Tag Archives: heart rate monitor

4iiii Viiva Heart Rate monitor revisited

Some time ago I posted about my general dissatisfaction with the 4iiii Viiva heart rate monitor.

In a nutshell, in addition to being a ANT+ and Bluetooth Low Energy (BTLE) heart rate monitor, it also acts as a bridge between ANT+ devices that don’t offer BTLE functionality. In my original review of the Viiva, I complained because few software offerings provided support for it and the data is sent to apps wasn’t accurate.

Well, I need to revise my opinion of the Viiva … it has gained adoption and now appears to be quite useful.

Those who use training programs (such as Zwift) with Apple TV have already learned that the Apple TV only supports 3 total BTLE devices connected. One of those devices slots is already taken by the remote control. That leaves only 2 more slots.

If you’re using a training program, you’ll need at least 3 devices connected (possibly more) …

  • Cadence sensor
  • Heart rate monitor
  • Trainer
  • Speed sensor (depending on the trainer)
  • Power meter (depending on the trainer)

In my case, I need a cadence sensor, heart rate monitor, and Kickr smart trainer (which acts as both a smart trainer and power meter).

You can use the Zwift companion app to gate the BTLE sensors, through the phone, to Zwift … but I find that to be somewhat twitchy (see my post on Zwift, which I will create later and link).

With the Viiva HRM, I’m able to pair my cadence sensor (which broadcasts in both ANT+ and BTLE) to it and feed both it and the heart rate data to the Apple TV without needing an extra BTLE connection slot.

So far it’s working well … the only issue I’ve had is that sometimes it takes a little while for Zwift to pick up the Viiva heart rate monitor.

Another option to accomplish the same thing is to use the North Pole Engineering (NPE) CABLE ANT+ to BTLE gateway. I tried using that but had problems with the hardware. It was probably defective. Getting support for the device, from the manufacturer, was pretty difficult. I ended up giving up, returning the device, and using the Viiva (since I already had it).