Stages SB20 - problems with Cadence, resistance, shifting

Stages SB20 appears to be having Four distinct problems with latest Stages SB20 firmware 1.12.24 and latest Zwift Game 1.59 on iOS (both iPad Pro and iPhone 14)

  1. Incorrect Cadence from the bike - reads 20-30rpm lower than actual cadence. Cadence from left power meter is correct.
  2. Resistance problems - sometimes gets very very easy when going from 0% to -1% grade on Tempus Fugit
  3. ERG unreliable in turning on - sometimes have to press the ERG button 3 times to get it working
  4. Shifting issues - sometimes shifts from 1 gear to next increase difficulty (watts at same rpm) by 50%. Might be a Stages SB20 issue?

I’m a SB20 user as well, my first question as always will be, did you check/replace powermeter batteries. When empty you get a lot of strange results

Edit, regarding erg. I have the same experience when starting a workout. I find it helpful to manually targeting the watts in the warm-up. Then after 15secs Zwift will automatically enable erg

Replaced powermeter batteries twice. First with Duracell. No improvement. Then with Energizer. No Improvement.

Stages SB20 does have issues with sometimes reporting incorrect power values or showing balance 100% on left. I am in the habit of opening up the app and performing a Zero Reset at which point the power and cadence show correctly in the Stages Cycling app (and the power shows correctly in Zwift)

When did you last replace them?

For some reason stages doesn’t like the Duracells, something to do with the coating.

Are you getting consistent numbers from the zero reset process, and in spec 840-940?

Duracell should only be used if you remove the Bitrex coating. Energizer should be ok. I default to Panasonic when I think anything is amiss.

Zwift doesn’t know about the shifters or what gear you are in so that makes me suspect some other problem.

Consistent results from zero result - yes. Left 794 Right 893 plus or minus one. Same results for more than a year. Just replaced the batteries two days ago, currently with Energizers.

The shifting does seem like a Stages issue - it intermittently reproduces within the Stages app. Almost seems like it is getting confused when it goes from gear 15 to gear 16 in a 30 gear Dream Drive setup, like maybe it is simulating a shift of front chainrings, even though that shouldn’t exist with Dream Drive?

Maybe I should get in touch with Stages

Dream Drive doesn’t simulate a front chainring shift. I use it with no issues like that.

794 is out of spec but not by a lot. If it’s under warranty you might get a crank arm replacement.

If you’re in the US the phone support is mostly broken but the web form sometimes works OK.

This is a bit of a “same” post but hoping that with more eyes we can solve this. I’m having nearly identical issues with my SB20 and zwift starting around the same time. I’ve similarly changed the power meter batteries and done a zero reset with no improvement. Stages support has not responded to my ticket. Have you made any progress and if so could you please update?

I get a proper cadence reading if I connect directly to a power meter (although if you have an imbalance then your power reading may be slightly off). This has been a useful workaround for at least some of the issues. I’ve also had better luck with “traditional” gearing instead of dream drive, but it’s still messed up sometimes (resistance may change with no change in gradient or gear shift; other times I shift up 6 gears and barely feel an increase in resistance).

I also see many of the problems when simply using the stages cycling app, no Zwift involved – cadence around 30, mystery resistance changes. So I do think this is more likely an issue solely with the SB20 and doesn’t involve Zwift.

If you connect to the left power meter, it will transmit the data for the right power meter, so it will not be slightly off. It will be the same as connecting to the bike, but with lower latency. If that works for you, just do it. And if that works for you I suspect it may be a result of Bluetooth or ANT+ interference since the values should be the same. If you use any device other than Apple TV, I recommend uploading a log file to and report back with the results. Share screenshots of the report or its ID so we can take a look.

Are you in the SB20 owners group on Facebook? That’s the best source of support when Stages is not responsive, as is usually the case with the US support desk. Some people have gone many months with no response. If the bike is a recent purchase you made with a credit card, I recommend talking to the card issuer about unpaying Stages for it. That can be powerful motivation for a recalcitrant supplier since they must take action or you get your money back.

I’ve currently unpaired the power meters, taken the battery out of the right (note: required zero reset to get the power “doubled” from the left side), and now connect Zwift to the left power meter for power & cadence, and the bike for resistance. Had one decent ride.

I think the right power meter has issues with invalid cadence readings (with or without Gyro enabled) and that is probably the biggest issue. Still had the bike fluctuate resistance unexpectedly, and it mostly seemed to go away after unplug/plug.

I also see most of the same problems on the stages cycling app, so I agree it is very unlikely to be Zwift.
I have a pair of Assioma pedals on a spin bike - was considering moving them to the Stages and seeing if that could be a permanent solution.

Unfortunately same issue with my newly purchased SB20. No resistance on anything less than 1% grade. Problem only started happening a few weeks ago (only a few weeks after purchasing this bike… now boat anchor). Exact same thing happening in Rouvy. I’ve tried everything I can think of with the bike.

Since this is happening in multiple apps, it doesn’t sound like a Zwift problem. If you’re located in the UK, contact Saddleback and you may get some help. If you’re anywhere else you’ll probably get no support. Consider returning the bike for a refund if Stages don’t respond to you. They are notorious for unresponsive support. If you want to talk to other knowledgeable SB20 owners, go to the SB20 owners group on Facebook.