Wrong cadence reading in workout

(Steven Gilbert (PACK)) #1

 I know that this has been asked before, but no answer is available as it was done via a private ticket with the user. When doing a workout (one of the GCN workouts) , the cadence measurement is completely wrong. My Garmin is reading correctly, and Zwift reads correctly when just cycling, but in workout it is completely wrong. The workout demands a certain cadence, and even though I am doing this according to my Garmin, Zwift thinks completely different. Where is it getting the reading from? 

(Paul Allen) #2

What are you using for a cadence sensor?

(Steven Gilbert (PACK)) #3

Zwift is configured to read my cadence from my Garmin cadence sensor. When I noticed that the reading was wrong I went back to the Ant+ configuration page to check, and it was showing the same cadence as my Garmin head unit. But in the workout it was different. 

(Jason K) #4

If it’s correctly paired on the pairing screen, my first thought would be that it’s related to the signal. Maybe a low battery or signal drops. Zwift doesn’t interact with your cadence outside of reading it, so there shouldn’t be any reason it’s different unless it’s being caused by an external factor.

(Steven Gilbert (PACK)) #5

It is correctly paired, and when I went to the pairing screen mid-workout, it was showing the correct value and correct sensor. But going immediately back to the workout the cadence was showing a completely different value to the pairing screen. My Ant+ sensor is on a cable directly under the bike about 10cm from the cadence sensor, and the sensor has fresh batteries. So I am going to eliminate all of those as factors, as well as anything external as the Garmin head unit and the Zwift pairing screen were both showing the same value.

I’m not sure if it is an issue with using ERG mode on a BKool pro trainer, as I have read on other threads that this is problematic. I have to admit that the power was all over the place, and maybe the cadence was being interpretted/inferred somehow?


(Russell Ashford V-Sprint MMH) #6

I experienced the same issue this evening, I was doing the GCN fast peddle workout. I was using the wahoo cadence sensor paired via BT with the Mac. Connection was good but cadence shown during the workout was not representative of my actual RMP cadence. It appread to be reverse calculated based on power, gradient & speed. As going up box hill it was showing cadence of 40-55, yet I was spinning at 85 & no matter how much quicker I span the cadence did not increase until the gradient leveld of. I was searching for a reply before dropping support a note on this.

(Steven Gilbert (PACK)) #7

@Russell - Now that you mention it, I remember the cadence on screen adjusting while I was going up hill too. Even though I was pedalling at the same RPM according to the Garmin, on screen it was dropping and telling me to pedal quicker.

(Tyler Shannon) #8

Hi Steven, 

Are you still having this issue? If so, I’d like to open a ticket, and get to the bottom of this for you. 

(Kathryn K) #9

I had the same issue tonight - after 1:23 ride at about 16 mph, FTP builder, Zwift said I’d gone 12.1 miles - that’s crazy.  I measured my own cadence by counting at many points during the ride, as I haven’t installed a cadence sensor, and I was always 90-100.  When I uploaded to Strava, Zwift said my average cadence was 51.  Simply false somewhere along the line…

(Russell Ashford V-Sprint MMH) #10

I had an open ticket regarding this issue, I’ve not ridden since the issue so can’t say if it was a one time issue but the feedback was as follows.

We’re investigating the issues we saw in your log, most of which seem to be bugs we haven’t seen before. Just to give you an idea of where we’re at:

The error messages I was seeing showing ANT+ in your logs may have been part of the issue since they shouldn’t have been showing up. We’re investigating this.
We think Zwift switched to using virtual cadence instead of your actual cadence sensor mid-ride, and we’re investigating why this may have happened.
We’ve confirmed that ERG mode messages aren’t showing up in the logs for BLE, and we’re going to work on fixing this - so you likely were in ERG mode, and the problem was more likely caused by whatever caused the cadence to switch.
Since you haven’t seen this issue since then, it sounds like this was (hopefully) more of a one-time issue for you, and not a problem with your setup. We’ll work on fixing the issues I mentioned on our end, but let us know if you see this problem come back again.

