Laser Spoke measures cyclists' power output
By C.C. Weiss
May 22, 2012
Modern electronics have given us the means to measure nearly every part of our performance – speed, distance, vertical, heart rate, etc. But there are still other variables that go unmeasured by the average athlete. The Laser Spoke provides a simple aftermarket solution for tracking cycling power.
The Laser Spoke is a universal digital measuring device that fits the rear wheel of everything from BMX bikes to road racing bicycles. It measures power, passed from your legs onto the drivetrain and wheels of the bike, at the spokes of the rear wheel through a laser-based optical system. The designers chose to use the rear wheel, as they say it acts like a torsion spring, twisting in response to the applied torque. The Laser Spoke measures the amount of twist, to give you a power readout.
The system consists of a laser and position-sensitive detector mounted on the hub, and a right-angle prism attached to the rim. In operation, the laser fires its beam at the prism, which then casts it back upon the detector. The detector produces an electrical signal that is proportional to the position of the laser beam, the beam deflection and the applied torque.
The Laser Spoke currently stores data by way of an SD card, but the company plans to use a removable USB module with flash memory. It is also working on an ANT + interface for the device that would allow for wireless communications with ANT + monitors.
Laser Spoke says that its system is less expensive than existing power monitors. It claims the system is accurate and, because it uses optics instead of moving parts, is more durable in the long run. Plans call for a final module that weighs no more than 150 grams (5.3 oz).
Laser Spoke is currently looking for funding on Indie GoGo. The company has its first prototype built and is trying to raise money to further develop it into a production-ready model.
Source: Laser Spoke