Another interesting bit on the showroom floor at Interbike 2015 was the Dynovelo spindle-based power meter. It inserts within the hollow spindle of most cranks and measures torque at the spindle (rather than at the spider as on most crank-based power meters, or at the crank arm as on Stages). Due to this method, the Dynovelo only measures the left leg's power, since the right leg's force doesn't twist the spindle. Still, it's an intriguing product that makes for some interesting possibilities. For example, this power meter fits into the Campagnolo Bora aero crank. It transmits on ANT+ only, and communicates and charges via USB. Check out the gallery for images of this interesting little device.
The Dynovelo installs into the hollow spindle of Shimano, Campagnolo, and SRAM cranks (among others).