Vector 3 Power Imbalance

I am riding on a trainer right now

I have a Garmin Forerunner 945 as my main recording tool (I do not have a head unit and trying to avoid buying one until next spring when I can get outdoors again)

I manage my Vector 3 (just go them a week ago) from my iPhone and currently running firmware version 3.80

I have tried the standard rotate the pedals till they wake up and leave them in the horizontal position so they can auto offset (I have this turned on).  I also leave them in this position when I'm done with my ride.

I have done two rides (45 min, 1 hour) at a pace to keep my heart rate low.  Since i'm a novice this means my power is ~125W and my speed between 18-20MPH.

Problem is my power balance is very Imbalanced.  My concern is I don't know if this is "real" or something is off with the pedals.    If it is real, I can at least work with somebody to correct this.  Personally I did not buy the power meters to measure my power.  I got them to give me feedback on my technique to make sure i'm not developing less than ideal habits.  

So...is there anything I can do to begin to figure out if the meters are right or is it me?

  • Have you done a manual calibration from the FR945? After a pedal installation you will need to do a manual calibration. The auto-calibrate function will handle small changes associated with temperature change, but not large changes caused by the installation process.

  • This is interesting.  The watch only has feature for "calibration prompt" as an option and nothing else in that regards.  Would this do it?  Documentation when not using a bike computer is basically non-existent.  Thanks again for your reply.  

      

  • You should be able to do a manual calibration using the watch, but you will need to be in communication with the sensor.

    Select your activity profile E.g. Bike. Then press and hold the up button. This will bring up a menu. The first item should be calibrate if you in communication with the power meter.

  • Just wanted to say this helped a ton.  Still an imbalance but nothing crazy anymore (43%/57%).   I guess I have a follow on question is do I keep doing this until it gets closer to 50/50?  At running such a lower power output today (100W avg) that I would not expect much since I was never really pushing hard (just a zone 2 heart rate effort).

  • It is always recommend to calibrate before a ride, but if the conditions at the start of next ride are similar to those at the end of the previous ride then you can likely let the auto-zero handle it.

    For me my imbalance is much greater at lower power levels as the dominate leg does proportionally more work, once the power level increases I have to incorporate both legs more equally and the balance becomes much more even and under extreme load it may even switch slightly to the other leg.

  • Again...thanks for the feedback.   Tried some tests last night at very light riding for 1/4 mile

    • Made sure my bike was level : 43%/57% (same as just above)
    • Intentionally used my "left" leg only'ish: 70%/30%
    • Had my friend use it (same shoe size): 48%/52%

    This is giving me a bit of confidence that the meter is working okay'ish but also causing me some concern that in thinking i'm so imbalanced do I need physical therapy (PT)?  Considering i'm pushing towards a half IM next August....

  • As @aweatherall noted, at very light efforts it is not uncommon to see a substantial imbalance.

    If you do want to try to practice pedaling skills, many training programs incorporate pedaling drills where you substantially focus on one leg (or even unclip one side, when the bike is mounted on a stationary trainer) and this might help you develop muscle activation. But again, it is quite common to have some imbalance and is not necessarily an indication that there is anything that requires intervention with physical therapy.

  • I own all three versions of Vector pedals.  I am ancient, but still riding a lot.  I injured my left knee years ago playing basketball, and finally had to have a knee replacement in March of 2017.  I did my physical therapy, and I still do some leg exercises at the gym.  I feel that my legs are close to equal in strength.

    My Vector1 pedals tend to measure my balance at about 48% - 52%.  Vector2 is usually 46% - 54%, and Vector3 is usually 50% - 50%.  The three units also tend to show different power levels, with Vector3 generally highest, but the difference isn't great, 10% or less.

    The Vector3 pedals issued a message a week or so ago that the right pedal had come unpaired to the left.  I saw power fall to roughly half what I usually produce, but after awhile, I was getting figures in my ballpark.  I think the left took over and acting like a 3S unit.  Today, I noticed that balance and other info was missing.  I paired the right pedal again (which is a pain - I cannot read the tiny etched number without a magnifying glass, so I wrote it on the outside of the pedal box for future reference).  I'll see if everything is OK tomorrow.

    The fact you are seeing left and right figures indicates your pedals are paired.

    I think I'd go for a "real" ride - at your normal levels of effort, for at least 30 minutes, and see what results you get.