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Quarq DZero Erratic Cadence and Power Readings
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Just thought I'd put this out there and see if you guys have any opinions or relevant experiences with regard to this.

I've been using a Quarq DZero power meter on my turbo trainer all winter and have noticed a weird phenomenon that arises when I do mechanical work on the bike. Each time, for the first couple of weeks (perhaps around 10 workouts or ~20 hours of riding) after refitting the Quarq to the bike it seems to give erratic cadence and power readings. For example, say I'm trying to hold a constant cadence of 90 rpm, my Garmin GSC-10 will say I'm holding it very steady in the 89-91 rpm range but the Quarq AxCad values will be jumping around all over the place in the 86-94 rpm range. What's more confusing is that after a couple of weeks, the Quarq AxCad measurements sort themselves out and become nice and steady like the GSC-10.

This process has happened to me twice now, once when I first installed the Quarq and a second time when I removed it to change chainrings and reinstalled; same process both times, with a couple of weeks of readings all over the place and then settles down to something acceptable. I trawled back through my TrainingPeaks library to find a nice visual representation for you guys; here's two identical steady-state workouts, two weeks apart before and after this apparent settling-in:

Note: the scales for both power and cadence are identical here and obviously the smoothing slider is set to zero for both.


February 16th:




March 2nd:




Furthermore, in between these two workouts, I found another one where the erratic cadence values seemingly fix themselves mid-workout; here the cadence was all over the place for the first 1/3rd of the workout as it had been for the last couple of weeks, I start doing some seated-to-standing transitions (the series of dips in cadence below) and after this the erratic cadence has fixed itself and has been great ever since:

February 24th:




The cadence itself doesn't annoy me so much, more the fact that the Quarq is using this rubbish cadence data to calculate the power and as you can see in the two workouts above, it has a big effect on the variability of that too.

It looks to me like there's some kind of mechanical settling-in going on here and the eccentric stress of the out-of-the-saddle efforts have fixed whatever was wrong and helped the Quarq to read more consistent values. Last time I checked all of the torques on the chainrings, bottom-bracket etc and nothing was amiss so I'm at a loss as to what could be happening, does anyone have any idea? Possibly the chainrings settling in and being forced up tightly against the chainring bolts or something? I've noticed a few complaints about Quarq's AxCad online and initially thought it just sucked compared to a magnet-based system, but then once it settled in it was almost identical to the GSC-10, so I'm thinking it might also be an issue for these people too. Has anyone seen this before with a Quarq or other crank-based power meter?

I'm planning on a full strip-down service of my bike at the weekend to get it ready for the outdoors again and fully expect to see the issue resurface for another few weeks. Just wondering if there's anything that I can do to avoid it returning?

Details:
Quarq DZero AL 110 BCD
SRAM Team GXP BSA bottom bracket (no frame adapters etc)
Shimano 105 5750 rings (50-34)

KMC X10-EL chain

N.B. regarding firmware, I was running v2.0 for the first workout here and upgraded to v3.0 that supposedly addresses an issue with erratic cadence values shortly thereafter and it didn't help at all; it was a couple of workouts later (Mont Gosford above) that the issue fixed itself mid-workout as shown.
Last edited by: awenborn: Mar 8, 17 4:24
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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Well, I'm not sure why you're going to such trouble to analyze the problem when there are two very simple solutions. Either use a magnet or contact Quarq customer support about it. Their support is great, my Riken just died and it's on the way back to me with only a 6 day turnaround including shipping both directions, and they are replacing it at no charge even though it's out of warranty.
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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They just released a firmware update to deal with similar types of problems that may help.
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Re: Quarq DZero Erratic Cadence and Power Readings [tttiltheend] [ In reply to ]
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Thanks for the reply.

First of all, I think I'm right in saying that with the DZero line Quarq dropped support for magnet-based cadence, so I don't think I could use one even if I wanted to; regardless I wouldn't really want to venture down that route when the accelerometer-based cadence values can work just as well.

And as for contacting support, sure that's an option but I don't think it's a fault with the Quarq, more of a quirk of setup and installation. I'm wondering if there's something I should be paying particular attention to when installing chainrings/bottom bracket/chainset to avoid this bedding-in process.
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Re: Quarq DZero Erratic Cadence and Power Readings [Tony5] [ In reply to ]
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I mentioned firmware at the end of my post.

Installing the latest (v3.0) update didn't make any difference at the time, I distinctly remember the hope and subsequent disappointment!
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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How are you seeing cadence from the GSC-10 and quarq? Are you using two computers that are paired to each independently?

I'm pretty sure the quarq d-zero still supports the cadence magnet.

get comfortable being uncomfortable
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Re: Quarq DZero Erratic Cadence and Power Readings [stevej] [ In reply to ]
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stevej wrote:
How are you seeing cadence from the GSC-10 and quarq? Are you using two computers that are paired to each independently?

