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Garmin 810 accuracy

by Dinyull
Wed, Jul 28, 2021 09:39
6

I've done a google search on this and didn't find anything relating to my problem.

My Garmin 810 head unit is approx 5 years old and in the past few weeks has been under reading the distance on maybe 1/3 of my rides.

When in Strava/ Garmin Connect and inspecting the route it's tracked me perfectly - there are no straight lines to indicate drop outs and when riding I haven't spotted any on-screen messages saying "searching for GPS" etc.

I always allow for it to connect to GPS prior to leaving and despite it being rainy/ cloudy this morning have also had problems in bright sunshine without a cloud in the sky.

I'm a daily commuter and route is just over 10 miles - I know it's trivial but at times it's measuring my route 1 mile less.

Just hoping my head unit isn't on it's way out.

Cheers

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6 comments

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steve_s1 | 2 years ago
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I have a Garmin 830 and notice after each ride is uploaded to Strava, if I get Strava to adjust the elevation it increases the initial value given by the Garmin, sometimes by quite a lot. It never adjusts the elevation down. 

There's more info about this here:

https://support.strava.com/hc/en-us/articles/115001294564-Elevation-on-S...

 

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0-0 | 2 years ago
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I have a similar issue with my 830 on all of my rides.
Some of it I believe is down to firmware updates over months/years. GPS accuracy etc.

Currently just using GPS, Garmin is about 0.3 mile under compared to Strava (if Strava is even correct).
If I use a 3rd party speed sensor, Garmin gives an "over" reading, compares to Strava.

I think the best way to get Garmin and Strava to try and match, would be to use a speed sensor and manually adjust the wheel circumference setting within your 810.
You'd have to look at some wheel circumference charts, to get a starting figure i.e. 700c 28mm = 2130 or 2136 if you believe Garmin.
Or try a tape measure 😁

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Dinyull | 2 years ago
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On ride home last week, with speed indicator on I noticed a lot of slower speeds than expected -  would be reading at 24mph one minute and then 13mph the next.

Have never used a speed sensor with the 810, and didn't think I was....

But over lockdown I was turbo training and the trainer came with a combined speed/ cadence sensor which I installed on the bike. Last week in particular the cadence was very intermittent (I'm assuming speed too as they run from same battery). So embarrasingly I think the whole issue is because of the battery life on that, and GPS has still been tracking ride hence prefect trace on garmin/ strava. D'oh!

Replaced battery in speed/ cadence, have hard reset the Garmin and installed latest firmware. If you hear nothing again assume it was the battery haha!!!

Thanks for the suggestions

 

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Dinyull | 2 years ago
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Thanks for the replies.

This morning was 2 miles out, and still when you delve into the route on strava/ garmin there are no obvious straight lines/ dropouts.

I've tried exporting the strava activity as a course and got the same mileage shown as recorded. Although not being a full paid up member of strava it had very reduced features.

Probably doesn't help that I only display cadance, heart rate and time on my screen - will add speed tonight to see if any obvious drop outs.

Will go with a hard reset this weekend, and see how I get on next week before I get in touch with garmin.

 

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Awavey | 2 years ago
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I've got an 810 and not noticed any more than a tenth or two variation on Strava mileage I do notice it drops GPS signal more frequently than it did,currently on GPS + Galileo. I did get lost in settings one time when I couldn't get it to connect to anything,but it mostly seems ok.

Have you tried exporting the Strava activity as gpx and loading as a course in Garmin to see if it shows any difference?

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PRSboy | 2 years ago
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How peculiar... I have an 810 and there are occasionally variances but nothing like that.  You can correct the mileage/elevation in Strava so you will book the miles you've done, but clearly it won't be correct on the Edge.

I would imagine that if it can't see the satellites properly it would flag a GPS signal lost error.  Perhaps try a hard reset of the unit (though you will lose any data/settings) or email Garmin help who are normally pretty good at suggestions.

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