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Stryd

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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, and with vastly greater accuracy than GPS. 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(see below for details. ) 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 Stryd's power estimate has improved to the point where it's a valuable training and racing tool. At $200 220 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. (Note that you need to have access to an iOS or Android device to setup Stryd.)
{{BuyStryd}}
=The Metrics=
Stryd provides an array of different metrics, which vary both in accuracy and usefulness.
* '''Pace and Distance'''. My testing has shown that the Stryd is stunningly accurate in its measurement of distance. It's the only [[Footpod]] that is accurate enough that it doesn't require calibration, something that greatly improves its usability. (It's possible to tweak the accuracy with calibration, but out of the box is should be much better than GPS.) If you look at [[GPS Accuracy| my testing of distance accuracy]] you'll see that the Stryd is right at the top of the chart, and is far more accurate than any GPS device I've tested. This accuracy is also reflected in its measurement of current running pace. I think that this feature alone makes the Stryd good value for money. (Stryd doesn't use or provide GPS data, it uses accelerometers. Depending on the watch, the data from Stryd can be combined with the Watch's GPS data so that Stryd gives distance and pace, and the watch's GPS can be used for navigation.) * '''Elevation. '''I suspect that Stryd is providing remarkably accurate elevation information. Due to limitations on data export I've not been able to perform any statistical evaluation, but anecdotally the data looks really good. Obviously, the Stryd cannot provide any absolute altitude information, but it does seem to be able to measure relative changes far better than either GPS or barometric altimeter'saltimeters. At the moment, this information is not as directly usable as I'd like, as it's only available in real time via their, not their watch integration. If you use the Connect IQ data field, it will record elevation as a custom data track, and it is possible to copy this to the standard elevation track using plugins to Sport Tracks. * '''Running Power'''. As I talk about in my page on [[Running Power Meters]], I believe that they are not power meters at all. Like other running power meters, Stryd does not actually measure running power, but attempts to estimate what the power would be based on the things it can measure. My assumption is that it is mostly using pace and elevation change, possibly along with [[Cadence]] or Ground Contact Time. As discussed in the section below on the testing running power, I have found that the latest Stryd firmware gives a good estimate of relative intensity. I've been able to use Stryd to more effectively pace myself on hilly runs, as well as giving additional insight into [[High Intensity Interval Training]]. The current version of Stryd has "wind detection" to adjust the power estimate based on ambient wind.
* '''Form Power.''' Stryd describing this metric as the "running in place power", but it's unclear what that really means more if it has any value. They suggest that a decrease in this value represents improved [[Running Economy]], but there is nothing to back that up.
* '''Cadence'''. Cadence is fairly trivial to measure for even a far simpler [[Footpod]], so Stryd nails this easily. It's arguably one of the most important running metrics, so you should pay attention to this. There are far cheaper ways of measuring cadence (like [[MilestonePod]]) but it's nice to have this included in the Stryd.
Note that Stryd provides no information on foot strike parameters such as pronation, or foot landing position.
=The Pod=
The Stryd pod is similar to other Footpods. It's slightly larger than most, and has an LED status light on the top. Stryd uses a rechargeable battery that they claim lasts about 20 hours, though my testing indicates it lasts much less time. That's good enough for most runners, but may be a problem for longer ultramarathons. Stryd recharges wirelessly, which is nice, as I hate fiddling around with connectors or losing specialist cablesthrough a small cradle (earlier versions used wireless charging. ) Stryd uses a 9-axis sensor rather than the typical [[Footpod]] that uses a 3-axis sensor. The Stryd pod weighs 0.32oz/9.1g, compared with the Garmin Footpod at 0.34oz/9.6g, and the rather oversized Polar Footpod at 1.0oz/28.1g. Stryd doesn't provide any details of the waterproof rating of their pod. With its wireless charging, I'd have expected it to be quite waterproof, but there are reports that it's IPX7Stryd claim IP67 waterproofing, which is submersed safe for submersion to 1 meter for up . However, that means that you can't run through water as the pressure due to 30 minutesfoot movement will exceed the pressure. That should be fine for nearly any running activity; would mean taking the pod off if you're more than ankle deep in going through water for more than 30 minutes then that will cover the pod, though I suspect you should be okay if you're having a bad timewalk through slowly.
<gallery widths=300px heights=300px class="center">
File:Stryd Wind (21).jpg|The pod has an LED on top (the white area in near the middle) that's used to convey status.File:Stryd (3).jpg|Here's The charging cradle is not much bigger than the Stryd pod on the shoe.File:Stryd Charging.jpg|Stryd , which is my first device that supports wireless chargingnice for travelling.File:Stryd Wind (1).jpg|I don't normally show packaging but the design is so minimalist yet elegant that I thought it was worth a picture. File:Stryd Comparison (12).jpg|Here's a visual comparison with some other Footpod's. From top left to bottom right there is the Stryd, Garmin Footpod, [[MilestonePod]] v3, Polar Sensor, Adidas, and [[MilestonePod]] v2.File:Stryd Comparison (3).jpg|This is a view of the Stryd and Garmin Footpods with their cradle to clip into pod on the shoe laces.File:Stryd Comparison (2).jpg|Looking sideways you can see the Stryd and Garmin Footpods have similar openings for shoe laces.