Yep, exactly. I had the Quarq paired to my Edge computer displaying power & cadence and then paired just the GSC-10 to my fenix 3 to compare the values. Held the two side-by-side and could see in real-time that whilst holding a fairly consistent spin, the GSC-10 was fluctuating +/- 1 rpm, whilst the Quarq was more like +/- 4 or 5 rpm.

I did this on a few occasions whilst troubleshooting it, but this is what convinced me that it was the Quarq's cadence values that were noisy and not just my inability to hold a constant spin! I appreciate that the two sensors might smooth their reported values to different degrees, but the fact that the Quarq managed to fix itself suggests something else.


stevej wrote:
I'm pretty sure the quarq d-zero still supports the cadence magnet.

You might be right on that, I vaguely recall reading somewhere that it wasn't but I could be wrong; it's not something I've looked into because it's not a route I think I need to go down at the moment.
Last edited by: awenborn: Mar 8, 17 6:23
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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awenborn wrote:
stevej wrote:
I'm pretty sure the quarq d-zero still supports the cadence magnet.


You might be right on that, I vaguely recall reading somewhere that it wasn't but I could be wrong; it's not something I've looked into because it's not a route I think I need to go down at the moment.

I understand where you are coming from. I'm a pretty technical person and a pretty OCD about my data. If I had a quarq (I used to have an older model), I would still run the magnet. As you are seeing with your data, the built in cadence is not quite bullet proof. This would drive me crazy and I would just run the magnet as it's pretty hard to screw that up unless you install it wrong. I think the benefit of not needing a magnet is if it ever falls off (has happened to me) and you won't lose your power data.

What bike do you have? I know my speed concept is bit a tricky to install a magnet in the right place so I ended up using a KMC chain catcher/magnet. You kill two birds with one stone.

get comfortable being uncomfortable
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Re: Quarq DZero Erratic Cadence and Power Readings [stevej] [ In reply to ]
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I've had less than ideal experiences with the magnetless cadence on Quarqs, but I don't have any experience with the DZero.

It's disappointing that when you call Quarq for support, about a range of issues, the first thing they tell you to do is to ditch the magnet and retest.

If I use 3s averaging on the magnetless cadence data, it seems a bit better.
Last edited by: rijndael: Mar 8, 17 6:30
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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Do yourself a favor and post this on the Wattage Forum. It's a google group and you should be able to find it. Leadership at Quarq responds to posts there.

And yes, DZero still supports the magnet.
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Re: Quarq DZero Erratic Cadence and Power Readings [davews09] [ In reply to ]
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How to enable magnet for dzero?

I would like to order this quarq, but I do not believe that accelerometer can be quite accurate like magnet. Software (firmware) could not increase its accurate, it is can just remove some spikes.
Last edited by: inv: Mar 14, 17 12:26
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Re: Quarq DZero Erratic Cadence and Power Readings [davews09] [ In reply to ]
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The cadence on mine is pretty unstable too, seems to moe around 6-8 rpm without any change in leg speed,on there latest firmware, have tried a magnet but it's not supported even though there is a hall switch present
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Re: Quarq DZero Erratic Cadence and Power Readings [davews09] [ In reply to ]
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davews09 wrote:
Do yourself a favor and post this on the Wattage Forum. It's a google group and you should be able to find it. Leadership at Quarq responds to posts there.

And yes, DZero still supports the magnet.


I've contacted Quarq support about this to see if they can shed any light on the issue. If they can't help I'll post it over on the Wattage Forum.

I also asked if the Quarq DZero supports magnet-based cadence and their response was:

"Unfortunately, there is not a way to use a magnet for cadence on the DZero"

Are you actually using a DZero with a magnet or was that just an assumption?
Last edited by: awenborn: Mar 17, 17 8:07
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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 i tried a magnet last week and it didn't pick up cadence,seems strange they don't support magnet as there is definitely a hall switch present and a recent bulletin actually showed where it was to force a firmware update after BLE was disabled on some units

https://www.quarq.com/...LE_update_rev_3a.pdf
Last edited by: neilridley: Mar 17, 17 10:53
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Re: Quarq DZero Erratic Cadence and Power Readings [neilridley] [ In reply to ]
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How did you test it to see if it picked it up?

I'm thinking about an issue where the unit is awake, already detected the need for accelerometer cadence, so it didn't fall back to the magnet. But if the unit was activated/awoken, and found the magnet before activating the Ax cadence, it would be fine.
Last edited by: rijndael: Mar 17, 17 11:21
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Re: Quarq DZero Erratic Cadence and Power Readings [rijndael] [ In reply to ]
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I swept the magnet past the marked area on back of spider,no cadence appeared on garmin, spider had been woken up previously by axcad though
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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I have excactly the same problem with my Quarq Dzero carbon. Its annoying, but it also have a practical consequence: when I use my Kickr with Trainerroad erg mode, so that the kickr uses the powermeter as guidance, the resistance is jumping up and down because of the erratic cadence.

