As some other SB20 owners have noted, I was able to resolve in two ways. First, by using an ANT+ connection and the MacOS SYSTM app to connect with the main bike signal.
Second, I was also able to connect to the iOS SYSTM app using the left-side stages power meter for power and cadence combined with the main bike signal for EGR only. Both signals use BLE.
In both cases, there are still a few issues. Issue 1: variability in cadence. When I’m holding a cadence of 90rpm, as reported by the Stages link app and my Wahoo Bolt, SYSTM is reporting a lot of variability, anywhere from 86 to 95 RPM. There is more variability using BLE with the iOS App than Ant+ using the MacOS app.
Issue 2: I get similar variability in power, but not to the same error level as with cadence. When testing, I’m using my Wahoo Bolt in EGR mode and just having SYSTM just record power.
Issue 3: When using EGR mode via the SYSTM app, both iOS and ANT+, changes in power level, up or down, are a second or two slower than with the Sufferfest iOS app.
I’ve shared this with the minions.
So do I have a few issues yes. Can I use Sufferfest (sorry SYSTM) and get a good workout, yes. There are growing pains with any new app, and I’m confident the minions will figure it out. Nothing like comfy nail chairs to focus their concentration.