As these bugs are on our side, I’m going to close your ticket now, but you can reopen it if you have any other questions by following the instructions.

(Steven Gilbert (PACK)) #11

@Tyler - I haven’t done a workout since which has a cadence requirement, and unfortunately won’t have time to for a while.

I’m happy for you to open a ticket and I can submit logs for the date in question if this helps. Looking at the feedback that Russell had above, it might be a switch to virtual cadence too

(Russell Ashford V-Sprint MMH) #12

I completed a short cadence based workout last night, I’m pleased to say the issues previously experienced did not occur. I did run the software update prior to starting so hopefully the bugs have been address. :+1:t3:

(Steve Mansfield) #13

I’m having this issue, the graph is from a workout just this week - 11th April 2017. Zwift updated itself automatically so I think I’m on the latest version.


I recorded the session on Zwift, Garmin 510 and Garmin 920xt, and you can see that the two Garmins agree, and Zwift is miles out





(Steve Mansfield) #14

If it helps, I didn’t have the issue on 24th March, I did from 31st March on

(Tony Truong) #15

I too am having issues with cadence showing correctly. I have never gotten the cadence to show up correctly. It seems to make up a number based on my power. If I’m riding at high power it will show my cadence as 95-105+ even though I’m at like 85. When I lower my power, suddenly the cadence goes down too.

I’m using the cyclops hammer and garmin cadence device.

(Matthew Miller) #16

So last night during my zwift ride I noticed when going up hill it was showing my cadence at 45-50 but in fact I was pedaling at 85-90 . This just started happening yesterday. So what changed and why isn’t Zwift displaying the correct cadence from my Garmin cadence sensor .  Up until yesterday it has always been accurate. What gives???

(Steven Gilbert (PACK)) #17

So this issue is back again. I’ve done a few workouts since and there was no problem. Suddenly yesterday, Zwift does a minor update (ver 1.0.19737, although I’m not sure what the update contains) and it is back again. The workout is a ZWO file I downloaded from WhatsOnZwift website and loaded into my workout directory.

At one stage I was going up the 15% incline out of the subway in London pedalling at about 110rpm (showing on my Garmin) doing about 100W (on a cool down), but on Zwift it says I was doing 17rpm and I was barely moving. Somehow it wasn’t reading mt cadence from my sensor, but inferring it from my speed and power.

Looking at the ZWO file, the intervals have a " pace=“0” " entry, which is not present in some of my other custom ZWO files. Could this be the issue?

(Larry Blanchard) #18

I experienced the same issue this evening during a WOW Aerobic session.  I felt like I was maintaining a consistent cadence, but as others have stated it seems to adjust based on power and terrain to produce the cadence.  I confirmed it by turning on my Garmin 500 which showed my cadence right about where I expected yet Zwift was off by 5 to 10rpm in both directions on the flat volcanoes route which doesn’t have much elevation.  The workout guide kept telling me to increase or decrease cadence almost the entire time.

(Lyndsey Malone) #19

I am also experiencing cadence issues with reading being way out during both during workouts and rides. Did an Ftp test yesterday and as I came to the start of the 20min ftp section although cadence was 90+ it became impossible to pedal as if I had dropped below the cadence threshold. On other rides during hill climbs cadence has suddenly jumped to 157. I’m using an ant+ sensor. I have paused rides and checked pairing, and I’ve also done a firmware update, none of things have helped. At the moment I can not do any workouts unless I upair the ant+ sensor.

(Kirsten Townsley) #20

I am having the same issue - I am training on an Elite Drivo with a Garmin cadence sensor and even though my cadence is staying at a fairly average rate, the Zwift app kept dropping it to around 43 - this impacted on speed etc (of course) especially uphill where at one stage, my cadence was about 40 and my speed was about 3kph.  The only way to get the cadence to read properly again would be to stop pedaling then restart but often the correct measure would only last a few seconds.  The set I was attempting required a certain cadence level so this made the ride fairly frustrating.  I played around with connections but it all seemed to be fine - any ideas?