Mio Fuse Review

The Mio Fuse Heart Rate and Activity Tracker
The Mio Fuse Heart Rate and Activity Tracker

Earlier this year, our own Jim Hodgson tested the Mio Link. That unit was very basic, functioning solely as a heart rate monitor that you wore on your wrist, instead of a chest strap. The Mio Fuse, tested here, adds a display and a ton more features on top of heart rate monitoring, making it a more versatile activity tracker. Jim enjoyed using the Link, but how did I get along with the Fuse?


I opted for the crimson-colored Fuse, with the other color option being cobalt. Only the inside of the silicone band is red, with the outside being black. It has good proportions and doesn’t look too exercise-y. You may not want to rock it at a fancy dinner, but in most other instances it won’t look out of place.

The underside of the Fuse; the green lights are what measures your heart rate
The underside of the Fuse; the green lights are what measure your heart rate

The band has plenty of holes for fine tuning the fit. Mio recommends positioning the unit 1-3 inches above your wrist bone, at least while tracking heart rate. While the band itself is comfortable, I’m not a fan of the closure system. If you don’t have the band positioned just right, the two metal prongs stick up slightly and will snag long sleeves, and when reaching into your pockets. Also, the end of the band comes unclipped too easily and will flap around. I realize that one of the ways Mio is trying to differentiate itself is through their unique band design, but for practical purposes, I would prefer a more standard setup.

Mio's unique band closure
Mio’s unique band closure


The sleek design and black face of the Fuse belie its capabilities. This thing has a long list of features:

  • Optical heart rate sensor
  • Bluetooth connectivity
  • ANT+ connectivity
  • On-screen heart rate display
  • Different colored LEDs displayed depending on heart rate zone
  • On-board watch and timer
  • Tracks steps, distance, and calories
  • Tracks pace, speed, and distance during workouts
  • Built-in memory
  • Calorie burn during workouts
  • Vibration alerts

Mio offers their own app, Mio GO, but the Fuse will work with a variety of other apps for cycling and running: Strava, Map My Ride, Wahoo, etc. The Mio GO will set your max heart rate (MHR) and zones using your age, but you can go through the settings on the app to alter that information if you need to. The simplest way to estimate your MHR is by subtracting your age from 220. For me, that would be 186, but I know my MHR is actually a bit higher at 188. From there you can adjust your target heart rate zones as well as set your resting heart rate.

Lots of stuff to customize in the app's menu
Lots of stuff to customize in the app’s menu

In addition to dialing in your zones, you can choose what info to display on the “All-Day” and “Workout” screens. I chose to have my heart rate displayed at all times during a workout. That made it easy to just glance down to see where I was and if I needed to pick it up or back off. Apart from having the actual number shown, the display will show one of five different colors, depending on your current zone. Blue for Zone 1; green for 2; yellow for 3; purple for 4; and red for 5, otherwise known as, “why the hell are you looking at your watch?” zone. Also, the whole unit will vibrate when you change zones, either up or down, to keep you on track. All of that customization is appreciated, even for a novice heart rate tracker like me.

Fine-tuning my heart rate zones
Fine-tuning my heart rate zones


Above, I mentioned that while the band was comfortable to wear all day, I wasn’t happy with the pokey metal prongs and the flapping end. Unfortunately, those weren’t my only gripes with the Fuse.

These little guys will snag sleeves and pockets
These little guys will snag sleeves and pockets

I’ve been wearing a watch pretty much since I figured out how to tell time. It’s been so long now that I feel naked without one. While the Fuse will tell you the time, you have to press a button or two to see it. A quick glance at the wrist to check the time is out of the question. This may seem like it’s not a big deal, but when you’ve spent the better part of your life wearing a watch, believe me, it’s noticeable. My girlfriend has been using a competing product, the Fitbit, and they get around this by using an accelerometer. When you raise your arm to look at your wrist, the Fitbit senses that and automatically turns on the display. Mio, if you’re listening, incorporate that feature into the next generation!

Wearing long sleeves, or positioning the Fuse too close to your gloves, can cause interference with the unit. I’ve inadvertently stopped the heart rate tracking because my jacket or the cuff of my glove pressed the wrong button. Definitely something to consider if you’re using it in chillier temps.

Starting with the first time I used the Fuse, I had trouble getting it to sync properly with the app. I downloaded the app and then got a message that I needed to update the Fuse’s software. The update would start, but then freeze. I ended up deleting the app and reinstalling it a few times before I was able to update the Fuse and get it all working properly.

When I would try to sync my daily activities or workouts to the app, I would often encounter an error message. Retrying the sync or closing and reopening the app would resolve the problem, but it was certainly frustrating. Interestingly, I had no issues pairing the Fuse with other apps, Strava for instance. Bottom line? The tech wasn’t as seamless as I had hoped for.


My time with the Fuse wasn’t all sour grapes. The battery life is excellent: I was able to get nearly a week out of a charge. The heart rate monitoring feature is its biggest selling point and that’s where the Fuse really excels. It seems to be very accurate, with only a couple of questionable data points during my test. The simple display is easy to read–very nice when you’re nearing the red zone and can’t afford to take more than a quick peak.

When you can get the Fuse to sync, you actually get some cool data - like this graph from one of my rides
When you can get the Fuse to sync, you actually get some cool data – like this graph from one of my rides

The band closure wasn’t my favorite, but the Fuse is very comfortable to wear all day long. Word is Mio will soon be adding a sleep tracking feature as well, so you can even wear it to bed.

While the Fuse has a lot going for it, it also has some big drawbacks. Maybe my complaints about the band are unique to me and you won’t have the same issues, but beyond that, Mio really needs to sort their app out. With a smoother interface, I would be willing to overlook some of the other quirks. As it sits now, I would personally hold off on purchasing a Fuse until those concerns are addressed.

MSRP: $149

Thanks to Mio for providing the Fuse for review