Cycleops Magnus and power

I am coming back to cycling and got myself a Cycleops Magnus trainer. At first I thought it would be super easy to use it with Zwift since they are even offered at Zwift website. After my first ride I felt the power a little weird so I read a little bit and found out that:

  • I have to calibrate it every time I use it (???)
  • The calibration should be done after a 10 min warmup
  • And to makes things worse the calibration should be done outside of Zwift using Rouvy App

This makes the user experience very bad at best. You warmup for 10 minutes on Rouvy, calibrate in Rouvy, get out of the bike, turn off Rouvy, connect to Zwift start a ride and then you have to warm up again at the beginning of the ride. This makes a 1 hour workout more like a 1h20min workout…

I would just like to wake up hop on my bike and ride without all this hassle and from what I understand the CycleOps Magus + Zwift does not allow that. In my opinion, Zwift should be able to calibrate your trainer while you warmup in the beginning of your workout session, shouldn’t be more complicated than that.

I was thinking of buying a Garmin Vector 3s to use as my power source while in Zwift, would this solve the problem? Can I use the Garmin Vector 3s to measure power in Zwift while Zwift control my Cycleops Magnus resistance?

What setup do you guys recommend to solve this issue?

Yes, I know it sounds like overkill! Personally I always did cold (no 10-minute warmup) calibrations on my Magnus in the Rouvy app before even I fired up Zwift and got consistent results. I still have my Magnus but I am using Favero Assiomas for power instead of the Magnus itself, and I never saw what the big deal about warm calibrations was. Others may disagree, but it worked for me (shrugs).

I used the Magnus for 2 years and only did rare calibrations and it worked great.

Just bought my Magnus and signed up for Zwift. Thought it would be great, but I get no resistance changes. And have yet to know if my rouvy calibrations are working. It just says keep pedaling…I finally stop and let it spin down and it says success. Then I start a zwift race and my avatar is so fast i have to stop trash the ride close zwift, start rouvy, try another calibration. All while my Peloton buddy gets to make fun of my decision.

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Jeremy, be sure to pair your Magnus as a controllable trainer in Zwift. Go for the FE-C option if you’re using a ANT+ connection. Do not, I repeat, not use Zwift to calibrate! You will be cranking out 1000 watts barely pushing the pedals like I did. Always do your spindowns in Rouvy while Zwift is not running.

I connect through Bluetooth, and there is a calibrate option right next to the trainer when you pair. Calibrates fine. I do this (cold) almost every ride, it doesn’t take more than a couple minutes, and you’re right back in the Zwift screen when done.

I have a similar set-up as you, except I have the M2 - the newer version of the Magnus. It’s a slight inconvenience to have to calibrate in Rouvy, but it’s quite straightforward. It seems accurate most of the time, thought lately, Rouvy tells me my calibration is a ‘success’, even though my rear wheel hasn’t stopped spinning down completely. I tend to do just a few minutes on the trainer, and haven’t ever a complete 10-minute warm-up. I connect to Zwift through AppleTV and Bluetooth. I haven’t had any trouble getting cadence, power, speed or HR (wahoo tickr) paired. Sometimes I’ve had to make sure Rouvy was shutdown/closed on my phone, and sometimes I’ve had to release my connection to Rouvy by turning Bluetooth off and then repairing the M2.

Everything had been working great, in both ERG-Training/Workout mode, and Ride mode. Randomly, just a couple of days ago, after about a month of having no issues, it seemed like it was stuck in ERG mode no matter that I was doing. A +15% grade felt the same as a -5%; nothing seemed to fix it. I ended up uninstalling Zwift and reinstalling it on my AppleTV, and I was back in business. I also have never used the calibration function in Zwift.

I also have the M2 trainer, which Zwift sold to me in a package as a recommended trainer. They have known about the calibration issue for a year, but tell everyone to use Rouvy to calibrate the trainer. I have the same issue as Dave, the Rouvy calibration reports a spin-down time before the rear wheel has stopped. I now have a Stages Power meter on a crank arm, and it consistently reports power 20-30W lower than Zwift, often much more, which is consistent with the spin-down thinking the rolling resistance is higher than it is, which would result if it thinks the wheel is stopping sooner than it does. CycleOps tech support told me if power accuracy is important in my training, I should use some other way to measure it. This is quite an admission given they claim +/- 5% accuracy for power. I have given up; although it is harder to make the connections, I will use my Stages meter for power on Zwift from now on so that I have more realistic speeds and a better idea of the training effect of my Zwift rides. This is disappointing given that with some effort, this should be an easy problem to fix.