Zwift cadence doesn't match actual cadence

Bugs and Support
1

I’m using a Quarq DZero power meter for my power and cadence readings. On the road there’s no problem whatsoever and the power readings are accurate for Zwift. The problem is I cant seem to get above 70 rpm no matter how high my cadnce is. On hills, it’s down as low as 15, even when I’m spinning at 100. This makes workouts with set cadence target impossible. The data in garmin connect also shows the incorrect cadence data. Any suggestions?

Thanks

Steve

2

Hi @Steve_Kerr2038 welcome to Zwift forums.
Are you using a smart trainer that broadcasts its own power and cadence signals? Having a power signal from the crank and also the trainer presents setup options that can work for you, or work against you. I have a power meter crank (Shimano) and a Saris smart trainer, and I’ve run into something like what you’re describing.

In general - if you have a controllable trainer, I’d recommend you pair Zwift to the trainer’s cadence, power and controllable signals and skip the power meter crank.

Sounds like your frustration’s worse in a structured workout using ERG mode? In ERG mode especially, you want changes in cadence to translate instantly to changes in power, which in turn quickly adjust resistance.

When I pair to my crank, that feedback loop seems noticeably slower compared to when I use the trainer’s power and cadence signals.

As far as the crank’s signal - I leave mine paired to the bike computer on my handlebars, and don’t pair it to Zwift at all. This way, Garmin Connect / Strava record my indoor and outdoors rides pulling data from the same source, and I don’t sweat the inherent variance compared to the data from the trainer.

Other routine things:

  1. Your crank meter’s batteries are topped up, yes?
  2. Is the firmware on the crank meter up to date? While you’re at it, update the firmware on your trainer too.
  3. I use a Windows laptop with an ANT+ dongle stuffed in a USB port. I find the ANT+ connection more reliable than the Bluetooth with my Saris, but YMMV. If you have a device that can you can use ANT instead, try that.
3

Hi Shooj. Thanks very much for the in-depth response. I’m using a new wahoo kickr so it’s capable of broadcasting its own power and cadence. I do get the option to pair either the power meter or trainer for cadence and power.

I initially decided to use my own power meter as I thought it would make the readings more comparable between road and trainer. I suppose it doesn’t really matter about the variables in power readings between the crank spider and the trainer. As long as it’s consistent obviously.

The batteries and firmware are charged and up to date on my power meter yes.

I think I’ll take your advice and just switch to cadence and power from the Kickr from now on. Isn’t the cadence from the Kickr just an estimate based on the rotation of the cassette?

Thanks

Steve

4

It is not a direct reading off of the crank like an old school magnet and pickup type sensor.

Trainer manufacturers have different ways to estimate cadence, but I’m not sure how Wahoo does theirs. It might be looking at the dead spots in your power output when the cranks are at 12 and 6 o’clock, and counting the frequency over several seconds? Just a guess.

5

Thanks Shooj. I’ll give it a go and see how I get on.

Thanks again for your help.

Steve