TrainerRoad doesn't officially support bridging devices.
While there are some cases where you may be able to get metrics from a bridging device, it won't be as reliable as connecting the sensor directly through ANT+ or Bluetooth (click for more information on each connection method).
We've had some luck with bridging devices, but most of them haven't worked as intended with our app. In some cases, we've found that only one device will be transmitted when running multiple devices through a bridging device. In others, we've found that it prevents the device from pairing to TrainerRoad entirely.
This behavior tends to vary from device to device, and to be safe, we generally recommend against a bridging device. Instead, we encourage purchasing a dedicated ANT+/Bluetooth dongle.
We may look into adding more compatibility with bridging devices in the future, but we don't have an ETA on this for the time being.
Troubleshooting Devices with Bridging Options
If you're unable to pair your sensor to TrainerRoad, and your sensor has a "bridging" option, we would recommend turning this off to make sure this isn't preventing the sensor from pairing.
Otherwise, if you're still experiencing issues pairing, we would recommend checking out our troubleshooting article here.