Stryd is not all it's cut out to be...maybe

This morning I ran twice with one watch hooked up to a Stryd and set to Always use for Pace and Distance and another just on GPS. In both cases the Stryd came up with a longer distance. First up was a trail run that we've been running for years so we know it is close to 9km. Stryd returned 9.31 where my GPS Trail Run gave 8.99 and my wife's 945 8.97km. Next up was parkrun. For those who don't know, parkrun is always 5km. Our parkrun has been accurately measured using a calibrated wheel so we know it's 5.04km from the wheel. And every GPS run we've done has been 5km +/-20m or so. This morning Stryd gave 5.24km while the GPS watches gave 5.02 and 5.01 respectively.

This wasn't the first time out with the Stryd. Several runs on a 400m track and a couple of other trails runs should have seen it calibrated by now. I haven't looked over earlier runs as I did want to make sure I had a number of different runs with the Stryd.

Let's see how things progress. I have done a couple of runs on a 400m track but not sure if I had the Stryd set up properly so can't comment on that except to say the watches gave the same distance. However, I now have the Stryd where I want it so can. and will, do some more comparison runs to see how this plays out.

Top Replies

Ablator2 over 2 years ago in reply to philipshambrook +6

I ve been using stryd for over 3 yrs and here's what I noticed after extensive testing.

I had to calibrate it on the track and my calibration factor was 101 but that was at 6:40 min/mile pace.

If I…
5135968 over 2 years ago +5

philipshambrook

I agree Philip, although both of my Styds come up short, not long. Actually neither Stryd agrees with each other, 2% distance difference between the 2 over a 10k and even power is different…
C.sco over 2 years ago +4

I absolutely love my Stryd, but like you, I'm not terribly impressed with its distance calculations. It's accurate to within maybe 5% or so, but really that's just not good enough, when my 6X GPS is accurate…

All Replies

0 subra over 2 years ago in reply to stephencousins

stephencousins said:
The Stryd is a power meter. It is supposed to be used to measure your power during your runs. It is not and never has been accurate for distance and pace.

I don't understand.

Power is a physical quantity defined as
power = force * speed
where
speed = 1 / pace

This means that if the speed is wrong, the power is also wrong.

0 5135968 over 2 years ago in reply to AndersB

I've sent you another file from today's run.

0 AndersB over 2 years ago in reply to 5135968

Great! Anything special you want to see in the graphs? I don't have time to look at it today but probably tomorrow.

0 5135968 over 2 years ago in reply to AndersB

I'm quite curious about how GPS and Stryd pace look compared. I suspect Stryd will be shorter than actual distance, if typical.

0 AndersB over 2 years ago in reply to 5135968

I've got a few minutes over so here is the comparison. So, it seems like the GPS is reporting more distance (and faster Pace) in the first half of the run and then it evens out more and more at the end.

Total distance reported by the watch/Stryd was 16 296.56 meters
Total calculated distance by GPS (without 3D correction) was 16 480.10 meters
Total calculated distance by GPS (with 3D correction) was 16 503.94 meters

Blue lines is watch/Stryd data and green lines is GPS data.

0 5135968 over 2 years ago in reply to AndersB

Thanks for doing that - I think Stryd has come up shorter %-wise this time around than the run I gave you a few days back.

It seems for me at least, pace from Stryd and GPS doesn't really show much difference, the graphs seem to match up very well for the most part, given the received wisdom that GPS pace is bad, and Stryd is good....

0 AndersB over 2 years ago in reply to 5135968

Yes, they seem to align up rather good. But be aware that the distance in the watch (without Stryd) for me always shows shorter distance than the calculated GPS distance. Due to that the accelerometer sometimes kicks in and gives faulty data. But I'm unsure if its the same for all users.

The green GPS pace line in your graph also has an 10 second rolling average.

0 5135968 over 2 years ago in reply to AndersB

You might have noticed from the .FIT data I gave you that there was some extra power and cadence developer fields.

That because - being a sucker for punishment! - I wore 2 Stryds on this run. The power recorded by each device is quite different - if you look at the 1:09:42 mark the power differential is 29 watts. I don't really see the point in running power, but I find it interesting how the 2 devices can report such different power readings. The device reporting the lower power also tends to be even shorter distance-wise than the Stryd providing the pace for this run.

0 AndersB over 2 years ago in reply to 5135968

I did not look so much at the data this time. I just processed the data needed for the graphs.

Funny that the two Stryds give so different data if they are mounted the same.

0 jvro over 2 years ago

Mine worked flawlessly for about a year. Distance was spot on with itself and more consistent than GPS. Then I started noticing it being more and more off. Not sure what's up, if the sensor is messed up or what but I haven't used it in a while. I should probably dust it off and try to update firmware and give it another try. I'd be more interested in it for pace now than overall distance.