Weird PowerMatch / ERG Mode Numbers?

Hello, I have been using Trainerroad consistently for about 5 months using a Tacx Vortex. I recently purchased a 4iiii left crank power meter to finally have power for outdoor riding as well as have more accurate power readings on the trainer. However, I feel like when I’m using the PowerMatch feature with ERG mode on the trainer I’m getting weird “spikes”. I feel like my power is pretty consistent and then my power will fluctuate between +/- 20 Watts usually and sometimes I feel like its even 30-40 Watts on occasion, I’m not saying I know I put out ultra-consistent power, but with intervals usually being around 200W target I feel like I would notice if I suddenly dropped my effort by 20%. Also, it seems like the only solution is to change up my cadence before power numbers start to go back on target.

Another similar issue Is that at the start of an interval my power seems very high (about 50W+ over target sometimes), and even though my trainer is in ERG mode the resistance will not change at all to match target power for about the first minute.

I think the issue is the Vortex giving me weird numbers and it almost seems like the power being displayed is flipping between my power meter reading, and my Tacx Vortex Readings. Another example of my indoor power numbers being strange is that on outdoor rides it seems like my power is decently higher than my indoor power. Today I did a fairly endurance-focused 3 hours, 50-mile ride and my numbers gave me a completely new power curve from 1 second to 2 hours and I don’t even feel like I was pushing myself.

I was wondering what you guys suggest I do. I’ve calibrated my power meter and trainer in the TrainerRoad app, and I currently have it set to PowerMatch auto as well. Is there something in settings I need to change? Should I just start using resistance mode on the trainer (if that even makes a difference)?

Sorry for the lengthy post but as you can imagine this issue can be incredibly frustrating at times,
thanks in advance.

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I’ve experienced a similar thing on my tacx vortex and ngeco power meter. Sometimes the start of an interval will overshoot 50+ W and not drop back down. I’ve had to pause and restart workouts to try to get the power to lock onto the correct target.
One thing I did change when I switched from trainer power to my power meter was adding 10 seconds of smoothing so I wasn’t watching the small fluctuations / brief mismatches. This only changes the displayed power and not what gets recorded.

Can you share a ride with the behavior you are describing?

Here’s one from last week

There’s a ton more power variation in there than I would expect to see from an ERG session on a smart trainer. It’s hard to tell what is causing the power to jump so significantly

For comparison this is part of my ride on Saturday with ERG and power match - so theoretically a less stable line should be expected due to power match

Interestingly I just wrote to Wattbike about this as I’m getting the exact same thing on my Atom and assumed hardware as it’s fine on my wheel-on trainer.

The swings are even bigger at the start of an interval, kept hitting over 500W when I was supposed to be targeting 300 on Friday, then it’d drop down to 170ish and keep swinging back and forth.

All over the place on a nice smooth one like Pettit too:

Do you have any subscriptions to anything else, could you try a Zwift workout to rule out hardware issues?

Well, as if the waters weren’t muddy enough yet. Don’t have Zwift but I may be able to push the workout to my Garmin then use the Garmin to control my trainer, we’ll see.

Yeah, seeing that definitely makes me think I have a serious hardware issue somewhere.

Hey @CamKimner,

I would recommend reaching out to our Support Team at to help you troubleshoot this issue. They can take a close look at your logs and should be able to give you a better idea of what is going on.

I do have one tip that you can try out in the meantime. To improve the performance of your smart trainer using PowerMatch, you can try using a smaller gear. Drop into your small ring in the front and use an easier gear in the back. This decreases the inertia of the freewheel and makes it easier for your trainer to execute ERG commands successfully.

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