</gallery>
=Testing Running Power Estimate=
I've found Stryd to be particularly useful in [[High Intensity Interval Training]], especially when using the [[Polar V800]] that has a native power support. With the V800, I can set the watch to display the maximum power for the current lap, which gives me a far better idea of how hard I'm pushing it on each interval than is possible any other way. You can see in the graph below that in short HIIT intervals the heart rate is a lagging behind power estimate, and my heart rate is still rising after I've slowed up.
[[File:StrydHIIT.jpg|center|thumb|400px|A HIIT interval from my [[Katana Run]] workout.]]
Below is an example from another runner during a marathon plus, mountainous training run. I've applied a lot of smoothing to the heart rate and power data, then scaled and aligned the two tracks. Over the first mile or so you can see the resting heart rate, rise up as of a warm-up, then the heart rate and power match reasonably well up and over the first hill, again suggesting that the Stryd power estimate is probably reasonable. For the second half of the run, you see heart rate rising above the power track, which I believe is an indication of [[Heart Rate Drift]], probably due to heat and dehydration. This shows one of the benefits of even a broad approximation of power compared with using heart rate for longer training runs. [[File:Stryd HR Drift.jpg|center|thumb|400px|]]However, it's also in indication of some of the weaknesses of mathematically estimating our rather than measuring it. If we look at the steep descent on the second hill, it looks like there is still some underestimation of power. The other possible issue is that Stryd is estimating for a typical runner, and each person's efficiency under different conditions is likely vary quite a bit. It's important to remember the limitations of this type of estimation, and avoid confusing it with what you'd get from a power meter.[[File:Stryd LpV Descent.jpg|center|thumb|400px|]]==Statistical Analysis of Power Estimate==
I've not performed any statistical analysis of Stryd's power estimate, mostly because I can't work out a reasonable way of doing this. Ideally, I'd be able to compare Stryd's power estimate with VO2 measurements from respiratory gas exchange, but I don't have the equipment, nor is it likely to be practical. The approach I've used above is to compare Stryd's power estimate with heart rate, but while heart rate is a well-established method of measuring exercise intensity, it's flaws (as noted in detail below) me know that he can only be used for relatively short periods of steady state exercise. (I'm hoping that someone will come up with a portable VO2 meter that will measure oxygen and carbon dioxide in your breath.)
==Stryd Power Estimate or Heart Rate?==
The use of heart rate for training has been established for many years, and heart rate based training has some useful advantages, as well as some significant shortcomings. I think the Stryd estimate of power output overcome some, but not all of the issues with heart rate based training. Personally, I don't see this type of power estimate completely replacing heart rate based training, only augmenting it.
* Heart rate responds to exercise intensity with a delay, while Stryd's power estimate is much closer to real-time.
* During longer exercise, [[Heart Rate Drift]] occurs that generally causes a higher heart rate for a given intensity. The reasons for this drift are complex, and include dehydration, fatigue, carbohydrate depletion. Using Stryd's power estimate ignores this drift, though it's unclear to me when to use heart rate and when to use the power estimate. In some situations, it seems likely that the drifted heart rate is a better estimate of intensity than an unmodified power estimate.
* There is a widespread myth that [[Maximum Heart Rate]] can be calculated, leading to some erroneous assumptions of how a given heart rate relates to the percentage of exercise capacity. In practice, both Heart Rate and maximum estimated power require a practical test.
* 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.
=Watch Support=
Stryd has support for a remarkable number of running watches. It supports both Bluetooth and Ant+, and it can look like a standard Footpod, a cycling power meter, or provide more sophisticated data. There are a large number of combinations of watches and configurations to consider, so I'll look at the general integration approaches and then look at specific watches.
* '''Footpod'''. Stryd can send standard Footpod data over both Bluetooth and Ant, giving the usual distance, pace, and cadence data. You can use it like this to get accurate distance, pace and Cadence data into the vast majority of watches I've tested. However, only a few watches will support this while recording a GPS track, and so most will need to be in indoor/treadmill mode. This means there's two modes to consider:
** '''Footpod with GPS'''. This is the ideal mode; you have your watch get all distance and pace data from Stryd, while still recording a GPS track. This will allow you to show where you've run, enable any navigation like back to start or breadcrumbs, and for things like Strava segments.
