Anyone understand how Garmin calculates height gain?
Itas always confused me and clearly isnt right at times
For example I did a series of 5 hill reps at lunch during the week.
The Garmin gives the following
Elev Gain 7 m
Elev Loss 5 m
Min Elev 19 m
Max Elev 27 m
Assuming the min and max elevation are above sea level (could be about right) then I did an 8m hill 5 times which should equal 40m elevation gain (I think this is an underestimation anyway as its a 3 contour hill on the map ie at least 10m) . But its giving me 7m in total apparently. Is there a way of setting this up differently that I dont know about?
Garmin height calculation
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Garmin height calculation
Orienteering - its no walk in the park
- andypat
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Re: Garmin height calculation
I don't know about Garmin, but I know SportTracks comes up with very similar sort of issues. Could it be that it only counts gradients greater than some minimum value, and part of your hill is a fairly gradual climb?
Another issue is where the height data comes from. That measured by the GPS is usually pretty poor; SportTracks has the option to correct it from stored digital data, and I think Garmin Connect must do something similar automatically, judging by what it reports.
Another issue is where the height data comes from. That measured by the GPS is usually pretty poor; SportTracks has the option to correct it from stored digital data, and I think Garmin Connect must do something similar automatically, judging by what it reports.
- roadrunner
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Re: Garmin height calculation
No idea what Garmin is doing it will depend on the device. Without a pressure sensor based system such a small hill will always be hit and miss. Even with a pressure sensor based system a small hill like that may well systematically under or over read.
With the code I have in IpBike you would systematically under count by about half the height variation that the pressure sensor gives when on the flat over something like a 4 second period. For the devices I have that means you loose about a meter each time you change from going up to down on the total ascent stat.
With the code I have in IpBike you would systematically under count by about half the height variation that the pressure sensor gives when on the flat over something like a 4 second period. For the devices I have that means you loose about a meter each time you change from going up to down on the total ascent stat.
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ifor - brown
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Re: Garmin height calculation
My understanding of the default setting for my Garmin is that it ignores the height data calculated directly from the GPS - as roadrunner says this is usually unreliable. After syncing with the computer what it does instead is estimate climb by superimposing the GPS track (latitude and longitude) onto a standard base map and essentially counting contours on the base map.
I guess that the accuracy you get depends on the accuracy of the GPS (and the contours on the base map in that location). Also the errors in all these calculations will be more significant on small climbs. E.g. if the errors are plus/minus 5m, that's a big error on your hill reps, but a small error on a climb of 100m.... so for accurate climb data then I recommend doing one long climb instead of many little ones
I guess that the accuracy you get depends on the accuracy of the GPS (and the contours on the base map in that location). Also the errors in all these calculations will be more significant on small climbs. E.g. if the errors are plus/minus 5m, that's a big error on your hill reps, but a small error on a climb of 100m.... so for accurate climb data then I recommend doing one long climb instead of many little ones
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Crex - white
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Re: Garmin height calculation
You can also apply different levels of smoothing in some applications to iron out some of the glitches and I'm sure others just do some smoothing without telling you. SportTracks has a slider to change it and you see the effect as you slide it. But those with a barometric sensor tend to be more accurate that those using the GPS sensor.
- Paul Frost
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Re: Garmin height calculation
I link my Garmin account to Strava and this always (without fail) produces different total height gain compared to Garmin Connect, whereas the distance covered is normally within 10 or 20m in total.
As has been said before some websites use different methods of calculation to determine the profile of your run.
You could try to map your reps on a website like Walkhighlands or Bikehike and see what results you get.
In the end it's only a number though, and you know in your legs how bloody hard the hill is
As has been said before some websites use different methods of calculation to determine the profile of your run.
You could try to map your reps on a website like Walkhighlands or Bikehike and see what results you get.
In the end it's only a number though, and you know in your legs how bloody hard the hill is
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plain lazy - blue
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Re: Garmin height calculation
My heights for the 3 Glasgow Parks races yesterday
Race 1 - 1.6k 5m climb - Garmin says 6m!
Race 2 - 2.3km 80m climb - Garmin says 8m???
Race 3 - 4.3km 65m climb - Garmin says 61m!
I give up.
Race 1 - 1.6k 5m climb - Garmin says 6m!
Race 2 - 2.3km 80m climb - Garmin says 8m???
Race 3 - 4.3km 65m climb - Garmin says 61m!
I give up.
Orienteering - its no walk in the park
- andypat
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