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Power Differences Between Edge 1040 Solar vs 1030 Plus vs Epix 2

CLYDESDALE1
over 2 years ago

I have two different Stages Generation 3 power meters on my 2 bikes.   Over several rides on my 23-mile loop on the two different bikes, the 1040 Solar consistently reads 7 watts lower than the 1030 Plus. This seems like a pretty big difference.  The Epix 2 reads consistently 2 watts lower than the 1040 Solar.  This is a small difference, and I can understand this.  I have all three units set to the same settings with the power averaging including zeros, smart recording, etc…... All three units show very close to the same time, distance and speed.  Has anybody else compared any of these units?  

Thanks

  • 0 over 2 years ago

    I would need to see the activity files from the different units recorded on the same ride to get an idea of what might be happening. 

  • 0 over 2 years ago

    Is crank arm length setting the same on all three devices?  I'm not sure if that will affect it or not.

  • 0 over 2 years ago in reply to eallison978

    Yes the crank arm lengths on both bikes are the same.  But the 7 watt average power difference between the 1040 and the 1030+ shows up on both bikes.   The normalized powers are closer with the 1040 NP = 174 watts, 1030+ Plus NP = 178 watts, Epix NP = 175 watts.

  • 0 over 2 years ago

    7w is nothing. % wise it’s small and on different rides hard to draw any conclusions.

    I’d say you need to test it on exactly the same ride to have any confidence that there is an issue. 

  • 0 over 2 years ago

    Are you recording with all three devices at the same time on the same ride and comparing?

  • 0 over 2 years ago in reply to eallison978

    Yes, I have all three units recording on the same rides.  I have done this using both bikes too.   A 5% error seems like a lot between the 1040 and the 1030+, But who knows?     

  • 0 over 2 years ago in reply to CLYDESDALE1

    In my opinion, there should be absoultely no differences in any of the devices.  They should all ready exactly the same.  They "should" be taking the number given to them by the power meter and averaging it across the ride.

    I asked about the crank length setting in the devices because that could potentially cause some math differences.  What I'm not sure about is if that number is passed to the power meter at the time when you set it, and the device never does anything with it beyond that moment, or if it somehow figures in with the algorithm that determines the average power.

  • 0 over 2 years ago in reply to eallison978

    You are assuming that all three units are receiving 100% of the data packets being sent. This is unlikely and depending on what packets are missed could impact the values.

    Most power meters do not send power. Then send torque and cadence based on either a fixed time interval or based on an event such as a completed crank revolution. The head unit then computes power using that data over the sampling period.

    The only way to really know what is going on is to unpack teh FIT activity files and look at the data.

  • 0 over 2 years ago in reply to aweatherall

    Excellent point , I had not considered packet loss.