Rotor’s Power power measurement crankset was shown at Eurobike, then highlighted in February’s ANT+ power profile update, but just finally started shipping in March with production continuing to ramp up.
It’s based on the 3D+ crankset, which launched several years back. That crankset and the power units started development five years ago, and their patents for this power system are about five years old. Rotor is still a small company though, so at that time it wasn’t feasible to push resources into developing the power system. Limited resources and the desire to get it absolutely right before unleashing it on the public meant a very, very long development cycle.
Unlike many other power meter options, it uses two independent power meters, one on each arm, each using four strain gauges inside the drilled out sections of the crank arms. The power units run on user replaceable CR2477 batteries, one per side, and transmit via ANT+. It measures at 500Hz, which US Brand Manager Phillip Lucas says is the highest rate currently on the market. The benefit is higher quality data transfer without “noise” polluting the numbers. He says there’s no shifting spikes or temperature shifts, and it only needs to be calibrated when you replace the batteries.
Not into Rotor’s elliptical chainrings but still intrigued? Perfect…
Most crankset powermeters provide a total power measurement computed from efforts on one crankarm. The Rotor Power power meter captures far more data and spits out four measurements:
- Rull total power
- True left/right power measurement of each leg individually rather than the combination of one up/one down then other up/other down of power meters that have a spider-based strain gauge only on one side.
- Torque Effectiveness – the sum of forward power minus heel drag to show how much real power each leg is putting out.
- Pedaling smoothness – maximum torque is compared to average torque
The Torque Effectiveness measurement allows you to fine tune your pedal stroke to reduce the “drag” when your foot is done pushing down and has to come back up.
All that data would currently have to be viewed on your computer using their PC program (no Mac version yet). The data is stored in the crank arms during the ride and can be downloaded via ANT+ to your computer. During riding, any current cycling computer that can show power and left/right will be able to display that in real time. They expect Garmin and O_Synce to have computers that’ll show the two torque data channels within six months. You’ll also have to wait for third party apps like Training Peaks, Strava, Garmin Connect, etc., to add those channels before you’ll be able to view it outside of their PC suite.
Weight for the Power crankset is 527g (175mm 130BCD spider, with batteries). The Power units themselves only add 30g over their standard cranksets. Unfortunately, they can’t be retrofit into used cranksets.
Price wasn’t firm at Eurobike, but it’s set now: The crankset without rings or BB is $2,350. It uses a 30mm spindle called UBB, which essentially means Universal Bottom Bracket and it should work with just about any type frame, regardless of BB. The only real exceptions are the two shown here, which are basically just some Trek bikes.
You can use it with standard chainrings, too. Anything with a 110BCD or 130BCD will fit. Battery life is rated at 300 hours.
Coming up: The following are in development:
- XX1 style elliptical chainrings
- MTB Power crankset
- Q-rings for new Dura-Ace cranks
- Possible Bluetooth addition to Power, but not anytime soon
- Considering a Mac version of their PC suite (yes, please!)
Check ’em out at RotorBike.com.