"More or less accurate" is the rub here; they can vary a lot. Some may use a basic one-dimensional accelerometer to simply count steps and multiply by a stride length. Others may use 2 or 3 accelerometer dimensions to calculate distance traveled. I think Stryd uses 6-axis accelerometer (3 positional and 3 rotational) as its basis to calculate movement. Stryd probably has far more advanced algorithms and more robust CPU because it needs accurate movement to get any semblance of accurate power.

I think if you read reviews and first-hand testimony, Stryd always wins the pace & distance accuracy over all other foot pods. I had a Garmin footpod and I have a Stryd now, and this has been my experience.

I haven't looked, but I'm sure someone (DCRainmaker?) has some empirical data comparing them side by side. If the OP is really concerned about accuracy and consistency, I'd recommend that he do a few searches of that nature. My guess is that at a steady-state, and within "normal" running paces, there's less than 5% variability among the top devices.

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One question: given the advanced algorithm, if you put the treadmill on, say 6% incline, is the device able to detect that? If so, how is that data expressed? Garmin's definitely does not.

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https://connect.garmin.com/modern/profile/domingjm

Yes, DCR and fellrnr have both done empirical analyses of pod accuracy. (fellrnr's protocal is defective for GPS comparison, but it is excellent for foot pod comparisons.)

Treadmill incline is an evolving thing with Stryd. In their words, "data will be perfect" at 1%. However, above that and you need to use the Stryd companion app to tell the device what the incline is. That is clunky in my opinion, but hey, I do not run on a treadmill much. The good thing is that they are actively working on it and enhancing the algorithms for treadmills. They will probably get there eventually. Also, these comments pertain specifically to power... it may be reasonably accurate for speed and distance at incline, since it does have excellent line of sight into movement.

Yes. Stryd. I don’t even use the power features very often. It’s just a damn consistent Bluetooth foot pod for zwift running.

I run 30-50 zwift miles on the treadmill a week, often on different (poorly calibrated) treadmills due to work travel, so I saw it as in an investment in having transferable pace data for any run workout.

I've been using the basic Garmin footpod for 3 or 4 years. I originally calibrated it on a 400 meter outdoor track while running precisely at 7:00 per mile/1600 pace. I hadn't changed the calibration factor since.

For six months out of the last 3 or 4 years I've run regularly on several different treadmills and on an indoor 200 meter track (all at the same gym). When on the indoor track, the footpod is spot on for distance...as long as I stay close to a 7:00/mile pace. The watch I have paired with pod is set to beep/auto-lap every half mile. At a 7:00 pace, it beeps at the same point on the track (every two laps) without fail.

If I run the same 200 meter track at a 6:30 pace, the footpod will give a more generous result (my watch will beep/auto-lap about 20-30 meters early). It thinks I am covering more distance than what I actually am.

At a 8:00 pace, it goes the other way. It auto-laps after each 420-430 meters.

Just for fun today (and as a result of reading this thread yesterday) I recalibrated the footpod while running on the 200 meter indoor track at a 8:00 pace. Then, I did a couple of more miles on the same track, at an 8:00 pace. My watch auto-lapped at the proper place (not 420-430 meters late like it always did when I was running 8:00/mile with the 7:00/ calibration).

All of this tells me my Garmin footpod is accurate...as long as I run at the same pace I calibrated it at. Faster or slower and it drifts slightly.

It also tells me the displayed pace on the 12 or so different treadmills I run on at the same gym vary greatly...like up to a minute/mile off. Obviously, vanity leads me to use the generous treadmills whenever they are available. After all, if the guy next to me peeks at my pace, I want him to think I am crushing him.

This is the set up I use and it's dead accurate.

The Garmin footpod auto calibrates to data collected via GPS during your outdoor runs. Just make sure that your footpod and GPS is connected to your Garmin for a few outdoor runs. The unit will default to GPS. The unit sets the calibration factor in the wrist unit, not the footpod.

Treadmills are pretty inaccurate as far a speed goes so I don't pay any attention to it at all. If you calibrate Zwift and use treadmill speed you'll simply calibrate Zwift to what the treadmill says and if it's out....Zwift will be also.

I calibrate Zwift to what my Garmin was telling me. To do this I just set up an indoor running screen on my Garmin that tells me what speed I'm running rather than pace and then calibrate Zwift. Go through the 3 stage calibration in Zwift dialling your treadmill up or down using what is displayed on the Garmin as the measure.

I can tell via RPE and heart rate that my footpod is spot on and now that Zwift is calibrated to my Garmin it all reads the same. I simply ignore what my treadmill is telling me.

I have a home treadmill however if you're using a gym this will mean that the error factor on any treadmill is eliminated as Zwift is set to your Garmin taking dodgy treadmills out of the equation.

Hope this helps