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Fractional Cadence values

Nikeow
over 2 years ago

May I know what is the purpose of the Fractional Cadence field?

From FIT file dumps, I see the values as a mixture of 0 and 0.5

I saw this being referenced here but doesn't seem like the way to handle the cadence for running vs cycling is consistent as I've seen the fractional cadence being 0 and 0.5 in the same file for running. (but for cycling it's consistent at 0)

https://github.com/GoldenCheetah/GoldenCheetah/issues/2060

  • +1 over 2 years ago

    The cadence fields in a FIT file represent RPMs. For cycling 1 RPM equals one full rotation of the cranks. For running 1 RPM represents a step from each leg. But most runners want to see SPM not RPM. If you double the RPM value you would never get an odd number. That is where the fractional_cadence value comes in, and why the only two values that you will see, in practice, are 0.0 and 0.5. When doubled the 0.5 gives you the option of having an odd value for SPM.

    The SPM calc looks like.

    SPM = (cadence + fractional_cadence) * 2

    For cycling the value does not need to be doubled, which is the reason that the fraction_cadence value is always zero.