BikeControl stops reliably sending shift commands when app goes to background / screen turns off (iOS, v4.4+)

[larizzo]

Since BikeControl version 4.4, I’m experiencing unreliable shifting when the app is no longer in the foreground or when the iPhone screen turns off.

BikeControl is being used to control virtual shifting in MyWhoosh, with a Zwift Bike as the hardware. Prior to v4.4, this setup worked perfectly even with the screen off.

Now, once the phone screen turns off or the app goes to the background, shift commands are no longer sent reliably.

Expected behavior

BikeControl should continue sending shift commands reliably while:
• The app is in the background, and/or
• The iPhone screen is turned off

(This was the behavior prior to v4.4.)

Actual behavior

When the app is not in the foreground:
• Shifts may work briefly, then stop
• Sometimes shifting up works but down does not
• Sometimes only a single shift is registered, then no further shifts
• Bringing BikeControl back into the foreground immediately restores correct shifting

Steps to reproduce
1. Open BikeControl on iPhone
2. Connect Zwift Bike and launch MyWhoosh
3. Verify shifting works normally while BikeControl is in the foreground
4. Turn off the iPhone screen or switch to another app
5. Attempt to shift gears
6. Observe unreliable or missing shift commands
7. Bring BikeControl back to the foreground → shifting works again

Environment
• BikeControl version: 4.4+ (worked correctly before this)
• iOS version: 26.2
• Device: iPhone 16
• Trainer/Bike: Zwift Bike
• Training app: MyWhoosh

[larizzo]

I’m uploading a log file. In the log, the last ~2–3 minutes before the app is backgrounded are where shifting stops working entirely. After that, I brought the app back into the foreground, shifted a few times, and then exported the log.

Additional note: Ok, I figured out when it seems to break: shifting stops about 10 minutes after the iPhone screen turns off, which makes me think it’s related to iOS putting the app into deep sleep. In previous app versions shifting would keep working for those 10 minutes, but now it stops almost immediately once backgrounded.

175505.314565 Buttons Shift Up Left.md

[jonasbark]

Thank you for reporting! The error visible in the logs are suspicious - I will provide a fix asap

[jonasbark]

A new version 4.7.2 was just released, which should fix the issue

Let me know if it doesn't

[pitkaha]

4.7.2+5 did not fix issue #241

[jonasbark]

Can you elaborate? No improvement at all?

[pitkaha]

Can you elaborate? No improvement at all?

Did further testing. Before that message I only tried quickly with Zwift on iPad and BikeControl on iPhone and after 30sec connection dropped and after that I connected Zwift Cliks and got on with my training.

Today I tried Zwift and BikeControl both on iPad with updated software and firmware -> connection drops in a same manner as before.

Tried also with Zwift on iPad and BikeControl on iPhone and this time connection did not drop with BikeControl on background and only Di2 as controllers. I opened 5 or so apps after minimising BikeControl, still no drops. Went on with my training, got a phone call 90min in, after that it started to drop connection every 25sec (opposed to 30sec before) if BikeControl wasn't open on iPhone.

All on 4.7.2+5.

[jonasbark]

Thank you for the feedback! It's hard for me to test properly, as I've never experienced any drops so far. Sounds like iOS is aggressively killing apps in the background if memory is sparse.

There are only two known ways to "defeat" it:

• using Bluetooth to connect to the other device (I'm working with the different trainer apps to support this properly)
• make BikeControl a "music player" - this is available as of 4.7.4 and might be worth a try: active "Act as media player" in the devices screen

[pitkaha]

Yep, I understand. I wish iOS would give some way to look at whats going on with RAM, not that easy to free it when you can't really say whats eating it. That 13 mini seems to have 4gb for what its worth.

I'll try those, tried to bluetooth one when it came out but didn't succeed, have to give it another go. Also connecting Zwift Click v2 at the same time with Di2 to BikeControl fixes the problem even if I never use those Clicks.