Shimano power meter - what we'd like to see

Dual-sided power meter from the component giant could change the game

With multiple US and Japanese patents filed for power-meter designs, Shimano appears close to having a power meter of its own. Jay Prasuhn of Lava Magazine recently posted photos of what appears to be a Shimano power meter prototype from a BMC triathlete camp. BikeRadar went digging through Shimano's various power-meter patents to research what could soon be a consumer product. We detail that information below, plus highlight the features we would like to see on a product that will likely recast the power-meter landscape.

What is patented: Dual-sided, crank-based power meter

Shimano has a number of patents filed on power meters, most submitted in early 2012 and then updated in late 2014. Some detail the various ways a cyclist's output could be captured — at the crank, bottom bracket, rear hub or chain — along with options for recording supporting data from cadence and hub engagement (vs coasting). The most interesting — and most recently updated — patent details a crank-based power meter with a "power-sensing device" on both left and right crank arms.

This patent, updated in November 2014, outlines how strain-gauge-based sensors embedded in both cranks could measure force in multiple ways: driving torque, out-of-plane force, radial force and torsional force. This patent describes a battery unit "disposed in the crank axle" and describes the communication to a head unit as wireless.

Shimano has a number of us and japanese patents on power meters:
Shimano has a number of us and japanese patents on power meters:

What already exists: Shimano BikeFitting power meter with detailed 3D analysis

Shimano isn't exactly starting from scratch with a consumer power meter. The Japanese engineering powerhouse has a rider motion and pedal-analysis capture system dubbed BikeFitting that it sells to retailers. Think Retül or Guru, but with real-time power analysis of the pedal stroke as well as biomechanic data capture.

Shimano bikefitting's pedaling analysis uses a dual-sided power meter to look at the 360-degree application of power, plus where on each pedal (l to r) the force is being applied:
Shimano bikefitting's pedaling analysis uses a dual-sided power meter to look at the 360-degree application of power, plus where on each pedal (l to r) the force is being applied:

Shimano's BikeFitting package already captures and displays a rider's power in multiple dimensions

Beyond the simple left-right wattage capture, the BikeFitting system measures and records a 360-degree view of where in the stroke each foot is applying what pressure, and it also can measure where on the pedal platform power is being applied, left to right.

While this latter function might require integrated pedals (perhaps not, as a sensor at the crank could calculate an approximate balance or particular popular pedal models could be pre-programmed), the 360-degree view is certainly doable on a consumer model. For this, the multiple force measurements detailed in a Shimano patent and Pioneer's current system both point to near-term feasibility for Shimano consumer product.

What does Shimano have to say about all this? For now, nothing. When asked about the power meter and in particular the prototype that appeared on LavaMagazine.com, Shimano spokesman Nick Legan gave us the boilerplate company comment: “Shimano is always working on new technologies and testing them in real-world conditions. That said, Shimano does not comment on prototypes or test samples."

Shimano bikefitting

What we'd like to see: high-quality data; supreme ease of use & compatibility; reasonable price

After years of two basic options — SRM for the pros, PowerTap for the rest of us — the power-meter market has exploded in the last two years, with the likes of Stages, Quarq, Garmin, Rotor, InfoCrank, Power2Max, Xpedo, Factor and more jumping in. Some tout accuracy, some boast price and others celebrate their features. But none yet offer the best of all worlds with ready compatibility to all bikes.

For the Shimano power meter, we want it all: a well-engineered, highly dependable product we can put on any standard bike without breaking the bank. Keith Bontrager gets credit for the saying: light, cheap, strong - pick two. For a Shimano power, we want to pick four: light, inexpensive, compatible, dependable.

For features, Garmin and other head units already offer a deep menu of metrics: power, l/r balance, torque effectiveness, pedal smoothness, percentage of FTP, and on and on. Some may argue we already have too much information that isn't actionable. Shimano could certainly deliver data for all these current metrics, but perhaps a more useful contribution would be clarity on What Actually Matters. Already collaborating with pro teams, coaches, biomechanic specialists and more, Shimano could distill some answers about what our screens should actually be showing. This may come further down the road.

BikeFitting's pedaling analysis looks at where on each pedal the power is applied, and how evenly around the stroke:
BikeFitting's pedaling analysis looks at where on each pedal the power is applied, and how evenly around the stroke:

BikeFitting.com's visual analysis is all fine and good — but we want the data (and the design behind it) to be platform-agnostic

The near-universal compatibility we'd like to see isn't limited to hardware. We want the Shimano power meter to play nice with our sites and software as well as our bikes and components. Pioneer's 360-degree pedal capture, for instance, is all fine and good except for three main problems. One, it requires a dedicated Pioneer head unit. Two, like much of the detailed power analysis, you can't really do it on the bike (unless on a trainer - and that has its own problems). And three, you're forced to use Pioneer's software, which of course isn't something you already do. We want Shimano to use its size and goodwill to offer riders a seamless transition with the head units they already use (um, Garmin) as well as the sites and software they already use, be that TrainingPeaks and GoldenCheetah or Strava.   

In terms of low weight, decent price and Shimano compatibility, Stages has already pushed the envelope with its sub-20g addition to a left Shimano crank (as well as alloy versions of SRAM, FSA and Cannondale models) that comes in at about half of Garmin Vector's dual-sided pedal model. But Stages is only left crank. InfoCrank has pushed its way into the conversation with dual-side information — but on its own alloy crank and BB system and steep price tag. Other power meters have other 'yes, but' caveats to their compatibility.

Considering the company's global reach, who better than Shimano to deliver a dependable, integrated power meter that plays well with your current bike and components? SRAM already got the jump by buying the Quarq power meter brand and plugging that product into its lineup. Time to start cranking, Shimano.

Ben Delaney

US Editor-in-Chief
Ben has been writing about bikes since 2000, covering everything from the Tour de France to Asian manufacturing to kids' bikes. The former editor-in-chief of VeloNews, he began racing in college while getting a journalism degree at the University of New Mexico. Based in the cycling-crazed city of Boulder, Colorado, with his wife and two kids, Ben enjoys riding most every day.
  • Discipline: Road (paved or otherwise), cyclocross and sometimes mountain. His tri-curious phase seems to have passed, thankfully
  • Preferred Terrain: Quiet mountain roads leading to places unknown
  • Current Bikes: Scott Foil Team Issue, Specialized S-Works Tarmac, Priority Eight city bike... and a constant rotation of test bikes
  • Dream Bike: A BMC Teammachine SLR01 with disc brakes and clearance for 30mm tires (doesn't yet exist)
  • Beer of Choice: Saison Dupont
  • Location: Boulder, CO, USA

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