Shimano powermeter crankset patents filed

Shimano has filed several patent applications for a powermeter crankset, integrating the strain gauge directly inside both left and right crank arms.

The application using the drawings shown here was filed in April 2012 as an addendum to an earlier March filing. It was published last September. The claims of the patent include a crank body, including the axle, a sensor support member inside the crank body and a power sensing device consisting of a strain gauge and semiconductor sensor to detect the strain.

In laymen’s terms, it shows a strain gauge inside the crank arm. Now, for the details…

Shimano powermeter crankset patents filed


From the outside, this would probably look like any other Shimano crankset. Everything’s hidden inside, with the strain gauge inserted through a bore above the pedal mount. Wires connect it to a battery in the axle, and somewhere on the system are transmitters to wirelessly send the data to a computer. The images suggest there could be a charging port on either end of the axle (but probably just the non-drive side since Shimano’s drive side crank is a closed design), but knowing how long batteries last in current power meters, it wouldn’t be that big a deal if it were fully enclosed. There’s also likely a plug to connect both sides to the battery to enable easy non-drive crank arm removal and total battery removal.

Shimano powermeter crankset patents filed

Where things get really interesting is in the planes of force measured:

  • Fig. 18 – driving torque
  • Fig. 19 – out-of-plane force
  • Fig. 20 – radial force
  • Fig. 21 – torsional moment force

The photo at the top of the post shows four sensors, one touching each wall of the crank arm, which would deform along with the crankarm under pedaling forces and let it measure flex in all directions. At present, it’s probably more data than any cycling computer can digest, but so was the hi-res output on the Factor Vis Vires at first. Maybe it’ll usher in new measurement metrics, or maybe it’s just a way of combining more and more data to present a more accurate measurement of your actual power output. The patent suggests the strain gauges and support structure will be permanently bonded inside the crank arms.

Shimano powermeter crankset patents filed

The filing also mentions that the effort calculated could also be used to “aiding operating a component of the bicycle”. Some of the other drawings show a commuter bike equipped with the system and a cycling computer. That could mean they’re looking at ways of integrating it into their STEPS e-bike systems using a less costly method of crank integration (it mentions a bolt-in/on version), providing motorized assist based on input.

But it’s far more fun to read that the filing mentions it could “wirelessly (or with wires) transmit information to one or more electrical bicycle components such as the cycle computer, the electronic front derailleur and the electronic rear derailleur.” Hmmm…the new D-Fly Di2 wireless transmitter just got more interesting.

Of course, all of this is speculation, and it’s likely the scope of the filing intentionally covers pie in the sky thinking to keep options open (for them, and closed to others). Shimano doesn’t comment on products or rumors until things are officially released. But, last time we found Shimano’s patents, some of them were quite telling of products to come (and some definitely were not). These fall into the “entirely possible” category and would usher in the sleekest power meter integration on the market. Time will tell…

Check out the full application on the USPTO website.

Huge thanks to Tehan for the tip!


  1. jcoudright on

    I’m sure this has to be designed around the crankset on their new fit bike that is out right now. It can even display the exact location of the pressure zones on your pedals.

  2. Robo on

    Since the dawn of Di2, I’ve said, combine it with a power meter, set a desired power output and cadence, run it through a computer, and let the system shift automatically for you. Auto trans on a bike. Here we go…

  3. Argh on

    In sports cycling constant power is not the issue. Good pedalling, power use in approprate situation is “the win”.

    For city riding.. okay.. but it is too pricy 🙂

  4. Star on

    @Freddie, best comment!
    And now the quality and durability and prices get better as Shimano rolls crank based power out to the far reaches of the world.

  5. alloycowboy on

    An Automatic transmission on a bicycles is a really dumb idea because it would never been in the right gear for sudden rapid terain changes.

    As for Shimano’s internal crank powermeter it is a fail because you need to be able to change the battery easily so external is obviously the way to go. I suspect both Sram and Shimano are talking to Stages to license the technology or buy the company out right.

  6. Mangobike1 on

    @alloycowboy. Don’t you think Shimano would have the power meter running off the Di2 battery (if that system is in place)? Or you could use that battery as the brain for the system. Even if you didn’t want Di2.

  7. bikejedi on

    could definetely see this as a further push by shimano to finally bring some modular integration to e-bikes. I doubt it is a blueprint for a production crank…who wants to buy a crank that is not only flexy, but allows you to measure it. Measuring flex or strain has been part of electric assist systems for a few years now, but has been within the motor hub along with various external sensors around the bb and or crank arms…would be nice to see it all integrated

  8. David on

    This published application is a “continuation in part” of a US application filed March 7, 2012. The corresponding Japanese application could be up to a year earlier under PCT rules.

  9. Thomas on

    How long before “Cease and Desists” are sent to power meter competitors. Nothing like using patents to kill off all the little guys.

  10. Tim on

    @Thomas – the “little guys” could invent and file patent applications too…..

    Cease and desist letters can only be sent once the patent has been granted – and that won’t likely be the case for a good 2/3 years.

  11. Tawe on

    Just remember, you’ve still got to turn the pedals round & round & round yourself.
    It’s only another powermeter. It can potentially be incorporated into Di2, to give you “the most efficient gear”, but you’ve still got to turn those pedals. No powermeter is a substitute for that.

  12. Dave B on

    “How long before “Cease and Desists” are sent to power meter competitors. Nothing like using patents to kill off all the little guys.”
    Apparently you don’t understand what patents allow. If other makes and designs are already in existence, Shimano can’t patent their design since a patent has to be “novel” and “unobvious”. If Shimano is granted patents on these power meters, they are not using someone else’s design and cannot force them out of business.

  13. Freddie T on

    I bet they are going to do a electronic dropper post that will sync itself to the optimum height for power output. And as you fatigue, it’ll make changes to compensate. That’ll be the new way the pros “add” weight to their bikes to meet the minimums. No more lead plugs in the crank spindle.

  14. Psi Squared on

    @Stewart Williams: Shimano is stealing nothing here.

    Hopefully Shimano will release a better a computer–one that actually records–to go with their power meter if or when it comes out. The Pro SCIO isn’t up to the task.

    A power meter from a company as big as Shimano could really put pressure on other power meter makers to lower prices, especially if Shimano could leverage some economies of scale for its pricing.


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