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[16.10] Quark XX1 Powermeter crank length

JothRi
over 4 years ago

Quarq XX1, 175mm length, cannot find setup menu

Setup -> Sensors & Accessories -> PWR  Quarq ->

  • Status
  • Calibration Prompt
  • Calibrate
  • About
  • Name
  • Remove

That's all, no crank length menu 

 

  • 0 over 4 years ago

    please post this to the garmin team using their mailadress from the beta thread. They should be aware of that.

  • 0 over 4 years ago

    i have the quarq XX1 as well and i do not even see the crk len in my fenix when connected (ANT+).

    by the way: why should there be a setting for the crank length in the fenix? this setting is not even in the AXS app. as i think that the quarq reports the power to the fenix, the crank length setting should be in the AXS app if this would make any difference for the measurement. and with the latest firmware of the quarq you do not even need to calibrate anymore.

    please correct me, if i miss something.

  • 0 over 4 years ago in reply to Bandit

    Posted in technical support SRAM, waiting for an answer

  • 0 over 4 years ago in reply to Bandit
    Bandit said:
    and i do not even see the crk len

    i think this new feature in 16.xx firmware 

  • 0 over 4 years ago

    I can understand the need for crank length when the force is measured at the end of the crank, as with pedals, but when the force is measured within the spider the crank length won't affect that measurement at all. 

  • 0 over 4 years ago in reply to JothRi

    When you use a torque wrench does it need to know exactly how far from the fulcrum you are holding the shaft and applying force? No. Does it need recalibration if you add an extension for extra leverage? No.

    Lever length only matters if you are taking measurement at the end of the lever (pedals). If you are measuring torque/force at a known, fixed distance from the fulcrum (spider) then lever length is not required to be known. Yes, longer levers will increase torque for the same force, but that will be reflected where it is measured, close to the fulcrum and not at the end of the lever/crank. 

  • 0 over 4 years ago in reply to eezytiger
    eezytiger said:
    When you use a torque wrench does it need to know exactly how far from the fulcrum you are holding the shaft and applying force? No

    If I press on the pedal with power 10N, and 175 mm from the center, then 10N * 0.175 m -> Torque = 1.75 N*m and  10N * 0.1725 m -> Torque = 1.725 N*m.

    If the power meter does not know the length of the vector to the axis of rotation, then I do not recognize so much I spend the forces !!!

    So that the two meter showed the same power, with a crank length of 172.5 mm, I need to put 10.145N, - spend 1.45% more energy.

  • 0 over 4 years ago in reply to eezytiger

    Perephrazing: Vector 3 knows the strength with which they put pressure on them, but does not know the length of crank. Quark measures the resulting force, but does not know the strength with which I put on the pedal.