Background. After reading great reviews of Garmin Foot Pod accuracy I decided to buy the FR60 to use for monitoring pace.
On initial calibration on a 400m track I found it to .01 miles off for 800m. I adjusted the error out.
I have been using the Foot Pod on different shoes for several weeks.
Yesterday I ran a popular 4.8mile loop at break through pace. I was a tad suspicious when the FR60 said I ran 5.4miles.
I might swerve around often but that seems a bit excessive. So I checked the course on mapmyride and it came out at 4.80miles.
Today I tested on the same 400m track for an 800 in the shoes used yesterday (not the same as initial calibration)
and found the FR60 was .04miles above.
Maybe it’s just me but I use my FR60 on three different pairs of shoes on both the trail, road and a track workout tonight and that little miracle pod is spot on. I love that thing. could it be your battery?
I’ll play nice here on this topic. Amongst the ST’ers,I may have the most experience with footpods back with the launch of the Polar S625. As Krull said, once you moved the pod, you created a variable and lost accuracy. My opinion is go to a track and calibrate your device, then go home and head out for a 1 mile run, know where the mile marker is. This will be helpful so when your out for a training run, you could dial it in. The day before a race you want move the pod to your race shoes, do an easy 1 mile out, 1 mile back and dial it in. I know this is easy for me to say, but get a second pod if possible or a second cradle. I also put the Polar S3’s where my laces start and not where I tie them. My experience is that area of laces does not really change much when putting on your shoes, thus one less variable.
I’ve completely given up on my FR60 and the foot pod. I’ve tried calibrating it several times, and have had it always on the same shoes, but I can’t get a consistent read. It’s even inconsistent during a single run. I did a half-marathon in spring - at the one mile mark, it was .04 miles short, at the 2 mile mark, it another .04 miles off, and at the 3 mile mark, it was an additional .15 miles off. My half-marathon was 12.2 miles, according to the FR60. That’s just one example.
Granted, I’ve only been running for 3 years, I’m not the best runner around (my half-marathon PR is 1:45 and some change), and I’ve probably got a very inconsistent tempo and stride length. So, maybe it’s more me than the FR60 - it probably works fine for people who are more consistent than I am.
Your experience was my expectation based upon my experience with initial calibration of Foot Pod requiring no adjustment.
I assumed the difference in my shoes/stride/pace/temperature would be managed by the Garmin software and measurement intelligence.
I attempted to put my Foot Pod in the same place on each shoe. My assumptions appear to be false for me.
It would be interesting to see the design spec for the Foot Pod accelerometer and FR60 software to see how they manage
for all variables. Further it would be nice to have an open source or hack to modify.
On a side note I run with people that have Garmin 610s who argue for their superior accuracy, I lost this round.
I don’t understand how all those things affect the accuracy.
Doesn’t the footpod basically counts the strides and assumes that the stride length is the same as the calibrated stride?
For example, if I run a 400m in 1:30 and take 135 strides. It assumes that my stride length is 400/135 = 2.96 m
To have accurate results I would have to keep the same stride length. If I decrease or increase the stride length due to variation in speed and keeping the same stride rate, the distance calculations will be wrong.
That was my basic assumption. Does Garmin do something way more sophisticated that it takes into account temperature, the position of the pod in the shoe, and the shoe impact?
That’s the same as my experience while using the RS200 and RS400. I would go as far as writing the calibration numbers on my shoes even with two different foot pods.
What you are thinking about is how a basic pedometer works. These footpods (Garmin, Polar) use more sophisticated methods, developed by Dynastream (a Canadian company purchased by Garmin). Here is the detailed white paper describing how it works: