SRM

Shimano Dura-Ace 7900 Wireless PowerMeter

By now, you should be familiar with the name, the Manx Missile. Charting the trajectory of his career through a couple of teams, and dozens of stage wins, one component has remained a fixture of his many bicycles—the Shimano Dura-Ace 7900 Wireless PowerMeter. Mixing Dura-Ace 7800 crankarms, DA-7900 chainrings, and the most sophisticated power measuring technology in cycling, the DA-7900 Wireless PowerMeter provides the most accurate Shimano power readings available.

The Shimano Dura-Ace 7900 Wireless PowerMeter matches precise power measurement with the stiffest crankset in the business. SRM pulled this off by improving the design of the meter's strain gauges. The eight strain gauges for the PowerMeter are a system of sensors that detect any resistance and vary their output when experiencing applied force. The next step is for the strain gauges to convert this data into electrical resistance so it can be measured. The refinements to the system offer stellar results. The 7900 PowerMeter expresses an accuracy of +/- 2.0% between 30 and 255 rpm with a wattage range between 0 and 4096 watts. Compared to the new G3 PowerTap that has the same range of accuracy, but only between 40 and 130 rpm, the SRM PowerMeter has nearly doubled the system accuracy of its greatest competitor while shaving grams in the process. You can also expect a weight savings over other power measurement systems, as the 7900 Wireless PowerMeter weighs in at an alarmingly low 820g with cranks, PowerMeter, and chainrings. SRM also extended the battery life of the 7900 PowerMeter to roughly 1400 hours, and provides a three-year manufacturer's warranty.

To provide a comfortable duration in the saddle, the Dura-Ace 7900 PowerMeter provides the best U and Q factors of any crankset, at 147.5mm. This is due to its reduction of lateral dimensions, and innovations with outboard bearing technology. More importantly, Shimano did this without compromising the driving factor of any crankset -- power transfer. The new 7900 chainrings are 20% stiffer than their predecessor, and this amounts to less wasted energy, greater efficiency, and higher top-end speeds.

The Shimano Dura-Ace 7900 Wireless PowerMeter is available in 170mm, 172.5mm, 175mm, and 177mm crankarm lengths in both standard and compact configurations. The PowerMeter operates wirelessly with ANT+ Sport, and is being offered as a standalone item. However, it is compatible with PowerControl 7, PowerControl VI, Garmin Edge 800, and Garmin Edge 500 CPUs.