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Rally XC200 power seems off

dsa1971
over 2 years ago

So I’ve had my rally xc200 pedals since nov 21 on my gravel bike. Outside on gravel I don’t do a lot of rides based on power but like to look back and some of the data to get a sense of how my RPE matched up with my power. 

inside I’ve had my road bike with Assiomas on them for a long time and use my elite direto. For the longest time I used powermatch in TrainerRoad with the Assiomas. At some point before a workout  I forget to charge the pedals and needed to use my direto exclusively. After that I did a couple of tests comparing the power for same workout between the direto and the Assiomas. The numbers were very close and Assiomas have a pretty good track record for accuracy. 

fast forward to the xc200s recently. So last weekend I did a long 5 hour gravel ride. Pretty steady pace. Felt pretty good and power numbers were pretty good for me for that amount of time.  So I decided the test the xc200s against my elite direto.   Put my pedals on, did a workout, and the xc200s were about 20 watts higher across the entire workout and for each interval compared the direto. Pedals were torqued appropriately. Calibrated. And angles reset. Only thing I didn’t do was calibrate the direto but that has rarely been an issue. 

is this normal? I expect some power difference but 20 watts is a lot.  Anybody else experience this? Of course I can solve this by always using the xc200s which is not a big deal but I think the 20 watt difference was a bit surprising to me. 

  • 0 over 2 years ago

    Mine seem to read lower. A few other people have the same problem as I have. They seems to read correctly when they were new. Garmin has not been very helpful either. If you find an answer please share. Huge bummer. 

  • 0 over 2 years ago in reply to JStez

    I haven't experienced that issue at all. Do you have the pedals Torqued to the correct spec?

  • 0 over 2 years ago

    Quite the opposite issue. I have a 260W FTP (Elite Suito, Direct Drive) and I just averaged 291W for 1 hour and 6 minutes outside on the XC100's (way off). Gave me a 20 minute power of 330W and a new estimated FTP (on strava) of 318W.

    I am physically incapable of producing these numbers and i'd say it's off by 30-50W. Currently looking to have them replaced as I just unboxed them today.

  • 0 over 2 years ago in reply to Gaudon

    Did you torque them down to the correct specs then after doing that did you do a few hard efforts then re-calibrate before you did your test?

  • 0 over 2 years ago in reply to jasontech

    They are, but the few hard efforts is questionable and largely why I'm waiting to put it on the trainer today to see how they perform. I definitely did several sprints on my ride last night just as a test. I rode maybe 500m up the street and back, re-calibrated, then did my ride (30k gravel, where they were reading wrong).

    At lunch time I'm going to put them on my trainer, recalibrate again and see how they perform.

  • 0 over 2 years ago in reply to Gaudon

    I don’t know. I guess they’re just not consistent. I suppose it’ll take time to sort them out, if Garmin is willing to stick it out. I’m back on the Quark right now. 

  • 0 over 2 years ago in reply to JStez

    I calibrated again (after my initial ride yesterday) at lunch today for a short test. I compared them to my elite suito and this time it was a lot closer to what I would expect. While it wasn't a scientific test, I did 1-2 minute efforts at 150, 200, 250, 300W and some sprints.

    They left side pedal was a little high, about 7% on 5 minute power, but overall far more accurate than my initial ride which was off by like 20%.

  • 0 over 2 years ago in reply to Gaudon

    In a sense, that’s a little more worrisome. A PM that is absolutely consistent vs sometimes accurate would be better, I think. Generally, I retest my values at different times during the season, and although it would be nice to know precisely what wattage I’m putting out, it’s not super important for me. As you know, The PM and tests give me my zones, and then I train and evaluate against the baseline. I just need it to be consistent, and it’s not. It’s a shame, nice idea. I hope it work’s out for you. 

  • 0 over 2 years ago in reply to Gaudon

    Hi, Wich tool did you use for the comparison?
    I have the same issue, high readings.

    Today in the afternoon I'm gonna compare the readings at the same time with a Quarq PM over a TrainingPeaks exercise and wanna compare as well.

    Thanks

  • 0 over 2 years ago in reply to acasber

    I used one that was built into zwiftpower's website. I will say, my left side only power meter is much more accurate now that I've told garmin support to hold off on replacing them.

    The first ride was completely out to lunch, but my followup zone 2 rides (~185W) have been quite on the money based on my HR zones and power as I'd expect on the trainer. Given the trainer is +- 1.5%, the pedals are +- 1%, L/R balance being a factor.. I think them being out by 3-5% is reasonable.