** '''Footpod without GPS'''. If your watch doesn't support the above "Footpod with GPS" mode, you have to set it to running indoors or treadmill mode where you lose all the GPS data. This works, but may not be what you want. (For watches that support Connect IQ, there is the option of using the "Stryd Race" app which will record GPS data along with Stryd data, but the features are a little lacking at the moment.)* '''Footpod with Power in Cadence'''. This is similar Note that Stryd used to be able to transmit the above scenario, but Stryd will put power into estimate in the Cadence cadence field. That gives you access to its power estimate on a wide range of watches, but there are two significant downsidesthis feature has been removed. Firstly, you don* '''Native Power'''t get Cadence information. Some watches will support the use of Power natively in running mode, which is arguably rather more important than an estimate of power unless you're really confident that your cadence just in Cycling mode (see below.) This is good. Secondly, because of the Bluetooth protocol, the Cadence field has a range of 0-255, and great option as it usually allows for displaying power estimates can be quite a bit larger. Thereforein different ways, stride divides such as the actual power by 10average over several time periods, so 210 watts will appear such as 21 steps/minute30 seconds or the lap. ThereforeThis mode also allows for things like run or lap maximum power, you lose a little bit of granularity, though in practice which I don't think that's a huge dealreally like for [[High Intensity Interval Training]]. This is only an issue Usually you also get the power data exported for Bluetooth watches; Ant+ works fineanalysis in other software, like Golden Cheetah. <span style='color:#FF0000'>Important: Stryd have stated they are removing this feature!</span>
* '''Cycling Power Meter'''. Stryd can send the same data that a cycling power meter would, so any watch that supports the cycling power meter will support stride in the same way. This gives some good support for power, and in indoor cycling mode you should be able to get pace, distance, and cadence data from the stride as well. There are a few annoyances with this approach, the biggest one being that you get your speed in MPH or KPH rather than min/mile or min/Km which would take some getting used to if you're a runner that used to thinking in terms of pace rather than speed. The other annoyance is that all of your data files will be considered as cycling rather than running, which could confuse your training log.
* '''Connect IQ'''. The advantages of Garmin's [[Connect IQ]] are shown in the ability for Stryd to add their sensor to any Garmin watch that supports Connect IQ. If you install the Stryd Connect IQ data field, it will show the power estimate, as well as recording all of the Stryd data into the fit file. Using this data field does not stop you using the Stryd as a normal Footpod at the same time. Because the Connect IQ only gives you the power, you still have two modes of Footpod integration, giving you two modes:
** '''Connect IQ + Footpod with GPS'''. The perfect solution; you get all the Stryd data, the distance/pace accuracy, and GPS for navigation.
** '''Connect IQ + Footpod without GPS'''. On the lower end Connect IQ enabled watches you have to set them to indoor/treadmill mode, so you get all the Stryd data, the distance/pace accuracy, but you don't have any GPS data.
* '''Suunto Spartan'''. The [[Suunto Spartan Ultra]] has explicit support for the Stryd, which is nice, but you can't use the Stryd for both power and distance/pace at the same time (except for "power in cadence".) However, the good news is that you get pace & distance from Stryd while also recording the GPS track. This is effectively the same as the "Footpod with GPS" mode.
Here's another way of looking at the options. I've ranked them in the order I'd use them, which is accurate pace & distance is the most important thing, then having GPS tracks for navigation, then having the power estimate, and lastly having the extra Stryd data.
{{:Stryd-Modes-table}}
*Stryd has a [[Connect IQ]] application that will record GPS data along with Stryd data, but the functionality is a little limited right now.
==Watch Specifics==
Here's a mapping of the modes above to specific watches. In all cases, I've prioritized accurate pace/distance information over either GPS data or the power estimate. I've put the detailed notes of how to pair Stryd with specific watches and how well they work at the bottom of this page.
==Bluetooth or Ant+==
Stryd supports both Bluetooth and Ant+, and both work well. Bluetooth has the limitation that you can only have one receiver talking to Stryd at a time, so you can't have it linked to two different watches simultaneously, or to a watch and your smart phone at the same time. (I have had occasions where the Stryd has stayed linked to my smart phone, so I've had to turn off Bluetooth on my phone to allow Stryd to link to a watch.) With Ant+ you can have as many watches linked simultaneously, and it's possible to have Stryd linked to both one Bluetooth watch and several Ant+ watches at the same time. If you're using Garmin [[Connect IQ]], you can have Stryd work as both a standard Footpod and connected via the Connect IQ data field.
