CycleOps Magnus Smart Trainer… First Ride(s) Impressions


  • Overall fit, finish and bike mounting is fine… basically what I expected.
  • Ride feel isn’t great, but about what I expected for this type of trainer.
  • Accuracy currently is not meeting my expectations.
    • Out of the box accuracy was high by more than 40w over my PowerTap Hub and PowerTap pedals… a 32.2% error… ouch!
    • There is no means (that I could find) to calibrate the Magnus using the PowerTap iPhone App,  Garmin devices, or the new TrainerRoad app.  They report calibration errors, crash or don’t provide a spin down option.  The only available option I found that worked is the CycleOps Virtual Training App.
    • After calibration using VT (and a 15 min warmup), the Magnus was 11w low or 5.4%.  The following day it was 10.8% low over a 1.5 hour ride without recalibrating.  For my third ride I did another 20 minute warmup with 4 consecutive calibration efforts, and was able to get my best accuracy… 4.5% low.
  • Response via email has been a disappointment.  I sent an email describing the calibration issue 8 days ago, with an automated response coming back the same day. No other response has been received.
  • At this point, I can’t recommend this product, until the accuracy issues are resolved, and the calibration is available on via another means than a paid subscription service. 


CycleOps Magnus Early Impressions:

I’ve always felt that doing very targeted intensity rides indoors on the trainer is one of the most effective ways of building power.  No stop signs, traffic concerns, weather… just you focusing on meeting your interval targets.  Using a traditional trainer with a power meter is great, but I believe smart trainers can be even more effective by allowing a wider range of cadences, generating very consistent power on intervals, and showing you no mercy on your workouts as a whole.  🙂

I had one of the original CompuTrainers.  It was okay several years ago, but I did have recurring problems with excessive tire wear.  I then went to a Wahoo Kickr, which was a fantastic upgrade. I have an article comparing the two from several years ago, located here.  Recently there have a lot of new products out in the market, with “lower” priced options around $600.  With a recent 20% holiday sale, I thought it was time to invest in a second trainer for my family, and chose a CycleOps Magnus trainer.

I had the opportunity to get a few rides in with the new Magnus trainer, and for comparison purposes, put a wheel with a PowerTab hub, as well as PowerTap P1 pedals. Here are my initial impressions on the general design:

  • It was easy to assemble, taking only a few minutes.
  • It is significantly lighter than the Wahoo Kickr (20 lbs vs 46 lbs).  l feel like this is something I could move to another location (e.g. group indoor ride, using it for FTP tests for athletes I coach, etc.) without a problem.
  • I like the easy locking mechanism for the skewer.  It’s quick and simple, and much faster than my Kurt Kinetic standard trainer, which uses a screw type mechanism.  It’s easier as a whole to put a bike on a wheel-on trainer than a wheel-off trainer like the Kickr.
  • I think the mechanism to tighten the trainer to the wheel is interesting.  You simply tighten it until it makes a clicking sound.  Theoretically this should make for great ride to ride consistency.  I was surprised that it did create more deflection in the tire than I would have tightened myself.

CycleOps Magnus next to the Wahoo Kickr

First ride performance impressions, tests, and frustrations:

  • From a ride standpoint, it isn’t as smooth as the Kickr.  The advantage of the light weight means less flywheel, so it feels less “road like”, which isn’t a huge deal to me. I think the lighter flywheel also means less consistency to a degree, as I noticed much more power variability than I see on the Kickr.
  • There was nothing in the literature discussing operation.  In particular, I was looking for calibration or zero offset procedure.  With no information, I tried riding it with no calibration change, as shipped from the factory.  I calibrated my PT hub and pedals, and then started my ride.  It wasn’t an impressive start:
  • Magnus from the factory, no change in calibration.

    Magnus from the factory, no change in calibration.







  • You can see a rather significant difference between the Magnus and the other two power meters.  The pedals averaged 6.7 watts higher than the hub, which makes sense for drive losses.  Unfortunately the Magnus read 46.8w higher than the hub… way out of calibration.
  • I stopped the ride and again looked at options for calibration.  I tried using a Garmin device, and it simply indicated calibration failed.  I tried using the PowerTap iPhone app.  I could connect to the Magnus fine.  When I tried to calibrate the device, the app would crash.  I tried the TrainerRoad option.  Under the new version of TR, there was no calibration option available.  I then tried the old version of TR, and if I connected on Ant+ FE-C and found a spin down option. I ran it, and found that it made the calibration much worse.  I was seeing 100-110w on my hub, and over 300w on the Magnus… not good.  I finally got my iPad out with the CycleOps VirtualTraining app.  There was a calibration mode for the Magnus.  It has you ride for 2 minutes, and then it does a spin down.
  • I performed the calibration three times with some riding in between, and the numbers looked much closer.  After calibration, the numbers significantly improved:
  • Magnus after calibration.

    Magnus after calibration.









  • After the calibration, the Magus was reading lower than the other two power meters, but much closer.  Again the pedals were higher than the hub, by 5.6w and the Magnus was now reading 10.4w lower than the hub… slightly worse than the 5% accuracy spec. at 5.8%.
  • For my second ride I did a 1.5 hour ride, without calibrating the Magnus to see if there was day to day variability.  This ride was one day after my first ride, without removing the bike, and essentially no space temperature changes.  I did pump up the tire to the original pressure, and tightened the knob until it clicked.  I also calibrated the other two power meters.  The Magnus power was reading noticeably low the entire ride, and ended up being 10.8% low compared to the hub.
  • I did a third ride a few days later.  I did a solid 15 minute effort, calibrated my power meters, and did four calibrations via VirtualTrainer on the Magnus.  Simply looking at the power meter differences in real time, the subsequent calibrations appeared to help improve tracking.  As I rode, I could see the numbers were closer, and in the end the average power was within 8w (low again), resulting in an overall deviation of 4.5%.

After my first weekend of rides, I sent much of the information off to customer service, for help on the accuracy issue as well as the calibration.  After 8 days… no response other than the automated email on the day I sent in my request.  I realize it’s the holiday season, but I’ve gotten several responses from TrainerRoad (as I discussed the lack of calibration options) and a couple of responses from BSX Insight on some questions on their running power meter data.  The point is… from other technology companies I’ve gotten great responses in the past week, and no response from CycleOps.

Why does the accuracy matter anyway?

  • From a practical standpoint, when using ERG mode (power output controlled automatically) if your trainer is consistently low relative to your actual power, it means that apps like TrainerRoad will push beyond the specified workout intensity.  This means that Sweet Spot focused workouts suddenly become FTP workouts… FTP workouts end up in the VO2 max realm.  Consistently overworking specified workouts can create excess/accumulated fatigue and possibly overtraining… which you’d never see in a Performance Management Chart, as your Intensity Factors and Training Stress Scores will all be under reported.  On the opposite end of the spectrum, consistently overstated workouts will result in lower than expected fitness over time… possibly wasting your precious time and energy.
  • For a longer discussion on accuracy and precision in non-smart trainers, see another blog I wrote here.

Final thoughts:

  • I would expect the accuracy issue can be overcome fairly easily via an upgrade the calibration app, and/or a firmware upgrade.  The out of the box accuracy was so poor… if you don’t have a power meter to verify accuracy it could lead you astray badly.
  • The lack of calibration support (other than the VirtualTrainer app) will be a challenge for those who are not customers of VirtualTraining.  CycleOps needs to get this into a phone app, as well as supporting TrainerRoad or other mainstream training applications.
  • At this point, I wouldn’t recommend the Magnus trainer until the accuracy and calibration issues are resolved.

Update 1/7/17

  • Seeing my blog, CycleOps VirtualTraining assured me that the free versions of their application will allow the unit to be calibrated, without a paid subscription.  I updated my verbiage accordingly.
  • I originally sent my first email to CycleOps on 12/20/16, and did not receive a response other than the automated email saying they received my email, and it would be answered in the order received.  I sent a follow up email on 1/3/16, with another automated response my email was received.  CycleOps has not responded or addressed anything… truly the worst service I’ve encountered on an exercise related product.