4iiii Viiiiva ANT+ & Bluetooth Heart Rate Monitor

The Viiiiva sits at the premium end of the chest-strap heart rate monitor market, competing directly with the Polar H10 and Garmin HRM-Pro Plus in the sub-$100 dual-protocol segment. What sets it apart from cheaper optical wristband alternatives isn't just accuracy — chest ECG-based HR detection fundamentally eliminates the motion artifact and perfusion noise that plague PPG sensors during high-intensity intervals, sprints, or cold-weather rides. The dual ANT+/Bluetooth simultaneous transmission is the headline hardware decision here, and it's not a minor convenience feature: it means the strap can feed a Garmin head unit over ANT+ and a Zwift session over BLE at the same time, without switching modes or pairing compromises. …More info