Dual Power Source Ramp Test

Hi friends,
I’ve known about a significant power differential between my Powertap P1 (left only) power pedal and my Elite Direto trainer for awhile, and for today’s ramp test I decided to run both separately. My methodology was probably not ideal: I paired the power meter to my Garmin and hit the lap button for each step of the ramp (that cognitive load is worth a few extra watts, right?). I forgot to hit it at the most crucial moment near the end of the test, but Garmin Connect says my Max Average 1 min power from the power meter was 423 W (18:34-19:33) vs. just 368 W (18:28-19:27) on the Direto. 58 watts is a massive difference!

TR gave me a new FTP of 276, which is a 12-watt increase since my last Direto-only ramp test 3 months ago. Taking 75% of my max minute with the power meter gives me 317, a 17 watts up from my last Powertap-only ramp test 6 weeks ago.

Calibrated both power sources during the warmup.

The photos show the steps for each file from Strava for comparison.

I guess I’m just asking for general insights on this disparity. I have no idea which is more accurate. Based on riding with others, I kind of suspect the truth is somewhere in the middle, but that might be wishful thinking. Moving forward I plan to use the Direto power indoors and the Powertap outdoors, just making the 13% adjustment to my targets.

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Why not use the pedals full time with power match? Indoor and outdoor power is the same then. This is what I do with my Vector 3S pedals and Kickr 2018. Works great.


I have done that, but it’s nice to keep the power pedal on my main outdoor bike rather than swapping all the time. It just takes a minute but it’s an extra step.

I’d also advocate using Powermatch. My Elite Turbo Muin reads too high at lower power and too low at higher power. Using my Rotor LT I know it’s consistent both indoors and out!

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“It just takes a minute” and your problems are solved. :wink:

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Yes been there done that. I have P1S and Elite Zumo around 30W difference

If you email elite they will ask you to record a power test on their app and eventually give you a file to download and update your trainer so that the trainer curve matches better to your pedals.

This improved things a lot for me but not enough to be confident in the trainer, I switched to use it PML linking the pedals to the trainer. Powermatch in the TrainerRoad app is another option.

There a few threads if you search Zumo and PML.

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