Breaking news, everyone! I did some tests and it turns out that the power meter (Favero Assioma Pro MX1) I used for the problematic BT rides actually shows values ca. 6,2% higher than my indoor wahoo trainer. That seems to be a pretty substantial difference. Luckily, the Favero app has an offset option. After the offset, the tests came out pretty close.
So hopefully this will solve my problems with the fitness signature.
In the meantime thanks to everyone who contributed and helped me troubleshoot the problem. A very helpful and responsive community here.
Some good news. After establishing the offset, I corrected the problematic fit files and reuploaded them to Xert. Now Xert says my TP is 200 instead of 218. That is actually VERY close to my FTP established by Trainer Road. And based on that I did two Xert workouts on my trainer, with 3 dots each, and I managed to complete both. The difficulty felt just right, like I remember from my Trainer Road workouts.
I will do some more testing and keep an eye on the results from the outdoor rides, but it all looks promising.
Hi,
because of the differences between individual power sources, I actually swap the pedals around. I use Garmin Rally pedals on my bike outdoors, and for indoor riding I have an Elite Direto XRT with a Zwift Ride, where I then move the pedal over. Around spring, I ran into exactly this problem, see this discussion, where my indoor workouts started to feel quite hard after I began riding outside and mixing power data from different sources. Unfortunately, before I realized what was going on, I ended up overtraining quite a bit, which led to several issues that put me out of training for almost two months.
When doing any conversion, you also need to be careful because it behaves differently in steady-state efforts versus short intervals, where the difference may not be as noticeable. From other discussions, Iāve also noticed that the most commonly recommended approach is to keep using the same power source all the time.
Thanks, yes, this seems to be the approach that Xert recommends, and it definitely makes sense.
However in my case, life gets in the way. Most weeks I ride a mix of gravel, MTB and indoor, so thatās a lot of pedal swapping. For me, the downside is that swapping pedals from bike to trainer is an extra step, which steals precious time from the training, and over time creates extra friction, which may affect my consistency or motivation. Especially if the pedals are dirty from MTB, i feel the need to clean off the dirt and regrease the thread, otherwise there is this crunchy sound when I screw the pedals onā¦
Also, my wife sometimes uses the trainer, and she needs platform pedals, so I have hybrid spd/platform pedals on the trainer. If I start using power meter pedals on the rmtrainer, that would mean even more swappingā¦
I am willing to try the offset accepting that it will not be perfect. If this does not work over time, I will revisit my approach.
Iām also curious how it will be if I have to change it a few times a weekā¦ Maybe Iāll start looking for another solution if it starts to annoy me. One of the reasons I bought the Zwift Ride was so I wouldnāt have to put my road bike on the trainer and could just jump on and ride whenever I needed to. Too bad they donāt come with a power meterā¦
This is also the first time Iāve had to deal with this, because Iāve never used XERT before, and Iāve been riding outdoors based on heart rate, only tracking watts as a secondary metric.
This is exactly why I bought the Zwift Frame too - putting the bike on and off the trainer at least once a week is just not a realistic proposition for me, I know it will just lead to skipped trainings. IME, for long term success with repeated activities like training it is important for me to remove as many mundane friction points as possible - have everything ready reasonably quickly, at hand, without searching, without elaborate multi-step setup and so on.
But I understand that offseting the power measurement between the trainer and the pedal is not a straightforward fix, the power differences are non-linear. So I guess time will tell if my setup works for me or not.
