Engineer Gennady Lubarsky has come up with a new power meter technology. Called Laser Spoke, the power meter uses the rear wheel of your bike as a torsion spring to measure power output. Mounted on the rear hub, the Laser Spoke power meter can easily be installed on any bike, whether it be road, mountain, cruiser, or BMX.
As you push on your pedals, all parts of your bike displace or deform slightly under the load. The power from your legs flows from your pedals to the rear wheel, where a traction force is produced in the contact between your wheel and the ground.
Having a certain level of flexibility, the rear wheel operates as a torsion spring twisted proportionally to this applied torque or force. Deformations of the hub, the rim, and the tire are negligible due to their construction and rigidity, so instead, the majority of twisting occurs in the spokes. The Laser Spoke power meter monitors this spoke twisting deflection using a laser.
The Laser Spoke power meter system includes the laser and a position sensitive detector inside a device mounted on the hub, with an optical right-angle prism attached to the rear wheel rim. As you ride, a beam is projected from the laser and forms a light spot on the detector surface. The detector then produces an electrical signal that is proportional to the position of the light spot and the beam deflection, resulting in the calculation of the applied torque. If the wheel is not loaded, the signal is equal to zero.
Calibration is integrated into the Laser Spoke device and can be done in real time within minutes while you are riding. Along with the power meter technology, the Laser Spoke device will have two acceleration sensors to monitor your speed.
Laser Spoke will eventually integrate ANT+ for communication with your bike computer or phone. In the first model, an SD Card will be used to store your ride data for upload to your computer.
Laser Spoke is currently running an Indiegogo campaign, where you can sign up to be a beta tester ($550) or pre-order the final power meter product ($750).
Given Garmin's continuous delay of the Vector pedal-based power meter, I am curious to see how the more affordable Laser Spoke system will perform in both commercial delivery timing as well as accuracy.