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{{DISPLAYTITLE:Stryd footpod review}}
Stryd is one of the most useful and impressive running technologies available. It's a [[Footpod]] that analyzes the movement of your foot with greater accuracy than most traditional Footpods. While a lot of the Stryd marketing focuses on their "running power meter" functionality, I see the greatest value coming from their accurate measurement of pace and distance. If you look at my [[GPS Accuracy| testing of GPS Accuracy]], you will see that Stryd gives a far more accurate measurement of distance than any GPS watch. It accurate enough that it really doesn't need any calibration, and unlike GPS, it should work in any situation. Not only is it providing accurate distance measurement, but it provides real-time pace, something that's impractical to achieve with any GPS device. While I believe [[Running Power Meters]] are quite different to cycling power meters and are more of a "power estimate" than a meter, I think that if you understand their limitations they can still be useful. At $200 I think that Stryd is good value for money, and it's one of the few running devices that I would replace unhesitatingly if I lost it. Currently Stryd is only available via [https://www.stryd.com their web site]. (I don't have any affiliate or sales link with Stryd.){{BuyStryd}}
=The Metrics=
Stryd provides an array of different metrics, which vary both in accuracy and usefulness.
I tested the distant accuracy of the Stryd using the same basic methodology as I do for my [[GPS Accuracy]] testing. (See [[GPS Testing Methodology]] for details.) I used a [[Polar M400]] configured to use the distance from the Stryd footpod. As you can see from the results, the Stryd is remarkably accurate, far better than any GPS device I've tested. My testing of pace is more anecdotal, but I've been able to hit my target paces using guidance from my Stryd. I've tested using a range of paces from 10:00 min/mile to 6:30 min/mile and the Stryd allows me to cover a given distance in just the right time.
[[File:GPS Accuracy.png|center|thumb|800px|An infographic of the accuracy of the GPS running watches. The top right corner represents the most accurate watches. (This graphic uses ISO 5725 terminology.)]]
==Accuracy on Single Track Trails==
My [[GPS Testing Methodology]] uses an asphalt/tarmac path rather than technical single track trails. This has raised the reasonable question of how Stryd would perform on more challenging terrain. To find out, I measured a section of what I will consider semitechnical singletrack. I used a surveying wheel, as my mountain biking skills are not up to using the US ATF certification process, and I'm not sure that that process would really work in this environment anyway. Measuring singletrack is a little challenging, but I was able to get consistent results from repeated measurements using the survey wheel to within a few inches. The trail I used is quite twisty, and has sections where I'm barely running, and my overall pace was about 11:00 min/mile rather than the 8:00-8:30 pace that I'd be maintaining on asphalt. Hopefully this gives a sense of the difficulty of the trail, and you can see a couple of images below. It's certainly not a truly technical singletrack where I'd be rock hoping, but it's also a trail where it's often difficult to get into a rhythm because of having to watch foot placement. I compared the Stryd with one of the most accurate GPS watches I've tried, the [[Polar V800]]. I'd never normally tried to measure a GPS device on the trail this twisty, as it just too challenging.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
!
! Accuracy<br/>(Combined)
! Trueness<br/>(Average Distance Error)
! Precision<br/>(From mean)
! Precision<br/>(From true)
|-
| Stryd
| 1.42%
| 1.19%
| 1.09%
| 1.62%
|-
| [[Polar V800]]
| 12.55%
| 12.42%
| 1.99%
| 12.68%
|}
As you can see, the Stryd does remarkably well, even on this challenging singletrack. It's more accurate than the Polar V800 would be on asphalt, which is quite an achievement. To put this into perspective, the best GPS watch, the Polar V800, had an appalling level of inaccuracy on the same course. I expected GPS to be a lot worse on this type of challenging terrain, but even I'm surprised by this level of problem.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
|- valign="top"
|[[File:Single Track (2).jpg|none|thumb|300px|]]
|[[File:Single Track (1).jpg|none|thumb|300px|]]
|}
==Accuracy Walking==
I've not done any statistical analysis of the accuracy of the Stryd while walking, mostly due to time constraints. However, my anecdotal use of Stryd while hiking on my testing course suggests that it's equally accurate when hiking in boots as it is when running.
=Treadmill Problems=
The Stryd is so accurate outdoors, I couldn't understand why it was so bad on a treadmill. To my chagrin, I discovered that the Stryd Footpod was right, and my treadmill was wrong. Accurately calibrating a treadmill proves to be rather more complex than I'd have expected, as the treadmill will slow down when your foot is in contact with the belt, then speed up when you're in the air. For details on how to evaluate your treadmill have a read of [[Treadmill Calibration]].
* A common use of heart rate data is to allow an athlete to train at their [[Lactate Threshold]], often referred to as [[Tempo Runs]]. The belief is that this training intensity is especially beneficial, though the available science indicates the opposite. If Tempo Runs made sense, then Stryd's power estimate would be quite valuable for hitting that pace accurately. I'm sure that many runners will use Stryd this way, even though the science indicates it is ineffective.
=Testing Battery Life=
I've not done a single long run that would allow me to test the battery life for an ultramarathon. However, on multiple shorter runs (25-120 minutes) I found that Stryd was reporting 10% battery life left after 5.5 hours, which is far short of the claimed 20 hours' battery life. However, this may well be due to one of the many watches I have paired to Stryd keeping the pod alive well after the run, plus I tend to pair my Stryd to different watches many, many times. I will attempt some more realistic testing in the near future. (If you're an ultrarunner who's used Stryd on a 20+ hour ultra, I'd love to hear from you.)
=Stryd For Ultrarunning?=
The claimed battery life for Stryd is only 20 hours, which is not long enough for many ultramarathons. Obviously, if you could have two Stryd pods, but that would be expensive. One option would be to use a Garmin watch that supports UltraTrac to extend the battery life along with the Stryd for accurate distance and pace. This would last for around 20 hours, and when the Stryd battery is dead, things would fall back to GPS. You may even be able to switch to normal GPS mode mid-run. I found that this worked nicely on a short run when I tested it out with the [[Garmin Fenix 3]]. I started off with the watch in UltraTrac mode and the Stryd connected. I then took the Stryd pod off to simulate the battery running out, and swapped to normal GPS mode.