=The AppCalibrating Stryd=The My testing shows that Stryd app is rather limitedremarkably accurate, but the company has reported that there can be some variation between Stryd devices. If you'd like to check your calibration, I'd recommend this process. (Note that the Suunto Spartan watches don't allow for any calibration.)* Check that your watch is set to get pace and distance from Stryd. The best way I mostly use 've found to verify this is to set the calibration factor to 0.5 and go for a short run. It will be immediately obvious that your pace is only half what it just should be.* Check the calibration factor is set to sync data with the web site1.0, and that any auto calibration is disabled. HoweverAuto calibration uses GPS, a key feature which is going to configure be far less accurate than Stryd . (If you're verifying a previous calibration, leave it set to that value but remember to transmit the power estimate adjust in the Footpodfinal calculations.) * Use a standard 400 m oval track at a time when you's Cadence fieldre confident you can run in a single lane for a number of laps. This feature is not currently supported The accuracy of a 400m track should be more than adequate for calibration, but if you're interested in the Android version of details, tracks are built in the app! US to various levels, with level 4 being suitable for national collegiate events. <gallery widths=300px heights=300px class=* You should run approximately 30cm/12"center">File:Stryd App (3)from the inside edge of the lane, not down the middle.png|The home page of For the first lane, running along the inside marker will reduce the distance by ~1m, running the app shows you outside edge will increase the recent runs distance by ~3m, and running down the "start training" button middle will increase the distance by ~1m. * You don't have to run with down the appfirst lane, but you have to adjust your distances for lanes that are farther out.File:Stryd App (5See table below.)* Start your watch and start running some distance before the start line. I would suggest at least 100 m.png|If This is partly because the stride will do some smoothing, and obviously when you click on a previous 're run starts you'll see this brief summaryre going from stationary to running. However, I've also noticed a number of watches that can be slow to start recording, so there first lap is rather short. For more information youYou'll need to use discard this first lap.* Run a number of laps hitting the lap marker as you parse the Stryd web sitestart, or some other landmark.File:Stryd App (1).png|If you * After the run using , look at the Stryd applap distances for the measured laps, this ignoring the first. The calculation is then fairly trivial; divide the screen youactual lap distance by the average lap distance to give your calibration factor.{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"! Lane! Total length|-| 1| 400.00 m|-| 2| 407.67 m|-| 3| 415.33 m|-| 4| 423.00 m|-| 5| 430.66 m|-| 6| 438.33 m|-| 7| 446.00 m|-| 8| 453.66 m|-| 9| 461.33 m|}Don'll get. It shows some basic datat use a race to calibrate, but given a phone screen as it would be nice typically very difficult to precisely run a straight line and hit the tangents perfectly. You can also have problems with start up on some graphs and more datawatches, customized fields, etcwhere it doesn't record the first few seconds of the run. File:==Example Calibration Data==I ran a calibration test on a university track, running in the third lane with my Stryd App on the inside (2left)foot.png|When running I not only wanted to validate the calibration, but I also wanted to check the stability across a range of paces, so I gradually increased my speed on a treadmill you can tell the app how fast your running each lap. My previously calculated calibration was 1.013x (or 101.3% in my Garmin) and what the incline isaverage error was 100. I haven't been able to work out what this is for15%, so please let me know if you find my new calibration was 1.013 / 1.0015 = 1.011507, which works outto 101.2% on my Garmin.File{| class="wikitable" style="margin-left: auto; margin-right:Stryd App auto; border: none;"! Distance (m)! Ratio! Error! Avg Pace! Best Pace|-| 414.8| 0.998724| -0.53| 9:40| 8:17|-| 414.1| 0.997038| -1.23| 9:40| 9:13|-| 416.7| 1.003299| 1.37| 9:14| 8:59|-| 414.8| 0.998724| -0.53| 8:59| 8:24|-| 416.3| 1.002335| 0.97| 8:33| 8:17|-| 414| 0.996798| -1.33| 8:31| 8:09|-| 415.8| 1.001132| 0.47| 8:03| 7:49|-| 417.4| 1.004984| 2.07| 7:46| 7:34|-| 417.2| 1.004502| 1.87| 7:31| 7:21|-| 415.5| 1.000409| 0.17| 7:12| 7:00|-| 416.4)| 1.png002576|There's a calendar view to pick a run for a given day1.07File| 6:Stryd App (46| 6:32|-| 417.2| 1.004502| 1.87| 6:34| 6:18|-| 417.9| 1.006188| 2.57| 6):10| 5:51|-| 415.1| 0.999446| -0.png23|5:41| 5:02|}=The setting screen allows you Stryd App=The Stryd app is rather limited, and I mostly use it just to set sync data with the Stryd to transmit power as Cadenceweb site. Due to limitations It is needed for use on the cadence field, you'll get power divided by 100, so 215 watts will be 22a treadmill. See below under "smartphone apps" for more details. </gallery>
=The Web Site=
I rather like the Stryd website. There's the usual calendar views of your runs, but there is some useful analysis you can do within their website. The biggest shortcoming I've found is that you can only show data by time, not by distance. If you look at the first graph below the hill shown by the purple line looks asymmetric because I'm going down much faster than I'm going up.
</gallery>
=Connect IQ Data Field=
The Connect IQ Data Field for Stryd will show power on a Connect IQ compatible Garmin watch. This doesn't interfere with using Stryd as the footpod at the same time, which is important. The Data Field will record not only power, but the other metrics like Ground Contact Time and the display is configurable to show power averaged over various time periods, lap average, or overall power for the run. Of course, you can only have one field configured, so you can't see both current power and lap average for instance. You also don't get alerts based on power value. If you put power into the cadence field you can do far more, adding current, lap average, alerts, etc.
[[File:Stryd ConnectIQ.png|center|thumb|300px|The configuration of the Stryd data field from within the Mobile App (you can configure it via the PC Garmin Connect app as well.]]
=Data Analysis=
** If you're pretending this is a cycling power meter, then everything should work just as it would for cycling power, but of course it looks like a cycling workout.
** If you're using the Garmin [[Connect IQ]] data field, then you'll need to have an application that supports importing customer data. I found that Golden Cheetah worked fine, as does SportTracks with the Custom Data Tracks plugin and the Garmin FIT plugin.
** If you're getting power as Cadence, then most applications should be able to handle that, but obviously you'll have it in the cadence field and it will be 10x lower (210w will be 21 steps/minute.)
* '''Cadence'''. Cadence is well supported by pretty much any analysis application, unless of course, your using the cadence field for power. Note that the Garmin [[Connect IQ]] data field will record the cadence value from the Footpod in addition to any other Cadence device.
* '''Elevation. '''I've found it tough to get elevation data into an analysis application. I'll update you if I find a good way of doing this.
* '''Form Power, Ground Contact Time, Vertical Oscillation, Leg Stiffness'''. These fields are all available via the Garmin [[Connect IQ]] data field, and can be viewed using Garman Connect.
[[File:StrydGarminConnect.png|center|thumb|500px|A view of the data collected using the Garmin [[Connect IQ]] data field with Stryd also connected as the Footpod, using a [[Garmin Fenix 3]].]]
=Stryd and Running Economy=
One advantage of Stryd is that it's power estimate can be used to then estimate [[Running Economy]] and [[Heart Rate Drift]]. You can read more about this at [[HrPwr]].
=Testing Distance and Pace=
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.
==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.
==Accuracy and Consistency at Different Paces==
My testing showed that Stryd remains consistent across a wide range of paces. I tested from 9:40 min/mile to 5:40 min/mile with no differences.
==Responsiveness ==
Stryd seems reasonably responsive to changes in pace, though it's hard to determine how the smoothing of Stryd interacts with any smoothing of the watch. I've found Stryd responds within a few seconds, though the power estimate is a little slower to adjust. Recent firmware updates have improved the responsiveness of the power estimate, though it's still a little slower than I'd like on rapidly changing slopes.
=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 main problem is my treadmill was speed display is way 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]].However, this variation makes it tricky to know what the "true" speed should be. Obviously, the average speed of the belt is completely wrong, as the speed of the belt while your airborne has nothing to do with your running speed. During the time your foot is in contact with the belt, should you use the minimum speed, the average speed or the maximum speed? With my treadmill, the difference between minimum and maximum during contact is about 15%, and between average and minimum is about 9%. I've found Stryd seems to be quite close to the minimum speed rather than the average during contact. I calibrated my treadmill and then calibrated Stryd to the corrected treadmill speed, which is a lot of effort and tricky to get right. A much simpler solution is to use the [[North Pole Engineering Runn Treadmill Sensor]], which measures the treadmill speed with far less effort and greater accuracy. [[File:Treadmill During Contact.jpg|center|thumb|300px|Treadmill speed during contact with the belt.]]
=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. I've seen one report of an ultrarunner who completed 100-miler in 28 hours and had 27% battery life. This is anecdotal, but encouraging.
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.
[[File:Stryd And Ultratrac.jpg|center|thumb|200px|Here's the GPS track, and hopefully you can see the straight lines that you get when the watch is in UltraTrac mode and only checking GPS infrequently. On the way back I had normal GPS mode.]]
=Calibrating Stryd=
Most devices that support Stryd as a Footpod will allow for calibration. I would strongly recommend that you don't attempt to calibrate Stryd as it's so accurate, I think you're unlikely to make things better rather than worse.
=Stryd Internals=
For those that are interested, here are the internals of a Stryd. (Thanks for Paul Day for the photo and the willingness to do the work.)
[[File:Stryd Internals Paul Day.jpg|center|thumb|300px|Stryd Internals (Copyright Paul Day, used with permission.)]]
=Stryd and Critical Power=
The Stryd app has started to support [[Critical Power]], a concept more widely used in cycling. The Stryd method of calculating Critical Power is to use one of 5Km/10Km race time, or a test protocol using just two durations. The research I've found on Critical Power suggests that more data points are needed to provide a valid measure of Critical Power, and especially W' (anaerobic work capacity). Most research uses a fixed power output to exhaustion rather than a time trial. A time trial includes aspects of pacing and skill, so this seems a poor substitute. (Typically, CP tests define "exhaustion" as when cycling cadence drops below 50 RMP.) I'd recommend using more test runs and using one of the many Critical Power calculators available online. Stryd also has an [https://blog.stryd.com/2019/07/09/introducing-auto-calculated-critical-power/ automatically calculated Critical Power], but I've not seen any independent validation.
=Stryd's Power Estimate Compared with Cycling Power=
I performed an incremental test with both Stryd for running and my Tacx Neo 2 for cycling. For running, I used a 400m track, increasing my pace from 10:00 min/mile to 5:30 min/mile over 14 laps. I then performed a similar test cycling, increasing the power gradually. I then mapped the power from each to my heart rate. In both cases I found a reasonable linear relationship between power and heart rate. Using the linear relationship, I found that Stryd power is generally quite a bit higher than Cycling power. For me, Stryd Power = (Cycling Power + 40) / 1.13, so 100w in Stryd is about 70w Cycling.
