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FW 13.30 bug - wrong crank length sent to power meter (Favero, but probably others)

wojtek_b
over 6 years ago

Presumably, with each calibration garmin sends crank length to the power meter. I realized, that despite the setting on the watch, it is sending some weird values. The only time when it sends right values happens when you set the crank length on the watch. With setting I mean CHANGE. So if you are using 172,5 you need to set something else, than change back to 172,5 and calibrate. With next calibration it will send 180... And I didn't manage to check when it happens, but finally it sends 208mm! Difficult to troubleshoot. I am using favero BePro, so I am able to check the crank length via PC. Check your power meters, because your good power results this year may be caused by this bug... 

  • 0 over 6 years ago

    The head unit doesn't send crank length to the power meter.

    The power meter sends torque and cadence to the head unit, and the head unit calculates power adjusting for the crank length stored in the head unit.

    I have the Assiomas rather than the bePro, but you can set the crank length via Favero app. However, this will get overidden by the crank length stored in the head unit, if any.

  • 0 over 6 years ago in reply to mcalista

    It does. I checked it. With BePros you can set the crank length via PC App as well as check the value set currently. Each time Fenix connects to the pedals, apparently the value is updated (as well each time you change it in the settings of Fenix). Even if I set the crank length on the PC App it is overriden next time fenix connects to the pedals. 

    For now, I deleted BePros and paired it again, and it seams that the correct value remains. However, I didn't have the possibility to test if for more than few connections. 

  • 0 over 6 years ago in reply to wojtek_b

    This would be very strange. What protocol would Fenix be using to push the crank length to BePros? ANT+? There's no such profile as far as I know. Private ANT? For Assiomas? I highly doubt it. So whatever it is, it probably isn't Fenix that's updating this setting in BePros.

  • 0 over 6 years ago in reply to volodp

    For now, re-pairing didn't help. I have contacted favero, and they confirm that head unit overwrites the values on bepros. 

    If during your last check you have found that the crank lenght was not correct also if you set it correctly previously, I suppose that for an unknow reason the cyclecomputer does not write the correct information on the sensors.
    Answering your question, considering that bePRO firmware did not changed in the past month, I suppose that maybe something changed on Garmin firmware so at the moment I do not know how it will be possible to avoid the same wrong behaviour in the future.
    Considering that even if you set the crank lenght through the software bePROUpdater, the same lenght value will be overwritten by the cyclecomputer if it has a different lenght,
    So, it is definitely caused by Fenix. I really believe, it may be similar case with other power meters. I have contacted garmin support, but they are not as responsible as favero, so I will now do the same thing they will suggest in first place - factory reset. I really hope I is caused by my conf, not the firmware update. 
  • 0 over 6 years ago

    After some of tests I confirmed empirically that the issue is in the newest version of FW. I downgraded to FW 12.50 and now it is correct. Don't you get to high power results since 13.00 ?