The only heart rate monitor


Your ultimate performance

coach in a real-time

heads up display.


The King of the Mountain

System powered by Strava.


Ride sends speed

and cadence to

any ANT+ cycle

computer or watch.


Stride sends speed and cadence

to any ANT+ display.


Android Requirements

Requires Android 4.3 or better, and Bluetooth 4.0 support on the phone. We have seen better BLE stability with Android 4.4 and Google Nexus devices. We have tested with Nexus 5, Samsung Galaxy S4, Note 3, and Note Pro (tablet). Older phones have been less stable, especially for firmware updates.

Where is PRECISION Shipping?


Friday Files

  • Friday File, May 22, 2015
    Today’s update is all about our production and your cranks. A few of you are noticing accuracy and/or…
  • Friday File, May 15, 2015
    Some app info and training wisdom for you this week! The 4iiii app supports the 4iiii Viiiiva heart…
  • Friday File, May 8, 2015
    Still on the theme of how to ride with power, one of our resident cyclists and self-proclaimed ‘enginerds,’…

Smarter – Faster – Safer