Page 2 of 2 FirstFirst 12
Results 26 to 41 of 41
  1. #26
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Quote Originally Posted by DaveG View Post
    Today I tried a ride with the CycleOps CVT software. This software does not let you scale the grade like Zwift. I saw the same difference in wattage between the Magnus and the PowerTap. I did learn one reason why you might want to use the scaling and that is gearing. The bike on my trainer is set up for the flats with a standard crank set and a small range cassette. I was really struggling on some grades. On the steepest part of my ride, all of a sudden I could barely turn over the pedals but the Magnus said I was putting out less than 50 watts I stopped, thinking that I damaged the trainer. The smell of burnt rubber was in the air. Finally I realized that the tire was jammed again the chainstays. This bike (old steel) has horizontal dropouts and my "massive" power had pulled the drive side forward. It seemed like I am going to have to move a bike with lower gears to the trainer now
    Well I guess you didn't have a wheel slippage issue

    I tried it this morning with 100% and it's a very different experience, you really need to keep your eye on the road to be ready to get in the right gears for climbs and descents. I was looking down at my Garmin at one point and a climb snuck up on me when I was in the big ring and ended up grinding over it at 25rpm cadence.

    There's a firmware update for the calibration which updated last night - you can only do it from an Apple device from what I can tell, then with the update I could only calibrate from an Apple device, my Android phone wouldn't show me the option like it did before and it won't work from my Garmin 820 either.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  2. #27
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    4,217
    Quote Originally Posted by Srode View Post
    Well I guess you didn't have a wheel slippage issue

    I tried it this morning with 100% and it's a very different experience, you really need to keep your eye on the road to be ready to get in the right gears for climbs and descents. I was looking down at my Garmin at one point and a climb snuck up on me when I was in the big ring and ended up grinding over it at 25rpm cadence.

    There's a firmware update for the calibration which updated last night - you can only do it from an Apple device from what I can tell, then with the update I could only calibrate from an Apple device, my Android phone wouldn't show me the option like it did before and it won't work from my Garmin 820 either.
    I performed the FW update this morning. Its funny but the support page for the Magnus still says there are no updates available and they will post instructions once there is one. So much for support

  3. #28
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    4,217
    Quote Originally Posted by Srode View Post
    I tried it this morning with 100% and it's a very different experience, you really need to keep your eye on the road to be ready to get in the right gears for climbs and descents.
    Agree. I did my first ride at 100% and it makes it harder in that you have to adjust to every change in grade. With my dumb trainer I just held the watts I was comfortable with and ignored any small changes in grade. I find myself getting out of the saddle more to power over the smaller hills. Definitely an improvement

  4. #29
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Did my first test of ERG mode today with it the Magnus - on a 20 minute interval targeting 245 on Zwift the power data file from my Garmin which was linked to the power2max meter on the bike showed a 247 average - only 2 watts off target average over 20 minutes - that's pretty good if you ask me. Watching the power data on the screen from Zwift and the Magnus, it was swinging around quite a bit like it wasn't a 3 second average displayed which I have set in Zwift.

    I also found playing around that it doesn't manage the power output very well if you are in the tallest gearing and targeting low output - like 125 watts, kept going over the target and it didn't bring me back down into range until I slowed down my cadence. Easy to manage just by shifting down a few gears though. It did fine managing a 90 watt target for single leg pedal drills when I was in the middle of the cassette and in the small ring up front.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  5. #30
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    4,217
    Quote Originally Posted by Srode View Post
    Did my first test of ERG mode today with it the Magnus - on a 20 minute interval targeting 245 on Zwift the power data file from my Garmin which was linked to the power2max meter on the bike showed a 247 average - only 2 watts off target average over 20 minutes - that's pretty good if you ask me. Watching the power data on the screen from Zwift and the Magnus, it was swinging around quite a bit like it wasn't a 3 second average displayed which I have set in Zwift.

    I also found playing around that it doesn't manage the power output very well if you are in the tallest gearing and targeting low output - like 125 watts, kept going over the target and it didn't bring me back down into range until I slowed down my cadence. Easy to manage just by shifting down a few gears though. It did fine managing a 90 watt target for single leg pedal drills when I was in the middle of the cassette and in the small ring up front.
    How did the Magnus power readings compare to the crank power meter?