=Using Stryd With Your Watch=
Here's my notes on the compatibility testing I've done so far. I've had occasional issues with devices connecting to Stryd at the beginning of a run. I've not found any pattern to this, and it seems to impact both Bluetooth and Ant+ devices, so make sure you have a connection before starting your run. I've also occasionally forgotten to turn off auto-calibrate, which is another gotcha.
{{:Stryd-Watches-table}}
* ==Garmin Fenix 3, Fenix 5X, 935==For the [[Garmin Fenix 3]], [[Garmin Fenix 5X]], [[Garmin Epix935]]:** Pair as a normal footpod. Settings -> sensors -> add new -> footpod. Under the sensor, set speed=always, distance=always, calibration -> auto calibrate disabled. (There's a full description of the process for the F5X on the review page.) ** These watches have the best Stryd support, but note that Garmin has abandoned the Epix, so there's no firmware updates. ** The [[Connect IQ]] data field gives power display, and it records all the other Stryd data like Ground Contact time. ** Pair the Fenix 5X /935 via Ant+, not Bluetooth for the Connect IQ to work. ** You can set the speed and distance to always come from the footpod so you still get GPS. This is obviously important for navigation and the mapping features of the 5X and Epix are , which is a key reasons reason for buying those watchesit over the 935.** These watches support Stryd for cycling power, but I wouldn't use that unless you want alerts for power being out of range. ** I found some smoothing and rounding of the pace data, but not much.** Occasionally I'll find the watch won't detect the Stryd at the start of the run. In those situations, I have to go into settings, sensors, Stryd, and select "connect", which time the watch connects fine and the connection persists when I go back to start the activity.** Note there are credible reports that Power data can be exported to tools like Golden Cheetah by exporting the Fenix 5 and 5S (but not FIT file from the 5XGarmin web site (activity page, click on the cog icon on the top right, select "export original") have Ant+ connectivity issues. I* '''d recommend connecting Warning: there are credible reports that the Fenix 5 and 5S (but not the 5X) have Ant+ connectivity issues. I'd recommend connecting them as Bluetooth Footpods, which means you will not get the Connect IQ support. '''. * ==Polar V800, M400, M430==For the [[Polar V800]], [[Polar M400]], [[Polar M430]]:** Pair as a normal footpod. Settings -> General Settings -> Pair and Sync -> Pair Other Device -> select Stryd. Then go to Settings -> Sports profiles -> Running -> Stride Sensor. Calibration=manual, factor = 1.0, sensor for speed=Stride Sensor. ** Remember this is using Note: I have the V800 working with both Stryd and a heart rate monitor (except Wahoo). * Remember this is using Bluetooth, so if you have a problem it might be because the Stryd is still linked to your phone.** You can set the M400/M430/V800 to give distance and pace from footpod, while recording GPS tracks. The menu just says "speed source" but it sets distance as well. The menu talks about "stride sensor" as that's what the Polar footpod is called. ** There's less smoothing of pace in these watches compared with others, so the display is nicely responsive. (I know from alpha testing other devices that the M400 actually has pretty much no smoothing at all.)** For There's no cycling power support in the M400/M430 you have to choose between cadence and , or other native power display, and as this pod support.* For the V800 there is Bluetooth, you get 210 watts displayed native support for Stryd as a cadence of 21power device. This feature may get removed in the future. ThereYou don's no cycling t need to pair Stryd as two separate devices (foot pod & power support in the M400/M430, or other native power pod supportpod), just pair once.** For V800 Power data can be exported to tools like Golden Cheetah by exporting the V800 there is native support for Stryd as a power deviceTCX file from the polar web site. You don't need to pair Stryd as two separate devices (foot pod & power pod)From the activity page, just pair onceselect "export session", then choose TCX. * ==Garmin 920XT, Vivoactive, Vivoactive HR, 235==For the [[Garmin 920XT]], [[Garmin Vivoactive]], [[Garmin Vivoactive HR]], [[Garmin 235]]:** Pair as a normal footpod. *** 920XT: Settings -> sensors -> add new -> footpod. Under the sensor, set speed=always, calibration factor -> auto calibrate disabled, factor=100.0. ** Connect IQ gives power display, and it records all the other Stryd data like Ground Contact time.*Power data can be exported to tools like Golden Cheetah by exporting the FIT file from the Garmin web site (activity page, click on the cog icon on the top right, select "export original").* You can't get distance from Stryd with GPS active, which means you have to run in indoor/treadmill mode. (The 920XT/235 can have pace from Stryd with GPS, but not distance).