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Vector 3 accuracy thread

Teriemer
over 7 years ago
So here we go... This is the accuracy thread for the V3.

Now for my first post here, I need to inform you, that my comparison is with a Kettler Ergoracer S (2016 model). Note this bike has a flywheel which resistance is being controlled electronic. The bike is calibrated according to a DIN std. and the bikes comes along with the calibration sheet. My bike is slightly below actual wattage. As a simpel test, I do get the same result when doing a FTP test either on Kettler or outside with a different powermeter. So the wattage must be about right.

Back when I had Vector 2, one funny thing, I had to set the pedalarm to 187 mm (actual is 170 mm) to get the same wattage as Kettler(!). Never the less is worked quite well. With that setting I got good comparable data from both sources. So when getting V3 in my hands, I started out setting the pedalarm length to 187 mm. Once done riding, I compared the data. To my surprise and happiness, I found that V3 had to be adjusted to 171 mm to perfectly aligned with Kettler. Sweet thing - so I adjusted to 170 mm. However on the following ride, V3 was clearly not showing enough(?!). Going through the same comparison, I calculated the adjusted pedalarm to now 198 mm...!?!

So my very first conclusion here, based on only two rides indoor on my Kettler with V3 is the following. To get aligned wattage, I see pedalarm length varies from 170 to 198 mm. That's a difference about 16%

Check out the charts below and let me hear your thought...

EDIT: can't upload my second picture. I'm gonna try again later...
ciq.forums.garmin.com/.../1280575.png
  • 0 over 7 years ago
    Hey guys. Just thought I'd throw in my 2 cents on this topic. My Vector 3's are consistently reading approximately 5% higher than my 2017 Wahoo KICKR. For example, here's a recent TrainerRoad workout


    Interesting! More data is excellent! :)

    I'd switch your Kickr out of 'ERG Smoothing Mode' for a more accurate representation of the power reported from it. It won't change the -+% you're seeing, but it'll be more useful than the flatlines you're seeing (which is kind of fakewatts (tm))



  • Former Member
    0 Former Member over 7 years ago
    Thanks for the replies guys. I forgot to mention that, prior to all rides, both Vectors (2&3) were calibrated via my Edge 820 and the KICKR calibrated via the Wahoo Fitness app after a 10 minute spin. I’ll turn off KICKR ERG mode power smoothing and post some more data.

    Cheers!
  • 0 over 7 years ago
    I'm seeing quite a bit of discrepancy though I will note I'm using two new power meters to compare (Kickr17 vs V3). I got my Kickr17 a couple days after release but haven't done much riding due to focus on running. A couple days before my race I received my Vector 3's and have since done two easy recovery easy spins in erg mode. I'm seeing about a 10% higher reading coming from my Vectors. I previously had a Kickr and Vector 2's that always read less than 2% of each other.

    I hope that this is software issue and a firmware update will clear this up.
  • Former Member
    0 Former Member over 7 years ago
    Got another workout in this afternoon and my Vector 3's continue to read 5% highter than my KICKR. Both devices were calibrated just prior to the workout.

    https://analyze.dcrainmaker.com/#/public/909239a9-8e07-4066-71e8-8da29672dcb9[FONT="Helvetica Neue"][/FONT]

    Interestingly, they both tracked very close for the first 3 minutes of the workout before diverging.
  • Former Member
    0 Former Member over 7 years ago
    Those values may be right. You would expect Vector to be a little higher than the KICKR because of where it is measuring power. No drive chain loses.

    The KICKR has a claimed accuracy of +/- 5% or +/-3% for the snap V2. So the values you are seeing are within the expected range. (Accuracy data taken from https://www.dcrainmaker.com/2017/07/...2-trainer.html)
  • 0 over 7 years ago
    The KICKR has a claimed accuracy of +/- 5% or +/-3% for the snap V2. So the values you are seeing are within the expected range. (Accuracy data taken from https://www.dcrainmaker.com/2017/07/...2-trainer.html)


    From Wahoo: Kickr (Direct Drive) Accuracy: + / - 2%

    I've had some very interesting developments in follow up to my first 24hrs with the Vector3.... Very positive results after swapping the pedals over to another bike. Steady state ERG power numbers are within a MUCH more acceptable range (I was seeing +20W around the 200-220W ranges I tested in steady state ERG. This was after an initial install, 40km ride outside, sprints, settling them in, etc).

    The variables I need to isolate today are the bike (factors that I suspect could contribute to Neo vs Vector3 reading different: bike flex / crankset/ epic drivetrain losses(unlikely)).... and the pedal torque. Snugging them on EXTRA tight may be the answer to getting them to behave?

    As always.... more data required. I'm on the case.


  • Former Member
    0 Former Member over 7 years ago
    Those values may be right. You would expect Vector to be a little higher than the KICKR because of where it is measuring power. No drive chain loses.

    The KICKR has a claimed accuracy of +/- 5% or +/-3% for the snap V2. So the values you are seeing are within the expected range. (Accuracy data taken from https://www.dcrainmaker.com/2017/07/...2-trainer.html)


    I don't know about that. First, I'm comparing to the direct drive version of the KICKR (+/- 2%), not the Snap. Second, as I've previously posted, my Vector 2's track closely to the very same trainer:

    https://analyze.dcrainmaker.com/#/public/f432948e-a482-498e-6a08-9c907141ad2f[FONT="Helvetica Neue"][/FONT]
  • Former Member
    0 Former Member over 7 years ago
    Sorry I did not know what model of KICKR you had. Vector 1/2 had a claimed accuracy of +/- 1.5%, so not as tight as Vector 3.

    As far as I known, none of the KICKR models have built in temperature compensation. If they do then please let me know. This might explain the offset?
  • Former Member
    0 Former Member over 7 years ago
    As far as I know, the KICKR doesn’t have temperature compensation. I doubt it would need it as it typically operates in a more controlled environment (ie indoors).

    I don’t believe this explains the offset. Over several indoor rides, Ive compared Vectors 2 & 3 to the same KICKR using the same testing protocol and the Vector 3 appears to be the outlier.

    There seems to be an accuracy issue here. I just hope it’s a software issue that Garmin can fix through a firmware update rather than a hardware issue with my pedals.
  • 0 over 7 years ago
    As far as I know, the KICKR doesn’t have temperature compensation. I doubt it would need it as it typically operates in a more controlled environment (ie indoors).

    As a point of reference, I have used Kurt Kinetic Road Machines for years, and more recently also started using a BKool controlled trainer. After riding for anything over about half an hour, the KK's resistance unit reaches a temperature of between 50 and 60 degrees Celsius. All that effort you are putting in ends up being dissipated as heat in the trainer's resistance unit. If your trainer is actively controlled, like the Kickr or the Bkool units, then they need to dump your power as well as any electrical power they consume in performing the erg control functions. Thus, it is vitally important for such a trainer to have some kind of temperature compensation if you are going to use the trainer's resistance setting as the target.


    I don’t believe this explains the offset. Over several indoor rides, Ive compared Vectors 2 & 3 to the same KICKR using the same testing protocol and the Vector 3 appears to be the outlier.

    The most effective way to confirm the performance of either your Vector 2 or 3 pedals is to do a hanging weight test. I don't know of any equivalent test you can do on the Kickr.