I cant stand it, is there any solution out there? Anyone got an answer from Quarq? To me this is unheard of, there is no reason that measuring and reflecting a steady cadence should be that hard. My Sigma from 1997 did this flawlessly:-)
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Re: Quarq DZero Erratic Cadence and Power Readings [sigbjorn] [ In reply to ]
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I've been noticing the same issue. I upgraded the firmware to version 3 which supposedly corrected the issue, and for the first few rides after the update the reported cadence was steady. However I have noticed that with recent rides the erratic cadence has returned.
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Re: Quarq DZero Erratic Cadence and Power Readings [sigbjorn] [ In reply to ]
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I still haven't permanently resolved my issue; it still comes-and-goes although recently it's not coincided with mechanical work on the bike, just happens at random times so I'm not sure what to think now.

As I mentioned above, I contacted Quarq support and after a bit of back-and-forth, which took a fair bit of time in itself because they seemingly take 24 hours to reply to each and every message, they said:

Quarq Support wrote:
I checked with our engineers and our engineering team is investigating the issue. We expect an update in 7-10 days, which we will share with you.
That was on March 23rd and I still haven't heard anything back. So much for Quarq's excellent support...
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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I spoke too soon, I just chased up with Quarq Support and they replied almost immediately saying:

Quarq Support wrote:
We found a bug within the firmware that is causing this issue. We have a fix that we are testing to make sure that it is stable and hope to have a new firmware shortly.
Fair enough, I retract my bitchy comment above!
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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I prefer they reanable the magnet cadence, don't like / trust accelerometers
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Re: Quarq DZero Erratic Cadence and Power Readings [neilridley] [ In reply to ]
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I totally see where you're coming from, but in my experience the Quarq DZero accelerometers can be as good as a magnet-based system. As I mentioned above, I monitored the Quarq's AxCad directly against a GSC-10 numerous times trying to troubleshoot it and when it's working well, they appear essentially identical, although admittedly that's under very forgiving testing conditions (i.e. on a turbo trainer, steady cadence, zero road buzz etc etc) and only an unscientific "eye-balling" the live numbers.

Unfortunately I didn't save any of that side-by-side data for comparison; I always discarded the duplicate recordings so as not to screw up my training log. I'm sure I'll repeat it when this new firmware comes out, so I'll make a point of saving the files and doing some stats to see just how the variability in the cadence data from each sensor compares.

I have to echo many other people's sentiments that Quarq certainly stand by their products and hopefully the new firmware will resolve this issue.
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Re: Quarq DZero Erratic Cadence and Power Readings [awenborn] [ In reply to ]
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Hi all. We have been working to correct this problem and should have new firmware out in 7-10 days. I posted this (below) as a comment on DC Rainmaker's Quarq DZero review and it's worth repeating here. I should also verify that DZero power meters cannot use a magnet for cadence.


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Quarq’s accelerometer cadence was designed so that a cadence discrepancy in any single pedal stroke would be adjusted in the next pedal stroke. Therefore cumulative accuracy is unaffected and there is little or no impact on cumulative power values such as kilojoules, average power and normalized power. In objective terms, single pedal stroke accuracy in the worst conditions varied from magnet-based cadence by a maximum of 2%. And benchmark tests showed the accuracy of Quarq’s accelerometer cadence matched or surpassed other products that use accelerometers. We shared this information in the Quarq website’s FAQ for many years.


With Quarq DZero we received reports and saw ourselves that cadence would sometimes bounce up and down on head units around a steady/single value. Thanks to great input (and patience) from customers and sound work by our engineers we have removed the bouncing from the display but also improved the sampling rate and further refined accelerometer readings such that DZero now matches the accuracy of magnet-based cadence in most conditions.


The new DZero firmware is going through the final stages of testing now.
Last edited by: troy@quarq: Apr 26, 17 14:03
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Re: Quarq DZero Erratic Cadence and Power Readings [troy@quarq] [ In reply to ]
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Is this something that could be applied to the previous version of the quarq that has access to improve the accuracy of its accelerometer based cadence? I know your stated policy is no further firmware updates for the previous product, but I'm hoping you reconsider given the large user base.
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Re: Quarq DZero Erratic Cadence and Power Readings [goodboyr] [ In reply to ]
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Hi goodboyr. We are going to meet and decide later this week. The previous generation power meters use a different circuit board and accelerometer, so it is not a straightforward update. They can also use a magnet for cadence. Those two things may see us stick to the policy. I will provide an update next week.
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