In-App PM Reading: Smart Trainer V. Pedals

I’ve been off the bike with an injury for a bit, and during that time I found a great deal on a smart trainer. It’s my first. Got it setup, synced, calibrated, etc. no problem. When using it this morning, I noticed that the TR app was reading both the trainer and my power pedals- 2 vastly different numbers (+/-15% or more). I hadn’t even thought to calibrate the pedals as I thought the trainer, in erg mode, would take the helm. Obviously the numbers from the pedals were out of whack, having not been calibrated in weeks and going from outdoor to indoor conditions. Once I realized this, I noticed the power reading displayed on my workout seemed like it might be showing an average of the 2 numbers? Is this something that might happen? It would go a long way for morale in explaining the massive loss of cycling fitness I’m experiencing! Or maybe the pedals have always read low and I was way stronger than I thought I was! I’m perfectly willing to accept that I just have a lot of work to do to get back to where I was but the whole scenario made me curious…

  • Just for clarity, did you see this info in the Devices menu and while pedaling along and watching values for the trainer and power meter pedals?
  • That is essentially backwards from what TR does when there are both a smart trainer and power meter paired to the app. Check out the PowerMatch support article for the official info.

  • Essentially, TR places the power meter at the top of the priority scale, and uses that data (not the trainer data) in the consideration that a power meter in use when you are on the trainer, and is used outside. It uses the power meter in order to maintain consistent power data for your rides in and out.

  • Nope, that is not at all what TR does. See above, TR displays the power data from the power meter, not the trainer or any form of combined value.
  • From the initial info shared above, you are seeing a notable difference between your trainer and power meter. Sadly, this is all too common here and you will find topics to that effect numbering in the hundreds.

  • First, it is important to calibrate your pedals regularly, just like the manufacturer recommends. That rings true for inside use just as much as outside use. Good practice is good practice. Get in the habit of doing the Zero Offset Calibration before each ride no matter where you are.

    • Who knows, but you may see the gap between your trainer and pedals close a bit once you get a proper calibration on the pedals.

    • In addition to calibrating your pedals, I’d also recommend doing a calibration on your trainer if you have not done so. Depending on the trainer you got, calibration frequency varies. Most wheel-on trainers should be done each and every ride after a 5-10 minute warmup for best results. Most wheel-off trainers should be done at least once per month, or anytime you move the trainer between different environmental conditions, and done after 5-10 minute warmup for best results.

    • For the record, TR says that calibration of the trainer is not necessary if you are using a power meter and PowerMatch. Regardless of that I still think it’s generally good advice. Adding to that, for anyone ever wanting to compare data like you were doing in the Devices menu, proper calibration of the trainer and power meter are essential.

  • Second, doing the above, and continuing to use PowerMatch (via pairing trainer and power meter) is your best course of action. This keeps your data consistent between your workout in and out.


Yes, I noticed the difference in the devices menu. I’ve been using TR for about a year but I always just scheduled the workouts as “outside”, sent them to my Garmin, and hit the numbers using my non-smart fluid trainer (when riding indoors) just because I didn’t want to use a phone/laptop/tablet. When I got this new Saris H3, I got a phone mount and started using the TR app proper, so I’m still figuring things out (smart trainer and app). For what it’s worth, the app is great- the workout cues and drills are an awesome addition and it’s totally silly in hindsight that I hadn’t been doing it this way sooner. The pedal calibration was totally an early AM un-caffeinated oversight on my part. I typically calibrate every ride, especially when changing environments.

If I understand correctly, it sounds like the TR app will default to the PM, in this case, the pedals (Assioma Duo), which if they were reading low would go some ways to explaining what I experienced. I would have to push that 10-15% harder on the trainer (assuming it was accurate) for the pedals to register the correct power for the intervals. Regardless- it’s all good! I appreciate the reply and will get things dialed in.

1 Like

Yup, you got it all right there. :smiley:

Thanks! I hastily set things up, eager to get pedaling again… wasn’t even trying to use Power Match or anything yet. I didn’t even know the pedals were paired. Lots of fun stuff to delve into!