Handling Outdoor Workouts When Power Meter is Inaccurate

I just started TR last week and have been loving it so far. Currently I’m on a low volume plan with 2 indoor workouts per week and a longer outdoor workout on the weekend. This past Saturday was my first outdoor TR workout and I thought it felt pretty easy. I noticed today on my indoor interval session that my bike’s power meter was reading about 10-15% higher than the smart trainer (which would explain while my efforts felt so easy).

My road bike has a left side 4iii power meter, and for indoor training I have an older Wahoo Kickr (v4/2018, I believe). I don’t want to make this a power meter thread - I’m perfectly fine with them reading differently - and frankly I’m not sure which meter is more accurate… I’m just wondering how I should handle the outdoor workouts knowing that my bike’s power meter seems to read high. Is there a way to bump up the difficultly of each outdoor session sort of how I see that option during indoor training to change the intensity? Or should I just shoot for power numbers 10-15% higher when riding outdoors? Any suggestions?

You didn’t use power match in the app?

If both meters are accurate, a crank based power meter should read marginally higher because of drivetrain losses before you get to the hub-based PM of the trainer. But the 10-15% you’re saying sounds a bit excessive. You could try putting your bike on another trainer & seeing if it’s just your trainer. If it gives the same discrepancy then it could be that your power meter is out & needs its sensitivity (“slope”) adjusted. Another thought is you could simply be pushing quite a bit harder with your left foot than your right, because a left-only power meter doesn’t know what the right is doing & will presume that the right is supplying the same power as the left. You’ll only know if that’s the case by testing with a dual-sided power meter & looking at the balance. As ArHu74 suggests, using the power match setting should solve this.

Hey @AMack6 :slight_smile:

It’s normal for your power meter and smart trainer to have different power readings, so Iike @ArHu74 and @roleypup I would recommend using PowerMatch.

Put simply, PowerMatch will use the power readings from your power meter to control your smart trainer. TrainerRoad will measure the power offset between your power meter and smart trainer; it will then adjust the resistance of your smart trainer based on that offset in power and the current interval target.

PowerMatch lets you get consistent power readings from their power meter both indoors and outdoors without having to give up the benefits of their smart trainer!

More info on how to use PowerMatch here:

Note: make sure to perform a calibration to both your trainer and 4iii power meter to make sure they are both reading power accurately.

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So actually I have a dual sided power meter on my gravel bike (which I can’t put on my trainer because it’s Sram XDR and the trainer is set up for Shimano), and historically my imbalance between L/R was slightly in favor of right (usually 51, 52 or 53 right).

I’ll look into this PowerMatch feature - I didn’t even know it existed. Thank you!

Aside from PowerMatch, assuming both power meters are “correct” (as far as that goes) and you’re regularly completing indoor and outdoor workouts, you could just aim to complete the outdoor workouts at the top of the prescribed range. Most outdoor workouts will have a ~20W range which spans ~10W in either direction from the target.