Strava / Garmin inconsistency

[simon.r]

For a while now I've been puzzled by the fact that the cumulative log I keep of my mileage (taken from the reading on my Garmin) is different to the cumulative mileage that Strava shows.

This evening, as an experiment, I went out with Strave on my iPhone and my Garmin 500. The Garmin showed 30.8 miles and Strava recorded 31.3 miles, so a difference of about 1.6%.

Has anyone else noticed this? Which is correct?

 

[Ihatehills]

Me and my missus cycle together often, I use a Garmin edge 200 and she uses map my ride, her milage is always slightly more than mine, I checked my Garmin against my car odometer and it was spot on so I reckon the smartphone gps isn't quite so accurate

 

[Hacienda71]

I record using a Garmin 705 or a 200 and download to Strava and Endomondo and occasionally onto Garmon connect. Strava tends to record the shortest distance. Not sure if they use different mapping or they record stop and starts differently, but there is a clear difference.

 

[Milkfloat]

My suspicion is that it is device related rather than strava. I say this, as a friend who rides with me always gets a slightly longer distance and average speed than me over the course of a long ride even though I ride the 1 mile to his house before we start the ride. This happens when I use two different devices (both with speed/cadence) and he uses his iPhone. My data is uploaded to strava, mapmyride, endomondo and Garmin with consistent results, his is the only one that varies.

 

[T.M.H.N.E.T]

This is due to how strava processes data. Totally normal

 

[cyberknight]

This is due to how strava processes data. Totally normal

Yup
Its mainly down to how strava calculates altitude , it always knocks .1 or so off my garmin data and as siad a smartphone gps will have a lower sampling rate so it will be less accurate .

 

[vickster]

My phone is more generous in distance, the garmin 800 more generous on average speed (I have both set to auto pause when stopped). Go figure, I doubt either is 100% accurate, so if you collect the data just be consistent and use one over the other

 

[Andrew_P]

I have feeling that Garmin is using the speed sensor and how that has been set up and Strava is using strict GPS and or Map data, they map the route using starting point and end point which will cut corners and have dropouts etc.

If I leave my speed sensor on auto wheel size the daily mileages vary greatly as does my wheel size, which I suppose is possible with slight weight variations and tyre pressure variations but I don't think it could mean variations of .1to .4 of a mile over a 14.9 mile commute. I think the variations are due a re-calculation taking part occasionally when there is poor GPS signal.

 

[Dogtrousers]

@vickster has it spot on. Just choose one or the other and use that for consistency.

All of these measures like distance, total climb, "moving average" speed , total calories burned etc are the result of algorithms that , to a greater or lesser extent, massage and pad out the data, and make various guesses. Add to that the fact that different devices produce data sets that differ in various ways.

Just pick one and stick with it and you can make comparisons between your rides and use them for planning future rides.

 

[Dogtrousers]

@vickster has it spot on. Just choose one or the other and use that for consistency.

All of these measures like distance, total climb, "moving average" speed , total calories burned etc are the result of algorithms that , to a greater or lesser extent, massage and pad out the data, and make various guesses. Add to that the fact that different devices produce data sets that differ in various ways.

Just pick one and stick with it and you can make comparisons between your rides and use them for planning future rides.

You can even get inconsistencies between data from one device. For example the odometer and total climb from the trip computer of my Garmin Oregon are always a wee bit more generous than the figures derived from the GPX track of the same ride.

 

[Dirk]

I use a Garmin 510; my missus uses a Garmin 200.
When we go out for a ride together, we never get the same results for distance and elevation.