  6. #31
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Quote Originally Posted by DaveG View Post
    How did the Magnus power readings compare to the crank power meter?
    Unfortunately the ride from Zwift didn't save to Strava so I don't have the power data from the Magnus to compare to the crank power. I'll compare tomorrow for sure. It was jumping around enough it was hard to tell for sure but looked to be about the same. Since the interval was set up on Zwift, and the power meter data to Zwift was coming from the Magnus, it should have been pretty close I think, but will have actual data tomorrow for you.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  7. #32
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    From this morning's ride - 20 minute power from the magnus was 209, and from the power2max it was 213 - pretty close. The magnus is off by more like 20 watts from what I can tell at lower power outputs like 125ish.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  8. #33
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Quote Originally Posted by DaveG View Post
    After the first loop I re-calibated the Magnus. I saw much closer numbers on the flats - maybe 3% difference. On Box hill the numbers were very close until about 5 minutes in. Then the Magnus was showing about 10-15 watts (@280w) lower than what my Powertap read. Could this be because of heat buildup on the Magnus? Itís impossible to say which is more accurate: the PowerTap or the Magnus but I can see that there are differences, and heat seems to play a roll. The results certainly are not linear
    I had the same issue with low readings after about an hour into the SST Med workout on Zwift today. At the start there was about 5 watts different between the Magnus and my Power2Max, then the last half of the second set of over/unders the difference grew to 25 watts very quickly, and it definitely was the Magnus that was off, not the power2max - it was pretty easy to tell from perceived effort and the increase in HR. That 25 watt difference stayed there all the way through the cool down till the end. I did save both the Zwift file and the Garmin file to compare on Strava for the comparison so the numbers I quoted are pretty accurate, not an estimate. It certainly made for a more challenging finish to the workout, but not what I wanted really. I sent an email to Cyclops about it and included the .fit file for them to review.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  9. #34
    RoadBikeReview Member
    Reputation: looigi's Avatar
    Join Date
    Nov 2010
    Posts
    7,160
    FWIW: Coast-down calibration mainly measures and corrects for the power lost due to the drag of the tire against the roller. If you ride for a while and touch the rear tire you'll feel that it's warm. That heat has come from your pedaling. The drag will vary depending on the force of the roller against the tire, the tire and its pressure, and the tire's temperature so it best to do it each time you put the roller against the tire and after riding for 5-10 minutes or so to warm up the tire.
    ... 'cuz that's how I roll.

  10. #35
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    4,217
    Quote Originally Posted by Srode View Post
    I had the same issue with low readings after about an hour into the SST Med workout on Zwift today. At the start there was about 5 watts different between the Magnus and my Power2Max, then the last half of the second set of over/unders the difference grew to 25 watts very quickly, and it definitely was the Magnus that was off, not the power2max - it was pretty easy to tell from perceived effort and the increase in HR. That 25 watt difference stayed there all the way through the cool down till the end. I did save both the Zwift file and the Garmin file to compare on Strava for the comparison so the numbers I quoted are pretty accurate, not an estimate. It certainly made for a more challenging finish to the workout, but not what I wanted really. I sent an email to Cyclops about it and included the .fit file for them to review.
    Interesting info. I dont mind if the Magnus is off at low efforts but when I am killing myself I want all the watts I've earned! Next time I do an FTP trest I plan to use the Powertap wheel as well and compare the results. Let us know what CycleOps comes back with. I have checked and even after hard efforts the Magnus stays very cool. I dont feel any heat buildup

  11. #36
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Quote Originally Posted by DaveG View Post
    Interesting info. I dont mind if the Magnus is off at low efforts but when I am killing myself I want all the watts I've earned! Next time I do an FTP trest I plan to use the Powertap wheel as well and compare the results. Let us know what CycleOps comes back with. I have checked and even after hard efforts the Magnus stays very cool. I dont feel any heat buildup
    Seems the biggest issue is higher wattage and after riding for a while, probably heat related even though I have a fan less than a foot from it pointed directly at the head unit. I have had it happen a few times now and am giving up on it, sending it back. I don't have time to mess with something that can't hold the target (losing training time) that's the reason I bought a smart trainer in the first place.

    I'm using an Elite Drivo now and haven't had any hiccups yet (knock on wood), and the power output on hard efforts after a couple of hours of use looks to be within about 1 watt on average of my crank based power meter. Its off a bit more around 100 watts but I really don't care how accurate it is in that range. It's also very quiet and smooth.

    I think the Magnus is a great option to get the full Zwift / online course experience for a reasonable price, but it lacks the accuracy to be used for longer HIT/structured workouts.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  12. #37
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    4,217
    Quote Originally Posted by Srode View Post
    Seems the biggest issue is higher wattage and after riding for a while, probably heat related even though I have a fan less than a foot from it pointed directly at the head unit. I have had it happen a few times now and am giving up on it, sending it back. I don't have time to mess with something that can't hold the target (losing training time) that's the reason I bought a smart trainer in the first place.

    I'm using an Elite Drivo now and haven't had any hiccups yet (knock on wood), and the power output on hard efforts after a couple of hours of use looks to be within about 1 watt on average of my crank based power meter. Its off a bit more around 100 watts but I really don't care how accurate it is in that range. It's also very quiet and smooth.

    I think the Magnus is a great option to get the full Zwift / online course experience for a reasonable price, but it lacks the accuracy to be used for longer HIT/structured workouts.
    Sorry it did not work out for you. I am a little disappointed with the accuracy issue myself but after thinking about it I dont do that many structured intervals where that will come into play. I haven't done another FTP test since I've had the Magnus (because they really, really hurt) but when I do I plan to compare my numbers with my PT wheel

  13. #38
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Quote Originally Posted by DaveG View Post
    I haven't done another FTP test since I've had the Magnus (because they really, really hurt) but when I do I plan to compare my numbers with my PT wheel
    Try building a Ramp test in Zwift custom workouts, they are less painful than the 20 minute test for sure. Start at 150 watts after warming up, then add 25 watts every 1 minute up to about 450. Ride till you can't, and take the average of the last 1 minute of the test, 75% of that number is your FTP. Adjust your power offset to match the PT wheel or do it with the PT wheel on to collect your results if the delta varies. The Magnus works very well for this I found.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  14. #39
    RoadBikeReview Member
    Reputation:
    Join Date
    Feb 2004
    Posts
    4,217
    Quote Originally Posted by Srode View Post
    Try building a Ramp test in Zwift custom workouts, they are less painful than the 20 minute test for sure. Start at 150 watts after warming up, then add 25 watts every 1 minute up to about 450. Ride till you can't, and take the average of the last 1 minute of the test, 75% of that number is your FTP. Adjust your power offset to match the PT wheel or do it with the PT wheel on to collect your results if the delta varies. The Magnus works very well for this I found.
    Thanks. I have never heard of this but a search showed there are many article about it.

    Curious, what made you decide to go with the DRivo versus the Kickr or another direct drive unit?

  15. #40
    RoadBikeReview Member
    Reputation: Srode's Avatar
    Join Date
    Aug 2012
    Posts
    2,514
    Quote Originally Posted by DaveG View Post
    Curious, what made you decide to go with the DRivo versus the Kickr or another direct drive unit?
    Good question, I did some research on the 4 options I would consider and it came down to reliability and accuracy. The Neo is a nice trainer but has reliability issues reported by MMSrepbike on the board here. The Hammer is a nice trainer but has had some heat issues from what I have read with longer harder workouts causing power drifts according to at least one user and that's one of the reason's I didn't want to keep the Magnus. That left the Drivo and Kickr - the Drivo wins on resistance, software/apps and accuracy, plus it was about $150 less because I could use the 20% March deal with Competitive cyclist on the Drivo and not on the Kickr. I've only done a couple rides on the Drivo so far, but happy with it today. I'll write some kind of brief thoughts on it after a couple weeks of use in a separate thread.
    Moderation is boring - do epic s##t

    Trek Domane
    Niner RLT9 (Gravel Bike)
    Trek Crockett

  16. #41
    Sir Descends-a-lot
    Reputation: trekninja's Avatar
    Join Date
    Mar 2017
    Posts
    9
    i went from a kinetic road machine to an elite kura. i will never use a wheel on trainer again. direct drive is quiter, smoother, better road feel, more realistic resistance. the power meter in the kura is soooo much more accurate too so thats another plus. do it once and do it once, go direct drive
    1985 Trek 670
    2016 Trek Fuel 9.8
    2017 Trek Domane SL6 Pro
    2017 Trek Crockett

Page 2 of 2 FirstFirst 12

Similar Threads

  1. Smart trainers - worth it? Any Kurt Kinetic Smart Power users?
    By multirider in forum Racing, Training, Nutrition, Triathlons
    Replies: 21
    Last Post: 04-17-2017, 07:53 PM
  2. Direct Drive
    By jarbiker in forum General Cycling Discussion
    Replies: 12
    Last Post: 09-03-2011, 06:44 PM
  3. Replies: 8
    Last Post: 06-25-2009, 09:32 AM
  4. Replies: 3
    Last Post: 01-21-2008, 07:58 PM
  5. rim drive trainers?
    By peterpen in forum Racing, Training, Nutrition, Triathlons
    Replies: 1
    Last Post: 10-09-2004, 07:48 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •