Review: Fitbit flex

Wearables are the hottest new category and combining technology and health was an inevitable intersection. While I’ve seen dozens of fitness trackers, this was the first that I’ve seriously...


Wearables are the hottest new category and combining technology and health was an inevitable intersection. While I’ve seen dozens of fitness trackers, this was the first that I’ve seriously embraced. Being addicted to data it’s surprising how little I knew about my activity and spending a few weeks with the Fitbit flex has certainly opened my eyes.

The flex tracker houses 3-axis accelerometer that measures your motion patterns to determine your calories burned, distance traveled, steps taken, and sleep quality. As you go about your day, you’re likely to get a surprise from time to time as the vibration motor kicks into action as you pass your daily goal.


The Fitbit flex has two modes, you can think of them as day and night, unless of course you work night shift, then feel free to reverse them. During the day when you’re active, the flex tracks your movement, mainly your steps and distance, while in sleep mode, you’ll discover how long you sleep for and what quality sleep you’re getting.

The algorithm to translate motion into useful information is a secret sauce like the secret herbs and spices, so I guess we just trust they are accurate. Actually if you’re really concerned, you could wear the flex next to a similar device, or even basic pedometer to confirm the accuracy, just make sure your benchmark device is accurate.

Not technically a mode, more of a feature is silent alarms. Configured through the web interface, you can choose to set the Fitbit flex to vibrate to wake you at the defined time. This is particularly useful if you have a partner that is frequently annoyed by your early alarm clock. The flex can vibrate to wake you, it takes a little bit to get used to, but a great feature. As someone who has slept through audible alarms, it’s highly unlikely you’ll sleep through this.

Syncing and Software

Thanks to the Fitbit’s Bluetooth Low Energy connectivity, your stats are always at hand. One of the great things is that without thinking about it, the data from your Fitbit is transferred to your pc, mac or smartphone. Despite having the ability to see the data on the web, I found myself loving the Windows 8 app for Fitbit.

Syncing occurs automatically any time Flex is within about 20 feet of the wireless sync dongle and is relatively motionless. I did find it strange that the flex demanded a one of your Mac or PC’s USB ports for the dongle, for those of us using ultrabooks, these are a precious commodity. Future versions should definitely leverage the Bluetooth connectivity inside most modern devices.

Switching between today’s stats and a historical view was simple and easy, as was interrogating the data collected like the distance, steps, calories burned, active minutes per day and sleep. Inputting your weight and food intake is completely optional and not something I paid much attention to.


Something I couldn’t ignore was the gamification aspect of Fitbit. After installing the software, I quickly added friends who were also Fitbit users. Seeing your daily progress compared to your friends drives you to take walks you otherwise wouldn’t. It may sounds strange, but gamification absolutely worked on me.

I do question the longevity of this artificial motivation, but that’s not a criticism of flex, but rather all fitness products that attempt this.

When using the fitbit, you’ll unlock achievements or badges, much like those from Foursquare minus the checkin. These add to the encouragement to walk further, but without any real world reward, these are likely to come by accident, rather than a targeted effort to achieve them.


Battery life

If you look at the spec sheet, the flex battery is supposed to last five days and it does, but that’s it. You’ll know from the LED lights that it’s fully charged and you’ll even get an email when it’s running low (20% or less). The biggest issue I had is that taking the tracker out of the band at least once a week is annoying enough, but having to dock it in a separate USB dongle to charge is ridiculous. There’s no reason the bands couldn’t contain wireless charging.

Perhaps the biggest issue with charging the flex is that you miss out on the data while it’s charging. If you charge on day 5, you miss tracking steps for that day, if you charge during the night, you miss sleep tracking. The only real solution would be to purchase an additional flex tracker and charge one, while using the other but this would obviously increase your cost.

If they could work out a way to induct kinetic energy like some watches do, then this problem may be a thing of the past.


The timing of this review allowed me to track something I had always wanted to track, how far you walk at a conference. Last week I attended Computex in Taipei, Taiwan and being Asia’s biggest trade show, there were multiple floors of products to walk. After screaming past my 10,000 step goal by lunch time, by mid afternoon I had clocked up 15,000 steps in a day. The evening approached and I wanted to see more of the night life in Taipei, so I hit the streets once again.

Street after street, block after block, I was sure that illusive 20,000 step goal was just around the corner. When I decided I could walk no more I took the lift back up to the room and jumped on the laptop to a disappointment. For a smart device, this highlighted how dumb the flex could be. With a lack of a GPS or clock, or really any sense of time and time zone, the flex didn’t know I’d travelled through time.

Basically the 2 hour difference between Australia (where my account was setup) and Taiwan had caused more than 4,000 steps to be logged against the next day. With no way to alter this retroactively, I had come agonizingly short of the 20K step goal. If you don’t travel, this isn’t an issue.


The Fitbit flex sells for A$129.95 and comes with Flex tracker, Large & small wristbands, wireless sync dongle and charging cable. Because you need to match your fitness hardware with your fashion, the flex comes in a number of colours, Black, Slate, Tangerine, Teal, Navy, Violet, Lime and Pink.



The mark of any good product is when you don’t want to give it back and that’s certainly the case with the flex. Whether it’s because the flex is amazing, or just simply because it’s finally given me a window into data that’s person, that’s human and about me is the question. There’s a load of competition in this space and the options are growing by the day.

Fitbit flex is a great product that does a limited set of things really well, their software and platform support is great. The price is right for this product and in reach of most who care about fitness as you’d easily spend more on a gym membership.

Stop waiting for the mythical iWatch and start using data to change your life today. My advice, if you want to take top spot on the leaderboard, attend a conference.



Creator of (formerly - the technology website provides a way to share the best content with an audience of millions each year. Also an app developer for Win8 and WP8 and Founder & CEO of - Changing the way products are developed.
One Comment

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  • Nick Merry
    26 June 2014 at 5:14 pm

    Great review Jason. I have to agree with most of what you say. In the past 6 months I have owned a Fitbit Flex, a Fitbit Force, an Up24 and a Sony Smartband. If you took elements from each of these four you would have the perfect band. The Fitbit Flex is daggy to look at the black colour of the band fades easily but it probably integrates the best. The Force was great until it broke and its only real benefit over the Flex was the LCD display and the ability to count stairs climbed.
    The Up24 is the more motivational in terms of apps and the hardware looks good but its design means it gets caught a lot on clothing and also on bedding whilst you sleep. It is also no convenient to wear under formal shirts.
    The Sony Smartband is the comfiest to wear by a country mile but the app is still in its infancy and Sony are determined to try and force you to get an Xperia phone to unlock the latest updates eg: cycling and transportation. On my Nexus 5 I found it slow to sync and hit and miss with the sleep. I like the way it can notify you of phone calls, emails etc by vibrating on your wrist and the module is waterproof and can be removed easily.
    I wore the Sony and the Up24 together on the same wrist for a week and noticed there was at least a 10 – 20% discrepancy in the step counting especially after a run.
    So if you could merge the Fitbit Force LCD with the Sony comfort and notifications and UP24 app motivation you would have the perfect fitness band but perhaps this is where Android Wear watches need to take it to the next level so you only need one item to wear on your wrist.

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