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Is garmin rally xc 100 compatible with oval chainring?

5351567
over 1 year ago

I am using absoluteBlack 34T chainring and rally xc100, are results actually correct? What can I expect? If I get offset is offset at least allways same or?

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  • 0 over 1 year ago

    I'm an XC100 user and while reading about power meters in general, discovered the potential oval issue....never had occurred to me and I use Absolute ovals on my trail bike and my fat bike and round on my Wahoo kickr trainer (100% used with Trainer Road which now has AI FTP detection).   My question is whether if having oval is a problem if you really only care about tracking your power and FTP progress for yourself and have no use for power data otherwise....meaning I don't really care what the FTP number is, just how it is changing.

    My experience so far is that the trainerroad FTP detection, which uses both indoor and outdoor data (round and oval mix but much more this time of year on oval) and the garmin FTP detection on my fenix 6 watch, are within 2-3% of eachother.

  • 0 over 1 year ago in reply to cwoodffr

    the absolute ovals are the "most rounded" ovals so there is only apprx 1-2% overmeasuring with that. With OSym, it is apprx 4%. the Rotor QRings are between these 1-2% and 4%. But i suggest everybody to LEARN to pedal correctly in circle and smooth with normal round rings, this "oval" thing is just hiding your pedaling weaknesses...

  • 0 over 1 year ago in reply to Luko79

    Thanks for the info.  Garmin claims 1% accuracy so that is pretty much within the measurement error rate.  I can live with that.

  • 0 over 1 year ago in reply to cwoodffr

    the claimed 1% accuracy is with round rings (and this is just a claim... ) yeah not a big difference (+1-2% in your case, so if You pedal with 204W these Rallys that is apprx 200-202W in reality, but these are really tiny diffs. ) but with ovals everybody is "stronger" (gets "bigger" watts) but the reason is only the slightly overmeasurements and nothing else. 

  • 0 over 1 year ago in reply to Luko79

    My only real use is to track progress in ftp over time, so if I have only ever run this style ring, then I don't see an issue.  I think if I were examining full dynamics with both pedals in play then I would be more fussed about it but I am an amateur mountain biker just trying to get stronger and using data to track progress.  For this use case I feel just fine about the small possible error.