Cycling Personal Area Network#

A reference document describing the connected device ecosystem used while riding.

Network Diagram#

graph TB
    subgraph Bike["🚴 Canyon Grizl CF 8 Di2"]
        Di2["Shimano Di2"]
        Favero["Favero Assioma SPD"]
    end

    subgraph Head["Handlebar"]
        Garmin["Garmin Edge MTB"]
    end

    subgraph Wrist["Wrist"]
        Watch["Apple Watch Ultra 1"]
        Watchlink["Watchlink"]
    end

    subgraph Pocket["Jersey Pocket"]
        iPhone["iPhone 16 Pro Max"]
    end

    Shokz["Shokz OpenRun Pro 2"]
    Varia["Garmin Varia"]

    Favero  -- "ANT+  ·  Power & Cadence"         --> Garmin
    Di2     -- "ANT+ / E-TUBE  ·  Gear & Battery" --> Garmin
    Varia   -- "ANT+  ·  Radar Alerts"            --> Garmin
    Garmin  -- "ANT+"                             --> Watchlink
    Watchlink -- "Bluetooth LE"                   --> Watch
    Watch   -- "Bluetooth"                         --> iPhone
    iPhone  -- "Bluetooth"                         --> Shokz

Components#

Canyon Grizl CF 8 Di2#

The bike. Carbon fibre all-road frame built around an endurance/adventure geometry. The CF 8 trim ships with a Shimano GRX Di2 electronic groupset — all shifting is electronic and wireless-capable via ANT+ with the optional D-Fly wireless unit.

Shimano Di2 Electronic Groupset#

Shimano’s electronic shifting system fitted to the Grizl. With the D-Fly wireless module (EW-WU111), the Di2 junction box exposes:

• Current gear position (front and rear)
• Drivetrain battery level
• Shift event counts

All data is broadcast over ANT+ to the Garmin Edge, which displays it natively and logs it to .fit activity files.

Favero Assioma SPD Power Meter Pedals#

Dual-sided crank-arm power meter integrated into the pedal body. Measures and broadcasts:

• Power (watts, per-leg and combined)
• Cadence (rpm)
• Left/right balance
• Pedal smoothness & torque effectiveness

Broadcasts simultaneously over ANT+ and Bluetooth LE, so both the Garmin Edge and the Watchlink can receive data at the same time without pairing conflicts.

Garmin Edge MTB#

Handlebar-mounted GPS bike computer. Acts as the primary data recorder for the ride, aggregating all on-bike sensor data into a single .fit file.

Receives from:

• Favero pedals — power, cadence, balance
• Shimano Di2 — gear position, battery
• Garmin Varia — approaching vehicle alerts
• Internal GPS — route, speed, elevation

Typical connected sensor profiles: Power Meter, Shifting, Radar, (Speed / HR if additional sensors paired).

Garmin Varia Radar Tail Light#

Mounted to the seatpost, the Varia combines a visible tail light with a 24 GHz radar that detects vehicles approaching from behind at up to 140 metres. Threat level and vehicle count are relayed to the Garmin Edge over ANT+, which triggers an on-screen alert and an audible tone before the vehicle reaches the rider.

The Varia operates autonomously as a tail light regardless of whether it has a paired head unit — the radar alerting simply won’t display without one.

Watchlink ANT+ → Bluetooth LE Bridge#

A small device that solves a fundamental incompatibility: Apple Watch has no ANT+ radio, and the Garmin Edge has no Bluetooth LE client mode. The Watchlink sits between them — it pairs to the Garmin Edge over ANT+ and relays that data to the Apple Watch over Bluetooth LE.

This means the Apple Watch receives the Edge’s aggregated data stream (power, speed, cadence, etc.) rather than talking to individual sensors directly.

Apple Watch Ultra 1#

Primary wrist-worn computer. While riding it:

• Receives power and cadence from Watchlink via Bluetooth LE
• Records an independent GPS track and workout via the Workout app or third-party apps
• Stays connected to iPhone over Bluetooth for notifications and audio routing
• Has its own cellular radio for standalone connectivity if the iPhone is left behind

iPhone 16 Pro Max#

Carried in a jersey pocket. Acts as the hub for audio and notification delivery during the ride. Connections:

The iPhone also provides a cellular data uplink used by the Watch when they share a connection.

Shokz OpenRun Pro 2#

Bone-conduction headphones worn over the cheekbones, leaving ears open to road and trail sounds. Connected to iPhone via Bluetooth.

• A2DP — stereo audio for music/podcasts
• HFP — hands-free profile for phone calls

Open-ear design means ambient noise (traffic, trail, other riders) is never masked, which is critical for safe riding.

ASCII Art#

                              ┌────────────────────┐
                              │  Garmin Edge MTB   │
                              └──────────┬─────────┘
                                         │
  ┌──────────────────────┐         ___  _┴_ handlebar
  │  Shokz OpenRun Pro 2 ├───────►(   )─╪═╪─────────────────────────────────┐
  └──────────────────────┘        (● ●) │ │                                  │
  ┌──────────────────────┐         ─┬─  │ │  top tube                 ┌──────┴──────────┐
  │  Apple Watch Ultra 1 ├──wrist───┤   │ ├───────────────────────────┤  Garmin Varia   │
  │  + Watchlink         │          │   │ │  seat tube                │  Radar Taillight│
  └──────────────────────┘          │   │ │                           └─────────────────┘
  ┌──────────────────────┐          │   │ │  Canyon Grizl CF 8 Di2
  │  iPhone 16 Pro Max   ├─pocket───┘   │ │ ─────────────────────────────────────────────
  └──────────────────────┘              │ │
                               ─────────┴─┴──────── chainstay ──────────────────────────
                                         ◉  ◄── Favero Assioma SPD Power Meter Pedals
                                        ╱ ╲
                         Shimano Di2 ──╱   ╲
             ●●●●●●●●●●●●                            ●●●●●●●●●●●●
           ●●            ●●                        ●●            ●●
          ●●              ●●                      ●●              ●●
          ●●      ◎       ●●                      ●●      ◎       ●●
          ●●              ●●                      ●●              ●●
           ●●            ●●                        ●●            ●●
             ●●●●●●●●●●●●                            ●●●●●●●●●●●●
            [front wheel]                            [rear wheel]

Protocol Summary#

Data Flow Summary#

Favero Pedals ──ANT+──────────────────────────────────────┐
Shimano Di2 ──ANT+/E-TUBE──────────────────────────────► Garmin Edge MTB ──ANT+──► Watchlink ──BLE──► Apple Watch Ultra 1
Garmin Varia ──ANT+───────────────────────────────────────┘    (records .fit)                                    │
                                                                                                                  └──BLE──► iPhone 16 Pro Max
                                                                                                                                    │
                                                                                                                                    └──BT──► Shokz OpenRun Pro 2