* ==Garmin Epix==For the [[Garmin Fenix 2Epix]]:** Pair as a normal footpod. ** Set While the "Foot Pod Speed" to "Always On". I expected this to just provided pace from StrydEpix supports [[Connect IQ]] it doesn't support the latest version, but so it actually does distance as well. The GPS track is recorded normally and navigation functions are enabledcan't use the Stryd Connect IQ apps. ** You have to choose between cadence and power displayPair as a normal footpod. (PowerSettings -> sensors -in> add new -cadence requires > footpod. Under the iOS Stryd app and this feature may be removed in the future.) * [[Suunto Ambit3]] (all models)sensor, set speed=always, distance=always, [[Suunto Ambit2| Suunto Ambit2 R]] ** Pair as a normal footpod calibration -> auto calibrate disabled. (donThere't pair as s a bike power pod if you're using a higher end Ambitfull description of the process for the F5X on the review page.). ** You have can set the speed and distance to ensure that always come from the sports mode footpod so you're using still get GPS. This is set to use a footpod. If you don't see obviously important for navigation and the Ambit3 search for a footpod when you start mapping features of the exercise, you need to change 5X and Epix are key reasons for buying those watches.* There is the configuration on option of using the Suunto web siteEpix in cycling mode to get power from Stryd. (* I've tested found some smoothing and rounding of the Ambit3 Run/Ambit2 R versionspace data, but not much.)** With Occasionally I'll find the watch won't detect the Ambit3, you need to disable auto-calibration, and the menu is a little hidden. Pair your Stryd, then hit at the start buttonof the run. In those situations, select "exercise"I have to go into settings, sensors, then choose an exercise that uses a footpod. Ensure that the Ambit3 has found your Stryd, then press and hold the Next button select "connect", which time the watch connects fine and the connection persists when I go back to bring up start the Activate menuactivity. If you have ==Garmin Fenix 2==For the [[Garmin Fenix 2]]:* Pair as a normal footpod active, there will be an option for disabling auto calibration. ** If a footpod is found, the Ambit3 & Ambit2 will get * Set the "Foot Pod Speed" to "Always On". I expected this to just provide pace and from Stryd, but it actually does distance from the footpod and override the as well. The GPS datatrack is recorded normally and navigation functions are enabled. ==Suunto Ambit3 (This means you can use the all models), Ambit2/3 in R==For the lowest GPS accuracy mode to extend battery life while getting accurate pace & distance from Stryd.[[Suunto Ambit3]] (all models) *, [[Suunto Ambit2| Suunto Ambit2 R]]:* You have to choose between cadence and power display. For the Ambit3 (Bluetooth), you get 210 watts displayed Pair as a cadence of 21. The Ambit2 normal footpod (Ant+) is rather unusual in that it will halve the value of the don't pair as a bike power, so 210 watts will be displayed as 105. (Power-in-cadence requires the iOS Stryd app and this feature may be removed in the futurepod if you're using a higher end Ambit).)** If you follow You have to ensure that the Stryd instructions for the Ambit3 sports mode you'll get power but wonre using is set to use a footpod. If you don't get pace/distance from Stryd. The only way see the Ambit3 search for a footpod when you start the exercise, you need to get power is from "power-in-cadence" as noted abovechange the configuration on the Suunto web site. (I've tested the Ambit3 Run/Ambit2 R versions. )** The With the Ambit3 & Ambit2 both do quite , you need to disable auto-calibration, and the menu is a bit of smoothing of pace informationlittle hidden. Pair your Stryd, so it's not quite as quick to respond as other some other watches. ** With then hit the higher end Ambit 2/3 (above start button, select "exercise"Run" models) you can use , then choose an exercise that uses a footpod. Ensure that the Ambit3 has found your Stryd in bike mode , then press and get hold the Next button to bring up the power estimate that wayActivate menu. HoweverIf you have a footpod active, I strongly believe that accurate there will be an option for disabling auto calibration. * If a footpod is found, the Ambit3 & Ambit2 will get pace and distance is vastly more useful than an estimate of power, so even from the footpod and override the higher end watches should be used in run mode with power in cadenceGPS data. * (This means you can use the Ambit2/Ambit2 Sport3 in the lowest GPS accuracy mode to extend battery life while getting accurate pace & distance from Stryd.) ** These two watches can support If you follow the Stryd as both instructions for the Ambit3 you'll get power pod and foot pod at the same time. (You canbut won't do this with the higher end Ambit3 watches as the Bluetooth protocol only allows one connectionget pace/distance from Stryd.) ** Pair as The Ambit3 & Ambit2 both do quite a normal footpod then pair again bit of smoothing of pace information, so it's not quite as quick to respond as a bike power podother some other watches. ** You have to ensure that With the sports mode higher end Ambit 2/3 (above "Run" models) you're using is set to can use a footpod the Stryd in bike mode and get the power podestimate that way. If you don't see the search for a footpod However, I strongly believe that accurate pace and/or distance is vastly more useful than an estimate of power pod when you start the exercise, you need to change the configuration on the Suunto web site. ==Ambit2/Ambit2 Sport==** If a footpod is found, These two watches can support Stryd as both power pod and foot pod at the Ambit2 will get pace and distance from the footpod and override the GPS datasame time. As above, you (You can use 't do this with the Ambit2 in higher end Ambit3 watches as the lowest GPS accuracy mode to extend battery life while getting accurate pace & distance from StrydBluetooth protocol only allows one connection. ) ** The Ambit2 does quite Pair