Right, Apple Watch + Bosch Smart System — a topic that generates more frustration than a flat tyre two miles from the car.
Here's the honest state of play:
What actually works
The Bosch eBike Flow app (which is what pairs with Nyon and the rest of the Smart System) has a companion Apple Watch app. On watchOS, it does one thing reliably:
broadcasts your Apple Watch heart rate into the Flow app so it gets recorded against your ride data.
@brendand confirmed this works seamlessly on his Orbea Wild
→ view post, and
@emtbPhil noted Flow v1.34 now stores HR data against rides properly
→ view post.
What doesn't work
Full watchOS 10/11/26 health integration — i.e. the watch treating the Bosch ride as a native cycling workout with all the bells and whistles — is
not supported. Bosch has deliberately restricted universal third-party device access, as
@Mikerb pointed out
→ view post. You won't see bike battery %, speed, or motor mode on the watch face.
@Armeniandave hit the same wall on his Cube Stereo SL
→ view post.
Setup checklist for your Ultra 3
• Install
Bosch eBike Flow on the iPhone (not eBike Connect — that's the old Classic+ app, different system entirely; Nyon is Smart System).
• Pair the bike to Flow via Bluetooth.
• Install the Flow Watch app on the Ultra 3 from the iPhone Watch app — it should auto-suggest once Flow is on the phone.
• On the watch, open Flow
before starting the ride. It hands HR to the phone, which logs it with the ride.
• Make sure iPhone Bluetooth stays on and the phone is on you during the ride — the watch routes HR through the phone, not direct to the bike.
If it's not appearing
watchOS 26.3 is very new — if the Flow Watch app is crashing or not installing, check Flow on the phone is updated to the latest version (currently 1.34+). Bosch tends to lag a release or two behind Apple's OS updates. Force-quit Flow on both devices and re-pair if HR isn't showing.
One quirk worth knowing: Nyon 4 itself can pair Bluetooth HR straps directly (per
@Rob Rides EMTB → view post) — but the Apple Watch
won't present itself as a generic BLE HR sensor to the Nyon. It has to go via Flow on the phone.
What's the symptom you're seeing — watch app not installing, not connecting, or HR not logging?
