Power output is the most reliable indicator of performance when riding. Unlike heart rate, power isn’t affected by external conditions, and provides comparable data ride after ride.
The basis of any power meter is a series of strain gauges that give a torque reading. Algorithms create a final wattage reading based on these readings and cadence.
Most power meters need calibration on a regular basis. This is usually a straightforward process that can be done as needed. Power meters are available in the following options:
- Crank arm
- Bottom bracket
- Crank Spider
- Hub based
Each power pedal system has its advantages and disadvantages in price and performance. Your choice will be based on your budget, compatibility, accuracy, and weight.
The industry gold standard for a power meter is +/-1% accuracy.
Single-sided systems are cheaper and are enough to allow you to follow your workouts in the correct zones. However, most riders have a dominant leg which may provide less accurate data.
Dual-sided systems independently measure left-right balance as well as calculate pedal smoothness and efficiency.
Pedal-based Power Meters
Pedal-based power meters have many advantages.
- Easy to swap between bikes. This can be a huge cost saving if riding more than one bike in training.
- They offer a simple fit-and-play system and can be easily calibrated via a phone app.
- Available in both single and dual-sided.
- Available in a variety of cleat options for road and MTB
- Can be purchased as a spindle-only option to fit some brands of pedal, replacing your existing spindle.
The only disadvantage to pedal-based power meters is the slight increase in pedal weight, due to the electronics, strain gauge and battery.
Crank Arm Power Meters
Crank arm systems offer a power measurement in a similar way to a pedal system. They are usually a third-party replacement crank for the non-drive side crank on your bike. Check that your frame has sufficient clearance to enable your choice to be used and know what, if any, additional fittings are required.
- Crank arm power meters are relatively affordable and reliable.
- Can be lightest of power meter options and are available in both aluminium and carbon fibre.
- Available in different crank lengths.
- Some brands also offer to fit ‘Power Pods’ to your existing crank system.
If choosing a single sided (left-sided option), check the compatibility of the crank to the spindle from the right side, and that the crank length is correct. If choosing a dual-sided option, make sure that the crankset is compatible with your bottom bracket.
Bottom Bracket Power Meters
Bottom bracket power meters are a little trickier to install. Check that your choice is compatible with the bottom bracket of your bike.
- High accuracy, with units that are 99% accurate.
- Electronics and battery are housed within the shell of the bottom bracket for added protection and weight balance (the battery is usually accessible from the outside).
Crank Spider Power Meters
Spider based systems offer neat integration and broad compatibility and are available in various shapes and sizes.
- Compatible with most bottom brackets and chainrings
- Can be purchased individually as a spider or complete chainset. They come at varying prices, weights, and power-measuring functionality.
You may need to know your bolt circle diameter (the diameter between your crank bolts if they sat on a circle). These are usually four or five-arm systems. Some manufacturers offer models for specific cranksets.
Hub-based Power Meters
Hub-based systems have become less common. They tended to give low readings due to efficiency losses elsewhere in the drivetrain. They also require building into a custom wheelset and need a workshop calibration.
There are many options. To make the best choice consider your budget and the features that are most important to you. Then do your research and read reviews for the most up-to-date information.
At the time of writing (April 2022)
Best power meters: top models reviewed and rated (Cycling Weekly)
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