Rotor Power powermeter crankset with dual measurement for true left right power balance capture

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…

Rotor Power powermeter crankset with dual measurement for true left right power balance capture

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:

  1. Rull total power
  2. 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.
  3. Torque Effectiveness – the sum of forward power minus heel drag to show how much real power each leg is putting out.
  4. 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.

Rotor Power powermeter crankset with dual measurement for true left right power balance capture

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.

Rotor Power powermeter crankset with dual measurement for true left right power balance capture

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.

Rotor Power powermeter crankset with dual measurement for true left right power balance capture

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


  1. crazyeddie on

    the road crank isn’t compatible with trek bb90 and wilier bb94, the mtb crank will not be compatible to trek bb90 (elite carbon 2009-2013 and top fuel carbon 2011-2012) and trek bb95 (other carbon mtbs from trek and gary fisher).

  2. RED on

    I hate the cutout in the spider…

    Understand they did it to improve left-right wireless communications.
    but if they could at least put a black rubber filler or something in place to spare the gaping hole.
    (something that would not impede the signal like metal…)

    Yet another use for black electrical tape?

  3. Almon on

    I’m seriously looking into this crank. I don’t care how it looks. I’m only interested in the results, I’ve been running Q-Rings for a long time and this is the next logical step.

  4. Psi Squared on

    There were some reports of sketchy data out of the new Rotor power meters when they were first released. Did the Rotor rep say anything about improvements to data fidelity?

  5. MMyers on

    Stoked on the XX1 rings.

    My next geared mtb will definitely be 1×11, but since I mainly ride singlespeed, I’m more interested in single ring offerings in something other that 34 tooth.

  6. MeToo on

    Have been running these since early spring. Managed to grab a set before they sold out. Have had continuous data, with very few hiccups. Enjoy.

  7. MeToo on

    Have run these since early spring. Received one of the few copies available. Runs smoothly. Installs easily. Have had few data hiccups, and have not noticed much if any data drift.

  8. Keith Wakeham on

    Those who want BTLE (BT smart), look for the Viiiva heart rate monitor. DCrainmaker did a review.

    As someone who’s been developing a powermeter in my free time (see blog), I can appreciate the wireless problems. and needing the cut out. It’s ugly, but needed. Some light plastic could work, but still attenuates the signal.

  9. RR on

    Hmmmm…. “Limited resources and the desire to get it absolutely right before unleashing it on the public meant a very, very long development cycle”….

    That’s a big call. They may well have had a “desire to get it absolutely right” but I don’t think the reality is remotely close. I for one hope new firmware fixes the problems that are evident to any member of the public who currently has one….

  10. Joel on

    I have one of these fitted and have been using it for the last month or so. The meter looks great and the power balance works well on the Garmin 500. Power is approximately where it should be, however there was one sprint that it reported 2,500 watts that I doubt actually happened – I suspect this may be due to the gauges being in the crank arms and there may have been a huge amount of flex when hitting a bump mid sprint.

    Otherwise, there is a problem widely reported on the Internet that I am experiencing – cadence reporting issues. Because there is no magnet on this model the cadence is estimated using other means – some sites report accelerometers, other sites report peak-peak measurement. Either way this needs tuning, as when the cadence is higher than about 90rpm the reported number (and resultant power) halves. So you end up with sets where cadence is reported at 110rpm for 1 second, 55rpm for 1 second, 112rpm for 1 second, 56rpm for 1 second, and so forth.

    Also, about every 20-30 minutes I will find that the unit will “reset” itself whilst moving – all figures drop to zero, then “—“, then about 5 seconds later they’re all back and working.

    In my mind whilst annoying these issues aren’t showstoppers, however a professional level rider would probably think otherwise, hence the garmin-sharp team (who rotor sponsor) still run SRM’s 😛

    I think the product still a work in progress, hopefully a firmware update is coming that will address the issues.


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