Need help with zwift

I need someone that knows zwift and/saris trainers to assist me please. Hoping they can call me to talk through the issue I am having. I live in Canada est time zone speak only English. Text me at 705-927-2 9 5 9 please to set up chat time.

Here my issues and history.

I bought a saris Magnus trainer used January 2024. It seemed to work fine all through last winter. I basically only use it for racing. I am (was) a “D” rider and my race score up until tonight was 177 (ish). I ride 3 to 4 times a week. I started to use again I the fall 2024 and was working fine. However a few times it dropped the “pairing” and lost my rides. I think i have solved that issue but if anyone has insight I will take it. The real issue is at some point a few weeks ago I went for a ride and the power / speed was all off. I could generate watts or anything. Was half the speed and power for same effort as I normally do. This occurred on the next race too. I emailed saris and they had me download app and upload firmware which seemed to fix it. Then it happens again. Same thing ride so slow and power so low that I could t even finish race. Uploaded firmware again and no fix. Called saris and they said try calibrating which I did. Then went for ride and my power and speed etc was right in line with where I was normally (where I thought I should be) this was last week (end of January 2025). Tonight went for a category sprint bump race and all of a sudden I can stay with “A” riders, my average watts are 340 (normally 220) and my avg speed jumped 20km/hr. Also didn’t feel anything like a hard ride. End of ride my ftp jump 100 and went from 177 race score to mid 300’s. I need to know what’s causing this. Also need to know what is correct. I am hoping someone has experienced this or knows how to fix it and confirm that it accurate.

The only other thing that comes into play is my wife uses the trainer with her own zwift account. We change bikes off it but that’s it. Tires are inflated, yellow knob tight, etc. I just don’t know why the discrepancy. I have all the race results and data to show swings from low to high etc.

Please help.

Saris recommends calibrating the Magnus (M2) trainer before every ride. The need for frequent calibration is a drawback of wheel-on trainers. If you leave a single bike on the trainer and maintain very consistent tire pressure and room temperature, perhaps you can get away with slightly less frequent calibration but it’s something you will have to do with annoying regularity especially if you are swapping bikes.

There’s no way to validate the power numbers you get from the trainer without having a second power meter.

Wheel on trainers are not very accurate without some sort of power meters being added as Paul has said. Smart trainers are much better and I have 2 Saris H3’s you can have if you ever come to Toronto and want to pick them up. They are essentially new, but I had a problem with with reception and the watts would occasionally drop out for a second or 2. The avatar did not stop, the ride did not end and al the data was there at the end of the ride - it was just annoying so I switched to a different trainer. They are set up for a shimano 10 speed cassett. Let me know if you are interested.