Trainer control

Smart trainer workout app

ERG mode, resistance control and structured workouts for FTMS-compatible trainers.

Three ways to control your trainer

VeloLoop communicates with smart trainers that support the Bluetooth FTMS (Fitness Machine Service) protocol. You can choose how VeloLoop interacts with your trainer:

Feedback Only

The default mode. VeloLoop reads your sensor data and provides ambient screen feedback but does not send commands to the trainer. You control resistance manually.

ERG Mode

The trainer automatically adjusts resistance to hold a target power regardless of your cadence. Ideal for structured workouts with specific watt targets.

Resistance Mode

Set a fixed resistance level. The trainer holds that resistance and you vary effort through cadence — closer to outdoor riding feel.

Structured workouts with trainer control

When you import a structured workout and enable ERG mode, VeloLoop sends the target power for each interval directly to your trainer. The resistance changes automatically between intervals — no manual adjustment needed.

Workouts can include up to 200 expanded steps with FTP-relative targets and repeat groups. Supported import formats:

  • ZWO — Zwift custom workouts
  • MRC / ERG — TrainerRoad and generic formats
  • FIT — Garmin workout files
  • JSON — VeloLoop's native format

Sensor support beyond the trainer

VeloLoop connects to multiple Bluetooth LE sensors simultaneously. In addition to your smart trainer, you can connect:

  • Heart rate monitors (BLE Heart Rate Service 0x180D)
  • Power meters (BLE Cycling Power Service 0x1818)
  • Cadence sensors (BLE Cycling Speed and Cadence 0x1816)
  • ANT+ devices with an optional USB receiver

The ambient screen feedback responds to whichever metrics you choose to target — power, cadence, heart rate or any combination.

Virtual speed and distance

When using a power source, VeloLoop can estimate virtual speed and distance using a flat-road physics model based on published cycling research. This gives your FIT activity files realistic distance values for platforms that display it.

Virtual distance is optional and can be toggled off if you prefer to record only the raw sensor data.

Compatible trainers

VeloLoop works with trainers that implement the Bluetooth FTMS protocol. Many modern smart trainers from established brands support FTMS. Check the compatibility page for details on supported BLE profiles and known-working configurations.

Note: Not every FTMS trainer has been tested with VeloLoop. If your trainer supports FTMS, it should work, but specific models may have implementation differences.

Try VeloLoop with your trainer

Free beta for Windows 11. Connect your FTMS trainer and start riding.

Join the beta