most affordable, direct force power meters capable of measuring both left and right leg power
  • Quick and easy installation if you buy a wheelset with the hub pre-installed. Swap out your old rear wheel for your new one and you’re ready to roll!
  • Hub-based power meters are easy to interchange between bikes. This assumes your rear wheels are compatible

Considerations:

  • If you purchase a stand-alone hub (not pre-laced into a wheelset), you need to have your local bike shop lace it up for you. This is easy for them, but an additional cost for you
  • In the event of a flat or wheel change in a race, you would lose your power meter. (This is unless your back-up wheels were also equipped with a hub-based power meter)

PowerTap G3 Hub

PowerTap G3 Hub-based Power Meter

PowerTap G3 Rear Disc Hub

Image of PowerTap G3 MTB power meter

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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