- The new Rotor Power cranks. Photo: Caley Fretz | VeloNews.com
- Battery and electronics reside in the black case on both crank arms, while the torque sensors are inside the crank itself. Photo: Caley Fretz | VeloNews.com
- Each crank arm gets its own torque sensors. Photo: Caley Fretz | VeloNews.com
- The cover shown on the Rotor Power units at Eurobike is just a rapid prototype. The final version will be a bit more refined. Photo: Caley Fretz | VeloNews.com
FRIEDRICHSHAFEN, Germany (VN) — Following up on its prototype soft launch at last year’s Interbike show, Spanish component company Rotor officially released its new Rotor Power crankset on Wednesday. The power meter offers up some new and intriguing data sets, including a sort of spin scan, left/right power, and something Rotor calls “torque efficiency.”
The unit is effectively two power meters mated together, one in each crank arm. The torque sensors themselves reside inside the hollow drill holes normally found on Rotor’s 3D crankarms. Four strain gauges reside in each arm, allowing for detection of torque on three planes.
The whole system, with Rotor’s new MAS adjustable spider, weighs in at only 556 grams, making it the lightest crank-based power meter on the market. The electronics associated with the power meter add only 30 grams to the regular 3D+ MAS cranks. A commonly used CR2477 battery can be changed with no tools, and the whole crank’s firmware can be updated with an ANT+ dongle.
The cranks use Rotor’s 30mm universal BB axle, which allows for installation on almost any bike, and will be available in both mountain and road versions from its launch around Christmas. Both mountain and road are versions are only available as doubles.
Impressively, Rotor’s testing has shown high resilience to the temperature changes that often throw strain-guage power meters out of calibration. The company is confident that calibration only needs to be performed after initial installation, or when swapping chainrings.
The crank is ANT+ compatible, so it can be used with any of the popular ANT+ head units. Rotor has no plans to introduce a head unit of its own.
The price is set at 1690 euros, or about $2,000, making it a bit less expensive than SRM, the current gold standard.
New data sets
Thanks to its dual-sensor setup and crank-based design, the Rotor Power cranks offer up three relatively unique data sets to users.
True left/right power, rather than a version calculated off a single set of torque sensors, is currently found only on the Look KeO Power pedals, and now on the Rotor Power cranks. Garmin’s 500 and 800 head units have the firmware to view this data in real time, as well as download it, though its usefulness is still somewhat up for debate.
A data set Rotor calls “pedal smoothness” is similar to CompuTrainer’s Spin Scan, but of course Rotor makes the figures available out on the road. Essentially, it allows Rotor to spit out a graph of torque around the pedal stroke, quickly showing where power spikes and dips. Currently, there is no head unit that can interpret this information, but Rotor is working to provide another Garmin firmware update to make it available.
The final Rotor Power feature, and the most unique, is called Torque Efficiency, and to our knowledge is available nowhere else on the market. Effectively, it allows a user to visualize any reverse torque — at the back of the pedal stroke if one doesn’t lift the leg, for example — that is counterproductive to forward movement. It is expressed as a ratio of positive-to-negative torque on each crankarm, basically showing how much your legs are working against each other.
Rotor is careful to note that the data isn’t intended to provide a training goal — a perfectly round stroke, or zero backwards torque, for example — but rather simply to provide the information for each rider to parse and utilize.