Default crank arm length is 172.5mm - Do I need to change it every ride?

_Pi3_
10 days ago

Hi, 

So far, I have a very positive experience with the Rally XC I own, below is one glitch I hope you can help me solve

My cranks are 175mm on the bike I use the most.

I noticed that, although I have changed this value earlier, the pedal goes back to the default 172.5...

Does anyone have an idea on the effect of magnitude of the miscalculation of the watts due to this imprecise setting?

Is there any way to change the default value?

Garmin could give at least an option to check this value before each ride (along with the recommended calibration procedure, I will do a separate whishlist thread)

Thanks

  • 0 10 days ago

    you need to set it right in the Connect app, and in the Edge (under sensor details also). because if these 2 values are different than overwrites itself as in your case. in the Edge: wake up the pedals, go in the sensors, find the Rallys, and under details there should be the crank length setting. in your case if the Edge is using 172.5mm instead of 175mm, then your Rally is undermeasuring the power with ~1.5% ( 172.5/175, so if you pedal with 200Watt in reality, then on the Edge you will see only 197Watt ). in normal case it stores this setting until you remove the pairing in the Edge and probably until if you change the batteries (but i am not sure in it, i had Vectors 12 years ago :) )

  • 0 10 days ago in reply to Luko79

    Thanks! Will try this as soon as I get my hands on the pedals this weekend.

    In my case I will make this adjustment on my fenix watch, I expect the same procedure applies.

    In the meantime, I found and selected to enable the calibration prompt so at least I will not forget that step.

    Thank you

  • 0 10 days ago in reply to _Pi3_

    yes, with fenix is the same, sensor menu and there (just as i wrote, this crank length submenu /and a few others also/ exist only if the pedals are awaken, so need to rotate the cranks before the procedure)