as a bit of smoothing of pace information, so it's not quite normal footpod then pair again as quick to respond as other some other watchesa bike power pod. * [[Suunto Spartan Ultra]]** To pair, scroll up You have to settings, select connectivity, select pair sensor, select Pair Foot POD, pair to Stryd. ** Ensure ensure that the sports mode you are 're using is set to use a sports mode that has the footpod enabledand the power pod. ** If you want to don't see the search for a footpod and/or powerpod when you start the exercise, you have need to set change the Stryd to use "Power In Cadence" configuration on the iOS appSuunto web site. This feature * If a footpod is not supported in found, the android app, and Stryd have said they Ambit2 will remove the feature in get pace and distance from the footpod and override the futureGPS data.** Like As above, you can use the other Suunto devices, there's quite a bit of dampening that reduces responsivenessAmbit2 in the lowest GPS accuracy mode to extend battery life while getting accurate pace & distance from Stryd. ** * [[Garmin 620]], [[Garmin 225]], [[Garmin 610]]The Ambit2 does quite a bit of smoothing of pace information, so it's not quite as quick to respond as other some other watches. ==Suunto Spartan Ultra/Trainer==For the [[Garmin 910XTSuunto Spartan Ultra]], [[Garmin 310XT]Suunto Spartan Trainer]]:** Pair The Spartan watches support Stryd for both the power estimate and the pace/distance while retaining GPS. You have to pair Stryd as a normal footpodonly, not as a power pod, which is a little counterintuitive.** You can't get distance from Stryd with GPS activeTo pair, which means you have to run in indoor/treadmill mode.** You have to choose between cadence and power display. (Power-in-cadence requires the iOS Stryd app and this feature may be removed in the future.)scroll up to settings, select connectivity, select pair sensor, select Foot POD, pair to Stryd. Do not pair as a power pod. Then go back to the connectivity menu, select paired sensors, select the footpod, scroll to settings, disable auto-calibration. * Ensure you are using a sports mode that has the footpod enabled and the power pod disabled. * Power data can be exported to tools like Golden Cheetah by exporting the FIT file from the Suunto web site (activity page, click on the tools on the right, select "export as FIT").* There's no calibration provided by the Suunto Spartan. ==Garmin 620, 225, 610, 910XT, 310XT==For the [[Garmin 620]], [[Garmin 225]], [[Garmin 610]], [[Garmin 910XT]], [[Garmin 310XT]]:* Pair Stryd as a normal footpod.* You can't get distance from Stryd with GPS active, which means you have to run in indoor/treadmill mode.==Other Watches==
* [[Leikr]]. I could not get the Stryd to work with the Leikr.
* =Smartphone Apps=I've tried a number of iPhone appswith Stryd, with varying results. ==Stryd iOS App==You need to use the Stryd app to update the firmware, and configure the device. It also is the only way of uploading your runs to the Stryd website for analysis. You can use the that during a run, but it's painfully rudimentary. It displays your pace in min/mile as a decimal fraction, so 8:30 min/mile is shown as 8.5 min/mile. Displaying time as a decimal fraction of minutes is both bizarre and frustrating. The app will display the power estimate, cadence, and distance, but there's no customization of the display, graphs, or any of the other amazing things you can do with such a large display. The main value I see in using the app for recording your runs is when you're on a treadmill, as it's the only option for setting the incline/decline.<gallery widths=300px heights=300px class="center"><gallery widths=300px heights=300px class="center">File:Stryd App (3).png|The home page of the app shows you the recent runs and the "start training" button to run with the app.File:Stryd App (5).png|If you click on a previous run you'll see this brief summary. For more information you'll need to use the Stryd web site.File:Stryd App (1). png|If you run using the Stryd app, this is the screen you'll get. It shows some basic data, but given a phone screen it would be nice to have some graphs and more data, customized fields, etc.File:Stryd iOS App (4).png| The display when running on a treadmill; note the edit button to bring up the screen to set the incline/declineFile:Stryd iOS App (3).png| The screen to set the incline/decline</gallery>==iSmoothRun==This is one of the better running apps, and has the best support I've found for Stryd. You can set it to take pace and distance from Stryd, and it will successfully use the power estimate. It's not free, but it's well worth the small fee for its functionality. [https://itunes.apple.com/us/app/ismoothrun/id410965399]<gallery widths=300px heights=300px class="center">File:iSmoothRun Stryd (3).png| The running display (configurable)File:iSmoothRun Stryd (1).png| Pairing with StrydFile:iSmoothRun Stryd (2).png| Post run analysis in the app</gallery>==Wahoo Fitness==The Wahoo Fitness app almost works, and it's free you can get the app to display the power estimate, but only if you have pace and distance set to GPS. <gallery widths=300px heights=300px class="center">File:Wahoo Stryd (2).png| Lots of power data shown while runningFile:Wahoo Stryd (1).png| Configuring Wahoo Fitness to get power data</gallery>==Strava iOS App==The Strava app won't take pace/distance from Stryd, nor will it use the power estimate. Fail.

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