Changes

* '''How far did I run?''' This is the most basic question, and the Fenix 5X has rather mediocre [[GPS Accuracy]]. For me, this amount of error in the distance would be unacceptable. For instance, on a 20-mile [[Long Run]] you could see an error of nearly a mile, which is enough to really mess up your training. The good news is that the Fenix 5X has great support for the [[Stryd]] footpod that gives awesome accuracy.

* '''How fast am I running?''' Knowing how fast you're running can be a nice to know, or it can be vital for your training or race performance. Because of the nature of GPS, watches that rely on GPS signal alone tend to have serious problems with current pace. The poor GPS accuracy of Fenix 5X tends to exacerbate this, with readings fluctuating by over a minute/mile regularly and up to two minutes/mile occasionally. So, if you want pace information you need to get a [[Stryd]] footpod.

* '''What's my cadence? '''[[Cadence]]''' '''is one of the most critical and often overlooked aspects of running. If you get your Cadence right, many other things naturally fall into place. The Fenix 5X will get [[Cadence]] from its internal accelerometer, as well as from a Footpod, or the [[Running Dynamics]] heart rate strap/pod. There are alerts for Cadence, which is great, and even a metronome feature. I don't think it comes any better than this.

=The Fenix 5X for Ultrarunning=

The Fenix 5X claims 20 hours of battery life, and I tested it under optimal conditions and managed to get 23 hours. That's tough to achieve in the real world, as you have to avoid using the map display, backlight, or changing the display too often. With the map display in constant use, I was still able to achieve the rated 20 hours, which is pretty good. This makes the Fenix 5X a great candidate for shorter races (50 miles/100k). But if you hope to be still moving during the [[Second Dawn]], then there are probably better options. You can charge the Fenix 5X on the run, but the position of the charging cable means you can't wear the watch while you're doing so (unlike the [[Garmin Fenix 3]].) See [[Best Running Watch#Watches for Ultrarunning| Watches for Ultrarunning]] for more details.

=Physical Characteristics=

The Fenix 5X is a big watch, and it's larger than I'm comfortable with as a 24 hour/day activity tracker. However, on the run it fells okay even on my diminutive wrists. The watch straps rotate where they connect to the watch body, unlike the Polar V800 where they extend from the watch body and therefore don't conform as well. The materials are excellent quality, and while it doesn't have the simplistic elegance of the [[Suunto Spartan Ultra]] it's still very nice. The exposed bolt heads make the Fenix 5 look rugged and sporty, though it's a bit fussy visually. The only thing that feels a little cheap and tacky is the watch strap itself on the cheapest version. It's nothing like the silky smooth and soft watch material that Suunto use. The display is reasonable, but when you compare it to the [[Suunto Spartan Ultra]] it seems a little small and low resolution. Given that the Fenix 5X is larger than the Fenix 5, I would've expected a larger display, but that's not the case. I suspect that the Fenix 5X is larger to allow for more memory for the maps, or perhaps more battery, though this is purely speculation.

* '''Bluetooth Footpod. '''Bluetooth Footpod's are not quite as standardized as one would like, so there are more issues here. I tested with the Polar Stride Sensor, Adidas Speed Cell, and [[MilestonePod]] and they all worked fine except for one common problem. If you set the distance to "always" the calibration factor is ignored when you're running outdoors. The calibration factor is used when GPS is off in treadmill mode. This is not a problem with Ant+ Footpod's. (See below for [[Stryd]] Footpod.)

* '''Bluetooth Biking devices (Speed, Power)'''. I've not tested any of these devices as I'm a runner, not a cyclist.

* '''Ant+ Footpod'''. Unlike the Bluetooth equivalent, the Ant+ Footpod worked fine. (See below for [[Stryd]] Footpod.)

* '''Ant+ Tempe'''. Even though the Fenix 5X has an internal thermometer, it also supports their external temperature sensor that's the same form factor as their Footpod. Being an external pod, it's a lot more accurate than the internal temperature sensor that's heavily influenced by your body heat.

* '''Wahoo'''. The [[Wahoo TICKR Run]] is a little unusual in that it also supports both Bluetooth and Ant+. Rather like [[Garmin Running Dynamics]] heart rate monitor, it's also capable of gathering rather more data than a typical heart rate monitor though you really need the smart phone app to make use of it. I found that the Fenix 5X would find the one who twice, once as a Bluetooth device and once as an Ant+ device. Pairing both ways seemed to cause some issues with the Fenix 5X connecting to the Wahoo at the start of the run, though it's possible this was either a user error on my part or just an oddity. Even stranger, the Fenix 5X would try to pair up with the one who is a Bluetooth Footpod, but I could never get anything to work in this mode.

* '''Stryd'''. Like the Wahoo, the [[Stryd]] Footpod is both Bluetooth and Ant+, but it's also both a Footpod and a power meter. I found it best to pair as just an Ant+ Footpod.

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|[[File:Garmin Tempe (2).jpg|none|thumb|300px|Her's another view.]]

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=GPS Accuracy=

I've tested the [[GPS Accuracy]] of the Fenix 5X with its initial release firmware, and it's possible that its accuracy will improve as the firmware matures. Based on my testing, the Fenix 5X certainly has plenty of room for improvement. At best, the GPS accuracy could be described as mediocre, and I think it's bad enough that it could significantly mess up your training. If you look at the middle, curved section, you can see that the Fenix 5X is doing particularly badly here. This is a challenging section, and reveals any weakness in a GPS watch. The right most segment with the right-angle turn is a section of the most watches do reasonably well on, but the Fenix 5X is struggling here as well. The tracks don't look too bad, you can see that the Fenix 5X is not able to calculate the distance correctly. The Fenix 5X doesn't get too badly confused going under the bridge, actually looks a little better in that area than the two Suunto watches shown for comparison. The blue lap markers are rather widely spread, again giving more evidence of poor GPS accuracy. It's possible that other versions of the Fenix 5 might have different GPS accuracy. It's possible that the plastic 935 might do a little better, but without testing it's impossible to know. (I buy all my test gear through retail channels. This allows me to be brutally honest in my reviews, as I don't need to keep the manufacturer happy in order to continue getting free samples or early access. The downside is that I'm more limited in the array of watches I can test. Therefore, it's unlikely that I will test other versions of the Fenix 5 at this point.) I've tested both the 4.20 and the 4.30 version of the GPS firmware (see below for details.)

As with all the watches I test, I first left the Fenix 5X in its "ready to go" mode with a clear view of the sky for over 30 minutes. This is to ensure that the chipset has ample time to download the almanac from the satellites, which should only take about 12 minutes. I also give the Fenix 5X at least five minutes after it has got a satellite lock before starting my run. This is to give it the best possible chance of having good accuracy. (Like most modern GPS watches, the Fenix 5X will download information on the satellite orbits when it's synced, but this predicted information is not as good as the live for data transmitted by the satellites themselves.)

[[File:Fenix 5X Soaking.jpg|center|thumb|300px|Soaking the Fenix 5X.]]

[[File:Fenix 5X Firmware.jpg|center|thumb|300px|Here's where the version number of the GPS firmware is located.]]

=Optical Heart Rate Monitoring=