Connect Your Devices

VeloLoop reads data from standard Bluetooth Low Energy cycling sensors. This guide explains which devices are supported and how to pair them.

Supported sensors

VeloLoop works with any cycling sensor that broadcasts one of the standard Bluetooth LE profiles listed below. That includes:

  • Smart trainers — via FTMS Indoor Bike Data or Cycling Power service
  • Power meters — via Cycling Power service
  • Heart-rate monitors — chest straps, arm bands, or watch HR broadcast via Heart Rate service
  • Cadence sensors — via Cycling Speed & Cadence service, or cadence fields from power meters and FTMS trainers
BLE ServiceUUIDProvides
Heart Rate0x180DHeart rate (BPM)
Cycling Power0x1818Power (watts), optional cadence
Cycling Speed & Cadence (CSC)0x1816Cadence (RPM)
Fitness Machine (FTMS)0x1826Power (watts) + cadence (RPM)

How to connect

  1. 1Turn on Bluetooth in Windows Settings.
  2. 2Wake your sensor — start pedalling or put on your heart-rate strap.
  3. 3Open VeloLoop and click Scan.
  4. 4Select a device for each metric you want to track.
  5. 5A single smart trainer can provide both power and cadence; a chest strap or arm band provides heart rate.

Metric priority

When a device advertises more than one service, VeloLoop picks the best source for each metric automatically:

Power—Cycling Power is preferred over FTMS Indoor Bike Data.
Cadence—FTMS is preferred, then Cycling Speed & Cadence (CSC), then crank-revolution fields from Cycling Power.
Heart rate—Uses the Heart Rate Measurement characteristic only.

Using an independent power meter with your trainer

If you have a separate crank or pedal power meter alongside a smart trainer, you can assign the power meter to the power metric and let the trainer supply cadence via its FTMS or CSC service. This gives you the accuracy of your dedicated power meter while still capturing cadence from the trainer.

Reconnection

If a sensor drops its Bluetooth connection mid-ride, VeloLoop automatically attempts to reconnect. It starts with a short delay and gradually backs off from roughly 2 seconds up to 30 seconds between retries. While reconnecting, screen feedback for that metric is paused so you are not penalised. Once the sensor reconnects, a fresh grace period begins before feedback resumes.

Stale data

If a sensor remains connected but stops sending new readings for 20 seconds, VeloLoop treats that metric as missing. Screen feedback for the affected metric is paused until fresh data arrives.

ANT+ supportOptional

VeloLoop can also read data from ANT+ heart-rate monitors, power meters, and speed & cadence sensors. ANT+ is an optional addition and requires two things:

  1. 1A USB ANT+ receiver plugged into your computer.
  2. 2The openant Python library installed separately (it is not included in the default VeloLoop installation).

When both are present, ANT+ devices appear alongside BLE devices during scanning. BLE remains the recommended connection method for most users.

Important notes

  • VeloLoop connects to one BLE device per physical sensor. If another app already holds the Bluetooth connection, VeloLoop cannot connect to that device.
  • BLE (Bluetooth Low Energy) is the primary and recommended connection method. ANT+ is available as an optional addition if you install the openant library and have a USB ANT+ receiver.
  • In Feedback Only mode (the default), VeloLoop only reads sensor data and never controls your trainer — safe to use alongside Zwift, TrainerRoad or other apps. Optional ERG and Resistance modes are also available for users who want VeloLoop to control an FTMS-compatible trainer.
  • Saved device addresses are not portable between Windows and macOS.