This winter I’ve been using my Tacx Neo 2T smart for TR and done exclusively indoors workouts, but as the winter slowly comes to an end I will start doing some endurance outdoors. I have the Garmin Rally power pedals and I know the reading is not exactly the same so here’s my question: How to do it without mixing outdoors/indoors FTP and different power meters? I will get a new AI FTP in a few days, should I just wait until then and switch to using the pedals for all power data? I feel like using pedals outdoors and trainer indoors would skew the results a bit.
Maybe do one session where I record a duplicate workout with the pedals to get a feel on the difference, probably I’m overthinking this?
Yep - you are overthinking it. The best thing would be to use the same power source for all workouts. However, they will be close enough that it is not something to stress about. Just ride and do the workouts.
I do a couple dual recorded sessions to see what the difference is. Unless it’s huge I then promptly forget there’s a difference and keep training. I had a Kickr Core that was reading 30W higher than my Assiomas. That I would alter things but I replaced that trainer a while back. My JetBlack Victory reads 3-4W high. I’m not concerned with that.
Yep. I put my bikes with PMs on my trainer and recorded their power separately. The trainer and PMs are all within +/-5W steady-state, which is plenty close enough for training purposes. When I’m serious about tracking my FTP, I do the tests as close to the same way a possible, which is much easier to do on the trainer.
In the past, I tried “power match” where I had a PM on the bike on the trainer. With power-match, the app uses the PM for power and controls the trainer by that. In my experience, the speed of response and steadiness of power regulation was poor compared to simply using the trainer for power, so I’ve since just used the trainer for power. That said, apps my have gotten better at “power-match”, but I’m happy with sticking with the trainer power for indoor workouts as it’s plenty close enough.
Not unless previous Kickr, 2 Magene spider power meters, and a Sigeyi spider power meter are also 30W low. All my power meters read within 1-2W except the Kickr Core.
Related, even Zwift saw the issue and had to postpone a pro event because trainers were way off.
Which app, TR? Sounds like they got it working well. I happen to have my backup road bike with no PM dedicated to the trainer and my Assioma Duos on my gravel bike so it’s easier to just use the trainer for power rather than swap bikes or pedals.
If it’s the same bike on the trainer and outdoors, use the Power Match feature.
Before doing that, though, do a dual recording (Neo 2T to TrainerRoad, pedals to your head unit, heart rate going to both if possible) and use DC Rainmaker’s comparison tool to see how different they are. If they’re vastly different, use Power Match and do a ramp test. If they’re only a few watts different, just do Power Match and keep on training.
If they’re vastly different and you just wait for AI FTP to sort it out, you’ll end up under- or over-training.
To add to that, the difference can change over time. When my Suito was new, it was bang on with my Quarq DZero. Now the two are quite far apart with a difference in slope and offset.
Totally true, they can change over time. Between your Suito and Dzero, which do you think changed, if not both of them? I compared my Duos to the Hammer when I first got them (Mar 2019), and several times since, most recently a couple of weeks ago. So far, they stayed within a ~5 Watts of each other with the pedals reading higher. Of course they both could have changed in the same direction. I need to put my mtbs with PMs on the trainer again to see how they compare.
I chose to trust the numbers of the DZero: it is the power meter I use when I am riding outdoors. Plus, it has an excellent reputation.
Of course, I could settle the issue if I bought Assioma pedal-based power meters … but at a certain point I have to accept I’m not dcrainmaker or gplama with drawers full of power meters. Or a lab.
Our top recommendation, though, would be to use PowerMatch so that all of your power data comes from one power meter. It’s often recommended to perform an FTP assessment when changing power meters, but if you can clearly tell how far off the readings are between your pedals and your trainer, you could try manually adjusting your FTP on your TR Account page. If it’s only a few watts off, though, we’d agree with others saying that it wouldn’t be worth worrying about – that discrepancy will come out in the wash and you probably won’t notice it much after using the pedals for a bit.
Hope that helps – feel free to let us know if you have any other questions!
Totally. I spread it out over 10 years getting my smart trainer in 2015 and my 3rd PM (Sigeyi spider) last summer. Prices have come way down over that time. My trainer’s list price was $1300 and the Sigeyi PM was $350.
Did 2h of endurance today, laptop had TR open and was connected to the Tacx NEO 2T and Garmin Edge connected to the calibrated Rally pedals. In the end the pedals reported my average power to be 12 W lower than the trainer. Not great but not bad either I guess. The pedals being one sided could definitely be a part of this as well. Combined with the measuring error on both the pedals and trainer I think it’s in the ball park.
Also the power graph coming from the pedals is not nearly as smooth as the trainer.
I will try updating the firmware on both and then try again soon
Could easily be the one sided pedal as you say. A 47/53 imbalance in your pedal stroke is not uncommon at all, and will account for a 12W discrepancy at 200W.
Yeah, unfortunately you are comparing apples and oranges. There is really no comparison between a trainer and a single-sided PM.
However, don’t just compare the average power. Use DC Rainmakers analyzer to compare the data from both across the entire ride so you can see where the differences lie. (But even this will be of limited use due to the nature of the two PM’s.)
Normal, from my (limited) experience. When I compared my Favero and Speedplay PM pedals vs. my H3, the pedal data graphs were much more jagged / stochastic than the trainer.
