I won't go into detail about what the Stryd footpod is. It has been reviewed in depth by multiple individuals including fellrnr and dcrainmaker being my two favourites. The big selling point for me purchasing the Stryd is the supposed high accuracy AND precision versus using GPS which is often unreliable here in downtown Toronto due to numerous skyscrapers.
I have been using the Stryd for about 1.5 months, averaging 50-70km/week, with a variety of indoor treadmill runs, outdoor workout runs, and the weekend long run. During the 6 weeks, I haven't attempted to calibrate or test the footpod - I have roughly looked at the GPS tracks and measured them against Google Maps Distance and found that it roughly correlated (or at least way more accurate than what GPS would have been). However, I decided to finally test the footpod for accuracy and precision before I rely on it fully for my next marathon (Tokyo 2020) and because on group tempo runs, I've noticed my average lap pace readings have generally been slower than what other runners are reporting.
In order to calibrate and test the footpod, I followed Stryd's own suggestions:
https://support.stryd.com/hc/en-us/articles/115004337834-Distance-and-Calibration
Roughly, this involved:
1. Find a proper running track with accurate markings (easy)
2. Obtain and distance wheel. Make sure the distance wheel is accurate against a very large ruler
3. Measure the track with the distance wheel
4. Run several laps and compare the stryd readings against my measured distance
Equipment used:
1. Stryd (newest version with Wind Detection). Running latest firmware (2.1.3)
2. Garmin Fenix 6 Pro Sapphire / Titanium. Running latest firmware (6.0.0.0)
3. Nike Pegasus 36 Turbo 2 with Stryd mounted on left shoe (firmly).
4. Milwaukee Tool 6 inch aluminum measuring wheel
To start off, I chose to do this test at the Central Technical Stadium running track. It's the second nicest track in downtown Toronto (the nicest being the UofT track, but not publicly accessible). Lanes are clearly marked. I measured the inside line of lane 2 on Google Maps and came up with ~406m which is roughly what one would expect. The next step was to physically measure the line with the distance wheel, which I first confirmed was accurate using a steel ruler:
The Stryd suggests using a 10m long ruler. I don't have a ruler that long so 8 ft of steel rulers will have to do. Running the measuring wheel along the rulers:
Now that I knew the measuring wheel was accurate. The next step was to take it to the track to measure the inside line of lane 2. I definitely got some funny looks when I did this (someone came up to me to tell me that it's 400m and asked why I was measuring the track!).
I started measurement at the start line, going counter-clockwise. I tried to keep the wheel on the line as best as possible. The first loop around, the measurement from the wheel was 1327ft
There was some ice covering the line and I had to go around it slightly. I decided to measure it a second time and removed the ice covering the line. The second go around yielded roughly the same distance, 1326 ft
Therefore, the two distance measurements are 1327ft and 1326ft. I'll settle on 1326.5ft, which converts to a measured distance of 404.2 meters. This is slightly shorter than the GPS measurement of 406.3 meters
I have been using the Stryd for about 1.5 months, averaging 50-70km/week, with a variety of indoor treadmill runs, outdoor workout runs, and the weekend long run. During the 6 weeks, I haven't attempted to calibrate or test the footpod - I have roughly looked at the GPS tracks and measured them against Google Maps Distance and found that it roughly correlated (or at least way more accurate than what GPS would have been). However, I decided to finally test the footpod for accuracy and precision before I rely on it fully for my next marathon (Tokyo 2020) and because on group tempo runs, I've noticed my average lap pace readings have generally been slower than what other runners are reporting.
In order to calibrate and test the footpod, I followed Stryd's own suggestions:
https://support.stryd.com/hc/en-us/articles/115004337834-Distance-and-Calibration
Roughly, this involved:
1. Find a proper running track with accurate markings (easy)
2. Obtain and distance wheel. Make sure the distance wheel is accurate against a very large ruler
3. Measure the track with the distance wheel
4. Run several laps and compare the stryd readings against my measured distance
Equipment used:
1. Stryd (newest version with Wind Detection). Running latest firmware (2.1.3)
2. Garmin Fenix 6 Pro Sapphire / Titanium. Running latest firmware (6.0.0.0)
3. Nike Pegasus 36 Turbo 2 with Stryd mounted on left shoe (firmly).
4. Milwaukee Tool 6 inch aluminum measuring wheel
 | ||
Peg Turbo 2 with Stryd on left shoe
|
To start off, I chose to do this test at the Central Technical Stadium running track. It's the second nicest track in downtown Toronto (the nicest being the UofT track, but not publicly accessible). Lanes are clearly marked. I measured the inside line of lane 2 on Google Maps and came up with ~406m which is roughly what one would expect. The next step was to physically measure the line with the distance wheel, which I first confirmed was accurate using a steel ruler:
 |
| Two 4ft rulers |
 |
| Exactly 8ft on the measuring wheel |
 |
| Starting line for measurement. It was a cold day at the track. |
 |
| First measurement was 1327 ft. There was a bit of ice covering the line and I had to go around it slightly |
 |
| Hard to see, but it was basically 1326 ft |
Now that I had a measured distance of lane 2 inside line (404.2m), I did 8 laps of the distance, starting with my foot on the line and ending on the line. The run was a bit awkward as I tried to ensure my left foot with the Stryd landed consistently on the inside line. The measured distance should be (8 * 404.2m) = 3233.6m. I also did two 400m (1 lap) cool down laps between the 8 lap sets.
This is the garmin GPS track. I don't know what the GPS distance would be but there's absolutely no way I'd get an accurate distance looking at that track! What about the readings from the Stryd?
CONCLUSIONS
Test #1 = 3140m (underestimate of 93.6m)
Test #2 = 3120m (underestimate of 113.6m)
The single laps came out to 400m and 390m, but those were not run with my foot consistently landing on the inside line. Regardless, they also consistently underestimate the full distance of lane 2 as it would be expected to be close to 407m.
Overall, the error from Test#1 is 2.9% from the "true value", and the error from Test#2 is 3.5% from the "true value". This preliminary test also explains why my group tempo run pace and marathon pace pick ups (target 4:20/km) always seem to be faster than my running partners who are using GPS for pace+distance.
Moving forward, I will do some more testing, including adjusting the calibration factor. As is, without calibration, I would not be comfortable using this for a marathon as an average error of 3.2% would equate to 1353m error by the end of 42.2km
*Addendum: as always, the Fenix watch was set to use speed (always), distance (always), cal. factor 100, auto-calibrate (disabled)
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