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Rotor launches INpower spindle-based power meter cranks

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With the introduction of INpower, Rotor now has both crankarm-based and spindle-based power meter options

With the introduction of INpower, Rotor now has both crankarm-based and spindle-based power meter options (Image credit: James Huang/BikeRadar)
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Rotor's new INpower spindle-based power meter is designed to work across the company's entire portfolio of 30mm-diameter cranksets - including both road and mountain bike models

Rotor's new INpower spindle-based power meter is designed to work across the company's entire portfolio of 30mm-diameter cranksets - including both road and mountain bike models (Image credit: James Huang/BikeRadar)
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Rotor also introduced its new 104mm BCD 1x-specific chainring with alternating narrow-wide teeth for use on most four-arm cranksets

Rotor also introduced its new 104mm BCD 1x-specific chainring with alternating narrow-wide teeth for use on most four-arm cranksets (Image credit: James Huang/BikeRadar)
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The associated power meter software shows an impressive amount of information - and in real time. Users can quickly see how smooth their pedal stroke is and how efficiently they're applying power

The associated power meter software shows an impressive amount of information - and in real time. Users can quickly see how smooth their pedal stroke is and how efficiently they're applying power (Image credit: James Huang/BikeRadar)
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All of the INpower power meters use Rotor's Trinity drilling system, which bores three longitudinal holes through the full length of the crankarm to save weight

All of the INpower power meters use Rotor's Trinity drilling system, which bores three longitudinal holes through the full length of the crankarm to save weight (Image credit: James Huang/BikeRadar)
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Rotor's UBB30 spindle system can be adapted to every major bottom bracket system with the lone exception being Trek's BB90 and BB95 integrated shells

Rotor's UBB30 spindle system can be adapted to every major bottom bracket system with the lone exception being Trek's BB90 and BB95 integrated shells (Image credit: James Huang/BikeRadar)
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We'll see how well the seal on the battery cap holds up to power washings

We'll see how well the seal on the battery cap holds up to power washings (Image credit: James Huang/BikeRadar)
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While many new power meters are now packing in both ANT+ and Bluetooth wireless capabilities, Rotor is sticking to just the former on the new INpower

While many new power meters are now packing in both ANT+ and Bluetooth wireless capabilities, Rotor is sticking to just the former on the new INpower (Image credit: James Huang/BikeRadar)
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Everything is housed entirely inside the spindle with the exception of the ANT+ antenna, which is affixed to the end of the non-driveside crankarm

Everything is housed entirely inside the spindle with the exception of the ANT+ antenna, which is affixed to the end of the non-driveside crankarm (Image credit: James Huang/BikeRadar)
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The Rotor INpower power meter uses standard AA batteries with a claimed run time of 300 hours. When it comes time to replace it, simply turn the access cap with your finger and pop in a new cell

The Rotor INpower power meter uses standard AA batteries with a claimed run time of 300 hours. When it comes time to replace it, simply turn the access cap with your finger and pop in a new cell (Image credit: James Huang/BikeRadar)
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Rotor houses two strain gauges and all of the electronics completely inside the 30mm-diameter aluminium spindle. As with any spindle-based power meter, INpower only directly measures output from the left leg and then doubles that to give an extrapolated total

Rotor houses two strain gauges and all of the electronics completely inside the 30mm-diameter aluminium spindle. As with any spindle-based power meter, INpower only directly measures output from the left leg and then doubles that to give an extrapolated total (Image credit: James Huang/BikeRadar)

This article originally appeared on BikeRadar

Rotor is supplementing its existing crankarm-based power meters with a new single-sided system called INpower that's built within the company's 30mm-diameter bottom bracket spindles. It weighs less than 55g, it's less expensive than Rotor's dual-sided system, there's a wide range of crankset options (including for mountain bikes), and it even uses refreshingly common (and cheap) AA batteries.

Rotor's new INpower power meter can be added to nearly any of the company's cranksets

Key features:

  • Spindle-based direct-measurement power meter with dual strain gauges
  • 30mm-diameter UBB aluminium spindle
  • 300-hour claimed run time
  • Requires one AA battery
  • Roughly 50g of additional weight
  • ANT+ wireless transmission
  • US$959-1139 / £TBC / €TBC / AU$TBC (left and right crankarms, spider, and spindle)
  • US$779-869 / £TBC / €TBC / AU$TBC (left crankarm and spindle only)
  • May availability

Tucking all of the critical bits inside the spindle offers up a number of practical advantages over a spider- or pedal-based power meter system. The axle-based format is largely protected from weather and impact, it's visually inconspicuous, and very compact. The cylindrical form factor uses just one AA battery for up to 300 hours of ride time – and when a replacement is needed, they're extremely easy to find.

Save for the small ANT+ antenna, which is affixed to the end of the non-driveside crankarm, all of the power meter hardware is enclosed inside the spindle

Since Rotor uses the identical spindle for all of its 30mm-diameter UBB (Universal Bottom Bracket) cranksets, this also means that the vast majority of the company's cranks now have direct-measurement power as an option, either as a complete crank or an add-on spindle-plus- crankarm subassembly for existing owners – and it's easily transferable. The UBB spindle will work with nearly every bottom bracket shell on the market, too, including standard BSA and ITA threaded, BB/PF30, PF86/92, BB386EVO, and BBright; the only major exception is Trek's BB90/95 system.

In addition to providing the usual on-bike power metrics, INpower also offers some unique graphical analysis tools when used with the associated desktop software or smartphone app. For example, Torque Effectiveness compares your total torque with your positive torque (essentially telling you how much your upstroke leg is fighting against your downstroke leg) while Pedal Smoothness tells you in real time if you're pedaling in circles or squares. Finally, the Optimum Chainring Angle function is specifically tailored to Rotor's elliptical Q-Ring chainrings, giving users precise guidance on how the rings should be oriented for maximum benefit.

The software offers up some rather interesting features to help improve your pedaling technique

In the event that other features are developed later, the system can be updated over the air via an ANT+ dongle.

While the new INpower certainly sounds appealing, there are some downsides. As with any spindle-based system, INpower only directly measures the output of your left leg; total power is merely an extrapolation that assumes equal output from both legs. In addition, the system is ANT+ only (as in there's no Bluetooth functionality) and the software won't work with Apple OS X operating systems. Most critically, the design is brand new so there's no way to predict long-term reliability.

The system is powered by a single AA battery, which resides beneath a tool-free cap on the non-driveside

Regardless, one immediate benefit of the new INpower system is that it's prompted Rotor to drastically lower the prices of its other power meters. The dual-sided Power drops to US$1,559 / €1,299 (from US$2,400 / €1,699) while the single-sided Power LT is now US$1,079 / €899 (from US$1,490 / €999).

We'll have a production sample of the new INpower in a couple of days so we expect to answer some of these questions shortly. 

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