California company MetriGear is working on an embedded power meter that will calculate your power output based on force applied to the pedals. Embedded in the hollow pedal spindle, the power meter requires no modification to your bike and is easy to set up, use and transfer between bikes.
Called Vector, the power meter uses a patent-pending, force sensing approach to measuring power. The power meter works by detecting the small amounts of strain that naturally occur in the spindle as you pedal. Using this strain, the Vector uniquely measure force vectors- the magnitude and direction of your pedaling effort.
Force vectors are measured independently of each leg and throughout the entire pedal stroke. Data is collected at a rate of more than half million samples per second. The Vector power meter looks for your productive force-the extent to which you pull up, pull across the top of your stroke and push down.
Integrated into the hollow spindle of stock bike pedals, the Vector power meter is a custom-designed system with over 60 piezoresistive strain gauges, accelerometers and temperature sensors. The sensors and electronics are sealed within the pedal spindle so protected from rain, mud, grease and general grime.
The Vector power meter has an accuracy of +/- 1.5% of actual force applied to the pedals so puts out consistent, reliable data. The system also precisely measures cadence so you don't need an extra cadence sensor in addition to your power meter.
Best part is, the Vector power meter is ANT+ compatible so will communicate with any ANT+ cycling computer. An external rechargeable battery pack securely mounts on the crank and a charge indicator will let you know when you need to top up the battery. The company is targeting a minimum of 20 hours of riding time between charges for the battery.
MetriGear is working on final testing and pricing and hope to release the Vector power meter sometime this year. A launch at Interbike perhaps? So far it appears that you won't be able to buy this as an aftermarket item as MetriGear needs to install the power meter into the pedals at the factory. MetriGear will most likely sell a set of standard pedals with the power meter already installed.
If you are a data nut and want to see all of the Vector testing and force calculations, check out the MetriGear blog.