SRM

Dura-Ace 9000 Wireless PowerMeter

Earlier this season, we saw Shimano-sponsored riders building up their machines with mostly complete Dura-Ace Di2 9000 drivetrains, save for something slightly askew around their bottom bracket junctions. Instead of completing their builds with Shimano's latest Dura-Ace FC-9000 11-Speed Cranksets, they were still running the older 7800-series crankarms mated to the current 11-speed 9000 chainrings. The reason? These pros weren't about to give up the crucial data provided by their SRM powermeters, and SRM was still putting the finishing touches on its latest power crankset package. Well the wait is over, as both Shimano and SRM's engineers have finally released their new design, and the results of the SRM Dura-Ace 9000 Wireless PowerMeter are nothing short of outstanding.

The SRM Dura-Ace 9000 powermeter relies on the precise power measurements that professional cyclists have depended on from SRM for years, but it now does so using an updated design. In order to accommodate the FC-9000 crankset, the SRM unit itself was built with a larger diameter over the previous 7900 version. Shimano and SRM's engineers found that this new platform more accurately measures the offset forces and inconsistent torque patterns for your left versus right leg. Additionally, this design allowed them to insert two batteries into it, which, according to SRM, provides roughly 3,000 hours of use before needing to be recharged. This now doubles the battery life compared to the 7900 iteration. Besides these updates to the SRM unit, it still relies on the tried-and-proven eight strain gauges for measuring data. 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 that it's able to be measured. The refinements to the system provide stellar results. The 9000 PowerMeter expresses an accuracy of +/- 2.0% between 30 and 255 rpm, with a wattage range between 0 and 4096 watts.

In addition to measuring power output, you're now able to run either compact or standard rings on one spider with the FC-9000 crankset. In fact, it's also lighter, just as stiff, and sleeker than 7900. On the surface, the FC-9000 is a complete departure from the traditional aesthetics of Dura-Ace. Gone are the days of the five-arm spider, and the necessity for a separate compact crankset has also fallen by the wayside. Instead, 9000 features a shift to a new four-arm spider design. This occurred for many reasons, but most notably, it's because the four-arm spider matches rigidity with 7900 while shaving around 52 grams. However, 9000 has more than meets the eye. Like 7900, you'll find the continuation of Shimano's Hollowtech II construction. Over the past few iterations of Dura-Ace, this manufacturing methodology has played an integral role in attaining weight reduction without sacrificing Dura-Ace's superior stiffness.

It's this balance of Shimano practicing tried-and-true forging methods, while still treading into unknown waters, that makes Dura-Ace more of a continuation than an innovation. We mean this in the best possible way. Shimano has learned what works, and over the years, has continually added to, and improved, the ideology of Dura-Ace. Hollowtech II and Hollowglide are prime examples of this. Strategic placement of hollow aluminum throughout the crankset and chainrings allows more structural material to be used, and when coupled with Shimano's integrated bottom bracket, creates an unrivaled weight-to-stiffness ratio.

The four-arm spider amplifies this characteristic, but more important to Shimano, it embodies its 'rider-tuned' philosophy. In this, Shimano created 9000 to work for you, the rider. Case in point, the four-arm design and the 'top-secret' BCD allows for front chainring combinations from 50-34 to 55-42t on the same spider.

The SRM Shimano Dura-Ace 9000 Wireless PowerMeter is available in 170mm, 172.5mm, and 175mm crankarm lengths in both standard (53/39t) and compact (50/34t) 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, or any other ANT+ compatible device.