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Not getting any FTP auto calculation after rides

windsurf_dean
over 5 years ago

I've a Stages L power meter and the Dual HR monitor that came with my 530 bundle. Both sensor data are being displayed during the ride.

I've ENABLED auto calculation.

But I've NEVER seen the new FTP notification after completing my rides. And my FTP number never updates (from what I manually entered before). Ride duration ranged from short 30 min all the way up to 3+ hours.

I've even manually entered lower FTP numbers, hoping that will trigger auto-calc. Nothing.

I've deleted my FTP number (it defaults back to 200) and deleted all my ride history from the device. Still nothing.

Is it something that I'm doing wrong? or is this a bug?

Is this a Garmin feature? Or a FirstBeat feature?

Thanks!

  • +1 over 5 years ago

    Auto detection depends on generating sufficient HR data both slightly below and slightly above your LTHR, so that the 530 can pick up the inflection point in heart rate variability that is associated with threshold.

    The majority of rides probably won't generate sufficient data in the relevant ranges - it generally takes 3-5 minutes of relatively steady state efforts above and below threshold. I find LT over-and-under sessions will usually give me an FTP figure at the end. 

    Under the My Stats heading, you should be able to access the guided FTP test, which should generate sufficient data.

  • 0 over 5 years ago in reply to mcalista

    Thanks for the input! Some further observations on my side...

    My LTHR is blank, on both 530 and GarminConnect. (I'm not a runner, thus likely the reason?)

    But thinking about what you said, I checked my max HR setting. It was showing 185 bpm, but I'm almost 49 yrs old! (220-49=171) Did the unit/GC think I'm only 35 yr old?

    Is this correlated to also why I'm seeing suspiciously low HR time-in-zone & anaerobic results from my activities?

    Thus I changed my birth year by +1 year, and then changed it back by -1 year. This caused a recalc of my max HR = 171 bpm now.

    Maybe the unit now will actually think I'm riding hard enough to be near my LTHR (what ever that might be)? We'll see if this makes any effect the next time I ride...

    ---

    Additionally, last night I noticed...

    That was pending my acceptance from 1.5 weeks ago. After accepting it, I then noticed this...

    My prev best 20 min power was stuck at the 16-bit binary number upper limit? Curious if this correlated with FTP auto-calc?

    So now i've changed TWO things. We'll see what happens now...

    Not very methodical for trying to isolate causes, I know. Slight smile

  • +1 over 5 years ago in reply to windsurf_dean

    1. MaxHR. The 220 minus age formula is OK for the population as a whole, but it is #$%^ at predicting maxHR for any one individual. I'm 48, but my maxHR is 184. From the screenshot, you have autodetect on, so it will have picked up any higher HR during a workout and updated your maximum with this. However, if there is a measurement error (dry skin at the start of a workout in cool conditions is a classic scenario for false high readings with a chest strap) that can distort zones.

    Perhaps go back though the HR tab on Garmin Connect, and identify when that high HR occurred, and then look at that ride in more detail. If it was during a hard effort, then your maxHR is probably higher than the age-based default. If it was an easy effort at the beginning of a workout, then it was probably a measurement error.

    2. 20 minute readings. This is the other method of creating an FTP. There was a problem in earlier versions of the 530 firmware with not filtering out erroneous power meter readings. 

  • 0 over 5 years ago in reply to mcalista

    Re: #1...

    Ah ha, found the offending workout! Yup, it was early on during the ride coming out of a stop light, so it's likely a measurement error.

    The next highest measured maxHR was 174, after sprinting down a gradual downhill. So 174 is likely real.

    Ok, thanks! I'll see how the unit responds after my next ride.

    ---

    As an aside, I've been tracking my FTP with the Xert - What's My FTP? custom data field. I'm a power meter newbie, just picked up an used Stages L gen3 two weeks ago. The Xert has been giving me consistent ~215 watts, with a high data point of 230.

    While a Zwift FTP test (short version) gave 187 w/ the PM. Although I prob didn't empty my tanks on that 20 min test...

  • 0 over 5 years ago in reply to mcalista

    Re: #2...

    I didn't get my power meter until after mid/late-Oct. Thus don't know how that 65535 value got in on 06-Sep-2019.

  • 0 over 5 years ago in reply to windsurf_dean

    YES!!! Got updated FTP (and LTHR)!

    Thus the cultrip was either:

    (1) the erroneously high MaxHR data point 1 of my prior workouts, or

    (2) not accepting the 20min Best Power (BP20) update from a few weeks ago.

    I'm guessing (1) since that's more related to FTP calc.

    Thanks  for the help!