Power Meters Reviewed
Note > The power meter products below are listed in approximate price order, lowest price first.
It wasn't many years ago that talk of monitoring a cyclist's pedaling power output was limited to pro cyclists and their training team. A power meter for a bike cost in excess of £3000 in 2010. How things have changed. It is now possible to get an accurate power meter for under £600. Power monitoring is now the accepted standard performance metric for most serious / competitive cyclists. Ask 95% of top flight Tour riders what their FTP (Functional Threshold Power) or Power Zone 3 is (Power Zones) and they will quote their latest power output figures.
The Science of Monitoring Power
The main component in measuring a rider's pedal power is a strain gauge. A strain gauge's resistance changes when force is applied to it. As the cyclist pedals these changes in resistance are converted to electrical signals. These signals are then transmitted wirelessly via a transmitter to a receiver unit, normal a bike computer, smartphone or wrist watch for further analysis.
Different Styles of Power Meter
There are various locations within a bike's drivetrain where a power meter can be installed. Because of this the power meter has evolved in various designs, styles and systems. The most popular power monitoring systems are (listed in order of ease of installation):
- Pedals (Garmin, PowerTap, Look)
- Crank Arms (Stages, Rotor, 4iiii)
- Crank Spider / Chainring (Quarq, SRM, Power2Max, PowerTap)
- Rear Wheel Hub (PowerTap)
Other than the specific style of power meter there are two other primary factors that need to be considered before parting with your cash.
- Single Sided or Total Power Output?
- Bluetooth or ANT+ data transmission?
Several of the pedal and crank based power meters give the option of single sided power monitoring only (normally about 40% cheaper) or dual sided for total power output. The single sided option will give an average Total Power Output by doubling the single sided readings. The choice of transmission systems depends on the brand of watch / bike computer. For example, bike computers from Garmin, Bryton and Lezyne use ANT+, whereas Polar & Suunto support Bluetooth 4.0.