3 reasons to buy Fitbit Flex 2 (and 3 reasons not to)

Fitbit's latest tracker is an upgraded version of its entry-level Flex wearable. Flex 2 is a quality fitness tracker with a competitive price, but it lacks a display and battery life could be stronger.

Fitbit's fourth new fitness tracker of 2016, Flex 2 ($100), is a worthy successor to the original Flex. It is the lightest, thinnest, most flexible Fitbit wristband, and Flex 2 doesn't look clunky next to your analog watch or smartwatch. It's also worth a look if you frequently swim for exercise.

However, Flex 2 has some unfortunate compromises. 

3 reasons why you should buy Fitbit Flex 2

1. Flex 2 is very thin and light

Flex 2 is 30 percent smaller than the first Flex model, according to Fitbit. It is the activity tracking wristband for people who aren't sure they really want a wearable. It's also thin and light, so it sits fairly unobtrusively next to a smartwatch or traditional timepiece.

2. Flex 2 is water resistant

Flex 2 is the first Fitbit designed to be worn in the shower, pool or ocean, with a water resistance rating up to 50 meters, or about 164 feet.

The Fitbit mobile app automatically detects swim workouts after a default of 15 minutes, but you can change that time setting. Using the app, you can enter a pool's length (Account > Advanced Settings > Swim Settings). Flex 2 then calculates the number of pool lengths you swam during workouts. The app also tells you how long you swam and how many calories you burned.

In my tests, Flex 2 recorded accurate swim workout data.

fitbit flex 2 swim data Fitbit

Swim workouts count toward your total daily active minute goal, but swim strokes aren't converted into steps, so they don't count toward your daily step goal. In other words, if you compete with coworkers or friends on the Fitbit leaderboard, swimming won't help you.

3. Flex 2 can be worn in different ways

Flex 2 is designed to be worn on your wrist, as part of a "bangle," or in a pendant. Bangles start at $90, and pendants costs $80 or more. Fitbit's "lookbook" guide can help you find appropriate styles. The Flex 2 tracker is a tiny component that easily pops in and out of bands and accessories and into its charger. (Flex 2 comes with yet another proprietary Fitbit charger.)

3 reasons why you should NOT buy Fitbit Flex 2

1. Flex 2 doesn't have a screen

In order to be ultra-thin and light, Flex 2 unfortunately lacks some key features.

Unlike the company's Charge 2, Blaze and Surge trackers, Flex 2 does not track heart-rate data. Like Zip and Alta, Flex 2 lacks an altimeter, so it doesn't count the flights of stairs you climb. And unlike every other Fitbit, Flex 2 lacks a screen; it uses LEDs to convey information.

It would be unfair to criticize Fitbit for not adding every possible feature to every product. The company does an excellent job of offering differentiated trackers and feature sets at a range of prices, targeted at different user types. However, the lack of a screen does results in compromises.

Consider the "Reminders to Move" feature in Flex 2 (as well as Alta, Charge 2 and Blaze), which tells you to get up and move if you don't walk at least 250 steps during the first 50 minutes of an hour. You then have 10 minutes to complete the minimum 250 steps-per-hour goal. Many health experts suggest "sitting is the new smoking," so the reminders feature is an important one. 

Again, Flex 2 lacks a screen, so its Reminders to Move alerts comes in the form of a magenta light, two white lights, and a vibration. That means you don't receive a second alert when you complete your 250 steps-per-hour goal. So unless you take your smartphone on your stroll and keep syncing Flex 2 to the Fitbit app, you won't know when you hit your hourly step goal. As a result, you could end up sitting down again before you complete those 250 steps.

In comparison, Charge 2 shows you when it's time to move, as well as when you complete your hourly step goal. You can also tap the screen to see exactly how many steps you walk during that hour. If you completed the 250 step goal for that hour, the screen shows how many hours of that day's hourly move goal you completed. 

2. Flex 2's possible problems tracking exercise

Because Flex 2 lacks a screen and a button, you can't stop and start workouts on the tracker, which is the most accurate way to track exercise. However, you can manually stop or start a run, walk, or hike using the Fitbit app — if you don't mind taking your smartphone along during workouts.

Fitbit's SmartTrack feature also automatically recognizes and records workouts such as runs, walks, outdoor bike rides, elliptical machine training, and exclusive to Flex 2, swimming.

Like other Fitbits with SmartTrack, Flex 2's sensors make an "educated guess" about your types of activities and the durations. Generally speaking, the feature works well on other Fitbits.

However, in my tests of the first Flex 2 the company sent me for review, it frequently underreported the length of my walks. Using the timer on my Apple Watch, for example, I recorded a 45-minute walk in my San Francisco neighborhood. Flex 2's SmartTrack recorded the walk as 34 minutes. I also saw similar discrepancies during other walks.

I told Fitbit about the problem, and the company sent me a second Flex 2. The newer Flex 2 didn't underreport my walks, so the first device I received may have simply been a faulty tracker. To be safe, if you decide to buy a Flex 2, consider purchasing it directly from Fitbit, because the company offers a 45-day return policy. 

3. Flex 2 battery life is weak

You might assume that because Flex 2 lacks a screen, it has great battery life. Fitbit says you can get up to five days from a charge, depending on how you use it. But in my tests, Flex 2 lasted only three days. A Fitbit spokesperson said the automatic swim workout detection feature could drain significant battery. I disabled the feature and got about four days of battery life as a result. That was an improvement, but it's still less than the 3.5 days to 4.5 days I get from the Charge 2.

Is Flex 2 right for you?

Flex 2 isn't designed for use by hardcore athletes, except perhaps swimmers. And based on my tests, I recommend that people who really want to improve their overall health purchase trackers that have screens.

Fitbit's Charge 2 ($150 to $180) is the best overall wearable, in my opinion. Fitbit's Blaze ($200 and up) and Surge are also solid options, though the latter fitness watch is nearly two years old. Garmin makes some worthy wearables, as well. Garmin's vivofit 3 costs $100 and is swim-proof, for example, and unlike Flex 2, it has a screen.  

If you're a fashionista, a dedicated swimmer or someone who's casually interested in tracking activities and sleep, and you don't want to spend more than $100, Flex 2 is worth a look— assuming you're OK with the above caveats. Fitbit's large community of users also means you're likely to find friends to compete against on the company's leaderboard. And I much prefer Fitbit's mobile app to similar options from Garmin and others.

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