Mio was founded in 1999 by mother of three Liz Dickinson, who created a strapless heart rate (HR) monitor sports watch. (It’s not to be confused with the GPS manufacturer Mio, which has a similar logo).
Mio now offers the Link wristband without the display. Instead it transmits your heart rate to a compatible device via Bluetooth Smart or ANT+, or even both concurrently to two separate devices.
It works using a pair of LEDs and an electro-optical sensor that senses the volume of blood passing beneath the skin – your pulse. Hospital finger clip sensors work in the same way, but until recently the technology was confined to stationary subjects. Mio’s accelerometer deals with signal disturbances caused by movement, giving electrocardiograph (ECG) accuracy in independent lab tests.
A USB charger powers eight to 10 hours usage. The soft-feeling silicone strap comes in two lengths and could be ideal for riders who find chest straps restrictive. It should be fitted snugly around the wrist higher than the wrist bone to avoid distortion from joint movement.
Pressing the internal button lights an LED that shows charge level, HR detection and HR zones, though on a bike, your device’s zone system will be more useful, as the flashing LED is hard to view when riding. Our Garmin easily detected the Mio, although initial on-the-bike readings were erratic.
Tightening the strap and changing its position made less difference than switching wrists, when readings became more consistent, although still occasionally suffered more lag in response than our chest strap. Light is the enemy of optical sensing, so the strap flexing can cause interference, but in the main, it performed reliably, and even when tight wasn’t intrusive.